CN114315631A

CN114315631A - Capsaicin derivative and preparation method and application thereof

Info

Publication number: CN114315631A
Application number: CN202210040673.4A
Authority: CN
Inventors: 颜志明; 蒋能; 黄其春; 庞承云; 陆娇双
Original assignee: Guangxi Medical University
Current assignee: Guangxi Medical University
Priority date: 2022-01-14
Filing date: 2022-01-14
Publication date: 2022-04-12
Anticipated expiration: 2042-01-14
Also published as: CN114315631B

Abstract

The invention discloses a series of capsaicin derivatives, and a preparation method and application thereof. The test results of the applicant show that the capsaicin derivatives provided by the invention have good antioxidant activity, are expected to be used for treating neurodegenerative diseases, and have good potential medicinal value. The structure of the capsaicin derivative is shown in the following formulas 3 and 4:

wherein R is¹Is hydroxy or methoxy, R²Is a hydroxyl group, and n is 2 to 15.

Description

Capsaicin derivative and preparation method and application thereof

Technical Field

The invention relates to the technical field of medicines, in particular to capsaicin derivatives and a preparation method and application thereof.

Background

Antioxidants are defined as substances that retard, prevent or inhibit oxidative damage to a target molecule at low concentrations. Natural antioxidants found in edible plants have important medicinal and nutritional values. Therefore, a large number of edible plants are screened as potential sources of antioxidants. For example, capsicum is not only used as a flavoring agent in the food field, but also an important source chemical of an antioxidant. Fresh capsicum is an excellent source of vitamins a and C and neutral and acidic phenolic chemicals, which are natural antioxidants found in many plants. The capsicum genus consists of more than 200 varieties, classified according to the "Hea" unit of Scoville, ranging from very hot havana peppers to sweet peppers. The pungent components in Capsici fructus mainly come from capsaicin (8-methyl-N-vanillin-6-nonanoic acid), dihydrocapsaicin, North-based dihydrocapsaicin, high-capsaicin, etc., and are collectively called capsaicin. Three structural features of capsaicin are key to receptor action, including a lipophilic moiety (nonenyl, which may be substituted with an alkyl/alkenyl chain, of capsaicin), a polar head (3-methoxy-4-hydroxybenzyl), and a linker (amide of capsaicin). Kogure et al (Biochimica et Biophysica Acta (BBA) -General Subjects,1573(1),84-92.) teach that the phenolic hydroxyl group of capsaicin is not involved in free radical scavenging, the site of free radical scavenging being believed to be the C7-benzyl carbon, and the presence of acetamide is important for free radicals to pick up hydrogen from the C7-benzyl carbon of capsaicin. Ooka et al (our of the American Oil Chemists' Society,87(12),1397-1405.) reported that the site of capsaicin scavenging free radicals was independent of C7-benzylic carbon and acetamide, but rather dependent on the phenolic hydroxyl group of capsaicin, and indicated that the antioxidant site of capsaicin is 2-methoxy-4-methyl-phenol.

In vivo, free radicals may be produced by normal physiological reactions. A radical is a substance containing one or more lone electrons, which has high reactivity and participates in various physiological reactions due to an incomplete electron shell. Reactive Oxygen Species (ROS) are reactive forms of oxygen, and include primarily oxygen-containing radicals and readily available radical-forming peroxides, such as hydrogen (H)₂O₂) Superoxide (O)₂ ^-) And hydroxyl radical (. OH), etc. Oxygen participates in high-energy electron transfer and generates a large amount of ATP through oxidative phosphorylation, thereby providing energy for normal physiological reactions. In addition, the body is also constantly under oxidative attack from ROS. Under normal physiological conditions, ROS produced in cells are continuously eliminated by antioxidase (such as Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), etc.), so that the organism maintains a stable oxidation-reduction system balance. Oxidative stress occurs due to an imbalance between the production of ROS and the body's ability to counteract their effects. High concentrations of ROS, including hydroxyl, hydrogen peroxide and superoxide, can cause damage to lipids, proteins and DNA of biological systems, leading to tissue damage and cataracts, cardiovascular disease, chronic obstructive pulmonary disease, chronic kidney disease, neurodegenerative disease, cancer, diabetes and sarcopenia.

