Compositions and methods for regulating melanogenesis

Abstract

Zinc bis (dibutyryl lysine), topical compositions comprising the same, and their use in skin whitening / lightening / homogenizing applications.

Description

[0001] Related applications This application claims priority to U.S. Provisional Patent Application No. 63 / 527,483, filed July 18, 2023, entitled “Novel Amino Acid Histone Deacetylase Modulator for the Treatment of Skin” and U.S. Provisional Patent Application No. 63 / 621,598, filed January 17, 2024, entitled “Composition and Method for Regulating Melanin Production”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a novel compound, bis(dibutyryl lysine) zinc (INCI name: bisbutyryl lysine zinc), also known as bis(N2,N6-dibutyryl lysine) zinc salt (2:1), and its application in skin whitening / brightening / evening skin tone, as well as its use in preventing, reducing and / or reversing pigmentation caused by sun exposure, laser treatment, acne and scars, and the formation of age spots, melasma, freckles, chloasma, etc. Background Technology

[0003] Skin color varies greatly among people around the world. It ranges from the deep brown of some Africans, Australians, and Indians in Asia, to the almost pinkish-yellow of some Northwestern Europeans. There are no people with truly black, white, red, or yellow skin. These are common terms and do not reflect biological reality. Human skin pigmentation arises from a series of complex cellular processes occurring in a group of cells called melanocytes located beneath the epidermis. These processes lead to the synthesis and transfer of pigment—melanin—which, in addition to determining skin color and tone, is a key physiological barrier against sun-induced damage such as sunburn, photoaging, and photocarcinogenesis.

[0004] The mechanism of melanin production is called melanogenesis. The resulting melanin accumulates / deposits in melanosomes (vesicles within melanocytes), which are then transferred from the melanocytes, taken up and internalized by keratinocytes, and subsequently transported to the skin surface. Skin pigmentation is primarily regulated by the amount and type of melanin synthesized by epidermal melanocytes. However, other contributing factors include: (a) the efficiency of melanosome (and thus melanin) transfer from melanocytes to neighboring keratinocytes; and (b) the subsequent distribution and degradation of the transferred melanosomes by recipient keratinocytes. Environmental factors also significantly influence skin color. For example, sun exposure significantly affects and increases the amount and rate of melanin production, typically leading to further darkening or “tanning” of the skin. Conversely, exposure to other factors, particularly substances that interfere with melanin production and / or melanin transfer, may result in reduced melanin production and / or a decreased rate or efficiency of its transfer, thus lightening the skin color.

[0005] In melanocytes, MITF (microphthalmia-associated transcription factor) plays a dominant role and is known as the "master transcription regulator" of the melanocyte lineage. Hemesath et al., microphthalmia, a critical factor in melanocyte development, defines a discrete transcription factor family. Genes Dev 1994; 8: 2770-2780; Nguyen and Fisher, MITF and UV responses in skin: from pigmentation to addiction, Pigment Cell Melanoma Res, 32(2): 224-236, 2019 Studies have shown that MITF is the most important transcriptional regulator driving the expression signals of numerous genes related to melanin production. It regulates the expression of genes that play key roles in cell differentiation, proliferation, and survival. MITF plays a crucial role in melanocyte development by regulating the expression of tyrosinase (TYR) and tyrosinase-associated proteins 1 (TRP1) and 2 (TRP2). MITF also regulates the expression of various pigmentation genes to promote melanocyte differentiation, and regulates essential genes for maintaining cellular homeostasis, including genes encoding proteins involved in apoptosis (e.g., BCL2) and the cell cycle (e.g., CDK2). Interestingly, many molecular pathways important for pigment cell development are also involved in melanoma formation; therefore, the mechanisms controlling pigment cell development may provide valuable insights into malignant transformation of cells. Hsiao and Fisher, The roles of Microphthalmia Transcription Factor and pigmentation in melanoma, Arch Biochem Biophys, 563, 28-34, 2014 ).

[0006] As mentioned earlier, melanocytes produce melanin, a pigment that is then transferred to keratinocytes. One of the roles this pigment plays is to help protect the skin from UV damage. Tyrosinase initiates the melanin biosynthesis pathway—melanin production—by oxidizing tyrosine to L-DOPA. MITF stimulates melanin production by activating the transcription of TYR and other pigment genes, including TRP1, TRP2 (DCT), PMEL, and MLANA. Yasumoto et al., Microphthalmia-associated transcription factor as a regulator for melanocyte-specific transcription of the human tyrosinase gene, Mol Cell Biol 1994;14: 8058-8070; Du J et al., MLANA / MART1 and SILV / PMEL17 / GP100 are transcriptionally regulated by MITF in melanocytes and melanoma. Am J Pathol 2003; 163: 333-343 MITF also regulates certain universally expressed genes that are crucial for melanocyte survival (e.g., BCL2) and proliferation (e.g., CDK2). McGill et al., Bcl2 regulation by the melanocyte master regulator Mitf modulates lineage survival and melanoma cell viability. Cell 2002; 109: 707-718; Du et al., Critical role of CDK2 for melanoma growth linked to its melanocyte-specific transcriptional regulation by MITF. Cancer Cell 2004; 6: 565-576 (Table 1). It is also worth noting that MITF target genes are abnormally regulated in melanoma.

[0007]

[0008] Melanocytes are subjected to a large amount of oxidative stress, not only due to exogenous damage to the skin such as ultraviolet radiation, but also because the melanin production process itself generates ROS, which is endogenous. Denat et al., Melanocytes as instigators and victims of oxidative stress, J Invest Dermatol, 134:1512- 1518, 2014Specifically, recent studies have shown that in B16 cells, the melanin inducer α-melanocyte-stimulating hormone (α-MSH) leads to the production of reactive oxygen species (ROS), while the NADPH oxidase inhibitor diphenyliodonium (DPI) inhibits the production of said ROS. GS Liu et al., Microphthalmia-associated transcription factor modulates expression of NADPH oxidase type 4: a negative regulator of melanogenesis, Free Radic Biol Med, 52(9):1835-1842, 2012 Interestingly, it is insensitive to antagonists of other ROS-generating enzyme systems, including mitochondrial enzymes, cyclooxygenase, and xanthine oxidase. Furthermore, these authors report that α-MSH activates its downstream signaling MITF to stimulate NOX4 gene expression. Notably, enhanced MITF signaling leads to NOX4 activation, which drives ROS generation, thereby increasing melanin synthesis. This series of actions appears to act as an internal feedback mechanism to fine-tune melanin synthesis in response to exogenous stimuli such as ultraviolet radiation.

[0009] Given the above, melanocytes appear to require an endogenous antioxidant system to combat ROS, including the thioredoxin and glutathione (GSH) antioxidant system. The thioredoxin antioxidant system consists of nicotinamide adenine dinucleotide phosphate (NADPH), thioredoxin reductase 1 (TrxR1), and thioredoxin (Trx). This system operates through the following mechanism: electrons are transferred from NADPH to TrxR1, enabling it to reduce the protein disulfide bonds on Trx, which can then further reduce its own substrate. Holmgren and Lu, Thioredoxin and thioredoxin reductase: current research with special reference to human disease, Biochem Biophys Res Commun, 396:120-124, 2010 Furthermore, TrxR1 is known to be elevated in the skin after UVR. Casidy et al., A Phase II randomized placebo-controlled trial of oral N-acetylcysteine for protection of melanocytic nevi against UV-induced oxidative stress in vivo, Cancer Prev Res (Phila), 10:36-44, 2017 ], and is highly upregulated in multiple cancer types. Thioredoxin reductase as a novel molecular target for cancer therapy, Cancer Lett, 236:164-174, 2006 The thioredoxin system is one of the major antioxidant systems that can resist oxidative stress and is present in all species. Lu and Holmgren, The thioredoxin superfamily in oxidative protein folding, Antioxidant Redox Signal, 2014; 21:450-470 The Trx system is involved in many key cellular functions, such as gene expression. Chang WH et al., Regulation of thioredoxin gene expression by vitamin A in human airway epithelial cells, American J Resp Cell Mol, 2002; 26: 627-635 ], DNA synthesis [ Sodeberg O et al., Interleukin-15 + 硫氧还蛋白可诱导B淋巴细胞白血病细胞中的DNA合成,但 对正常B细胞无此作用,《白血病》,1997年;第11卷:1298 - 1304页 Signal transduction Bai J et al., 硫氧还蛋白在神经生长因子介导的PC12细胞信号 转导和神经突生长中的关键作用,《神经科学杂志》,2003年;第23卷:503 - 509 Cell growth and apoptosis Liu H et al., 凋亡信号调节激酶1(ASK1)的激活 由肿瘤坏死因子受体相关因子2介导 需要先解离ASK1抑制剂硫氧还蛋白 [ Nadeau P et al., Ask1的二硫键介导的多聚化及其被硫氧还蛋白-1还原调节H 2 O 2 诱导的c - Jun NH 2 末端激酶激活和 凋亡,《分子细胞生物学》,2002年;第20卷:2198 - 2208页 Furthermore, it has been shown that Trx reduction can inhibit melanin synthesis by reacting with tyrosinase, thereby inhibiting tyrosinase activity. Subsequently, it has been reported that TrxR1 activity is associated with different skin phototypes I-VI (Fitzpatrick skin type system), with significantly higher enzyme activity in darker skin compared to lighter skin. Schallreuter KU et al., 硫氧还蛋白还原酶。在不同色素减退性疾病中自由基 还原中的作用,《皮肤病学文献》,1987年;第123卷: 615-619 Furthermore, it has been found that stable knockdown of TrxR1 leads to a significant decrease in melanin levels and tyrosinase activity in melanocytes. Cassidy P et al., 硫氧还蛋白还原酶1基因敲低破坏黑素细胞中的色素 合成,《自由基生物学与医学》,2018年,第128卷:S64 These studies indicate that high levels / activity of TrxR1 are associated with melanin formation, providing further information on the role of cellular antioxidant proteins in melanin production. Furthermore, after acute UVB treatment, melanocytes exhibited elevated levels of UV-induced DNA damage in the form of 8-oxo-2'-deoxyguanosine. On the other hand, TrxR1 has been found to positively regulate melanocyte homeostasis and pigmentation during development, thereby protecting against UVB-induced DNA damage and oxidative stress. Carpenter et al., 硫氧还蛋白还原酶1调节小鼠的色素沉着和光生物学 Melanocytes in vivo, J invest Dermatol, 142(17): 1903-1911.e5, 2022 The thioredoxin antioxidant system provides an ingenious framework for studying the redox regulation of physiological processes. Recent data offer compelling first-hand in vivo evidence demonstrating that oxidoreductases play a role in the positive regulation of skin pigmentation, melanocyte homeostasis, and UV-induced oxidative stress. Carpenter et al., Thioredoxin Reductase 1 Modulates Pigmentation and Photobiology of Murine Melanocytes in vivo, J Invest Dermatol, 142(17):1903-1911.e5, 2022 ].

