A menthol derivative with skin penetration function and a preparation method thereof
By designing a menthol derivative chimeric molecule with dual pH and ROS responses, the problem of low permeation efficiency of existing menthol derivatives in inflamed areas was solved, achieving targeted activation of lesions and improved transdermal absorption efficiency in inflamed areas.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- MINGXING KEPAI BIOTECHNOLOGY (SHANGHAI) CO LTD
- Filing Date
- 2026-05-06
- Publication Date
- 2026-07-31
AI Technical Summary
Existing menthol derivatives cannot simultaneously respond to the abnormal increase of reactive oxygen species in the inflammatory microenvironment, resulting in low permeation efficiency in chronic or non-alkalized inflammatory areas. Furthermore, they are not effectively coupled with biomimetic phospholipid structures, thus failing to form smart molecules that combine the functions of carrier and permeation promoter.
A biphilic chimeric molecule was designed, comprising a menthol core, L-amino acid residues, pH-responsive hydrazone bonds, ROS-responsive disulfide bonds, and phosphatidylcholine fragments. Through the construction of ester bonds, hydrazone bonds, and disulfide bonds, dual responsive control of the skin microenvironment was achieved. Combined with selective hydrolysis by phospholipase A2, a nanocarrier with biomimetic self-assembly capability was formed.
It remains stable in healthy skin, selectively releases active ingredients in inflamed areas to achieve targeted activation of lesions, reduces non-specific irritation, improves transdermal absorption efficiency, and adapts to changes in the complex skin microenvironment.
Smart Images
Figure CN122483100A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of biomaterials technology, and in particular to a menthol derivative with skin penetration-enhancing function and its preparation method. Background Technology
[0002] Menthol, a natural monoterpene compound, has long been widely used as a chemical penetration enhancer in transdermal drug delivery systems due to its excellent skin penetration enhancement ability, cooling sensation, and low acute toxicity. Its mechanism of action mainly involves reversibly disrupting the orderly arrangement of intercellular lipids in the stratum corneum, lowering the phase transition temperature of the lipid bilayer, and thus enhancing the transmembrane diffusion of drug molecules. In recent years, in order to overcome the defects of free menthol, such as high volatility, non-specific penetration enhancement effect, and easy skin irritation at high concentrations, researchers have devoted themselves to chemically modifying its structure and developing a series of menthol derivatives.
[0003] While some studies have introduced pH-sensitive hydrazone bonds into existing menthol derivatives, they have failed to respond simultaneously to the abnormal increase of reactive oxygen species in the inflammatory microenvironment, resulting in low permeation efficiency in chronic or non-alkalized inflammatory areas. Many derivatives are used only as passive permeation-enhancing units and have not been effectively coupled with biomimetic phospholipid structures to form smart molecules with both carrier and permeation-enhancing functions. Summary of the Invention
[0004] In view of the aforementioned existing problems, the present invention is proposed.
[0005] Therefore, this invention provides a menthol derivative with skin penetration-enhancing function and its preparation method to solve the problem of failing to respond simultaneously to the abnormal increase of reactive oxygen species in the inflammatory microenvironment, resulting in low penetration-enhancing efficiency in chronic or non-alkalized inflammatory areas, and the fact that many derivatives are only used as passive penetration-enhancing units and are not effectively coupled with biomimetic phospholipid structures to form smart molecules with both carrier and penetration-enhancing functions.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a menthol derivative having skin penetration-enhancing function, comprising: The menthol derivative is an amphiphilic chimeric molecule, the structure of which includes a menthol core, L-type amino acid residues, pH-responsive hydrazone bonds, ROS-responsive disulfide bonds, and phosphatidylcholine fragments. The menthol core forms an ester bond with the carboxyl group of the L-type amino acid residue through a C8–C12 alkylene spacer arm, and the amino group of the amino acid residue forms a hydrazone bond with the aromatic aldehyde. The spacer arm or amino acid side chain is connected to a hydrophobic chain containing a disulfide bond, and the menthol core or spacer arm is further connected to the sn-2 position of the phosphatidylcholine glycerol backbone.
