L-histyl-β-alanyl-cinnamic acid derivatives and their uses in cosmetics

Abstract

This invention discloses an L-histyl-β-alanyl-cinnamic acid derivative and its use in cosmetics. Specifically, this invention provides an L-histyl-β-alanyl-cinnamic acid derivative, which is a compound as shown in formula (I). The compound provided by this invention has good water solubility and stability, antioxidant and anti-glycation properties, brightens skin tone, and has excellent ultraviolet protection performance, and will have great potential in the cosmetics field.

Description

Technical Field

[0001] This invention relates to an L-histyl-β-alanyl-cinnamic acid derivative and its use in cosmetics. Background Technology

[0002] UV exposure can induce the production of reactive oxygen species (ROS) in the skin, accelerating collagen degradation, melanin deposition, and wrinkle formation, thus accelerating photoaging. Highly effective anti-aging ingredients need to simultaneously provide antioxidant, anti-wrinkle, and anti-glycation benefits, ideally with UV protection as well; however, currently, single ingredients often fail to achieve all these benefits.

[0003] Cinnamic acid and its derivatives exhibit significant bioactivity in numerous fields. In cosmetics, some cinnamic acid derivatives possess antioxidant, skin-conditioning, and skin-brightening effects. For instance, p-hydroxycinnamic acid has been studied for treating pigmentation problems, while methoxycinnamic acid, due to the conjugation of the acrylic group and benzene ring in its molecular structure, exhibits excellent UV absorption properties and has been widely used in sunscreen products. In the pharmaceutical field, cinnamic acid derivatives have potential applications in treating cancer, bacterial infections, diabetes, and neurological disorders. However, cinnamic acid and its derivatives suffer from poor stability, poor solubility in both water and oil phases, and susceptibility to degradation by light, heat, and oxygen, leading to yellowing and inactivation. These issues significantly limit their use in cosmetics.

[0004] Carnosine (β-alanyl-L-histidine), a natural dipeptide, is widely found in human tissues such as muscles and the brain. It possesses excellent anti-glycation and anti-aging effects, inhibiting collagen degradation, reducing the formation of advanced glycation end products (AGEs), and improving skin problems such as sagging and dullness caused by glycation. However, in practical applications, carnosine has limited penetration efficiency in the skin, is easily hydrolyzed by carnosinase in the skin environment, has a half-life of less than 30 minutes, and is difficult to sustain its effects on the dermis. Furthermore, when used alone, its overall effect on improving skin aging has significant room for improvement.

[0005] Existing technologies have developed many cinnamic acid derivatives (such as p-hydroxycinnamic acid, p-methoxycinnamic acid, caffeic acid, citric acid, ferulic acid, etc.), which have partially improved stability but sacrificed some bioactivity, failing to achieve both brightening and anti-aging effects simultaneously. Currently, the traditional method of combining cinnamic acid and its derivatives with carnosine is mainly a simple physical compounding, but this has significant drawbacks. First, the synergistic effect is insufficient; the two molecules have independent structures, and their transdermal absorption is asynchronous, making it difficult to achieve effective concentrations at the target site simultaneously. Second, the stability problem has not been fundamentally solved; the simple physical compounding system cannot avoid the degradation and deterioration of cinnamic acid and its derivatives. Third, carnosine is a water-soluble molecule, while cinnamic acid is an oil-soluble molecule; their formulation compatibility is poor, making widespread application difficult.

[0006] Therefore, there is a need to develop a cinnamic acid derivative with good bioactivity, high stability, and good formulation compatibility to meet the needs of cosmetics. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of insufficient biological activity, poor stability and poor water solubility of cinnamic acid derivatives in the prior art, and to provide an L-histyl-β-alanyl-cinnamic acid derivative with good water solubility and stability, antioxidant, anti-glycation, skin brightening and excellent ultraviolet protection performance.

[0008] The present invention solves the above-mentioned technical problems through the following technical solution:

[0009] This invention provides an L-histyl-β-alanyl-cinnamic acid derivative, which is a compound as shown in formula (I).

[0010] ;

[0011] The wavy line directly connected to the double bond indicates that the double bond is of E or Z configuration;

[0012] Structural unit for , , , , or .

[0013] In some implementations, the double bond is of the E configuration.

[0014] In some embodiments, the L-histyl-β-alanyl-cinnamic acid derivative is

[0015] , , , , or .

[0016] This invention also provides a method for preparing an L-histyl-β-alanyl-cinnamic acid derivative, comprising the following steps:

[0017] In the presence of a solvent and a base, the compound shown in formula (II) undergoes a demethylation reaction to produce the compound shown in formula (I);

[0018] ;

[0019] Among them, structural units The definition is as described in any embodiment of this invention.

[0020] In some embodiments, the method for preparing the L-histyl-β-alanyl-cinnamic acid derivative further includes the following steps:

[0021] In the presence of a solvent and a coupling agent, carnosine methyl ester and the compound shown in formula (III) undergo a condensation reaction to give the compound shown in formula (II);

[0022] .

[0023] In some embodiments, the method for preparing the L-histyl-β-alanyl-cinnamic acid derivative further includes the following steps:

[0024] Carnosine and methanol undergo an esterification reaction to produce carnosine methyl ester;

[0025] .

[0026] The conditions and procedures for the demethylation, condensation, and esterification reactions described herein are conventional reaction conditions and procedures for such reactions in the art.

[0027] In some embodiments, methanol is also used as a solvent in the esterification reaction.

[0028] In some embodiments, acetyl chloride is also added to the esterification reaction.

[0029] In some embodiments, the molar ratio of carnosine to acetyl chloride in the esterification reaction is 1:(2~6); for example, 1:4.

[0030] In some embodiments, the esterification reaction is carried out at a temperature of 10–40 °C; for example, 15–25 °C.

[0031] In some embodiments, the esterification reaction is carried out under a protective gas atmosphere, such as nitrogen atmosphere.

[0032] The esterification reaction process can be monitored by conventional detection methods in the art (e.g., HPLC, TLC, NMR, etc.), generally until carnosine disappears or the reaction stops, and the reaction time can be 2 to 6 hours; for example, 4 hours.