[0010] As is well known, glutathione (GSH) not only exerts its antioxidant effect by scavenging free radicals, but also participates in the formation of melanin. GSH's involvement in melanin production is mediated through two different mechanisms. First, GSH directly interacts with the active site of tyrosinase, activating tyrosinase activity when the GSH concentration is below 3 mM, while inhibiting tyrosinase activity at higher GSH concentrations. Jara et al., The role of sulfhydryl compounds in mammalian melanogenesis - the effect of cysteine and glutathione upon tyrosinase and the intermediates of the pathway, Biochim Biophys Acta, 967, 296-303, 1988 Secondly, the reaction between the GSH thiol group and dopaquinone leads to the formation of a thiol-dopa conjugate, ultimately generating a sulfur-containing pigment, pheomelanin, rather than eumelanin. Jara et al., The role of sulfhydryl compounds in mammalian melanogenesis - the effect of cysteine and glutathione upon tyrosinase and the intermediates of the pathway, Biochim Biophys Acta, 967, 296-303, 1988; Rorsman et al., Thiols in the melanocyte, Pigment Cell Res. 1, 54-60, 1988; Motohashi et al., Inhibitory effects of sulfur-compounds on melanin formation reaction by tyrosinase. Chem. Pharm. Bull. 39, 142-145, 1991Conversely, research by del Marmol and colleagues showed that inhibiting GSH synthesis promotes tyrosinase activity and favors eumelanin production in human melanoma cells. del Marmol et al., Glutathione depletion increases tyrosinase activity in human melanoma cells. J. Invest. Dermatol. 101, 871-874, 1993 Therefore, GSH, as an antioxidant with anti-melanin production properties, has recently become a focus of attention in evaluating its suitability as a skin whitening agent. Lu Et al., Modulating skin color : role of the thioredoxin and glutathione systems in regulatory melanogenesis, Biosci Rep. 41(5): BSR20210427, 2021 ].

[0011] In the fields of cosmetics and cosmetology, beautiful skin begins with healthy skin: radiance, even skin tone, and translucency are the overall indicators defining healthy skin. As mentioned above, skin pigmentation is primarily regulated by the amount and type of melanin synthesized by melanocytes. Ito SA, Chemist's view of melanogenesis, Pigment Cell Res, 2003; 16: 230-236; Kasraee B, Peroxidase-mediated mechanisms are involved in the melanotoxic and melanogenesis-inhibiting effects of chemical agents, Dermatol, 2002; 205:329-339 However, other contributing factors include: (a) the efficiency of melanosome (and thus melanin) transfer from melanocytes to adjacent keratinocytes, a process facilitated by the adhesion protein E-cadherin, and (b) the subsequent three-dimensional spatial distribution and degradation of the transferred melanosomes by the recipient keratinocytes. Hearing VJ, Regulating melanosome transfer: who’s driving the bus, Pig Cell Res, 2007; 20:334-335 ].

[0012] Hyperpigmentation, hypopigmentation, and other pigmentary disorders are very common and can be caused by a variety of factors, including diet, skin trauma, environmental factors, medications, and disease. Post-inflammatory hyperpigmentation can also occur after laser and similar treatments. Common pigmentary disorders include melasma (dark patches that appear during pregnancy) and liver spots (which typically appear with age), which may be a side effect of birth control pills and / or a persistent consequence of acne, burns, bites, and other skin injuries, as well as vitiligo. Similarly, freckles, melasma, and sun-induced pigmentation can appear, increase, worsen, or become more difficult to fade or lighten with age. Therefore, these age-related skin color problems are among the most troubling and / or common skin care issues for middle-aged and older adults.

[0013] To address these types of pigmentation disorders, various formulations have been developed, particularly for treating age spots and freckles, or for achieving an even skin tone. However, such treatments are not limited to treating diseases; in some cultures / markets, they are also used simply to alter or modify people's natural skin tone. These treatments are often referred to using several different terms, including "skin whitening agent," "skin brightening agent," "skin tone evening agent," and "skin brightening agent." The specific terminology used often depends on regulatory requirements rather than performance or application. For example, the term "skin whitening" is very common in Asia, but the U.S. Food and Drug Administration (FDA) does not allow its use. Other commonly used terms include melanin inhibitor, depigmenting agent, and tyrosinase inhibitor (tyrosinase is a key enzyme responsible for melanin synthesis). Regardless of the terminology used, the basic principle is that they all involve the production and / or reduction of melanin production rates. In this specification, the terms "skin whitening agent," "skin brightening agent," and "skin tone evening agent" will be used because these terms are physiologically more appropriate.

[0014] Several reagents and methods for skin whitening have been developed and marketed. These methods include oral administration of high-dose vitamin C, parenteral administration of glutathione, and topical application of vitamin C and / or cysteine. However, vitamin C suffers from stability issues, especially in water-based formulations, leading to changes in color and odor. Thiol compounds (such as glutathione and cysteine) exhibit weaker and / or generally poorer depigmentation properties.

[0015] Hydroquinone and its derivatives are perhaps the most widely used skin-whitening agents. However, while these compounds are effective, they have serious adverse side effects. Even at concentrations below 2%, hydroquinone is both irritating and cytotoxic to melanocytes. With growing concerns about its safety, most hydroquinone and its derivatives are being phased out or completely banned for topical use. Kojic acid depigmenting agents present similar problems.

[0016] Many polyphenols found in plant extracts have also been used for skin whitening / evening skin tone purposes. The melanin-inhibiting activity of natural polyphenols, such as anthraquinones, has been reported. Jones et al., Modulation of melanogenesis by aloeosin: a competitive inhibitor of tyrosinase, Pigment Cell Research, 15, 335-340, 2002 ], arylbenzofurans Lee et al., Mulberoside F isolated from the leaves from the leaves of Murus alba inhibits melanin biosynthesis, Bio Pham Bull, 25, 1045-1048, 2002 ], chalcones Nerya et al., Chaicones as potent tyrosinase inhibitors: the effect of hydroxyl positions and numbers, Phytochem, 65, 1389-1395, 2004 ], coumarins [ Masamoto et al., Inhibitory effects ofesculetin on melanin biosynthesis, Biol Pharm Bull, 27, 422-425, 2004 ], flavonoids Yokoto et al., The inhibitory effect of glabridin from licorice extracts on melanogenesis and inflammation, Pigment Cell Research, 11, 355 - 361, 1998; No et al., Inhibition of tyrosinase by green tea components, Pharmacol Letters, 65, 241 - 246, 1999; Nerya et al., Glabrene and Isoliquiritigenin as tyrosinase inhibitors from Licorice roots, J Agr Food Chem, 51, 1201 - 1207, 2003; Kubo et al., Flavonols from Heterotheca inuloides: Tyrosinase inhibitory activity and structural criteria, Bioorganic&Medicinal Chemistry, 8, 1749 - 1755, 2000 Stilbenes Shin et al., Oxyresveratrol as the potent inhibitor on dopa oxidase activity on mushroom tyrosinase, Biochem Biophys Res Common, 243, 801 - 803, 1998; Kim et al., Oxyresveratrol and hydroxystilbene compounds, J Biol Chem, 277, 16340 - 16344, 2002 ], and low molecular weight tannins [ Chaudhuri et al., Inhibitory effects of Phylianthus emblica tannins on melanin synthesis, Cosmetics&Toiletries, 122(2), 73 - 80, 2007 Exemplary patents describing the use of natural and synthetic phenolic compounds as skin whitening agents include: US 6,649,150 (Chaudhuri et al.); US 6,969,509 (Chaudhuri et al.); US 5,670,154 (Hara et al.); and US 5,880,314 (Shinomiya et al.).