[0007] Secondly, the present invention provides a method for preparing a menthol derivative with skin penetration enhancement function, comprising: Menthol was esterified with L-leucine to obtain a menthol-amino acid conjugate. A hydrazone bond was constructed by introducing benzaldehyde-like compounds into the conjugate to obtain a pH-responsive prodrug intermediate; A pH / ROS dual-responsive menthol prodrug derivative was obtained by introducing a thiol-containing alkyl chain into a prodrug intermediate and oxidizing it to form a disulfide bond. Selective hydrolysis of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position yields a monoacylphospholipid intermediate. A pH / ROS dual-responsive menthol prodrug derivative was esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule.
[0008] In a preferred embodiment of the method for preparing the menthol derivative with skin penetration-enhancing function described in this invention, the step of esterifying menthol with L-leucine to obtain a menthol-amino acid conjugate includes: In anhydrous dichloromethane, using N,N'-dicyclohexylcarbodiimide as a condensing agent and 4-dimethylaminopyridine as a catalyst, the hydroxyl group of menthol and the carboxyl group of L-leucine are esterified to obtain the menthol-L-leucine conjugate.
[0009] As a preferred embodiment of the method for preparing the menthol derivative with skin penetration enhancement function described in this invention, the step of introducing a benzaldehyde compound into the menthol-amino acid conjugate to construct a hydrazone bond to obtain a pH-responsive prodrug intermediate includes the following steps: In anhydrous methanol, the free amino group of menthol-L-leucine conjugate undergoes a condensation reaction with the aldehyde group of 4-hydroxybenzaldehyde to form a hydrazone bond, yielding a pH-responsive prodrug intermediate.
[0010] As a preferred embodiment of the method for preparing the menthol derivative with skin penetration enhancement function described in this invention, the specific steps are as follows: Introducing a thiol-containing alkyl chain into the pH-responsive prodrug intermediate and oxidizing it to form a disulfide bond to obtain a pH / ROS dual-responsive menthol prodrug derivative: First, 11-mercaptoundecanoic acid is activated and then esterified with the side chain hydroxyl group of the pH-responsive prodrug intermediate to obtain an intermediate containing a thiol side chain. The intermediate was then oxidatively coupled with iodine solution to form a disulfide bond between the two thiol groups, yielding a pH / ROS dual-responsive menthol prodrug derivative.
[0011] In a preferred embodiment of the method for preparing the menthol derivative with skin penetration-enhancing function described in this invention, the step of selectively hydrolyzing 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position to obtain a monoacylphospholipid intermediate includes the following steps: In a pH 8.0 buffer system, the sn-2 ester bond of 1,2-dipalmitoyl-sn-glycerol-3-phosphate choline was hydrolyzed by phospholipase A2 to obtain 1-palmitoyl-2-hydroxy-sn-glycerol-3-phosphate choline.
[0012] As a preferred embodiment of the method for preparing the menthol derivative with skin penetration enhancement function described in this invention, the step of esterifying the pH / ROS dual-responsive menthol prodrug derivative with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule includes the following specific steps: After activating the terminal carboxyl group of the pH / ROS dual-responsive menthol prodrug derivative, it is esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate under the catalysis of 4-dimethylaminopyridine, and then linked through a C10 alkylene spacer arm to obtain the amphiphilic menthol-phospholipid chimeric molecule.
[0013] As a preferred embodiment of the preparation method of the menthol derivative with skin penetration enhancement function described in this invention, the amphiphilic menthol-phospholipid chimeric molecule is purified by silica gel column chromatography or reversed-phase high-performance liquid chromatography with a purity of not less than 95%, and the structure is confirmed by nuclear magnetic resonance hydrogen spectroscopy and high-resolution mass spectrometry.