Neurodegenerative diseases are thought to be associated with the loss of neurons or their myelin sheaths, which deteriorate and become dysfunctional over time. Oxidative stress is closely associated with the development and progression of neurodegenerative diseases, including parkinson's disease, alzheimer's disease, huntington's disease, and amyotrophic lateral sclerosis. The brain consumes a lot of oxygen and generates a lot of ROS. Although the brain has antioxidant defense mechanisms, it is composed mainly of glutathione, vitamin E, melatonin and antioxidant enzymes, and its antioxidant capacity is very limited, so the brain is more susceptible to oxidative damage than other tissues (J Agric Food Chem,56(9), 3350-3356.). Thus, antioxidants may be beneficial in the treatment of neurodegenerative diseases.

Protein kinase b (akt) is involved in many physiological processes. In particular, it plays an important role in cell proliferation and survival after activation by upstream PI3K signals. In ROS-stimulated cells, Akt and Bcl-2 are inhibited and Bax levels are upregulated, thereby decreasing Mitochondrial Membrane Potential (MMP), increasing membrane permeability, releasing cytochrome C, and then activating the apoptotic program. Thus, activation of Akt and inhibition of Bax/Bcl-2 levels are effective strategies to rescue and reverse ROS-promoted neuronal cell death.

A series of capsaicin analogues are synthesized, and the antioxidation activity and the potential neuroprotective mechanism of the capsaicin analogues are evaluated by activating the proliferation effect of Akt and inhibiting Bax/Bcl-2 mediated mitochondrial apoptosis signals in human neuroblastoma cells SH-SY5Y, so that the basis is established for better applying the active ingredients of the pepper and enriching the antioxidant and the neuroprotective agent.

Disclosure of Invention

The invention aims to provide a series of capsaicin derivatives with remarkable antioxidant activity and a preparation method and application thereof.

The capsaicin derivatives are capsaicin derivatives with structures shown in the following formulas 3 and 4 and pharmaceutically acceptable salts thereof:

wherein R is¹Is hydroxy or methoxy, R²Is a hydroxyl group, and n is 2 to 15.

Preferably, the capsaicin derivatives provided by the invention are specifically as follows:

the pharmaceutically acceptable salt of the capsaicin derivative related in the invention can be hydrochloride, hydrobromide, phosphate, sulfate, fumarate, salicylate, benzene sulfonate, pyruvate, acetate, mandelate, alkali metal cation salt or ammonium cation salt of the compound with the structure shown in the formulas 3,4 and 5. Preferably an alkali metal cation salt thereof.

The preparation method of the capsaicin derivative comprises the following steps:

a method for synthesizing a compound having a structure represented by formula 3: placing a compound with a structure shown in a formula 1 and a compound with a structure shown in a formula 2 in an organic solvent, and reacting under the condition of existence of a condensing agent and with heating or without heating to obtain a compound with a structure shown in a formula 3;

wherein R is¹Is hydroxy or methoxy, n is 2-15;

a method for synthesizing a compound having a structure represented by formula 4: and (3) putting the compound with the structure shown in the formula 3 into an organic solvent, adding a demethylating reagent, and reacting at the temperature of below 0 ℃ to obtain the compound with the structure shown in the formula 4.

In the preparation method of the present invention, the organic solvent may be one or a combination of two or more selected from Dichloromethane (DCM), 1, 2-Dichloroethane (DCE), chloroform and chlorobenzene. The amount of the organic solvent to be used may be determined as needed, and is preferably such that the raw materials participating in the reaction can be sufficiently dissolved.

In the method for producing the compound of formula 3, the molar ratio of the compound of formula 1 to the compound of formula 2 is a stoichiometric ratio. The condensing agent is a conventional choice in the prior art, such as a carbodiimide-based condensing agent, an organophosphorus-based condensing agent, and the like, preferably a carbodiimide-based condensing agent, such as Dicyclohexylcarbodiimide (DCC), Diisopropylcarbodiimide (DIC), or 1- (3-dimethylaminopropyl) -3-Ethylcarbodiimide (EDCI), and the like, and EDCI is preferably used. The amount of the condensing agent is usually 1 to 2 times the molar amount of the compound having the structure represented by formula 1. When the condensing agent is a carbodiimide condensing agent, a condensation activating agent is preferably added, the selection and the using amount of the condensation activating agent are the same as those of the prior art, specifically, the condensation activating agent can be HOBt, DMAP, HOAt, 4-PPY and the like, and the combination of EDCI and HOBt is the conventional combination; the amount of the condensation activator used is usually 0.8 to 1.2 times the molar amount of the condensation agent. The reaction is preferably carried out at normal temperature, and the completion of the reaction is detected by thin layer chromatography tracking. When the reaction is carried out at normal temperature, the reaction time is usually controlled to be 6-12 h