[0017] At least in patent literature, a class of polyphenol compounds that have received widespread attention are based on substituted resorcinols and their derivatives. Early applications, including US 4,959,393 (Torihara et al.), employed n-alkyl-substituted resorcinols, particularly those based on C2 to C3. 12 Alkyl-substituted resorcinols. Subsequent applications, including JP 5-04905 (Hamazaki et al.) and WO 2006 / 049184 (Fukunishi et al.), focus on compositions containing 4-alkylresorcinol derivatives, including straight-chain and branched C2 to C3-chain compounds. 12 Alkyl-substituted resorcinols and their salts. Others use such 4-alkylresorcinols (particularly n-butylresorcinol) in combination with certain branched polymers (e.g., alkyl methacrylates), JP 2001-010925 (Seto et al.). Chaudhuri has used high-purity 4-hexylresorcinol (over 99%) as a skin whitening agent and has obtained a patent based on this innovation (EP 2,152,685). This hexylresorcinol is marketed by Sytheon as Synovea® HR, which can be used alone or in combination with other skin whitening ingredients (e.g., niacinamide (EP 2,152,685) or acetylshogaol (Synoxyl® AZ; US 510,838,241)).

[0018] While early research on resorcinol appeared to focus on simple alkyl-substituted resorcinols, recent attention has shifted towards more complex resorcinols substituted with hydrocarbon and / or heteroatom groups. Heteroatom-substituted resorcinols include thiolated, thiazide (especially dithiazide), amide, amine, ketone, and carboxyl-substituted resorcinols, as shown in US 5,468,472 (LaGrange et al.), US 6,875,425 (Harichian et al.), US 6,852,310 (Harichian et al.), and JP1125563 (Sakai). Perhaps the most significant focus is on more complex hydrocarbon-substituted resorcinols, particularly cycloalkyl resorcinols and their substituted derivatives. Such skin whitening agents are described more fully in, for example, US 2006 / 0257340 (Nair); US 6,878,381 (Collington); US 6,933,319 (Browning et al.); US 6,852,747 (Bradley et al.); US 6,828,460 (Browning et al.); US 6,797,731 (Bradley et al.); US 6,590,105 (Bradley et al.); US 6,541,473 (Bradley et al.); and US 6,132,740 (Hu).

[0019] While substituted resorcinols and their derivatives have received considerable attention, they are not without their problems. For example, despite their relatively good skin-whitening effects, they often suffer from stability issues, particularly color stability. Subsequently, efforts have been made to improve their stability by adding various additives, including metal oxides (US 6,863,897 (Love et al.)) and terpenoids (US 6,858,217 (Kerschner et al.)); however, the success of these methods has been limited.

[0020] Therefore, despite various advances, there remains a need for skin whitening agents that are not unstable (especially oxidatively unstable), which can affect the color and efficacy of skin whitening compositions and cosmetic / therapeutic preparations to which the skin whitening agent is added.

[0021] Similarly, there is still a need for skin whitening agents that do not produce or cause skin irritation and sensitization-related problems, or other possible skin or health consequences.

[0022] In general, there is still a need for more skin whitening agents, especially highly effective ones. Crucially, there remains a need for highly effective, stable, and non-irritating skin whitening agents.

[0023] In addition, there is a need for skin whitening agents that are multi-targeted and compatible with other skin whitening agents, preferably synergistic with other skin whitening agents, and especially that allow for the use of fewer and fewer skin whitening active ingredients without affecting efficacy.

[0024] Finally, there is still a need for a skin-whitening composition that can achieve any or all of the above goals, is easy to use, and has high efficacy. Summary of the Invention

[0025] Based on the teachings herein, the following active agents and compositions are provided as multi-target skin whitening and skin tone evening agents and compositions that have antioxidant activity by reducing oxidase activity.

[0026] Based on the first aspect of the teachings herein, a novel compound, namely bis(di-n-butyryl lysine) zinc, also known as bis(N2,N6-di-n-butyryl lysine) zinc salt (2:1), is provided, as shown in structure 1: , And bis(diisobutyryl lysine) zinc, also known as bis(N2,N6-diisobutyryl lysine) zinc salt (2:1), is shown in structure 2: .

[0027] According to the second aspect of the teachings herein, a novel topical composition is provided comprising: (i) zinc bis(di-n-butyryl)-lysine, zinc bis(diisobutyryl)-lysine, or a mixture thereof (collectively, “zinc bis(butyryl)-lysine component”), preferably zinc bis(n-butyryl)-lysine, (ii) a skin-lightening agent, optionally but preferably not (i), and (iii) a dermatologically acceptable carrier. Preferably, these compositions are topical skin-lightening / brightening / evening skin tone compositions, or, depending on the choice of a dermatologically acceptable carrier, are topical compositions having different primary uses in addition to the ability to lighten, brighten, and / or even out skin tone (particularly skin pigmentation). For the former, while these formulations are effective as skin-lightening / brightening / evening skin tone compositions, they are also suitable as preventative compositions for routine use (particularly daily use) to prevent the formation of pigmentation spots caused by sunlight, lasers and other treatments, or scarring, as well as pigmentation spots caused by other factors, including diet and / or pharmaceuticals and / or physiological changes. For the latter, dermatologically acceptable carriers can be formulations whose primary purpose is not skin whitening / brightening / evening skin tone, including but not limited to cosmetics, moisturizers, sunscreens, sunburn treatments, anti-aging products, and topical pharmaceutical products intended for the treatment of acne, eczema, psoriasis, etc., in which the presence of the zinc dibutyryl lysine component provides additional benefits / properties for skin whitening / brightening / evening skin tone.

[0028] The compositions taught herein (preferably skin-whitening compositions) typically comprise from about 0.05 wt% to about 20 wt%, preferably about 0.1 wt% to about 10 wt% of a zinc dibutyryl lysine component, more preferably di(di-n-butyryl lysine) zinc, based on the total weight of the formulation. Exemplary preferred compositions comprise from about 0.5 wt% to about 5 wt%, particularly about 0.5 wt% to 2 wt%, based on the total weight of the composition. As described, the zinc dibutyryl lysine component can be used alone or in combination with one or more other skin-whitening, skin-tone-evening, and / or skin-brightening agents (collectively, "second skin-whitening agents"). When a second skin-whitening agent is present, its amount is typically the typical amount used for that agent, generally on the order of about 0.01 wt% to about 20 wt%, preferably about 0.5 wt% to about 10 wt%, and most preferably on the order of about 0.1 wt% to about 5 wt%. If a synergistic effect is observed, the amount of either or both skin-whitening agents can be reduced to achieve the same desired effect, although the above ranges still apply. Due to reduced concerns regarding the zinc dibutyryl lysine component (especially di(di-n-butyryl) lysine zinc), it is preferable to reduce the amount of the second skin whitening agent, by up to 50% or more. Most preferably, when a synergistic effect is present, the amount of the second skin whitening agent is from about 0.5% by weight to about 2.5% by weight. Furthermore, when using the second skin whitening agent, the weight ratio of the zinc dibutyryl lysine component to the second skin whitening agent is preferably 10:1 to 1:10, preferably 5:1 to 1:5, and most preferably 2:1 to 1:2. Of course, the specific ratio also depends in part on the molecular weight of the other skin whitening agents.

[0029] Zinc dibutyryl lysine, particularly zinc di(di-n-butyryl lysine), alone or in combination with one or more other skin-whitening agents, is incorporated into a conventional, dermatologically acceptable carrier for application / delivery to a subject. Such a carrier can be a dedicated carrier for the skin-whitening agent or the formulation itself, such as cosmetics, sunscreens, moisturizers, etc. Whether in a formulation or a dedicated carrier, the skin-whitening compositions taught herein may optionally contain effective amounts of one or more skin-protecting and / or therapeutic ingredients, such as sunscreens, antioxidants, vitamins, anti-inflammatory agents, moisturizers, emollients, humectants, amphoteric surfactants, alcohols (more specifically ethanol), and mixtures thereof, in conventional amounts.

[0030] Finally, according to the third aspect of the teachings herein, a method is provided for lightening skin pigmentation, evening out skin tone, and / or preventing skin discoloration and / or undesirable pigmentation, comprising applying the above-described composition to the skin. Specifically, the skin-whitening composition of the present invention is for external use and may be in the form of a cream, lotion, spray, solution, ointment, gel, or any other topical dosage form. The amount applied can provide a thin film on the skin to which it is applied, similar to the application of moisturizers and sunscreens. Generally, it is applied at least once daily to areas of skin where an even skin tone and / or skin whitening is desired until the desired skin tone or whitening effect is achieved. Preferably, especially when used to prevent or alleviate symptoms of skin pigmentation or discoloration, the skin-whitening composition taught herein is applied daily, particularly to areas of skin prone to undesirable pigmentation or discoloration and / or areas exposed to factors causing undesirable pigmentation or discoloration. Similar to sunscreens, the composition of the present invention is preferably reapplied when prolonged sun exposure continues and / or when there is concern that the composition may be washed off (e.g., due to sweating, swimming, etc.). Detailed Implementation

[0031] All patents, patent publications and technical articles cited in this article are incorporated herein in their entirety.