[0014] As a preferred embodiment of the method for preparing the menthol derivative with skin penetration enhancement function described in this invention, menthol is esterified with L-leucine to obtain a menthol-amino acid conjugate. A hydrazone bond was constructed by introducing a benzaldehyde compound into the menthol-amino acid conjugate to obtain a pH-responsive prodrug intermediate; By introducing a thiol-containing alkyl chain into a pH-responsive prodrug intermediate and oxidizing it to form a disulfide bond, a pH / ROS dual-responsive menthol prodrug derivative is obtained. 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine was selectively hydrolyzed at the sn-2 position to obtain a monoacylphospholipid intermediate. The pH / ROS dual-responsive menthol prodrug derivative was esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain the amphiphilic menthol-phospholipid chimeric molecule.
[0015] As a preferred embodiment of the preparation method of the menthol derivative with skin penetration enhancement function described in this invention, the transdermal delivery formulation is used to promote the penetration of water-soluble active ingredients into the stratum corneum of the skin, wherein the water-soluble active ingredients are selected from polypeptides, nucleic acids or small molecule water-soluble drugs. The menthol derivative is present in a concentration of 0.1% to 5% in the formulation. It forms a nanocarrier through self-assembly of an amphiphilic structure. Under the low pH or high reactive oxygen species conditions of the skin inflammation microenvironment, it triggers hydrazone bond hydrolysis or disulfide bond cleavage, releasing the menthol nucleus in situ to reversibly disturb the lipid arrangement of keratinocytes, thereby enhancing the transdermal absorption of the co-loaded active ingredients.
[0016] The beneficial effects of this invention are as follows: By introducing benzaldehyde compounds to construct hydrazone bonds on menthol-amino acid conjugates, the molecule's responsiveness to the pH of the skin microenvironment is achieved. It remains stable in healthy acidic skin, while selectively hydrolyzing in the alkaline region of inflammation to release active ingredients, achieving targeted activation of lesions and reducing non-specific stimulation. Phospholipase A2 is used to selectively hydrolyze 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position to accurately obtain monoacylphospholipid intermediates, preserving the amphiphilic structure and biocompatibility of natural phospholipids, providing a clear reaction site for subsequent directional coupling, and ensuring that the chimeric molecule has biomimetic self-assembly capabilities. Attached Figure Description
[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 A flowchart illustrating the preparation method of a menthol derivative with skin penetration enhancement function. Detailed Implementation
[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0022] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a method for preparing a menthol derivative with skin penetration enhancement function, comprising: S1. Esterify menthol with L-leucine to obtain menthol-amino acid conjugate.
[0023] Furthermore, in anhydrous dichloromethane, using N,N'-dicyclohexylcarbodiimide as a condensing agent and 4-dimethylaminopyridine as a catalyst, the hydroxyl group of menthol and the carboxyl group of L-leucine were esterified to obtain the menthol-L-leucine conjugate.
[0024] It should be noted that the reaction achieves ester bond linkage while retaining the α-amino group of L-leucine, which not only endows the molecule with hydrophobicity but also provides the necessary nucleophilic site for the subsequent construction of pH-responsive hydrazone bonds.
[0025] S2. A benzaldehyde-like compound was introduced into the conjugate to construct a hydrazone bond, resulting in a pH-responsive prodrug intermediate.
[0026] Furthermore, in anhydrous methanol, the free amino group of the menthol-L-leucine conjugate undergoes a condensation reaction with the aldehyde group of 4-hydroxybenzaldehyde to form a hydrazone bond, yielding a pH-responsive prodrug intermediate.
[0027] It should be noted that the formed hydrazone bonds remain stable in the acidic environment of healthy skin, while they are selectively hydrolyzed in the alkaline microenvironment of inflamed or damaged areas, achieving targeted release from the lesion and avoiding non-specific stimulation.
[0028] S3. A thiol-containing alkyl chain is introduced through a prodrug intermediate and oxidized to form a disulfide bond, yielding a pH / ROS dual-responsive menthol prodrug derivative.
[0029] Furthermore, in anhydrous methanol, the free amino group of the menthol-L-leucine conjugate undergoes a condensation reaction with the aldehyde group of 4-hydroxybenzaldehyde to form a hydrazone bond, yielding a pH-responsive prodrug intermediate.
[0030] It should be noted that the introduced disulfide bonds can be specifically broken in the highly reactive oxygen species environment of inflamed skin, and work synergistically with the pH response mechanism to achieve dual microenvironment-triggered release, thereby improving the spatiotemporal precision and safety of penetration enhancement.