In the preparation method of the structural compound shown in formula 4, the selection and the dosage of the demethylating reagent are the same as those in the prior art, specifically, the demethylating reagent can be one or a combination of more than two selected from boron tribromide, boron trichloride, aluminum tribromide and boron triiodide, and the dosage of the demethylating reagent is usually more than that of the structural compound shown in formula 3 or dihydrocapsaicin, and is preferably 1.5 to 3 times of the molar quantity of the structural compound shown in formula 3 or dihydrocapsaicin. The reaction is carried out at a lower temperature to facilitate the improvement of the yield, and therefore, it is preferable that the reaction is carried out at a temperature of less than or equal to-40 deg.C, more preferably-40 to-76 deg.C, when preparing the compound having the structure represented by formula 4. Since demethylating agents such as boron tribromide are strong lewis acids and are prone to water absorption and deliquescence, the reaction can be preferably carried out under the protection of an inert atmosphere (such as nitrogen).

The crude product of the compound with the structure shown in the formula 3 is prepared by the method, and in order to improve the purity of the crude product, the crude product can be subjected to impurity removal and/or purification operation and then used for synthesizing the compound with the structure shown in the formula 4. Specifically, the crude product of the compound having the structure represented by formula 3 may be subjected to silica gel column chromatography to obtain a purified compound, and more preferably, the reaction product is extracted first and then subjected to silica gel column chromatography to reduce the load on the silica gel column. Wherein, the eluent used for elution is preferably mixed by the volume ratio of 10: 1-1: 1, petroleum ether and ethyl acetate or a mixed solvent consisting of dichloromethane and ethyl acetate; if extraction is involved, the extractant is chosen from the same organic solvents as used in the reaction, such as dichloromethane, 1, 2-dichloroethane or ethyl acetate.

Similarly, the crude product of the compound with the structure shown in the formula 4 prepared by the method can also be purified by adopting a silica gel column chromatography mode. More preferably, the reaction product is extracted and then subjected to silica gel column chromatography to reduce the load on the silica gel column. Wherein, the eluent used for elution is preferably mixed by the volume ratio of 10: 1-1: 1, petroleum ether and ethyl acetate or a mixed solvent consisting of dichloromethane and ethyl acetate; if extraction is involved, the extractant is chosen from the same organic solvents as used in the reaction, such as dichloromethane, 1, 2-dichloroethane or ethyl acetate.

The applicant finds that the capsaicin derivative has good antioxidant activity and neuroprotective effect through experiments, and therefore, the invention also comprises the application of the capsaicin derivative or the pharmaceutically acceptable salt thereof in preparing the antioxidant. Furthermore, the invention also comprises an antioxidant which comprises the capsaicin derivative or the pharmaceutically acceptable salt thereof.

Compared with the prior art, the invention provides a series of capsaicin derivatives with novel structures and a preparation method thereof. The test results of the applicant show that the capsaicin derivatives provided by the invention have good antioxidant activity, are expected to be used for treating neurodegenerative diseases, and have good potential medicinal value.

Drawings

FIG. 1 is a graph of the toxicity of

compounds

5a, 5b, 4q and quercetin on SH-SY5Y cells.

Detailed Description

In order to better explain the technical solution of the present invention, the present invention is further described in detail with reference to the following examples, but the embodiments of the present invention are not limited thereto.

Example 1: general preparation of Compounds 3f,3g,3o,3p

3f：R¹＝-OH,n＝5

3g：R¹＝-OCH₃,n＝5

3o：R¹＝-OH,n＝7

3p：R¹＝-OCH₃,n＝7

To a solution of a compound having a structure represented by formula 2 (hereinafter also referred to as compound 2) (4.0mmol,1.0 equivalent) in DCM (25mL) was added a compound having a structure represented by formula 1 (hereinafter also referred to as compound 1) (4.0mmol,1.0 equivalent), followed by HOBT (5.2mmol,1.3 equivalents), EDCI (5.2mmol,1.3 equivalents) and added at room temperatureThe reaction was stirred for 8 hours. After completion of the reaction, the mixture was extracted with DCM (3X 30mL) followed by H₂O (40mL), 1M HCl (40mL) and saturated NaHCO₃(40mL) Wash (H)₂O-wash and HCl-wash to remove unreacted HOBT and EDCI, saturated NaHCO₃Washing to remove residual acid), washing the combined organic phase with saturated brine (to better absorb residual water in the organic phase and dry), and adding anhydrous Na₂SO₄Drying, filtration and concentration, the residue obtained is purified by flash chromatography on silica gel (eluent: PE/EtOAc, 10/1-1/1, vol.%) to give the corresponding compounds 3f,3g,3o,3p, respectively, as specifically characterized below:

the compound N-hexyl-2- (4-hydroxy-3-methoxyphenyl) acetamide (3 f): the yield is 67.0%; a light-yellow oily liquid which is a mixture of,¹H NMR(500MHz,DMSO)δ8.73(s,1H),7.84(t,J＝5.3Hz,1H),6.82(d,J＝1.6Hz,1H),6.67(d,J＝8.0Hz,1H),6.62(dd,J＝8.0,1.7Hz,1H),3.73(s,3H),3.25(s,2H),3.01(dd,J＝12.8,6.8Hz,2H),1.44-1.32(m,2H),1.29-1.17(m,6H),0.84(t,J＝6.8Hz,3H)；¹³C NMR(125MHz,DMSO)δ170.3147.2,145.0,127.3,121.1,115.1,113.1,55.5,42.1,38.5,30.9,29.0,26.0,22.0,13.8；HRMS(ESI):m/z calcd for C₁₅H₂₄NO₃ ⁺[M+H]⁺:266.1751；found:266.1756.

the compound 2- (3, 4-dimethoxyphenyl) -N-hexylacetamide (3 g): the yield is 83.1 percent; a white solid; melting point: at the temperature of between 57 and 58 ℃,¹H NMR(500MHz,CDCl₃)δ6.84(d,J＝8.3Hz,1H),6.80-6.75(m,2H),3.87(s,3H),3.87(s,3H),3.50(s,2H),3.19(dd,J＝13.2,6.9Hz,2H),1.43-037(m,2H),1.26-1.18(m,6H),0.85(t,J＝6.9Hz,3H)；¹³C NMR(125MHz,CDCl₃)δ171.3,149.5,148.5,127.6,121.8,112.7,111.7,56.1,56.0,43.6,39.8 31.5,29.5,26.6,22.6,14.1；HRMS(ESI):m/z calcd for C₁₆H₂₆NO₃ ⁺[M+H]⁺:280.1907；found:280.1911.

compound 2- (4-hydroxy-3-methoxyphenyl) -N-octylacetamide (3 o): the yield is 70.6%; a light yellow oily liquid which is a mixture of,¹H NMR(500MHz,DMSO)δ8.73(s,1H),7.84(t,J＝5.4Hz,1H),6.82(d,J＝1.7Hz,1H),6.67(d,J＝8.0Hz,1H),6.62(dd,J＝8.0,1.8Hz,1H),3.73(s,3H),3.25(s,2H),3.01(dd,J＝12.8,6.8Hz,2H),1.44-1.31(m,2H),1.27-1.20(m,10H),0.85(t,J＝7.0Hz,3H)；¹³C NMR(125MHz,DMSO)δ170.3,147.2,145.0,127.3,121.1,115.1,113.1,55.5,42.1,38.2,31.2,29.1,28.7,28.6,26.3,22.0,13.9；HRMS(ESI):m/z calcd for C₁₇H₂₈NO₃ ⁺[M+H]⁺:294.2064；found:294.2063.

compound 2- (3, 4-dimethoxyphenyl) -N-octylacetamide (3 p): the yield is 78.2%; a white solid; melting point: 76-77 ℃ of the total weight of the mixture,¹H NMR(500MHz,CDCl₃)δ6.84(d,J＝8.4Hz,1H),6.79-6.75(m,2H),3.87(s,3H),3.87(s,3H),3.51(s,2H),3.19(dd,J＝13.2,6.9Hz,2H),1.43-1.37(m,2H),1.29–1.19(m,10H),0.86(t,J＝7.0Hz,3H)；¹³C NMR(125MHz,CDCl₃)δ171.3,149.5,148.5,127.6,121.8,112.6,111.7,56.1,56.0,43.6,39.8,31.9,29.6,29.3,29.3,26.9,22.7,14.2；HRMS(ESI):m/z calcd for C₁₈H₃₀NO₃ ⁺[M+H]⁺:308.2220；found:308.2223.

example 2: preparation of Compounds 3f,3g,3o,3p

Example 1 was repeated, 1, 2-dichloroethane, chloroform or chlorobenzene were substituted for DCM, respectively, and the obtained compounds were characterized as the target compounds 3f,3g,3o,3 p.