[0033] In some embodiments, the solvent in the condensation reaction is DMF.

[0034] In some embodiments, the coupling agent in the condensation reaction is one or more of DCC (dicyclohexylcarbodiimide), DIC (diisopropylcarbodiimide), EDC (1-ethyl-(3-dimethylaminopropyl)carbodiimide), HATU (O-(7-aminobenzotriazol-1-yl)-N,N,N',N'-tetramethylurea hexafluorophosphate), and TBTU (O-benzotriazol-N,N,N',N'-tetramethylurea tetrafluoroborate); for example, DCC.

[0035] In some embodiments, the condensation reaction is further complicated by the addition of an adjuvant, which is one or more of HOBt (1-hydroxybenzotriazole), HOAt (1-hydroxy-7-aminobenzotriazole), NMM (4-methylmorpholine), DIPEA (diisopropylethylamine), and DMAP (4-dimethylaminopyridine); for example, HOBt and DMAP.

[0036] In some embodiments, the molar ratio of carnosine methyl ester and the compound shown in formula (III) in the condensation reaction is 1:(0.8~1.5); for example, 1:1.

[0037] In some embodiments, the molar ratio of carnosine methyl ester to the coupling agent in the condensation reaction is 1:(1~2); for example, 1:1.5.

[0038] In some embodiments, the molar ratio of carnosine methyl ester to the adjuvant in the condensation reaction is 1:(2-4); for example, 1:3.

[0039] In some embodiments, when the auxiliaries are HOBt and DMAP, the molar ratio of HOBt to DMAP is 1:(1.5~2.5); for example, 1:2.

[0040] In some embodiments, the condensation reaction is carried out at a temperature of 10-40 °C; for example, 25 °C.

[0041] The condensation reaction process can be monitored by conventional detection methods in the art (e.g., HPLC, TLC, NMR, etc.), generally until carnosine methyl ester disappears or no longer reacts, and the reaction time can be 1 to 3 hours; for example, 2 hours.

[0042] In some embodiments, the condensation reaction further includes the following post-processing step: after the reaction is complete, the reaction solution is filtered, and the filter cake is purified by HPLC.

[0043] In some embodiments, in the demethylation reaction, the solvent is a mixture of an organic solvent and water; for example, a mixture of THF and water; the volume ratio of the organic solvent to water may be 1:(0.5~3); for example, 1:1.

[0044] In some embodiments, the base in the demethylation reaction is an alkali metal hydroxide, such as lithium hydroxide.

[0045] In some embodiments, in the demethylation reaction, the molar ratio of the compound as shown in formula (II) to the base is 1:(1.5~2.5); for example, 1:2.

[0046] In some embodiments, the reaction temperature in the demethylation reaction is 10-40 °C; for example, 15-25 °C.

[0047] The reaction process of the demethyl esterification reaction can be monitored by conventional detection methods in the art (e.g., HPLC, TLC, NMR, etc.), generally until the compound shown in formula (II) disappears or no longer reacts, and the reaction time can be 1 to 3 hours; for example, 2 hours.

[0048] In some embodiments, the demethylation reaction further includes the following post-treatment steps: after the reaction is completed, HCl aqueous solution is added to quench the reaction, the pH is adjusted to 5, and the mixture is purified by rotary evaporation and HPLC.

[0049] The present invention also provides a carnosine methyl ester cinnamic acid derivative, which is a compound as shown in formula (II);

[0050] ;

[0051] Among them, structural units The definition is as described in any embodiment of this application.

[0052] This invention also provides a method for preparing a carnosine methyl ester cinnamic acid derivative, comprising the following steps:

[0053] In the presence of a solvent and a coupling agent, carnosine methyl ester and the compound shown in formula (III) undergo a condensation reaction to give the compound shown in formula (II);

[0054] ;

[0055] Among them, structural units The definition is as described in any of the claims in this application.

[0056] In some embodiments, the conditions and operation of the condensation reaction are as described in any one of the present applications.

[0057] The present invention also provides a cosmetic comprising the L-histyl-β-alanyl-cinnamic acid derivative as described in any embodiment of the present invention.

[0058] In some embodiments, the concentration of the L-histyl-β-alanyl-cinnamic acid derivative in the cosmetic is 10 to 10,000 ppm. The concentration refers to the mass fraction of the L-histyl-β-alanyl-cinnamic acid derivative in the cosmetic.

[0059] In some embodiments, the cosmetic has one or more of the following effects: (1) inhibiting advanced glycation end products (anti-glycation); (2) inhibiting DPPH free radicals (antioxidant); (3) inhibiting tyrosinase activity; (4) good stability; (5) good water solubility; and (6) good ultraviolet absorption performance.

[0060] The present invention also provides the application of L-histyl-β-alanyl-cinnamic acid derivatives as described in any one of the claims in cosmetics.

[0061] Unless otherwise stated, the definitions of groups and terms recorded in this specification and claims, including definitions as examples, exemplary definitions, preferred definitions, definitions recorded in tables, and definitions of specific compounds in the examples, can be arbitrarily combined and combined with each other. Such combinations and combinations of group definitions and compound structures should fall within the scope of this specification.

[0062] The term "cosmetics" refers to chemical industrial products or fine chemical products that are applied to any part of the human body surface, such as skin, hair, nails, lips, and teeth, by means of smearing, spraying, or other similar methods, for the purpose of cleansing, maintaining, beautifying, modifying appearance, or correcting body odor and maintaining a good condition. Without impairing the effectiveness of this invention, the L-histyl-β-alanyl-cinnamic acid derivatives or cosmetics provided by this invention may be appropriately compounded as needed with various ingredients commonly used in the cosmetic field, such as powder components, moisturizers, emulsifiers, thickeners, metal ion masking agents, pigments, pH adjusters, skin nutrients, vitamins, preservatives, antioxidants, antioxidant auxiliaries, fragrances, etc.