[0032] The term “substantially free” as used herein and in the appended claims means that the amount of the compound or ingredient (if present) is insufficient to cause any skin irritation or sensitization upon topical application: in this respect, it is as if the formulation substantially (if not completely free) of the compound or ingredient.

[0033] As used herein, the term "dermatologically acceptable" means that the composition or its components are suitable for application to human skin without excessive toxicity, incompatibility, instability, irritation, allergic reactions, etc.

[0034] As used herein, the terms "topical" or "topically" refer to the application or delivery of an identified material or composition to or onto the surface of the skin or part of the skin.

[0035] As used herein, the term "safe and effective amount" refers to an amount of a compound or composition sufficient to produce the intended results or effects without causing excessive toxicity, sensitization, or allergic reactions.

[0036] The term “post-inflammatory hyperpigmentation” as used in this article refers to changes in melanin content in response to inflammatory events such as acne, scratches, laser treatment, insect bites, sunburn, etc.

[0037] Finally, as stated above, the term "zinc dibutyryl lysine fraction" refers to zinc di(di-n-butyryl lysine), zinc di(diisobutyryl lysine), and mixtures thereof. References to zinc di(n-butyryl lysine) or zinc di(diisobutyryl lysine) refer to the specific compound itself.

[0038] Based on the teachings herein, active agents and compositions containing such active agents are provided as multi-target skin whitening and skin tone evening agents and compositions that have antioxidant activity by reducing oxidase activity, as summarized in Table 2 below.

[0039] Table 2: Cellular antioxidants involved in melanin production

[0040] [ Y Lu et al., Modulating skin colour: role of the thioredoxin and glutathione systems in regulating melanogenesis, Bioscience Reports, 2021, 41 (5): BSR20210427 ] Specifically, in accordance with the first aspect of the teachings herein, a novel compound, namely bis(di-n-butyryl lysine) zinc, also known as bis(N2,N6-di-n-butyryl lysine) zinc salt (2:1), is provided, as shown in Structure 1: , And bis(diisobutyryl lysine) zinc, also known as bis(N2,N6-diisobutyryl lysine) zinc salt (2:1)], as shown in structure 2: .

[0041] According to the second aspect of the teachings herein, a novel topical composition is provided comprising: (i) zinc bis(di-n-butyryl)-lysine, zinc bis(diisobutyryl)-lysine, or a mixture thereof (collectively, “zinc bis(butyryl)-lysine component”), preferably zinc bis(n-butyryl)-lysine, (ii) a skin-lightening agent, optionally but preferably not (i), and (iii) a dermatologically acceptable carrier. Preferably, these compositions are topical skin-lightening / brightening / evening skin tone compositions, or, depending on the choice of a dermatologically acceptable carrier, are topical compositions having different primary uses in addition to the ability to lighten, brighten, and / or even out skin tone (particularly skin pigmentation). For the former, while these formulations are effective as skin-lightening / brightening / evening skin tone compositions, they are also suitable as preventative compositions for routine use (particularly daily use) to prevent the formation of pigmentation spots caused by sunlight, lasers and other treatments, or scarring, as well as pigmentation spots caused by other factors, including diet and / or pharmaceuticals and / or physiological changes. For the latter, dermatologically acceptable carriers can be formulations whose primary purpose is not skin whitening / brightening / evening skin tone, including but not limited to cosmetics, moisturizers, sunscreens, sunburn treatments, anti-aging products, and topical pharmaceutical products intended for the treatment of acne, eczema, psoriasis, etc., in which the presence of the zinc dibutyryl lysine component provides additional benefits / properties for skin whitening / brightening / evening skin tone.

[0042] Other skin-whitening, skin-tone-evening, and / or skin-brightening active agents are well-known and widely available. Generally, any known skin-whitening agent can be used in combination with the zinc dibutyryl lysine component. Exemplary and suitable skin-whitening agents are discussed in the background section above and in the patent references mentioned herein. It is obviously impossible to list all known skin-whitening agents; however, examples of suitable skin-whitening, skin-tone-evening, and / or skin-brightening agents that can be used in combination with the zinc dibutyryl lysine component include, but are not limited to: Phyllanthus emblica (… Phyllanthus emblica Fruit extract, Terminalia chebula ( Terminalia chebulaFruit extracts, bearberry extract, mulberry extract, licorice extract, propolis extract, acerola cherry fermentation product, cucumber extract, green tea polyphenols, grape seed extract, pine bark polyphenols, resveratrol, oxidized resveratrol, arbutin, coumarins, flavonoids, nicotinamide, anthraquinones, xanthones, lignans, glycyrrhizin, curcumin, dihydrocurcumin, tetrahydrocurcumin, epigallocatechin-3-gallate, hydroxybenzoic acid compounds or their derivatives, tomato glycolipids, perilla plants, ligusticum (Ligustrum lucidum) Extracts of *Lactarius delavayi*, psoralen, ascorbic acid and its derivatives (including ascorbate glucoside, ethyl ascorbic acid and tetrahexyldecyl ascorbate), kojic acid, α-arbutin, glutathione, azelaic acid, glycolic acid, linoleic acid, coffee berry extract, hydroquinone, *Pancratium maritimum* extract, resveratrol, bisabolol, p-methoxyphenol, 4-hydroxyanisole, hydroquinone monomethyl ether, N-acetyl-4-S-cysteine, α-tocopherol (vitamin E), *Broussonetica kazwoki*, *B. papyrifera*, *Cornus officinalis*, *Rhus chinensis* The resorcinols include javanica, Pinus densiflora, orchid extract, aloe vera extract, pycnogenol, cinnamic acid, gallic acid, ellagic acid, umbelliferone, Boswellia, N-acetylglucosamine, retinoic acid (especially retinoic acid), ferulic acid, quercetin, tranexamic acid, thiamidol, soybean, and alkyl resorcinols (especially hexylresorcinol, butylresorcinol, and phenylethylresorcinol), as well as any combination of two or more of the above. While certain polyphenolic skin whitening agents, such as substituted resorcinols and their derivatives, are particularly desirable and beneficial, it should be recognized that many of the above-mentioned resorcinols contain considerable levels of impurities and other substances, especially when the resorcinol content is high or significant. Therefore, resorcinol-based skin whitening / tone-evening agents are preferably those with relatively high purity and / or low resorcinol content; otherwise, many of the beneficial effects of the present invention may be compromised.

[0043] Other suitable skin-whitening agents include glycosamines, also known as amino sugars, which should be used in safe and effective amounts. The glycosamine compounds used in this invention are described in U.S. Patent No. 6,159,485. Glycosamines can be synthetic or of natural origin and can be used as pure compounds or mixtures of compounds (e.g., extracts of natural sources or mixtures of synthetic materials). For example, glucosamine is commonly found in many shellfish and can also be extracted from fungal sources. The term "glycosamine" as used herein has a broad meaning, including glycosamines themselves, their isomers and tautomers, and their salts (e.g., hydrochlorides). Glycosamines are available from, for example, Sigma Chemical Co. Exemplary suitable glycosamines include glucosamine, N-acetylglucosamine, glucosamine sulfate, mannosamine, N-acetylglucosamine, galactosamine, N-acetylgalactosamine, their isomers (e.g., stereoisomers), and their salts (e.g., hydrochlorides). Preferred glycosamines are glucosamines, particularly D-glucosamine and N-acetylglucosamine, especially N-acetyl-D-glucosamine.

[0044] Another class of skin-whitening agents are N-acyl amino acid compounds, including but not limited to N-acylphenylalanine, N-acyltyrosine and their isomers (including their D- and L-isomers), salts, derivatives, and mixtures thereof. A suitable example of an N-acyl amino acid is N-undecenoyl-L-phenylalanine, which can be marketed under the name Sepiwhite. TM Purchased from Seppic (France).

[0045] The skin-whitening compositions taught herein typically comprise from about 0.05 wt% to about 10 wt%, preferably from about 0.1 wt% to about 10 wt%, of a zinc dibutyryl lysine component, particularly bis(di-n-butyryl) zinc, based on the total weight of the formulation. Exemplary preferred compositions comprise from about 0.5 wt% to about 5 wt%, particularly from about 0.5 wt% to 2 wt%, of a zinc dibutyryl lysine component based on the total weight of the composition. As described, the zinc dibutyryl lysine component can be used alone or in combination with one or more other skin-whitening, skin-tone-evening, and / or skin-brightening agents (collectively, "second skin-whitening agents"). When a second skin-whitening agent is present, its amount is typically the typical amount used for that agent, generally from about 0.01 wt% to about 20 wt%, preferably from about 0.5 wt% to about 10 wt%, and most preferably on the order of about 0.1 wt% to about 5 wt%. If a synergistic effect is observed, the amount of any one or both skin-whitening agents can be reduced to achieve the same desired effect, although the above ranges still apply. Due to reduced concerns regarding the zinc dibutyryl lysine component (especially di(di-n-butyryl lysine) zinc), it is preferable to reduce the amount of the second skin whitening agent, by up to 50% or more. Most preferably, when a synergistic effect is present, the amount of the second skin whitening agent is from about 0.5% by weight to about 2.5% by weight. Furthermore, when using the second skin whitening agent, the weight ratio of the zinc dibutyryl lysine component to the second skin whitening agent is preferably 10:1 to 1:10, preferably 5:1 to 1:5, and most preferably 2:1 to 1:2. Of course, the specific ratio also depends in part on the molecular weight of the second skin whitening agent.