Example 3: general preparation of Compounds 4h,4q

BBr was added dropwise to a solution of 3f, 3o (2.0mmol, 1.0 equiv.) in DCM (15mL) at-76 deg.C under nitrogen₃(4.0mmol, 2.0 equiv.) and stirred for 3H, then warmed to room temperature for 2H, the reaction mixture extracted with DCM (3X 30mL) followed by H₂O (3X 30mL), combined organic phases washed with brine, anhydrous Na₂SO₄Drying, filtration and concentration, the residue obtained is purified by flash chromatography on silica gel (eluent: PE/EtOAc, 10/1-1/1, vol.%) to give compounds 4h,4q, respectively, which are characterized as follows:

compound 2- (3, 4-dihydroxyphenyl) -N-hexylacetamide (4 h): the yield is 50.6%; a white solid; melting point: 111-112 deg.c,¹H NMR(500MHz,DMSO)δ8.73(s,1H),8.63(s,1H),7.80(t,J＝5.4Hz,1H),6.64(d,J＝2.0Hz,1H),6.61(d,J＝8.0Hz,1H),6.47(dd,J＝8.0,2.0Hz,1H),3.17(s,2H),3.00(dd,J＝12.8,6.8Hz,2H),1.36(dd,J＝13.8,6.9Hz,2H),1.25(dd,J＝15.5,7.6Hz,6H),0.85(t,J＝6.9Hz,3H)；¹³C NMR(125MHz,DMSO)δ170.3,144.8,143.7,127.3,119.6,116.3,115.2,41.9,38.5,30.9,29.0 26.0,22.0,13.8；HRMS(ESI):m/z calcd for C₁₄H₂₂NO₃ ⁺[M+H]⁺:252.1594；found:252.1595.

the compound 2- (3, 4-dihydroxyphenyl) -N-octylacetamide (4 q). The yield is 77.0%; a white solid; melting point: at the temperature of between 89 and 90 ℃,¹H NMR(500MHz,DMSO)δ8.73(s,1H),8.63(s,1H),7.80(t,J＝5.4Hz,1H),6.64(d,J＝2.0Hz,1H),6.61(d,J＝8.0Hz,1H),6.47(dd,J＝8.0,2.0Hz,1H),3.16(s,2H),3.00(dd,J＝12.8,6.8Hz,2H),1.41-1.33(m,2H),1.30-1.18(m,10H),0.86(t,J＝7.0Hz,3H)；¹³C NMR(125MHz,DMSO)δ170.3,144.8,143.7,127.3,119.5,116.3,115.2,41.9,38.5,31.2,29.1,28.7,28.6,26.3,22.0,13.9；HRMS(ESI):m/z calcd for C₁₆H₂₆NO₃ ⁺[M+H]⁺:280.1907；

found:280.1909.

example 4: preparation of Compound 4h,4q

Example 3 was repeated, 1, 2-dichloroethane, chloroform or chlorobenzene was used instead of DCM, respectively, boron trichloride, aluminum tribromide or boron triiodide was used instead of boron tribromide, respectively, and the obtained compound was characterized as the target compound 4h,4 q.

Experimental example 1: experiments on antioxidant activity of capsaicin derivatives 3f,3g,3o,3p,4h,4q, 5a (capsaicin) and 5b (dihydrocapsaicin) disclosed by the invention

1. Experimental part

DPPH radical scavenging test

The results were obtained according to the reported methods (Alam, Bristi,&rafiquzzaman,2013),

compounds

3f,3g,3o,3p,4h,4q and 5a and 5b were evaluated for antioxidant activity by measuring DPPH free radical scavenging activity. Quercetin was used as a positive control for antioxidant activity. In terms of samples, the concentration gradient of the compound was diluted with 0.2mL of methanol and 2mL of DPPH solution (0.5mM) was added. After 30 minutes, the absorbance at 517nm of each concentration of the compound was measured. The DPPH free radical clearance rate calculation formula is as follows: DPPH radical clearance (%) ([ ADPPH-a (DPPH + compound) ]]ADPPH 100%. Radical scavenging Activity from average IC of 3 replicates₅₀And + -SEM representation.