[0063] The positive and progressive effects of this invention are as follows:

[0064] 1. The L-histyl-β-alanyl-cinnamic acid derivative provided by this invention exhibits excellent performance in anti-oxidation, anti-glycation, skin brightening, and UV protection, combining the multiple effects of cinnamic acid derivatives (antioxidant, brightening, UV protection) with carnosine's anti-aging and anti-glycation properties. Compared to using carnosine alone, its skin brightening and antioxidant effects are significantly improved; compared to using cinnamic acid derivatives alone, its anti-glycation and anti-aging effects are significantly improved. Furthermore, it is effective at the ppm level, with low irritation, and has broad application prospects in the cosmetic and skincare fields for anti-aging and skin improvement.

[0065] 2. The compound provided by this invention has high stability, retaining a high degree of integrity even after one month at 48 °C, and its color and appearance remain stable.

[0066] 3. All the compounds provided by this invention are water-soluble compounds, with a solubility of more than 10% in aqueous solution. This solves the application problem of cinnamic acid derivatives, increases their upper limit of use, and the stability of the compounds with the new structure is also greatly improved, which greatly expands their application range in skin care products.

[0067] 4. The compound provided by this invention also has ultraviolet absorption effect, which can absorb ultraviolet rays and reduce sunburn. It can protect against ultraviolet rays while anti-aging and repairing, and has great potential in the cosmetics field.

[0068] 5. The compounds provided by this invention have the effects of improving skin radiance, improving skin softness, repairing dull skin, and brightening skin tone, making the skin look more vibrant and youthful. Attached Figure Description

[0069] Figure 1 The 1H NMR spectrum of the L-histyl-β-alanyl-cinnamic acid derivative of formula (6) is shown.

[0070] Figure 2 Stability data for L-histyl-β-alanyl-cinnamic acid derivatives.

[0071] Figure 3 The UV absorption spectrum of the L-histyl-β-alanyl-cinnamic acid derivative is shown. Detailed Implementation

[0072] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0073] Example 1: Synthesis of L-histyl-β-alanyl-cinnamic acid derivative

[0074] The reagent information used in the preparation process of this invention is shown in Table 1.

[0075] Table 1. Information on reagents used

[0076]

[0077]

[0078] Taking cinnamic acid carnosine of formula (1) as an example, the specific synthesis steps are as follows:

[0079] ;

[0080] The esterification reaction was carried out as follows: Carnosine (formula (A), 10 g, 44.20 mmol) was dissolved in 250 mL of methanol, and acetyl chloride (13.81 g, 175.93 mmol) was added dropwise. The mixture was stirred at room temperature for 4 h under a N2 atmosphere. After the reaction was completed, the reaction solution was filtered, and the solvent was removed by vacuum concentration using a rotary evaporator to obtain crude white solid carnosine methyl ester (10.5 g).

[0081] The condensation reaction was carried out as follows: Carnosine methyl ester (5 g, 20.81 mmol) and cinnamic acid (formula (B1), 4.04 g, 20.81 mmol) obtained from the esterification reaction were dissolved in 100 mL of DMF solution, and coupling reagents DCC (6.44 g, 31.22 mmol), HOBt (2.81 g, 20.81 mmol), and DMAP (5.08 g, 41.62 mmol) were added. The reaction solution was stirred at 25 °C for 2 h. After completion, the reaction solution was filtered. The filter cake was purified by preparative HPLC (Phenomenex luna C18 column (250*70 mm, 15 μm); mobile phase [H2O (0.04% HCl)-acetonitrile]) to obtain a yellow solid (2 g, 4.80 mmol).

[0082] The demethylation reaction was performed as follows: 2 g (4.80 mmol) of the yellow solid obtained from the condensation reaction was dissolved in a mixed solvent of THF:H2O (1:1, 15 mL each), and LiOH (403.08 mg, 9.61 mmol) was added. The reaction mixture was stirred at room temperature for 2 h. After completion, the reaction was quenched with 1M HCl, the pH was adjusted to 5, and the solvent was removed by vacuum concentration using a rotary evaporator. The residue was purified by preparative HPLC (WePure Biotech XP tC18 250*70*10 μm column; mobile phase [H2O (10 mM ammonium bicarbonate)-acetonitrile]) to obtain the final product, white solid cinnamic acid carnosine (formula (1), 628 mg), with a yield of 30.6% and a purity of 94.3%.

[0083] Equation (1) 1 H NMR (400 MHz): δ 2.39-2.52 (3H, 2.45 (dd, J = 6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (2H, 3.12 (d, J = 6.74 Hz), 3.12 (d,J = 6.74 Hz)), 3.30-3.43 (2H, 3.36 (dd, J = 6.52, 6.52 Hz), 3.36 (dd, J =6.52, 6.52 Hz)), 4.58 (1H, dd, J = 6.74, 6.74 Hz), 6.68 (1H, d, J = 15.58Hz), 6.94 (1H, d, J = 1.71 Hz), 7.35-7.62 (7H, 7.43 (dddd, J = 8.08, 7.24,1.99, 0.46 Hz), 7.43 (tt, J = 7.24, 1.32 Hz), 7.50 (dddd, J = 8.08, 2.28,1.32, 0.46 Hz), 7.55 (d, J = 15.58 Hz)), 7.69 (1H, d, J = 1.71 Hz).

[0084] Synthesis method of p-hydroxycinnamic acid carnosine of formula (2): The raw materials and preparation method are basically the same as those of the compound of formula (1), except that: the cinnamic acid (formula (B1)) in the condensation reaction is replaced with p-hydroxycinnamic acid (formula (B2)) to obtain p-hydroxycinnamic acid carnosine of formula (2). 1H NMR (400 MHz): δ 2.39-2.52 (3H, 2.45 (dd, J =6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (3H, 3.12 (d, J =6.74 Hz), 3.12 (d, J = 6.74 Hz)), 3.28-3.42 (3H, 3.35 (dd, J = 6.52, 6.52Hz), 3.35 (dd, J = 6.52, 6.52 Hz)), 4.58 (1H, dd, J = 6.74, 6.74 Hz), 6.54(1H, d, J = 15.57 Hz), 6.83-6.99 (4H, 6.89 (ddd, J = 8.02, 1.79, 0.44 Hz), 6.94 (d, J = 1.71 Hz)), 7.42-7.59 (4H, 7.49 (d, J = 15.57 Hz), 7.53 (ddd, J =8.02, 1.91, 0.44 Hz)), 7.69 (1H, d, J = 1.71 Hz).