[0046] The zinc dibutyryl lysine component (with or without a second skin whitening agent) is delivered or applied to the skin using a suitable, dermatologically acceptable carrier. Such carriers are well-known and widely available. Preferably, the carrier and excipients are those suitable for long-term and repeated application to the skin without causing sensitization, irritation, or inflammation. The specific carrier material depends on the delivery method itself. For example, skin whitening / even skin tone / skin brightening compositions can be in the form of lotions, creams, gels, foams, emulsions, dispersions, sprays, liposomes, aggregates, etc. Each composition typically contains any known topical excipients and agents required to achieve the specific form of the final composition. Suitable excipients include, for example, mineral oils, silicone oils, and emulsifiers. In the simplest embodiment, the carrier can be water, alcohol, or a water / alcohol combination, or other solvents or solvent systems in which the aforementioned active ingredient can be, for example, dissolved, dispersed, emulsified, etc. Preferably, the skin-whitening composition should contain excipients, etc., to form a substantially stable, homogeneous skin-whitening / skin-tone-evening composition, and / or to impart consistency and viscosity to the skin-whitening / skin-tone-evening composition so that the active ingredients are not easily lost after application to the skin. Typically, the carrier contains from about 30% by weight to more than 99% by weight, preferably 40% by weight to 99% by weight of the skin-whitening composition.

[0047] In general, any known carrier or base composition used in conventional cosmetic and / or dermatological applications / compositions can be used to practice the teachings herein. Similarly, those skilled in the art will be able to readily identify and understand which carriers may be used, taking into account the intended form and / or delivery method of skin-lightening / evening skin tone compositions. Suitable supports and support compositions are detailed in, for example, the following literature: Gonzalez et al. - US 7,186,404; Aust et al. - US 7,175,834; Roseaver et al. - US 7,172,754; Simoulidis et al. - US 7,175,835; Mongiat et al. - US 7,101,536; Maniscalco - US 7,078,022; Forestier et al. - US 5,175,340, US 5,567,418, US 5,538,716 and US 5,951,968; Deflandre et al. - US 5,670,140; Chaudhuri - US 7,150,876, US 6,831,191, US 6,602,515, US 7,166,273, US US 6,936,735, US 6,831,191 and US 6,699,463; Chaudhuri et al. - US 6,165,450 and US 7,150,876; Bonda et al. - US 6,962,692; Rodan et al. - US 9,144,434; Wang et al. - US 5,830,441; and Auspitz et al. - US 2007 / 0110685 A.

[0048] In addition to, or as an alternative to, the skin-whitening compositions taught herein may also include, and preferably include, one or more other ingredients, including those that are themselves skin-active ingredients and have an effect or function on the skin. Exemplary auxiliary skin-active ingredients include antioxidants, sunscreen active ingredients, vitamins, anti-inflammatory agents, moisturizers, emollients, hydrating agents, anti-acne ingredients, etc. Such auxiliary active ingredients include, but are not limited to, bakuchiol, isosorbide dicaprylate, Terminalia chebula fruit extract, ethyl linoleate, isosorbide dilinoleate, isosorbide disunflowerseedate, and mixtures thereof. Alternatively, or in addition, these compositions may also contain other ingredients that are unrelated or minimally related to the intended end use or therapeutic application of these compositions, but contribute to the preparation and / or longevity / stability of these compositions, and improve their aesthetic aspects. Exemplary inactive ingredients include solubilizers, surfactants, stabilizers, thickeners, preservatives, buffers, dyes, fragrances, flavorings, opacifiers, colorants, etc. Each of these ingredients is typically present (where applicable) in the usual amounts of those ingredients. It is unnecessary to specify all possible specific active and inactive ingredients and additives that can be added to the compositions taught herein, as these ingredients are well-known and widely available, and any attempt to do so would inevitably result in excessive detail.

[0049] Another type of ingredient that can be used is a penetration enhancer, which is neither strictly a skin-active agent nor an inactive ingredient. Specifically, this additive, after being applied to the skin, acts directly on the permeability of the skin barrier: increasing the rate and / or amount of penetration of certain other compounds into the skin layers. Exemplary organic penetration enhancers include dimethyl sulfoxide; isopropyl myristate; decanol, undecanol, or dodecanol; propylene glycol; polyethylene glycol; C 9-11 C 12-13 Or C 12-15 Fatty alcohols, azones, alkylpyrrolidones, diethoxyethylene glycol (penetration enhancers), lecithin, etc. Surfactants can also be used as penetration enhancers. Similarly, each is used in the usual dosage for this type of ingredient.

[0050] Alternatively, instead of specifically formulating compositions based on the zinc butyryl lysine component, the zinc butyryl lysine component (preferably di(di-n-butyryl) zinc) dissolved in a solubilizer / solvent can be added to existing product formulations and commercially available products. For example, the zinc butyryl lysine component can be added to existing cosmetics, sunscreens, moisturizers, skin serums, anti-aging compositions, acne treatments, general skincare products, skin-renewing products, topical pharmaceutical products, etc., or to the base compositions used to produce the aforementioned products.

[0051] The final dosage form and preparation method of the skin whitening compositions taught herein depend in part on their application method and the other ingredients to be added to the composition or the composition to which zinc dibutyryl lysine component is to be added. Therefore, these compositions can be in the form of solutions, suspensions, emulsions, microcapsules, liquid-containing microcapsules, powders, creams, lotions, gels, sustained-release formulations, aerosols, sprays, etc. The compositions described below can be prepared using any method known in the art for cosmetic and / or dermatological / topical formulations. Such methods include conventional mixing, stirring, dissolving, granulation, sugar coating preparation, grinding, emulsification, suspension, encapsulation, homogenization, etc. All of these methods are conventional in the art. Furthermore, during preparation, it may be necessary to add known pH adjusters to maintain a suitable pH value for the topical composition, especially when alkaline ingredients are intended to be used. Generally, the pH value should be neutral to slightly acidic, and can be as low as pH 4. However, a pH value in the range of about 5 to about 7 is preferred, and more preferably in the range of 5 to 6.5.

[0052] The skin whitening / evening skin tone composition of the present invention can be used as a preventative measure to prevent or inhibit skin darkening, or as a treatment to address existing skin darkening and / or uneven skin tone, and / or simply for brightening the skin. In the former case, the skin whitening / evening skin tone composition is applied to areas of the skin that are prone to skin darkening, such as sun-exposed areas of skin in cases of sun-induced hyperpigmentation (including melasma); areas prone to acne and other types of inflammation or skin damage, or areas of skin expected to receive inflammation-related treatments (such as laser treatment, which may trigger post-inflammatory hyperpigmentation); and areas of skin where hyperpigmentation has been reduced and a particular skin color and / or tone is desired. Preferably, the skin whitening / evening skin tone composition is applied to skin on which an individual desires a lighter and / or more even or radiant skin tone, especially skin that has already developed hyperpigmentation and / or uneven or patchy skin tone. For example, in an extreme case, an individual may wish to whiten the entire body of their skin, in which case the composition should be applied to the entire body. Alternatively, individuals may focus on specific areas of their skin, in which case the composition should be applied only to areas that are darker than other parts of the body, such as those affected by prolonged sun exposure and UV radiation, or acne. Indeed, a desire for beauty may also lead some individuals to use skin-whitening and even-toning products to diminish the appearance of sunburn, freckles, etc. More importantly, however, this method aims to whiten and even out skin tone in areas of hyperpigmentation and / or uneven or patchy skin, often caused by or related to physical and / or physiological factors, including trauma, inflammation, laser treatment, age, sun exposure, diet, medication or pharmaceutical treatment, pregnancy, etc. Most preferably and beneficially, especially from a psychological perspective, this method is particularly suitable for treating hyperpigmentation and uneven skin tone, or patchiness, caused by trauma, inflammation, laser treatment, diet, medication or pharmaceutical treatment, pregnancy, and other physiological conditions or diseases and / or their related treatments besides typical skin aging. This allows individuals troubled by hyperpigmentation and / or uneven skin tone or patchiness to avoid the stigma and inferiority complex associated with those conditions. In this regard, age spots and sunspots caused by prolonged sun exposure are normal phenomena in the aging process of adults; however, for children, adolescents, and young adults who have / have had acne, eczema, vitiligo, melasma, etc., the occurrence of such hyperpigmentation and / or uneven skin tone or patchiness can be more traumatic. Even if uneven skin tone, like vitiligo, cannot be completely eliminated, it can be alleviated: any change, especially from a personal or psychological perspective, is considered a positive change.

[0053] As mentioned above, the duration and frequency of application vary. Generally, the composition should be applied continuously until the desired skin whitening and / or evening skin tone effect is achieved. If the composition is used as a preventative measure, it should be applied while factors that may cause hyperpigmentation persist, especially in cases of concern about post-inflammatory hyperpigmentation. Similarly, once the desired skin whitening and / or evening skin tone level is achieved, it may be necessary to reduce the amount of skin whitening composition applied and / or decrease its frequency of application to maintain the established skin color, tone, and / or radiance. Alternatively, it can be applied daily as a routine to maintain the given skin appearance and radiance, as well as an even skin tone.