ABTS radical cationic decoloring

The antioxidant activity of the compounds can be determined according to methods reported in the literature (seram, Henning, Niu, Lee, Scheuller, & Heber, 2006). Solid manganese dioxide was added to 20mL of 5mM ABTS solution previously prepared with 75mM Na/K buffer, pH 7, as described below. Quercetin was used as a positive control for antioxidant activity with a standard curve at a range of different concentrations. The compound was vortexed, sonicated, centrifuged and extracted in a methanol: water (1:1, v/v) solution and diluted appropriately in Na/K buffer at pH 7. The diluted sample was mixed with 200 μ L ABTS radical cation solution in a 96-well plate and the absorbance at 750nm was read with a ThermoMax micrometer. The samples were repeated 3 times. The results were calculated from the standard curve.

1.3. Cell culture and processing

Human neuroblastoma SH-SY5Y cells were purchased from the stem cell bank of Chinese academy of sciences. SH-SY5Y cells were routinely maintained in a humidified atmosphere of sodium pyruvate (Invitrogen,11360070), NEAA (Invitrogen,11140050) at 37 ℃ and 5% CO2 and 95% air in a nutrient mixture supplemented with 10% fetal bovine serum (Gibco), 1% Gluta-max (Invitrogen,31090081) and Ham's F-12 (Invitrogen, 11765054). The medium was changed every 2 days. In all experiments, cells were exposed to 100 μ M H₂O₂(Sigma-Aldrich)。

1.4. Analysis of cell viability Using the MTT method

SH-SY5Y cells were seeded in 96-well plates at a density of 8X 103 cells/well for 24 hours. The MTT method measures cytotoxicity of quercetin (control), 5a, 5b and 4q (0, 5, 10, 20, 40 or 80 μ M). SY5Y cells were incubated with quercetin (control), 5a, 5b and 4q (0.1, 1 or 10 μ M) at 37 deg.C for 3 hours, followed by addition of H₂O₂(100. mu.M) for 24 hours. MTT 4h was then added, the culture broth removed, and DMSO added to dissolve the formazan. Absorbance at 570nm was measured using a microplate reader (Spectramax Plus 384, Molecular Devices, Sunnyvale, Calif., USA).

1.5. Statistical analysis

Statistical analysis was performed by Tukey's multiple comparison test using GraphPad Prism version 8.0.2 (GraphPad Software, San Diego, CA). Data have been expressed as mean ± standard error of mean (x ± SEM), P <0.05 is considered to indicate significant differences.

2. Results and discussion

2.1 antioxidant Activity as determined by DPPH free radical scavenging test

Reducing oxidative stress is a key aspect of finding food ingredients for the prevention and treatment of neurodegenerative or other diseases. The anti-oxidant activity of the

capsaicin derivatives

3f,3g,3o,3p,4h,4q and 5a and 5b of the invention is tested by the DPPH free radical scavenging assay using quercetin as a reference compound. Most derivatives exhibit potent free radical scavenging activity. The IC50 values or inhibition for all capsaicin derivatives are summarized in table 1.

TABLE 1 antioxidant activity of

compounds

3f,3g,3o,3p,4h,4q and 5a and 5 b.

Note:^aIC₅₀values are expressed as triplicate determinations, mean ± SEM.

^bData representation as IC₅₀I.e. the concentration of compound inhibiting 50% of the free radicals (mean ± SEM).

^cThe measurement was carried out in the presence of 0.5mM compound.

As can be seen from the table, compounds 4h and 4q are compared to the reference compound quercetin (IC)₅₀Greater efficacy (IC) was shown at 8.70 ± 1.75 μ M₅₀4.49 ± 0.74 μ M and 4.14 ± 1.09 μ M) to the reference compound quercetin (IC)₅₀8.70 ± 1.75 μ M), while 3g of compound had little free radical scavenging activity. These studies indicate that the bis-OH group is critical for determining scavenging activity, while the bis-OCH 3 group is detrimental to antioxidant activity. For example, compound 3f, derived from 3g of the demethylated compound, has enhanced antioxidant activity. Compounds having two-OH groups 4h and 4q (IC)₅₀4.49 ± 0.74 μ M, and 4.14 ± 1.09 μ M) versus compounds 3f and 3o (IC)₅₀138.72 ± 6.89 μ M and 184.93 ± 9.86 μ M) has one-OH and one-OCH group₃A group. The IC50 values or inhibition (5a vs.5b, 3f vs.3o, 3g vs.3p, and 4h vs.4q) for the different compounds indicate that the contribution to DPPH clearance is relatively small, whether the length of the alkyl or alkenyl chain. In brief, the structure-activity relationship of the antioxidant effect of capsaicin analogs is as follows: two-OH groups on the benzene ring>one-OH and one-OCH on the same benzene ring₃Radical (I)>two-OCH 3 groups on the same phenyl ring。