[0085] Synthesis method of p-methoxycinnamic acid carnosine of formula (3): The raw materials and preparation method are basically the same as those of the compound of formula (1), except that: cinnamic acid (formula (B1)) in the condensation reaction is replaced with p-methoxycinnamic acid (formula (B3)) to obtain p-methoxycinnamic acid carnosine of formula (3). 1H NMR (400 MHz): δ 2.39-2.52 (2H, 2.45 (dd, J= 6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (2H, 3.12 (d, J =6.74 Hz), 3.12 (d, J = 6.74 Hz)), 3.28-3.42 (2H, 3.35 (dd, J = 6.52, 6.52Hz), 3.35 (dd, J = 6.52, 6.52 Hz)), 3.77 (4H, s), 4.58 (1H, dd, J = 6.74,6.74 Hz), 6.53 (1H, d, J = 15.58 Hz), 6.94 (1H, d, J = 1.71 Hz), 7.16 (2H,ddd, J = 8.80, 1.24, 0.46 Hz), 7.40-7.56 (4H, 7.46 (ddd, J = 8.80, 1.75, 0.46Hz), 7.49 (d, J = 15.58 Hz)), 7.69 (1H, d, J = 1.71 Hz).

[0086] Synthesis method of 3-hydroxy-4-methoxycinnamic acid carnosine of formula (4): The raw materials and preparation method are basically the same as those of the compound of formula (1), except that the cinnamic acid (formula (B1)) in the condensation reaction is replaced with 3-hydroxy-4-methoxycinnamic acid (formula (B4)) to obtain 3-hydroxy-4-methoxycinnamic acid carnosine of formula (4). 1H NMR (400 MHz): δ 2.39-2.52 (3H, 2.45 (dd, J = 6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (3H, 3.12 (d, J = 6.74 Hz), 3.12 (d, J = 6.74 Hz)), 3.29-3.42 (3H, 3.35(dd, J = 6.52, 6.52 Hz), 3.35 (dd, J = 6.52, 6.52 Hz)), 3.92 (4H, s), 4.58(1H, dd, J = 6.74, 6.74 Hz), 6.54 (1H, d, J = 15.58 Hz), 6.76 (1H, dd, J =8.44, 0.45 Hz), 6.94 (1H, d, J = 1.71 Hz), 7.24 (1H, dd, J = 1.95, 0.45 Hz), 7.50 (1H, d, J = 15.58 Hz), 7.62-7.75 (3H, 7.68 (dd, J = 8.44, 1.95 Hz), 7.69(d, J = 1.71 Hz)).

[0087] Synthesis method of 3,4-dimethoxycinnamic acid carnosine of formula (5): The raw materials and preparation method are basically the same as those of the compound of formula (1), except that the cinnamic acid (formula (B1)) in the condensation reaction is replaced with 3,4-dimethoxycinnamic acid (formula (B5)) to obtain 3,4-dimethoxycinnamic acid carnosine of formula (5). 1H NMR (400 MHz): δ 2.39-2.52 (2H,2.45 (dd, J = 6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (2H,3.12 (d, J = 6.74 Hz), 3.12 (d, J = 6.74 Hz)), 3.29-3.42 (2H, 3.35 (dd, J =6.52, 6.52 Hz), 3.35 (dd, J = 6.52, 6.52 Hz)), 3.79 (4H, s), 3.95 (4H, s),4.58 (1H, dd, J = 6.74, 6.74 Hz), 6.54 (1H, d, J = 15.68 Hz), 6.77 (1H, dd, J= 8.44, 0.44 Hz), 6.94 (1H, d, J = 1.71 Hz), 7.22 (1H, dd, J = 1.95, 0.44Hz), 7.51 (1H, d, J = 15.68 Hz), 7.62-7.74 (2H, 7.68 (dd, J = 8.44, 1.95 Hz), 7.69 (d, J = 1.71 Hz)).

[0088] Synthesis of Ferulic Acid Glyceryl Ether Carnosine (Formula (6)): The raw materials and preparation method are basically the same as those of the compound in Formula (1), except that cinnamic acid (Formula (B1)) in the condensation reaction is replaced with ferulic acid glyceryl ether (Formula (B6)). The preparation method of ferulic acid glyceryl ether (Formula (B6)) is as follows: 3-methoxy-4-hydroxycinnamic acid (873.85 mg, 4.50 mmol) is dissolved in 15 mL of ethanol, and triethylamine (455.33 mg, 4.50 mmol) and glycidol (333.33 mg, 4.50 mmol) are added. The reaction solution is stirred at 60 °C for 12 h. Then, water (20 mL) is added to the reaction solution, and the mixture is extracted with ethyl acetate (20 mL × 3 times). The organic layer is then washed with saturated brine (20 mL). After drying with anhydrous sodium sulfate, the mixture is filtered and concentrated under reduced pressure to obtain the residue. Purification by silica gel column chromatography (hexane / ethyl acetate system) yielded a white solid ferulic acid glyceryl ether (formula (B6)). The remaining steps were consistent with the preparation of compound (1), yielding ferulic acid glyceryl ether carnosine as shown in formula (6). 1H NMR (400 MHz): δ2.39-2.52 (3H, 2.45 (dd, J = 6.52, 6.52 Hz), 2.45 (dd, J = 6.52, 6.52 Hz)), 3.06-3.18 (3H, 3.12 (d, J = 6.74 Hz), 3.12 (d, J = 6.74 Hz)), 3.29-3.42 (3H,3.35 (dd, J = 6.52, 6.52 Hz), 3.35 (dd, J = 6.52, 6.52 Hz)), 3.43-3.55 (3H,3.49 (d, J = 5.49 Hz), 3.49 (d, J = 5.49 Hz)), 3.75 (4H, s), 4.00 (1H, dddd,J = 5.49, 5.49, 5.27, 5.27 Hz), 4.10-4.22 (3H, 4.16 (d, J = 5.27 Hz), 4.16(d, J = 5.27 Hz)), 4.58 (1H, dd, J = 6.74, 6.74 Hz), 6.53 (1H, d, J = 15.68Hz), 6.73 (1H, dd, J = 8.43, 0.44 Hz), 6.94 (1H, d, J = 1.71 Hz), 7.22 (1H,dd, J = 1.95, 0.44 Hz), 7.44-7.74 (4H, 7.51 (d, J = 15.68 Hz), 7.58 (dd, J = 8.43, 1.95 Hz), 7.69 (d, J = 1.71 Hz). The proton NMR spectrum of the compound shown in formula (6) is as follows: Figure 1 As shown.