[0031] S4. Selective hydrolysis of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position yields a monoacylphospholipid intermediate.
[0032] Furthermore, in a pH 8.0 buffer system, the sn-2 ester bond of 1,2-dipalmitoyl-sn-glycerol-3-phosphate choline was hydrolyzed by phospholipase A2 to obtain 1-palmitoyl-2-hydroxy-sn-glycerol-3-phosphate choline.
[0033] It should be noted that the phospholipase A2-mediated selective hydrolysis at the sn-2 position ensures that only a single hydroxyl reaction site is exposed, avoiding the generation of isomeric byproducts and providing structural certainty for subsequent targeted coupling with prodrug derivatives.
[0034] S5. The pH / ROS dual-responsive menthol prodrug derivative is esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule.
[0035] Furthermore, after activating the terminal carboxyl group of the pH / ROS dual-responsive menthol prodrug derivative, it was esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate under the catalysis of 4-dimethylaminopyridine, and then linked through a C10 alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule.
[0036] The amphiphilic menthol-phospholipid chimeric molecule was purified by silica gel column chromatography or reversed-phase high-performance liquid chromatography with a purity of not less than 95%, and its structure was confirmed by proton nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry.
[0037] Menthol was esterified with L-leucine to obtain a menthol-amino acid conjugate. A hydrazone bond was constructed by introducing benzaldehyde compounds into the menthol-amino acid conjugate to obtain a pH-responsive prodrug intermediate; By introducing a thiol-containing alkyl chain into a pH-responsive prodrug intermediate and oxidizing it to form a disulfide bond, a pH / ROS dual-responsive menthol prodrug derivative is obtained. 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine was selectively hydrolyzed at the sn-2 position to obtain a monoacylphospholipid intermediate. A pH / ROS dual-responsive menthol prodrug derivative was esterified with a hydroxyl group at the sn-2 position of a monoacylphospholipid intermediate via an alkylene spacer arm.
[0038] Transdermal delivery formulations are used to facilitate the penetration of water-soluble active ingredients into the stratum corneum of the skin, wherein the water-soluble active ingredients are selected from peptides, nucleic acids, or small molecule water-soluble drugs; The menthol derivative is present in a concentration of 0.1% to 5% in the formulation. It forms a nanocarrier through self-assembly of an amphiphilic structure. Under the low pH or high reactive oxygen species conditions of the skin inflammation microenvironment, it triggers hydrazone bond hydrolysis or disulfide bond cleavage, releasing the menthol nucleus in situ to reversibly disturb the lipid arrangement of keratinocytes, thereby enhancing the transdermal absorption of the co-loaded active ingredients.
[0039] It should be noted that the resulting chimeric molecule has both a phospholipid biomimetic head and a smart responsive hydrophobic tail, and can self-assemble in the aqueous phase to form a nanocarrier, effectively encapsulating water-soluble drugs and synergistically improving transdermal delivery efficiency.
[0040] Example 2 is the second embodiment of the present invention. This embodiment provides a menthol derivative with skin penetration enhancement function and its preparation method, including: L-leucine and 4-dimethylaminopyridine were dissolved in anhydrous dichloromethane. A dichloromethane solution of N,N'-dicyclohexylcarbodiimide was added under ice bath cooling. After stirring, a dichloromethane solution of menthol was added dropwise. The ice bath was removed, and the reaction was stirred at room temperature. The precipitate was removed by filtration. The filtrate was washed successively with dilute hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine. The organic phase was dried and concentrated under reduced pressure to obtain the crude product. Purification was achieved by silica gel column chromatography to obtain a white solid. The 1H NMR spectrum showed that the characteristic peak of menthol coexisted with the α-proton signal of L-leucine, while the carboxyl signal disappeared, confirming the formation of an ester bond.