[0054] The amount of skin whitening / evening skin tone composition to be applied to the skin depends on the form of the composition and its application method. Generally, the amount applied is sufficient to provide a thin film of the composition on the treated skin. Typically, a small amount of the composition (e.g., 0.1 ml to 5 ml) is applied to the skin from a suitable container or applicator and spread on and / or rubbed into the skin by hand or fingers or a suitable tool.

[0055] Preferably, the skin-whitening composition is applied to the entire body or areas of skin requiring skin whitening and / or evenness of skin tone at least once daily, more preferably at least twice daily, until the desired improvement in skin appearance is achieved or manifested. This timeframe will vary significantly depending on factors such as the desired degree of whitening and / or evenness of skin tone, the initial skin depth and / or degree of unevenness, the frequency of application, the individual's activity level and whether the composition is washed off or wiped away during that activity, the concentration of the skin-whitening ingredients in the composition (especially the zinc dibutyryl lysine component), and the presence of other ingredients that may enhance, inhibit, or delay the skin-whitening efficacy of the zinc dibutyryl lysine component. More preferably, especially for those compositions that also contain sunscreen active ingredients, particularly when intended to prevent or reduce hyperpigmentation caused by UV exposure, the skin-whitening / evening skin tone composition should be applied before sun exposure, preferably at least 15 minutes in advance, and reapplied at least every 2 hours or more, especially when the individual is engaged in activities / actions that may cause the sunscreen composition containing the skin-whitening composition to smudge or rub off, such as swimming; washing dishes, windows, etc.; washing hands and / or face; contact sports activities; activities that induce excessive sweating, etc.: all behaviors / events that cause the composition containing the sunscreen to smudge or be lost prematurely.

[0056] In terms of application duration, the standard application cycle is 7 days to 6 months or longer. However, considering the other benefits of zinc dibutyryl lysine (especially di(di-n-butyryl) zinc), even after achieving the desired skin brightening and / or evening skin tone effect, it may be desirable to continue using these compositions as part of daily care to improve overall skin health and / or combat the effects of natural skin aging, and more importantly, to combat the harmful effects of sun exposure and air pollution. In this regard, users can follow the following routine: apply skin brightening compositions or other skin care products with zinc dibutyryl lysine (especially di(di-n-butyryl) zinc) as a key or core active ingredient to achieve the desired skin brightening and / or evening skin tone until the desired effect is achieved; subsequently, use daily moisturizers, sunscreens, and / or cosmetic compositions that also contain this zinc dibutyryl lysine (especially di(di-n-butyryl) zinc) as a means of continuous prevention and treatment.

[0057] Example Example 1: Preparation of di-n-butyryl lysine L-lysine hydrochloride (1 mol) and butyric anhydride (2.2 mol) or butyryl chloride (2.2 mol) were added to tetrahydrofuran and distilled water, and the mixture was stirred at 30 ± 5 °C for 12 to 16 hours. Sodium carbonate was then added to the reaction mixture, and the mixture was stirred at 30 ± 5 °C for another 12 to 16 hours. Sodium chloride and hydrochloric acid were then added, and the mixture was stirred for 30 minutes. The aqueous layer was then separated. The remaining organic layer was distilled under vacuum at <40 °C. The crude product was further purified by column chromatography. The purified product was characterized by spectroscopic methods as di-n-butyryllysine.

[0058] Example 2: Preparation of diisobutyryl lysine Diisobutyryl lysine salt was prepared by the same method as described in Example 1, except that isobutyric anhydride (2.2 mol) or isobutyryl chloride (2.2 mol) was used instead of butyric anhydride or butyryl chloride, respectively.

[0059] Example 3: Preparation of bis(di-n-butyryl)zinc The di(n-butyryl) lysine (2 mol) from Example 1 was mixed with methanol and zinc hydroxide (1.1 mol), heated to 65°C, and maintained at this temperature for 12 hours. The reaction mixture was then filtered to remove any undissolved salts. The filtrate was distilled under vacuum at <40°C to remove the solvent. The crude product was washed with acetone and n-heptane. The purified product was dried under vacuum at <40°C and identified as zinc di(n-butyryl) lysine by spectroscopic analysis.

[0060] Example 4: Preparation of bis(diisobutyryl lysine)zinc Zinc di(diisobutyryl lysine) was prepared according to the same method as described in Example 3, except that the diisobutyryl lysine salt of Example 2 was used instead of the di-n-butyryl lysine salt.

[0061] Example 5: Preparation of bis(di-n-butyryl lysine)calcium The dibutyryl lysine (2 mol) from Example 1 was mixed with methanol and calcium hydroxide (1.1 mol), heated to 65°C, and the mixture was maintained at this temperature for 12 hours. The reaction mixture was then filtered to remove any undissolved salts. The filtrate was distilled under vacuum below 40°C to remove the solvent. The crude product was washed with acetone and n-heptane. The purified product was dried under vacuum below 40°C and identified as bis(di-n-butyryl lysine) calcium by spectroscopic analysis.

[0062] Example 6: Preparation of bis(diisobutyryl lysine)calcium Di(diisobutyryl lysine) calcium was prepared according to the same method as described in Example 5, except that the diisobutyryl lysine salt of Example 2 was used instead of the di-n-butyryl lysine salt.

[0063] Example 7: Expression of microphthalmia-associated transcription factor (MITF) DNA microarray EpiDermFT tissues were obtained from MatTek and equilibrated overnight in a cell culture incubator. The following day, tissue samples were placed in individual containers, and 3 μl of one of the following solutions at 100 μg / ml was added to each tissue sample: zinc di-n-butyryl lysine (ZDBL), lysine, calcium lysine, zinc lysine, or calcium di-n-butyryl lysine: each sample was prepared in triplicate. All stock solutions were prepared at 20 mg / ml in DMSO and further diluted in sterile distilled water. The recommended doses used were based on cytotoxicity data. Water was used as a negative control. After incubation for 24 hours, RNA was extracted from the treated tissue samples and prepared for transcriptome analysis to assess its effect on the expression of microphthalmia-associated transcription factor (MITF) genes (if available). Results are shown in Table 3. Sequencing data were generated by Azenta Life Sciences (HiSeq 2 × 150 bp). Analysis was performed using raw FastQ files provided by Azenta.

[0064] MITF gene expression As shown in Table 3, MITF expression was only inhibited by ZDBL treatment, while lysine and three other lysine derivatives (i.e., calcium lysine, zinc lysine, and calcium di-n-butyryl lysine) were not significantly altered.

[0065] Table 3: Effects of MITF gene expression

[0066] FPKM (million fragments per thousand bases).

[0067] PCR was used to verify MITF gene expression. To verify the above results, a second analysis was performed on the tissue samples, this time using High-Capacity RNA-to-cDNA. TM cDNA was prepared using a kit (Thermo Fisher Scientific). PCR primers from Realtimeprimers (Elkins Park, PA) and an AzuraView GreenFast qPCR Blue MixLR (Azura Genomics, Raynham, MA) detection system with BioRad iCycler iQ were used to measure the expression of applicable genes via real-time quantitative PCR. After normalizing gene expression to GAPD (housekeeping genes), efficiency was used. The Ct method was used to quantify the results. If the p-value determined by the two-tailed t-test was ≤0.10, the modulation fold was ≥1.7, and the expression level was high (required cycle number <30), then differential expression of the gene was considered to exist. The results are summarized in Table 4.

[0068] Table 4: PCR-verified MITF gene expression

[0069] Compared to water.

[0070] Example 8: Inhibitory activity of thioredoxin reductase 1 (TrxR1) Thioredoxin is known to affect the substrates for melanin production. Y Lu et al., Modulating skin colour: role of thioredoxin and glutathione systems in regulating melanogenesis, Bioscience Reports, 2021; 41 BSR20210427 Therefore, an investigation was conducted to evaluate the effects of zinc di(di-n-butyryl)-Cal (ZDBL), calcium di(di-n-butyryl)-Cal, and their combinations on the inhibition of thioredoxin reductase (if any). Test materials were prepared by dissolving 0.01 gm of each test material in 1 ml of ethanol to prepare stock solutions. For analysis, serial dilutions of the stock solutions (1 to 4-fold) were prepared using buffer (100 mM potassium phosphate containing 10 nM EDTA, pH 7.0) to determine the IC50. 50Thioredoxin reductase 1 (Raybiotech, catalog number 228-12536-2) was added to the sample, and the mixture was incubated at room temperature for 1 hour. After incubation, working buffer (phosphate buffer containing 2 mM DTNB and 0.2 mM NADPH) was added. The plate was read at 412 nm for 30 minutes to determine the inhibition rate. The results are summarized in Table 5.

[0071] Table 5: Inhibitory activity of thioredoxin reductase 1

[0072] The average of two readings.

[0073] The results shown in Table 3 indicate that ZDBL, CDBL, and combinations thereof have similar inhibitory effects on thioredoxin reductase 1.