[0089] Example 2: Anti-glycation efficacy test of L-histyl-β-alanyl-cinnamic acid derivatives

[0090] 1. The causes of human skin aging are divided into endogenous and exogenous factors. Exogenous factors mainly include sun exposure, oxidation, and glycation. Glycation here refers to the non-enzymatic glycosylation reaction of proteins. That is, under non-enzymatic conditions, the free amino groups of macromolecules such as proteins, amino acids, lipids, or nucleic acids undergo a series of reactions such as condensation, rearrangement, cleavage, and oxidative modification with the carbonyl groups of reducing sugars, ultimately forming advanced glycation end products (AGEs). AGEs are closely related to skin aging. Excessive AGEs can undergo glycation cross-linking reactions with skin elastic fibers and collagen. AGEs are brown in color, ultimately causing the skin to appear yellowish and lose elasticity.

[0091] Conventional AGEs have fluorescent properties. The principle of AGEs generation by glucose and bovine serum albumin undergoing glycation in vitro can be used to create a model. After adding the sample to be tested, the level of inhibition of AGEs is evaluated by fluorescence quantitative method to reflect its anti-glycation efficacy.

[0092] 2. Experimental Methods

[0093] (1) Fructose and bovine serum albumin (BSA) were dissolved in phosphate buffer (0.2 mol / L, pH=7.4) to a final concentration of 1.5 mol / L and 60 mg / mL, respectively, to construct a protein saccharification system.

[0094] (2) Experimental grouping: A blank group, a sample group, a positive control group, a control group A, a control group B, and a control group C were set up. No sample was added to the blank group. The sample group was 1000 ppm L-histyl-β-alanyl-cinnamic acid derivative (Formulas 1 to 6). The positive control group was 1000 ppm aminoguanidine. The control group A was 1000 ppm cinnamic acid. The control group B was 1000 ppm carnosine. The control group C was a simple physical mixture of 500 ppm cinnamic acid and 500 ppm carnosine.

[0095] (3) Take 500 μL of BSA, 500 μL of fructose solution and 500 μL of the test sample, place them in a 10 mL sample tube, and incubate them together at 50°C for 24 h as the experimental group. The blank group is replaced with 500 μL of deionized water, and the positive control group is replaced with 500 μL of aminoguanidine.

[0096] (4) After incubation, dilute with phosphate buffer 20 times, and use a fluorescence microplate reader to detect the fluorescence intensity at an excitation wavelength of 370 nm and an emission wavelength of 440 nm to calculate the amount of AGEs generated.

[0097] (5) AGEs inhibition rate (%) = (1 − fluorescence intensity of this group / fluorescence intensity of blank group) × 100%

[0098] 3. Experimental Results

[0099] The results of the anti-glycation experiment for different groups are shown in Table 2 below. Compared with the blank group, *P<0.05, **P<0.01, ***P<0.001.

[0100] Table 2. Experimental results of AGEs inhibition rate

[0101]

[0102] As can be seen from the experimental results in Table 2, the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) prepared in this invention all have a significant inhibitory effect on AGEs (advanced glycation end products) at a concentration of 1000 ppm, with inhibition rates ranging from 61.20% to 74.52%. Among them, 3,4-dimethoxycinnamic acid carnosine (Formula 5) has the best inhibitory effect, with an inhibition rate of up to 74.52% on AGEs, demonstrating good anti-glycation efficacy. In addition, the cinnamic acid carnosine shown in Formula (1) is prepared by chemical covalent coupling of cinnamic acid and carnosine. Its inhibition rate on AGEs at 1000 ppm is 61.20%, which is higher than that of cinnamic acid (inhibition rate 20.11%) and carnosine (inhibition rate 44.74%) at the same concentration, and also higher than that of a simple physical mixture of cinnamic acid and carnosine (inhibition rate 36.59%). This demonstrates that coupling cinnamic acid with carnosine produces a powerful anti-glycation effect, exhibiting a synergistic effect superior to that of either of the two raw material compounds or their physical mixture. This L-histyl-β-alanyl-cinnamic acid derivative has a low effective concentration but significant efficacy, showcasing its potential application in skincare products. Therefore, the L-histyl-β-alanyl-cinnamic acid derivative prepared in this invention combines the dual effects of carnosine's anti-glycation properties and cinnamic acid's antioxidant properties, effectively delaying skin aging and improving dull skin tone.

[0103] Example 3: Antioxidant efficacy test of L-histyl-β-alanyl-cinnamic acid derivative

[0104] 1. Oxidative stress refers to an imbalance between free radicals and the body's antioxidant defense system. Under ultraviolet radiation, the body produces a large number of free radicals. Free radicals are highly reactive molecules with unpaired electrons that can trigger chain reactions, leading to cell membrane lipid peroxidation, protein denaturation, and DNA damage, thereby promoting the occurrence and development of various diseases, including cardiovascular disease, neurodegenerative diseases, diabetes, and skin aging. Studies have shown that carnosine, as an antioxidant, can protect cells from oxidative stress by scavenging free radicals, inhibiting free radical generation, or repairing oxidative damage. Cinnamic acid derivatives mostly contain phenolic hydroxyl groups (-OH) and unsaturated double bonds (C=C) in their molecular structure, which can effectively scavenge free radicals and reduce the formation of oxidation products.