[0041] The above-mentioned menthol-L-leucine conjugate and 4-hydroxybenzaldehyde were dissolved in anhydrous methanol, and a catalytic amount of p-toluenesulfonic acid was added. The mixture was heated under reflux, cooled, and the solvent was removed by vacuum evaporation. The residue was precipitated with diethyl ether, filtered, and dried under vacuum to obtain a pale yellow solid. The infrared spectrum showed an absorption peak of C=N stretching vibration, and the proton nuclear magnetic resonance spectrum showed a characteristic signal in the imine proton region, indicating that the hydrazone bond was successfully constructed.
[0042] 11-Mercaptoundecanoic acid, N-hydroxysuccinimide, and N,N'-dicyclohexylcarbodiimide were dissolved in anhydrous N,N-dimethylformamide and activated by stirring at room temperature. Separately, the above pH-responsive prodrug intermediate was dissolved in N,N-dimethylformamide, triethylamine was added, and then the above activation solution was slowly added dropwise. The reaction was carried out at room temperature. The reaction solution was diluted with water and extracted with ethyl acetate. The organic phase was washed with water, dried, and concentrated to obtain a thiol-containing intermediate. The intermediate was dissolved in tetrahydrofuran, and after purging with an inert gas, a tetrahydrofuran solution of iodine was added dropwise. The reaction was stirred in the dark, and a quencher was added to terminate the reaction. The mixture was extracted with ethyl acetate, and the organic phase was treated to obtain a reddish-brown oily substance. Mass spectrometry showed a molecular ion peak, and the free thiol detection was negative, confirming the formation of disulfide bonds.
[0043] 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine was dissolved in a buffer solution, and phospholipase A2 was added. The mixture was stirred at a constant temperature and the reaction was carried out. After the reaction was completed, the system was adjusted to neutral, and a mixture of chloroform and methanol was added for extraction. The organic phase was separated and concentrated under reduced pressure. The mixture was purified by reversed-phase silica gel column chromatography to obtain a white powdery monoacylphospholipid intermediate. The phosphorus nuclear magnetic resonance showed a single phosphorus signal, indicating that the selective hydrolysis at the sn-2 position was completed.
[0044] A pH / ROS dual-responsive prodrug derivative was dissolved in anhydrous dichloromethane, and N-hydroxysuccinimide and N,N'-dicyclohexylcarbodiimide were added for activation at low temperature. Separately, a monoacylphospholipid intermediate was dissolved in a small amount of dimethyl sulfoxide, and 4-dimethylaminopyridine was added. The activation solution was slowly added dropwise, the mixture was heated to room temperature, and the reaction was continuously stirred. The reaction solution was washed with saturated sodium bicarbonate solution, and the organic phase was dried, concentrated, and purified by preparative thin-layer chromatography to obtain a light yellow viscous product.
[0045] The obtained product was subjected to 1H NMR spectroscopy, which showed characteristic signals of menthol methyl, leucine α-proton, hydrazone imine proton, disulfide ortho-methylene, and phosphatidylcholine N-methyl. The molecular ion peak measured by high-resolution mass spectrometry was consistent with the theoretical value. The purity determined by high-performance liquid chromatography was not less than 95%.
[0046] This embodiment successfully prepared the target amphiphilic menthol-phospholipid chimeric molecule, which includes a menthol core, L-leucine residues, hydrazone bonds, disulfide bonds, and a phosphatidylcholine head. It has dual pH / ROS response characteristics and self-assembly capability, and can be used for subsequent transdermal delivery studies.
[0047] Comparative Example 1: This comparative example used commercially available menthol (purity ≥99%) to directly prepare a transdermal formulation, with all other conditions the same as in Example 1. Specifically, menthol was dissolved in an ethanol-propylene glycol mixed solvent to a final concentration of 2% (w / w) to promote the transdermal absorption of fluorescently labeled insulin (a model water-soluble peptide). In vitro porcine skin permeation experiments showed that the cumulative drug permeation over 24 hours was 18.3 ± 2.1 μg / cm³. 2 Histopathological examination revealed a significantly loosened stratum corneum structure and a transepidermal water loss (TEWL) value that was 2.8 times the baseline value, indicating irreversible damage to the skin barrier function. This result demonstrates that while traditional menthol has a penetration-enhancing effect, it lacks responsive control and easily leads to non-specific irritation and barrier disruption.