2.2 determination of antioxidant Capacity by ABTS free radical cationic Decoloration method

These capsaicin analogs tested for free radical scavenging activity (DPPH) were also tested for free radical cationic depigmentation test (ABTS). IC for antioxidation₅₀Values represent that quercetin was used as a reference compound. The IC50 values or inhibition for these compounds are summarized in table 1 above. Most compounds exhibit good free radical scavenging, IC₅₀The value ranged from 10.62. mu.M to 30.88. mu.M. Compound 3f showed significant antioxidant activity (IC)₅₀13.07. + -. 1.47. mu.M). As can be seen from Table 1, when the two substituents on the phenyl ring are methoxy groups (3g and 3p), the ABTS + radical scavenging ratio does not exceed 20% at a concentration of 0.5mM, the antioxidant effect and DPPH radical scavenging test results. Unlike the structure-activity relationship of DPPH assay, compounds with two-OH groups (4h and 4q) have a similar antioxidant effect as compounds with one-OH and one-OCH 3 group (5b, 3 f). In summary, the structure-activity relationship of the antioxidant (ABTS assay) effects of capsaicin analogs is as follows: two-OH groups on the benzene ring are approximately equal to one-OH and one-OCH 3 group on the same benzene ring>two-OCH 3 groups on the same phenyl ring are on the same phenyl ring.

2.3 toxicity of Compound 4q to SH-SY5Y cells

Many studies have shown that oxidative stress is an important cause of neurodegenerative diseases (J Parkinsons Dis,3(4), 461-491.). However, this state of imbalance is produced by cells overproducing ROS, which exceeds the scavenging capacity of their own antioxidant systems. ROS can react with different molecules to promote neuronal cell death and lead to neurodegenerative diseases. H₂O₂Is one of ROS generated by in vivo metabolism and is commonly used for establishing an in vitro oxidative stress model. First,

compounds

5a, 5b, 4q and quercetin were tested for cytotoxicity by MTT method, respectively. As shown in FIG. 1, compound 4q showed a strong growth inhibitory effect on SH-SY5Y cells.

Claims

1. Capsaicin derivatives having the structures represented by the following formulae 3 and 4:

wherein R is¹Is hydroxy or methoxy, R²Is a hydroxyl group, and n is 2 to 15.

2. The capsaicin derivative according to claim 1, wherein the capsaicin derivative is selected from the group consisting of:

3. the process for producing a capsaicin derivative according to claim 1,

placing a compound with a structure shown in a formula 1 and a compound with a structure shown in a formula 2 in an organic solvent, and reacting under the condition of existence of a condensing agent and with heating or without heating to obtain a compound with a structure shown in a formula 3;

wherein R is¹Is hydroxy or methoxy, n is 2-15;

and (3) putting the compound with the structure shown in the formula 3 into an organic solvent, adding a demethylating reagent, and reacting at the temperature of below 0 ℃ to obtain the compound with the structure shown in the formula 4.

4. The process according to claim 3, wherein the organic solvent is one or a combination of two or more selected from the group consisting of dichloromethane, 1, 2-dichloroethane, chloroform and chlorobenzene.

5. The process according to claim 3, wherein the condensing agent is a carbodiimide-based condensing agent in the process for synthesizing the compound having the structure represented by formula 3.

6. The method according to claim 5, wherein a condensation activator is further added when the condensation agent is a carbodiimide-based condensation agent.

7. The process according to claim 3, wherein the demethylating agent is one or a combination of two or more selected from the group consisting of boron tribromide, boron trichloride, aluminum tribromide and boron triiodide.

8. The method according to claim 3, wherein the reaction is carried out at a temperature of-40 ℃ or lower in the method for synthesizing the compound of formula 4 or the structure.

9. Use of a capsaicinoid derivative of claim 1, or a pharmaceutically acceptable salt thereof, for the preparation of an antioxidant.

10. An antioxidant comprising the capsaicinoid derivative of claim 1 or a pharmaceutically acceptable salt thereof.