[0105] DPPH (2-diphenyl hydrazy) is a stable free radical commonly used to evaluate the in vitro antioxidant activity of antioxidant components. DPPH free radicals possess a single electron and exhibit strong absorption at 517 nm, turning their alcoholic solution purple. In the presence of a free radical scavenger, the absorption gradually disappears due to the pairing of the DPPH free radical with its single electron. The degree of fading is quantitatively related to the number of electrons accepted, allowing for rapid quantitative analysis using a spectrophotometer. The determination of DPPH free radical scavenging rate is a widely used method for screening and evaluating the antioxidant capacity of antioxidants; a higher DPPH scavenging rate indicates stronger antioxidant capacity.

[0106] 2. Experimental Methods

[0107] (1) Prepare a 0.1 mmol / L DPPH solution with anhydrous ethanol and store it in the dark.

[0108] (2) Experimental grouping: A blank group, a sample group, a positive control group, a control group A, a control group B, and a control group C were set up. The blank group was a solvent (ethanol) without any sample. The sample group was 100 ppm L-histyl-β-alanyl-cinnamic acid derivative (Formulas 1 to 6). The positive control group was 100 ppm glutathione. The control group A was 100 ppm cinnamic acid. The control group B was 100 ppm carnosine. The control group C was a simple physical mixture of 50 ppm cinnamic acid and 50 ppm carnosine.

[0109] (3) Add 2 mL of sample solution and 2 mL of DPPH solution to the same test tube, shake well, let stand in the dark at room temperature for 30 min, and measure its absorbance A. 样品 At the same time, the absorbance A0 of 2 mL DPPH solution mixed with 2 mL solvent (ethanol) was measured.

[0110] (4) Calculation formula: DPPH free radical scavenging rate (%) = (A0 - A 样品 ) / A0×100% (A0 is the absorbance of DPPH at 517 nm without sample; A 样品 (The absorbance of the DPPH of the sample added at 517 nm)

[0111] 3. Experimental Results

[0112] The antioxidant experiment results for different groups are shown in Table 3 below. Compared with the blank group, *P<0.05, **P<0.01, ***P<0.001.

[0113] Table 3. Experimental results of DPPH inhibition rate

[0114]

[0115] As can be seen from the experimental results in Table 3, the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) prepared in this invention all exhibit significant DPPH free radical inhibition effects at a concentration of 100 ppm, with inhibition rates ranging from 29.77% to 35.56%. Among them, p-hydroxycinnamic acid carnosine (Formula 2) showed the best inhibition effect, with an inhibition rate of up to 35.56% against DPPH, demonstrating excellent antioxidant efficacy. In addition, the cinnamic acid carnosine shown in Formula (1) is prepared by chemical covalent coupling of cinnamic acid and carnosine. Its DPPH inhibition rate at 100 ppm is 29.77%, which is higher than that of cinnamic acid (inhibition rate 15.32%) and carnosine (inhibition rate 19.49%) at the same concentration, and also higher than that of a simple physical mixture of cinnamic acid and carnosine (inhibition rate 24.26%). This indicates that coupling cinnamic acid and carnosine can produce a strong antioxidant effect, which is superior to that of the two raw material compounds and the physical mixture of the two raw material compounds. This L-histyl-β-alanyl-cinnamic acid derivative has a low effective concentration but a significant effect, demonstrating its potential application in skincare products.

[0116] Example 4: Inhibition of Tyrosinase Activity by L-Histyl-β-Alanyl-Cinnamic Acid Derivatives

[0117] 1. In the biosynthesis of melanin in the skin, tyrosinase is a key enzyme that acts on dopa to form dopaquinone, which then spontaneously undergoes a series of reactions to ultimately form melanin. Tyrosinase catalyzes the conversion of dopa to dopaquinone in a phosphoric acid solution at pH 6.8, and the absorbance can be measured at 475 nm using a spectrophotometer. Raw materials that inhibit tyrosinase activity can reduce the conversion of dopa to dopaquinone, thereby lowering the absorbance. The inhibitory effect of the raw materials on tyrosinase activity can be evaluated based on changes in absorbance.

[0118] 2. Experimental Methods

[0119] (1) Experimental grouping: Sample group, positive control group, control group A, control group B and control group C were set up. The sample group was 1000 ppm L-histyl-β-alanyl-cinnamic acid derivative (Formula 1 to Formula 6), the positive control group was 1000 ppm kojic acid, control group A was 1000 ppm cinnamic acid, control group B was 1000 ppm carnosine, and control group C was a simple physical mixture of 500 ppm cinnamic acid and 500 ppm carnosine.

[0120] (2) Prepare the sample into a test solution of the corresponding concentration and prepare the reaction system according to the amount of each reagent added in Table 4.

[0121] Table 4 Sample Addition Settings

[0122]

[0123] In the formula:

[0124] T: The average of three absorbance values ​​of the sample tube, i.e., the absorbance of the solution after the sample reacts with tyrosinase;

[0125] T0: Sample background absorbance;

[0126] C: The average of three absorbance readings from the enzyme reaction tube, i.e., the absorbance of the tyrosinase and dopa reaction without the addition of sample;

[0127] C0: Solvent background absorbance.

[0128] (3) Mix the sample and tyrosinase thoroughly and incubate in a 37 °C water bath for 10 min. Add levodopa solution to each tube in sequence, control the reaction time of each tube to 5 min, and immediately transfer the reaction solution of each tube into a cuvette and measure the absorbance at 475 nm.

[0129] (4) Tyrosinase activity inhibition rate (%) = [1-(T-T0) / (C-C0)]×100%

[0130] 3. Experimental Results

[0131] The results of the tyrosinase activity inhibition rate experiments for different groups are shown in Table 5 below.

[0132] Table 5. Results of the experiment on the inhibition rate of tyrosinase activity.