[0074] Example 9: Tyrosinase inhibitory activity Further studies were conducted to evaluate the inhibitory effects of zinc di(di-n-butyryl)-lysine (ZDBL), calcium di(di-n-butyryl)-lysine (CDBL), and zinc lysine on tyrosinase, a key enzyme in melanin production. Stock solutions of the test compounds were prepared in DMSO at 20 mg / ml and further diluted with sterile distilled water. Sterile distilled water served as a negative control, and kojic acid (200 μM, dissolved in distilled water, Sigma Aldrich, St. Louis, MO, catalog number K3125) served as a positive control / reference. Based on Pomerantz [ Biochem Biophys Res Common., 16(2): 188- 94, 1964 ] and Ohguchi et al. Biosci Biotechnol Biochem, 67:1587-1589, 2003 The method employed an in vitro tyrosinase inhibition assay, with samples tested three times in duplicate. Briefly, a stock solution of mushroom tyrosinase (Sigma # 31281630) was prepared in PBS (phosphate-buffered saline) at 2000 U / ml and aliquoted in 1 ml portions, stored at -20°C. The final concentration used in the experiment was 16 U / well (80 U / ml). The tyrosinase substrate L-DOPA (AcrosOrganics, Fair Lawn, NJ) was used at 5 mM. The reaction was carried out in a 96-well plate system, initiated by adding the enzyme to the reaction mixture and allowing it to react for 80 minutes. Colorimetric signals proportional to the conversion of L-DOPA to melanin (A0.05) were acquired using a SpectraMaxi3x multifunction detection platform from Molecular Devices (Sunnyvale, CA). 450nm The increase in melanin production is calculated using the following formula: ΔM = [A 450nm(t=80min.) +Tyrosinase] - [A 450nm(t=80min.) -Tyrosinase] ΔM represents the increase in melanin, A represents the absorbance under given experimental conditions, t represents the time point, 450 nm represents the wavelength used for quantitative melanin analysis, and "-tyrosinase" represents the background reading without enzyme addition under the same experimental conditions. Statistically significant differences were defined as a deviation >25% compared to the water control group, with a p-value <0.05 (calculated using a two-tailed t-test). The results are summarized in Table 6.

[0075] As can be seen from the results in Table 6, bis(di-n-butyryl)zinc is very effective in inhibiting tyrosinase activity, especially at higher concentrations, while structurally similar analogues, bis(di-n-butyryl)calcium and lysine zinc, are ineffective.

[0076]

[0077] Example 10: NADPH oxidase (NOX-4) inhibitory activity The direct effects of zinc di(di-n-butyryl)-L-lysine (ZDBL), calcium di(di-n-butyryl)-L-lysine (CDBL), and sodium butyrate on NADPH oxidase 4 (NOX-4) were investigated. In this study, 0.01 g of sample was dissolved in 1 ml of propylene glycol to prepare a solution. For analysis, the sample stock solution was serially diluted 1 to 2 times using buffer to determine the IC50. 50 Values. Analysis was performed according to the NOX4 ELISA kit (My BioSource, catalog number MBS2505108). Results are summarized in Table 7.

[0078] Table 7: Inhibitory activity of NADPH oxidase (NOX-4)

[0079] The results shown in Table 7 indicate that ZDBL, CDBL, and sodium butyrate have similar effects on the inhibition of NOX-4 enzyme activity.

[0080] Example 11: Melanin Synthesis The direct effects of zinc di(di-n-butyryl)-lysine (ZDBL), calcium di(di-n-butyryl)-lysine, and zinc lysine on melanin production in melanocytes were investigated. In this study, B16-F1 melanocytes (catalog number CRL-6323, ATCC, Manassas, VA) were seeded at a density of 10,000 cells / well in DMEM containing 10% FBS, and test materials were added 24 hours later. A stock solution of the test materials was prepared in DMSO at 20 mg / ml and then further diluted with sterile distilled water immediately before adding the test cells. Hexylresorcinol (lot number 25071VSP10420422) (from Sytheon Ltd, Parsippany, NJ) was used as a positive control. Three days after adding the test material, cells were observed using a Nikon Eclipse TS100 inverted microscope, and pigmentation was assessed using the Cusabio melanin colorimetric competitive ELISA assay (catalog number E14051h) from Lifeome, Oceanside, CA. Colorimetric signals were acquired using a Molecular Devices MAX190 microplate spectrophotometer, and processed using SoftMax 3.1.2PRO software. Paired t-tests were used to calculate the p-value representing statistical significance, with a statistical significance threshold set at p=0.05 and a difference of 15% compared to the water control group. The results are summarized in Table 8.

[0081] Table 8: Inhibition of Melanin Synthesis

[0082] Water was used as a control – melanin content 100 (p=1.00) + Using hexylresorcinol (5 μg / mL) as a positive control: melanin inhibition was 17% of the control (p= The result of 0.007 confirms the effectiveness of this solution.

[0083] Microscopic observation revealed no obvious signs of cytotoxicity, such as cell rounding and / or detachment. Colorimetric quantitative analysis showed that 200 μg / ml of zinc bis(di-n-butyryl)-lysine had statistically significant melanin-inhibiting activity, while ZnLys and CDBL had no significant effect on melanin inhibition. Hexylresorcinol exhibited slight but statistically significant inhibitory activity, technically validating the experiment.

[0084] preparation As described above, compositions containing zinc dibutyryl lysine can take many different forms (both physical and pharmaceutical), i.e., as a pure formulation of zinc dibutyryl lysine in a carrier, or as a multi-component topical therapeutic composition. Several suitable formulations are listed below.

[0085] Formulation 1: Skin whitening lotion The preparation of this formulation involves first adding phase A to a main vessel equipped with a homogenizer. Then, phase B is slowly added to phase A. Once phase B is fully dispersed in phase A, the mixture is heated to 65-70°C. Simultaneously, phase C is placed in a secondary vessel and mixed, then heated to 70-75°C. Once both mixtures have reached the appropriate temperature, phase C is added to the phase A-B mixture, and the mixture is mixed for 15-20 minutes. Simultaneously, phase D is added to the secondary vessel and heated to 75°C. Once the zinc dibutyryl lysine component has dissolved, phase D is added to the ABC mixture, and the mixture is mixed for 5-10 minutes. Once the mixture is homogeneous, mixing is switched to side-sweep mixing, and the mixture is cooled to room temperature. Notes: pH 4.5-5.0; Viscosity: Rotor-TE, S95; Speed: 0.3 rpm; Range: 200,000-500,000 mPas.

[0086] Formulation 1

[0087] Formulation 2: Moisturizing and skin-whitening essence Formulation 2 is prepared by the following method: Phase A components are incorporated into a homogenizer and mixed. While Phase A is being mixed, Phase B components are added and mixed until homogeneous. Simultaneously, Phase C components are mixed in a secondary reactor until homogeneous, then added to the Phase A / B mixture, and the mixture is mixed for 10-15 minutes. Phase D components are incorporated into the secondary reactor and heated to 75°C to dissolve the zinc dibutyryl lysine component. Once dissolved, heating is stopped, and the mixture is allowed to cool to room temperature before being added to the Phase A / B mixture, and the mixture is mixed for 5-10 minutes. Notes: pH 5.5-6.0; Viscosity: Rotor-TD, S94; Speed: 2.0 rpm; Range: 8000-11000 mPas.

[0088] Formulation 2

[0089] Formulation 3: A skin-tone emulsion containing hexylresorcinol Formulation 3 was prepared by the following method: First, phase A was added to a main vessel equipped with a homogenizer. Then, phase B was slowly sprinkled into phase A. Once phase B was completely dispersed in phase A, the mixture was heated to 65-70°C. Simultaneously, phase C was placed in a secondary vessel and mixed, and heated to 70-75°C. Once both mixtures reached the appropriate temperature, phase C was added to the phase AB mixture, and the mixture was mixed for 15-20 minutes. Simultaneously, the first two components of phase D were added to the secondary vessel and heated to 75°C. Once the zinc dibutyryl lysine component dissolved, the mixture was cooled to 45°C, and hexylresorcinol was added and mixed until homogeneous. Then, the mixing of the ABC phase mixture was switched to side-sweep mixing, and the mixture was cooled to 45°C. Afterward, phase D was added to the ABC phase mixture and mixed for 5-10 minutes, allowing the total mixture to cool to room temperature. Notes: pH value 4.5-5.0; viscosity: rotor-TE, S95; speed: 0.3 rpm; range: 200,000-500,000 mPas.

[0090] Formulation 3

[0091] Formulation 4: Skin brightening lotion containing bakuchiol Formulation 4 was prepared by the following method: First, phase A was added to the main vessel equipped with a homogenizer. Then, phase B was slowly sprinkled into phase A. Once phase B was completely dispersed in phase A, the mixture was heated to 65-70°C. Simultaneously, phase C was placed in the auxiliary vessel and mixed, and heated to 70-75°C. Once both mixtures reached the appropriate temperature, phase C was added to the phase AB mixture, and the mixture was mixed for 15-20 minutes. Simultaneously, phase D was added to the auxiliary vessel and heated to 75°C. Once the zinc dibutyryl lysine component dissolved, phase D was added to the ABC mixture and mixed for 5-10 minutes. Once the mixture was homogeneous, the mixing was switched to side-sweep mixing, and the mixture was cooled to room temperature. Notes: pH 4.5-5.0; Viscosity: Rotor-TE, S95; Speed: 0.3 rpm; Range: 200,000-500,000 mPas.

[0092] Formulation 4

[0093] Formulation 5: Skin whitening lotion Formulation 5 is prepared using the same method as formulation 4.