[0048] Comparative Example 2: A control molecule with a similar structure but lacking hydrazone and disulfide bonds was synthesized in this comparative example: the menthol-L-leucine conjugate was directly linked to a monoacylphospholipid intermediate via a C10 alkylene chain, skipping steps S2 and S3. The resulting molecule was amphiphilic and could self-assemble into nanoparticles, but lacked pH or ROS responsiveness. A 2% concentration transdermal gel was prepared for delivery of the same model drug. In a healthy skin model, the drug permeation rate after 24 hours was 35.6 ± 3.4 μg / cm³. 2 It was superior to Comparative Example 1; however, under simulated inflamed skin conditions, the permeability only increased slightly to 38.2±2.9 μg / cm³. 2 The lack of responsive enhancement indicates that chimeric molecules lacking intelligent response mechanisms cannot achieve targeted and enhanced delivery to lesions, limiting their application value in the treatment of inflammatory skin diseases.
[0049] Comparative Example 3: Step S3 was omitted in this comparative example. Only a prodrug intermediate containing a hydrazone bond was constructed and coupled with a monoacylphospholipid to obtain a chimeric molecule that was pH-responsive only and ROS-free. A transdermal formulation was also prepared at a concentration of 2%. Under alkaline conditions, the drug permeation reached 52.1 ± 4.0 μg / cm³. 2 This is superior to Comparative Example 2; however, in a highly reactive oxygen species (ROS) environment, the permeation rate did not increase, indicating that it could not respond to the oxidative stress microenvironment. In contrast, the dual-response molecule in Example 1 increased its permeation rate to 68.7 ± 5.2 μg / cm under the same ROS conditions. 2 These results demonstrate that a single response mechanism is insufficient to cover the multiple microenvironmental characteristics of complex inflammatory skin, and that a dual-response design has a synergistic effect.
[0050] In summary, this invention achieves molecular responsiveness to the pH of the skin microenvironment by introducing benzaldehyde compounds into the menthol-amino acid conjugate to construct hydrazone bonds. It remains stable in healthy acidic skin, while selectively hydrolyzing in the alkaline region of inflammation to release active ingredients, achieving targeted activation of lesions and reducing non-specific stimulation. Furthermore, it employs phospholipase A2 to selectively hydrolyze 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position, precisely obtaining a monoacylphospholipid intermediate. This process preserves the amphiphilic structure and biocompatibility of natural phospholipids, providing a clear reaction site for subsequent directional coupling and ensuring that the chimeric molecule possesses biomimetic self-assembly capabilities.
[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A menthol derivative with skin penetration enhancement function, characterized in that: The menthol derivative is an amphiphilic chimeric molecule, the structure of which includes a menthol core, L-type amino acid residues, pH-responsive hydrazone bonds, ROS-responsive disulfide bonds, and phosphatidylcholine fragments. The menthol core forms an ester bond with the carboxyl group of the L-type amino acid residue through a C8–C12 alkylene spacer arm, and the amino group of the amino acid residue forms a hydrazone bond with the aromatic aldehyde. The spacer arm or amino acid side chain is connected to a hydrophobic chain containing a disulfide bond, and the menthol core or spacer arm is further connected to the sn-2 position of the phosphatidylcholine glycerol backbone.
2. A method for preparing a menthol derivative with skin penetration enhancement function, wherein the menthol derivative with skin penetration enhancement function as described in claim 1 is characterized in that: include: Menthol was esterified with L-leucine to obtain a menthol-amino acid conjugate. A hydrazone bond was constructed by introducing benzaldehyde-like compounds into the conjugate to obtain a pH-responsive prodrug intermediate; A pH / ROS dual-responsive menthol prodrug derivative was obtained by introducing a thiol-containing alkyl chain into a prodrug intermediate and oxidizing it to form a disulfide bond. Selective hydrolysis of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position yields a monoacylphospholipid intermediate. A pH / ROS dual-responsive menthol prodrug derivative was esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule.
3. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 2, characterized in that: The specific steps for esterifying menthol with L-leucine to obtain a menthol-amino acid conjugate are as follows: In anhydrous dichloromethane, using N,N'-dicyclohexylcarbodiimide as a condensing agent and 4-dimethylaminopyridine as a catalyst, the hydroxyl group of menthol and the carboxyl group of L-leucine are esterified to obtain the menthol-L-leucine conjugate.
4. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 3, characterized in that: The process of introducing benzaldehyde compounds into the menthol-amino acid conjugate to construct hydrazone bonds yields a pH-responsive prodrug intermediate. The specific steps are as follows: In anhydrous methanol, the free amino group of menthol-L-leucine conjugate undergoes a condensation reaction with the aldehyde group of 4-hydroxybenzaldehyde to form a hydrazone bond, yielding a pH-responsive prodrug intermediate.
5. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 4, characterized in that: The process of introducing a thiol-containing alkyl chain into the pH-responsive prodrug intermediate and oxidizing it to form a disulfide bond to obtain a pH / ROS dual-responsive menthol prodrug derivative is as follows: First, 11-mercaptoundecanoic acid is activated and then esterified with the side chain hydroxyl group of the pH-responsive prodrug intermediate to obtain an intermediate containing a thiol side chain. The intermediate was then oxidatively coupled with iodine solution to form a disulfide bond between the two thiol groups, yielding a pH / ROS dual-responsive menthol prodrug derivative.
6. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 5, characterized in that: The step of selectively hydrolyzing 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine at the sn-2 position to obtain a monoacylphospholipid intermediate is as follows: In a pH 8.0 buffer system, the sn-2 ester bond of 1,2-dipalmitoyl-sn-glycerol-3-phosphate choline was hydrolyzed by phospholipase A2 to obtain 1-palmitoyl-2-hydroxy-sn-glycerol-3-phosphate choline.
7. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 6, characterized in that: The specific steps for esterifying the pH / ROS dual-responsive menthol prodrug derivative with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm to obtain an amphiphilic menthol-phospholipid chimeric molecule are as follows: After activating the terminal carboxyl group of the pH / ROS dual-responsive menthol prodrug derivative, it is esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate under the catalysis of 4-dimethylaminopyridine, and then linked through a C10 alkylene spacer arm to obtain the amphiphilic menthol-phospholipid chimeric molecule.
8. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 7, characterized in that: The amphiphilic menthol-phospholipid chimeric molecule was purified by silica gel column chromatography or reversed-phase high-performance liquid chromatography to a purity of not less than 95%, and its structure was confirmed by nuclear magnetic resonance hydrogen spectroscopy and high-resolution mass spectrometry.
9. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 8, characterized in that: Menthol was esterified with L-leucine to obtain a menthol-amino acid conjugate. A hydrazone bond was constructed by introducing a benzaldehyde compound into the menthol-amino acid conjugate to obtain a pH-responsive prodrug intermediate; By introducing a thiol-containing alkyl chain into a pH-responsive prodrug intermediate and oxidizing it to form a disulfide bond, a pH / ROS dual-responsive menthol prodrug derivative is obtained. 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine was selectively hydrolyzed at the sn-2 position to obtain a monoacylphospholipid intermediate. The pH / ROS dual-responsive menthol prodrug derivative is esterified with the sn-2 hydroxyl group of the monoacylphospholipid intermediate via an alkylene spacer arm.
10. The method for preparing the menthol derivative with skin penetration enhancement function as described in claim 9, characterized in that: The transdermal delivery formulation is used to promote the penetration of water-soluble active ingredients into the stratum corneum of the skin, wherein the water-soluble active ingredients are selected from polypeptides, nucleic acids, or small molecule water-soluble drugs; The menthol derivative is present in a concentration of 0.1% to 5% in the formulation. It forms a nanocarrier through self-assembly of an amphiphilic structure. Under the low pH or high reactive oxygen species conditions of the skin inflammation microenvironment, it triggers hydrazone bond hydrolysis or disulfide bond cleavage, releasing the menthol nucleus in situ to reversibly disturb the lipid arrangement of keratinocytes, thereby enhancing the transdermal absorption of the co-loaded active ingredients.