[0133]

[0134] As can be seen from the experimental results in Table 5, the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) prepared in this invention all exhibit significant inhibitory effects on tyrosinase activity at a concentration of 1000 ppm, with inhibition rates ranging from 47.23% to 71.14%. Among them, 3,4-dimethoxycinnamic acid carnosine (Formula 5) showed the best inhibitory effect, with an inhibition rate of up to 71.14% on tyrosinase activity. In addition, the cinnamic acid carnosine shown in Formula (1) is prepared by chemical covalent coupling of cinnamic acid and carnosine. Its inhibition rate on tyrosinase activity at 1000 ppm is 47.23%, which is higher than that of cinnamic acid (inhibition rate 32.21%) and carnosine (inhibition rate 15.99%) at the same concentration, and also higher than that of a simple physical mixture of cinnamic acid and carnosine (inhibition rate 25.68%). This indicates that preparing a conjugate from cinnamic acid and carnosine through appropriate chemical modification has a synergistic effect in inhibiting tyrosinase activity and thus melanin production, with significantly better results than either of the two raw material compounds or their physical mixture. This result demonstrates the beneficialness of chemically conjugating cinnamic acid derivatives and carnosine in this invention. The prepared L-histyl-β-alanyl-cinnamic acid derivative improves the stability of cinnamic acid derivatives without losing their original brightening effects; on the contrary, it enhances the skin-brightening effect. This may be related to the improved structural stability of the cinnamic acid derivative and the anti-glycation properties of carnosine.

[0135] Example 5: Stability test of L-histyl-β-alanyl-cinnamic acid derivative

[0136] 1. Experimental Methods

[0137] Weigh out 5 mg of each of the L-histyl-β-alanyl-cinnamic acid derivative powders (Formulas 1 to 6), dissolve them in 5 mL of ultrapure water to prepare a 1 mg / mL solution, and place them in a 48 °C oven for 4 weeks. At week 0, week 1, week 2, and week 4, take 1 mL from each bottle, and determine its purity by high-performance liquid chromatography (HPLC). Visually observe the changes in color appearance. The control group consisted of a cinnamic acid solution of the same concentration. The stability of each sample was evaluated by measuring its purity at 254 nm. The stability calculation formula is as follows:

[0138] Stability (%) = Peak area ratio at week n / Peak area ratio at week 0 × 100%

[0139] 2. Experimental Results

[0140] The stability of each group of samples under light-protected conditions at 48 °C is shown in Table 6 and Figure 2 As shown.

[0141] Table 6. Stability test results of L-histyl-β-alanyl-cinnamic acid derivatives

[0142]

[0143] From Table 6 and Figure 2 It can be seen that the original cinnamic acid retained about 78% after one week, and only 60% after four weeks, and all of it turned yellow, indicating very poor stability. Therefore, its application in cosmetics is very limited. Among the six derivatives prepared in this invention, the compounds shown in formulas (5) and (6) have the best stability, maintaining more than 99% integrity after four weeks, and showing no significant change in color appearance. The purity of the other L-histyl-β-alanyl-cinnamic acid derivatives was also higher than 75% after four weeks, which is better than that of cinnamic acid. This indicates that the conjugate of cinnamic acid and carnosine improves the stability of cinnamic acid and broadens the application range of this type of cosmetic raw material in formulations.

[0144] Example 6: Solubility of L-histyl-β-alanyl-cinnamic acid derivatives

[0145] 1. Experimental Methods

[0146] Weigh out 5 mg of each of the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) powders (4 portions), add 5 mL, 500 μL, 50 μL and 25 μL of ultrapure water respectively, and solubilize them in an ultrasonic cleaner at room temperature for 15 min. Observe their solubility.

[0147] Evaluation criteria: visual inspection to determine if it is a clear aqueous solution and whether there are insoluble solid residues on the tube wall, etc.

[0148] 2. Experimental Results

[0149] The water solubility test results of each group of samples are shown in Table 7.

[0150] Table 7. Results of water solubility determination of L-histyl-β-alanyl-cinnamic acid derivatives

[0151]

[0152] As shown in Table 7, the solubility of the original cinnamic acid in aqueous solution is less than 1%, which poses a significant challenge to its application in cosmetic formulations. It is prone to precipitating solids, making the formulation system cloudy, or affecting other components. However, chemically coupling cinnamic acid derivatives with carnosine greatly improves water solubility, especially the compounds shown in formulas (2) to (6), whose aqueous solution solubility can reach 20%. Water-soluble raw materials can seamlessly integrate with water-based systems (the most common base in cosmetics, such as toners, serums, lotions, and facial masks), and can be stably dispersed without the need for adding large amounts of emulsifiers and cosolvents (such as alcohol and oily components), significantly reducing formulation complexity and simplifying the production process. At the same time, it can improve skin absorption efficiency and optimize efficacy.

[0153] Example 7: UV protection performance of L-histyl-β-alanyl-cinnamic acid derivatives

[0154] 1. Cinnamic acid derivatives, due to the presence of conjugated double bonds and benzene rings in their molecular structure, possess excellent ultraviolet absorption properties. For example, ethylhexyl methoxycinnamate (OMC) is a good absorber in the UVB region, effectively blocking ultraviolet rays in the 280-320 nm range. It has a high absorption rate, is non-irritating to the skin, and has good safety, making it almost an ideal sunscreen agent that can be added to sunscreens, sun lotions, sunscreen sprays, and other products.

[0155] In this embodiment, the ultraviolet absorption spectra of the prepared L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) were measured to evaluate the ultraviolet protection performance of the L-histyl-β-alanyl-cinnamic acid derivatives.

[0156] 2. Experimental Methods

[0157] Weigh out L-histyl-β-alanyl-cinnamic acid derivative powder (Formulas 1 to 6) and ethylhexyl methoxycinnamate powder, respectively, and dissolve them in anhydrous ethanol to prepare a 50 μM solution. Take 400 μL of the solution and pour it into a quartz cuvette, and detect its ultraviolet absorption spectrum in a UV-Vis spectrophotometer.

[0158] 2. Experimental Results

[0159] The UV absorption spectra of L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) and ethylhexyl methoxycinnamate are shown in [reference needed]. Figure 3 .