[0094] Formulation 5

[0095] Formulation 6: Skin whitening lotion with pollution and blue light protection effects Formulation 6

[0096] Formulation 6 was prepared as follows: First, phase A was added to a main vessel equipped with a homogenizer. Then, phase B was slowly sprinkled into phase A. Once phase B was fully dispersed in phase A, the mixture was heated to 65-70°C. Simultaneously, phase C was placed in a secondary vessel and mixed, then heated to 70-75°C. Once both mixtures reached the appropriate temperature, phase C was added to the phase AB mixture, and the mixture was mixed for 15-20 minutes. Simultaneously, phase D was added to the secondary vessel and heated to 75°C. Once the zinc dibutyryl lysine component dissolved, phase D was added to the ABC mixture and mixed for 5-10 minutes. The mixing of the ABC mixture was then switched to side-sweep mixing, and the mixture was cooled to 45°C. Simultaneously, the aqueous component of phase E was added to a separate vessel and heated to 45°C, then the Terminalia chebula extract was added and mixed until dissolved. Afterward, phase E was added to the ABCD mixture and mixed until homogeneous, then the batch was cooled to room temperature. Notes: pH value 4.5-5.0; viscosity: rotor-TE, S95; speed: 0.3 rpm; range: 200,000-500,000 mPas.

[0097] Formulation 7: Anti-aging cream Formulation 7 is prepared by the following method: Phase A components are combined and mixed in a vessel equipped with a homogenizer. While Phase A is being mixed, Phase B components are added and the mixture is mixed until homogeneous. Simultaneously, Phase C components are mixed in a secondary vessel until homogeneous, then added to the Phase A / B mixture, and the mixture is mixed for 10-15 minutes. Phase D components are added to the secondary vessel and mixed until homogeneous. Once the new active ingredient has dissolved (slight heating may be necessary to promote dissolution), Phase D is added to the Phase A / B mixture, and the mixture is mixed for 5-10 minutes. Then, Phase E is added and mixed until homogeneous. Notes: pH 5.5-6.0; Viscosity: Rotor-TE, S95; Speed: 0.3 rpm; Range: 400,000-700,000 mPas.

[0098] Formulation 7

[0099] Formulation 8 Formulation 8 is prepared as follows: Phase A components are combined and mixed in a homogenizer. While Phase A is being mixed, Phase B components are added and mixed. Once Phase B is dispersed, the mixture is heated to 65-70°C. Simultaneously, Phase C components are mixed in a secondary reactor and heated to 70-75°C until homogeneous. Once both Phases AB and C have reached the specified temperatures, Phase C is added to Phase AB and mixed for 15-20 minutes. Phase D components are added to the secondary reactor and mixed until homogeneous (slight heating may be necessary to promote the dissolution of new active ingredients). The ABC phase mixture is then mixed using a side-sweep method, cooled to 45°C, and Phase D is added and mixed. Phase E is prepared in the secondary reactor and mixed until homogeneous. Phase E is then added to the ABCD phase mixture and mixed for 5-10 minutes, followed by cooling to room temperature. Notes: pH 4.5-5.0; Viscosity: Rotor-TE, S95; Speed: 0.3 rpm; Range: 200,000-500,000 mPas.

[0100] Formulation 8

[0101] Formulation 9: Anti-aging emulsion Formulation 9 is prepared by the following method: Phase A components are combined and mixed in a homogenizer. While Phase A is being mixed, Phase B components are added and mixed. Once Phase B is dispersed, the mixture is heated to 65-70°C. Simultaneously, Phase C components are mixed in a secondary reactor and heated to 70-75°C until homogeneous. Once both Phases AB and C have reached the specified temperatures, Phase C is added to Phase AB and mixed for 15-20 minutes. Phase D components are added to the secondary reactor and mixed until homogeneous (slight heating may be necessary to promote the dissolution of new active ingredients). The mixing of Phases ABC is changed to a side-sweep mixing method and cooled to room temperature. Once room temperature is reached, Phase D is added and mixed for 5-10 minutes. Notes: pH 4.5-5.0; Viscosity: Rotor-TE, S95; Speed: 0.3 rpm; Range: 200,000-500,000 mPas.

[0102] Formulation 9

[0103] It is understood that those skilled in the art will be able to fully utilize this invention through the foregoing description. Furthermore, although the invention has been described with reference to the specific embodiments and examples described above, it should be understood that other embodiments, variations, and modifications utilizing the inventive concept are possible without departing from the spirit and scope of the invention, and are within the skill of those skilled in the art. Therefore, the foregoing preferred embodiments should be understood as exemplary only, and not as limiting the remainder of this disclosure in any way.

Claims

1. The compound zinc bis(dinormalbutanoyl lysine), which is shown as Structure 1: 。 2. The compound zinc bis(diisobutanoyl lysine), which is shown as Structure 2: 。 3. A composition comprising: (i) a zinc dibutanoyl lysine component selected from the group consisting of zinc bis(dinormalbutanoyl lysine), zinc bis(diisobutanoyl lysine), and mixtures thereof; (ii) optionally a skin lightening agent other than (i); and (iii) a dermatologically acceptable carrier.

4. The composition of claim 3, wherein the zinc dibutanoyl lysine component is zinc bis(dinormalbutanoyl lysine).

5. The composition of claim 3, wherein the zinc dibutanoyl lysine component is zinc bis(diisobutanoyl lysine).

6. The composition of any one of claims 3 to 5, wherein the skin lightening agent (ii) is present.

7. The composition of claim 6, wherein the skin lightening agent is selected from the group consisting of hydroquinone, bakuchiol, acetyl gingerone, and combinations of any two or more thereof.

8. The composition of any one of claims 3 to 7, wherein the zinc dibutanoyl lysine component is present in an amount of about 0.05 wt% to about 10 wt% of the total weight of the composition, the skin lightening agent (ii) is present in an amount of about 0.05 wt% to about 20 wt% of the total weight of the composition if present, and the weight ratio of the zinc dibutanoyl lysine component to the skin lightening agent (ii) is about 10: 1 to about 1 :

10.

9. The composition of any one of claims 3 to 7, wherein the zinc dibutanoyl lysine component is present in an amount of about 0.1 wt% to about 10 wt% of the total weight of the composition, the skin lightening agent (ii) is present in an amount of about 0.1 wt% to about 10 wt% of the total weight of the composition if present, and the weight ratio of the zinc dibutanoyl lysine component to the skin lightening agent (ii) is about 5: 1 to about 1 :

5.

10. The composition of any one of claims 3 to 9, further comprising one or more effective amounts of a skin protective or therapeutic ingredient.

11. The composition of claim 10, wherein the one or more skin protective or therapeutic ingredients are selected from the group consisting of a sunscreen active ingredient, an antioxidant, a vitamin, an anti-inflammatory agent, a moisturizer, an emollient, a humectant, and mixtures thereof.

12. The composition of claim 10, wherein the one or more skin protective or therapeutic ingredients are selected from the group consisting of bakuchiol, isosorbide dioctanoate, Terminalia fruit extract, ethyl linoleate, isosorbide dilinoleate, isosorbide dikikinoleate, and mixtures thereof.

13. The composition of any one of claims 3 to 12, wherein the dermatological carrier is a formula product or a base composition for producing a formula product selected from the group consisting of a cosmetic, a sunscreen product, a moisturizer, a skin serum, an anti-aging composition, an acne treatment, a general skin care product, a skin rejuvenation product, a topical pharmaceutical product, or a sunburn treatment.

14. The composition of any one of claims 3 to 13, further comprising one or more dermatologically acceptable amphoteric surfactants, ethanol, or mixtures thereof.

15. A method for lightening / brightening / evening skin tone, maintaining skin coloration and even skin tone, and / or preventing skin discoloration, the method comprising applying to an area of skin in need of the intended effect a composition containing an effective amount of a dibutyryl lysine zinc component selected from the group consisting of zinc di(dinormal butyryl lysinate), zinc di(diisobutyryl lysinate), and mixtures thereof.

16. The method of claim 15, wherein the composition comprises (i) a dibutyryl lysine zinc component, (ii) optionally a skin lightening agent other than (i), and (iii) a dermatologically acceptable carrier.

17. The method of claim 15 or 16, wherein the dibutyryl lysine zinc component is zinc di(dinormal butyryl lysinate).

18. The method of any one of claims 15 to 17, wherein the skin lightening agent (ii) is present and is selected from the group consisting of hydroquinone, acetyl gingerone, and combinations thereof.

19. The method of any one of claims 15 to 18, wherein the dibutyryl lysine zinc component is present in an amount of about 0.05 wt% to about 10 wt% of the total weight of the composition, the skin lightening agent (ii) is present in an amount of about 0.05 wt% to about 20 wt% of the total weight of the composition if present, and the weight ratio of the dibutyryl lysine zinc component to the skin lightening agent (ii) is about 10: 1 to about 1 :

10.

20. The method of any one of claims 15 to 19, wherein the composition is applied to all or substantially all of the area of the skin to achieve the effect of overall skin lightening / brightening / evening of skin tone.

21. The method of any one of claims 15 to 19, wherein the composition is applied to an area of the skin that exhibits hyperpigmentation and / or uneven or mottled skin tone.

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