[0160] Depend on Figure 3It is evident that the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) prepared in this invention exhibit certain ultraviolet absorption within the wavelength range of 280–340 nm. Among them, the ultraviolet absorption intensity of the compound shown in Formula (5) is comparable to that of ethylhexyl methoxycinnamate, indicating that this compound can act as an ultraviolet absorber, absorbing ultraviolet rays and alleviating sunburn. Furthermore, based on the experimental results in Examples 2, 3, and 4, it can be seen that the L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) prepared in this invention also possess anti-glycation, anti-oxidation, and skin-brightening effects, and their stability and water solubility are significantly improved compared to the raw material cinnamic acid. This indicates that, compared to traditional ingredients, L-histyl-β-alanyl-cinnamic acid derivatives demonstrate more advantages, capable of both blocking ultraviolet rays and providing anti-aging and repair, and have great potential in the cosmetics field.

[0161] Example 8: Human efficacy of an essence containing L-histyl-β-alanyl-cinnamic acid derivative.

[0162] (1) Preparation of anti-oxidation and anti-glycation essence: 4% 1,3-butanediol, 0.5% betaine, 0.02% sodium hyaluronate, 0.08% xanthan gum and deionized water (added to 100%) were stirred and mixed to prepare the base essence. 100 ppm L-histyl-β-alanyl-cinnamic acid derivatives (Formulas 1 to 6) were added to the base essence respectively as sample groups 1 to 6.

[0163] (2) Volunteer selection: The selection of subjects followed the medical and ethical standards for human testing. All subjects must participate in the test voluntarily and sign an informed consent form before the test. 120 healthy female subjects aged 18-45 years were recruited and randomly divided into 6 groups of 20 each.

[0164] (3) How to use the experimental samples: After cleansing their face in the morning and evening, the subjects used the serums of samples 1 to 6 respectively. Each time, they used one pump (about 0.2 g) of serum and gently massaged it until absorbed. During the experiment, other anti-oxidation and anti-glycation skin care products were discontinued.

[0165] (4) Before and one month after the use of the sample, the subjects’ facial images were collected using VISIA-CR, the subjects’ facial skin roughness SEr was collected using VC20 Plus, the skin glossiness was measured using GlossymeterCL200, the skin elasticity parameter R2 of the test site was determined using Cutometer MPA580, and the skin test area was measured three times using CM-26d skin colorimeter. L*, a*, and b* were recorded to calculate the corresponding ITA° values ​​(individual type angle; the larger the ITA° value, the lighter the skin color, and vice versa).

[0166] Before the test, the subjects washed their faces with the same facial cleanser and stabilized their skin in a constant temperature and humidity (temperature: 21 °C ± 1 °C, humidity: 50% ± 10%) room for 20 minutes to maintain skin stability before the above test was performed.

[0167] (5) The results are shown in Table 8 below:

[0168] Change rate after product use = (Data after use - Data before use) / Data before use × 100%

[0169] Table 8 Results of skin parameters before and after using the sample serum

[0170]

[0171] According to the data in Table 8, after using the serum containing L-histyl-β-alanyl-cinnamic acid derivatives for one month, the subjects experienced a significant decrease in skin roughness, and improvements in skin elasticity and radiance to varying degrees. The skin ITA° values ​​also significantly increased, indicating that the subjects' skin tone lightened to varying degrees. The overall anti-aging and brightening effects of the serum were recognized by over 90% of the subjects. These results demonstrate that the serum containing L-histyl-β-alanyl-cinnamic acid derivatives provided by this invention has the effects of improving skin radiance, enhancing skin softness, repairing dullness, and brightening skin tone, making the skin look more vibrant and youthful.

Claims

1. An L-histyl-β-alanyl-cinnamic acid derivative, characterized in that, which is a compound of formula (I) ； wherein the wavy line directly connected to the double bond indicates that the double bond is in the E or Z configuration; Structural unit To , , , , or .

2. The L-histidyl-β-alanyl-cinnamic acid derivative according to claim 1, wherein the L-histidyl-beta-alanyl-cinnamic acid derivative is , , , , or .

3. A process for the preparation of L-histidyl-β-alanyl-cinnamic acid derivatives, characterized in that, which comprises the following steps: the compound of formula (II) is subjected to a de-methylation reaction in the presence of a solvent and a base to form the compound of formula (I); ； wherein the structural unit is as defined in claim 1.

4. The production method according to claim 3, wherein the method for preparing the L-histidyl-beta-alanyl-cinnamic acid derivative further comprises the following steps: the compound of formula (II) is subjected to a de-methylation reaction in the presence of a solvent and a base to form the compound of formula (I); ； wherein the structural unit is as defined in claim 1.

5. The production method according to claim 4, wherein the method for preparing the L-histidyl-beta-alanyl-cinnamic acid derivative further comprises the following steps: the compound of formula (II) is subjected to a de-methylation reaction in the presence of a solvent and a base to form the compound of formula (I); 。 6. A carnosine methyl ester cinnamic acid derivative, characterized by the method for preparing the L-histidyl-beta-alanyl-cinnamic acid derivative further comprises the following steps: ； wherein the structural unit is defined as in claim 1.

7. A method for preparing a carnosine methyl ester cinnamic acid derivative, characterized by, the compound of formula (II) is subjected to a de-methylation reaction in the presence of a solvent and a base to form the compound of formula (I); which is a compound of formula (II) ； wherein the structural unit is as defined in claim 1.

8. A cosmetic product, characterized by, which comprises the following steps:

9. The cosmetic product according to claim 8, wherein the compound of formula (II) is subjected to a de-methylation reaction in the presence of a solvent and a base to form the compound of formula (I); the L-histidyl-beta-alanyl-cinnamic acid derivative of claim 1 or 2. The concentration of the L-histidyl-beta-alanyl-cinnamic acid derivative of claim 1 or 2 in the cosmetic product is 10-10000 ppm.

10. Use of the L-histidyl-beta-alanyl-cinnamic acid derivative of claim 1 or 2 in a cosmetic product.

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