JP2020002127A - Esculin lipoic acid ester with antioxidant activity and method of preparing the same - Google Patents

Abstract

To provide an antioxidant as a food and cosmetic additive, and a method of preparing the same.SOLUTION: The invention provides the esculin lipoic acid ester compound represented by formula I in the figure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to Chinese Patent Application No. CN201810649366. Filed on June 22, 2018. Claims priority to Issue X, the contents of which are incorporated by reference for all purposes as if fully set forth herein.

  The present invention relates to food and cosmetic additives, particularly to esculin lipoate having antioxidant activity and a method for producing the same.

  Due to technological advances in the food additive industry, the development, manufacture, and application of food antioxidants have greatly advanced. Antioxidants are important food additives. It is mainly used to prevent or delay the autoxidation of oils in foods. It also prevents nutrient damage, browning, and fading due to oxidation during storage. At the same time, more and more antioxidants are also used in the cosmetics industry, as research has shown in recent years that human skin ages due to oxidation and UV irradiation. Further research is underway to develop new antioxidants. Synthetic and semi-synthetic antioxidants are receiving increasing attention.

Esculin (a compound of formula II) is a coumarin compound extracted from the dried bark or dried epidermis of the olein tree of the genus Oleaceae, and is an active ingredient of the Chinese herbal medicine Qinpi (Cortex Fraxini). Esculin has anti-inflammatory, antibacterial, diuretic, and antitumor effects. There are no reports on the use of esculin as an antioxidant.

Lipoic acid (a compound of formula III, also known as alpha-lipoic acid and alpha-lipoic acid) is a coenzyme present in mitochondria that, like vitamins, eliminates free radicals that accelerate aging and disease . Lipoic acid enters cells after being absorbed by the gut in the body. It has both fat-soluble and water-soluble properties. It has been used in the treatment and prevention of various diseases such as heart disease and diabetes. It is believed to preserve and regenerate other antioxidants such as vitamins C and E.

In one embodiment, the present invention provides a compound of formula I (esculin lipoate):

In one embodiment, the present invention provides a method for preparing a compound of formula I. The method comprises reacting a compound of formula II with a compound of formula III to obtain a compound of formula I.

  In another embodiment, the reaction of the compound of Formula II with the compound of Formula III places the compound of Formula II and the compound of Formula III in a molar ratio of 1: 1 to 1: 1.3 in the reactor. Adding an organic solvent, N, N'-dicyclohexylcarbodiimide (DCC), and a catalyst to obtain a reaction mixture, and heating the reaction mixture under sonication at 30-55 ° C. for 3-4 hours. Process.

  In another embodiment, the organic solvent is acetonitrile or THF, and the catalyst is benzyltriethylammonium chloride or thionyl chloride.

  It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

  The accompanying drawings, which are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, explain the principles of the invention. Help.

Scavenging activity of sample and control solutions at different concentrations

  Reference will now be made in detail to embodiments of the invention, examples of which are illustrated in the accompanying drawings. The following examples illustrate the invention, but the invention is not limited to the examples.

[Example 1]
Preparation of esculin lipoate (compound of formula I)

  100 mg (0.29 mmol) of esculin and 66.6 mg (0.32 mmol) of lipoic acid were placed in a 100 mL reactor. 60 mL of acetonitrile was added to form a reaction mixture. Then 61.9 mg (0.3 mmol) of DCC and 3.5 mg of thionyl chloride were added to the reaction mixture. The reaction mixture was heated at 35 ° C. under sonication and nitrogen atmosphere for 4 hours. The reaction mixture was cooled to room temperature, concentrated under reduced pressure, filtered, and dried over sodium sulfate. Then, the solvent in the reaction mixture was removed to obtain 137.9 mg of esculin lipoate (88.79% yield).

¹ H NMR (400 MHz, DMSO-d6) δ (ppm): 7.74 (1H, d), 6.87 (1H, s), 6.73 (1H, s), 5.90 (1H, d), 5.81 (1H, d) , 5.31 (1H, s), 4.01-4.30 (3H, m), 3.89 (1H, t), 3.52 (3H, s), 3.39-3.50 (2H, m), 2.63-2.49 (3H, m), 2.30 (2H, t), 2.00-1.71 (4H, m), 1.53 (2H, q), 1.28 (2H, m); ¹³ C NMR (400 MHz, DMSO-d ₆ ) δ (ppm): 173.4, 160.6, 148.6, 145.8, 143.0, 113.6, 111.0, 109.7, 102.7, 78.9, 76.3, 73.6, 71.5, 63.4, 40.7, 38.3, 34.0, 29.3, 28.1; MS (ESI) for (M + H) ⁺ : 529.12

[Example 2]
Preparation of esculin lipoate

  100 mg (0.29 mmol) of esculin and 66.6 mg (0.32 mmol) of lipoic acid were placed in a 100 mL reactor. 60 mL of acetonitrile was added to form a reaction mixture. Then 61.9 mg (0.3 mmol) of DCC and 6.7 mg of benzyltriethylammonium chloride (TEBAC) were added to the reaction mixture. The reaction mixture was heated at 45 ° C. under sonication and a nitrogen atmosphere for 4 hours. The reaction mixture was cooled to room temperature, concentrated under reduced pressure, filtered, and dried over sodium sulfate. Next, the solvent in the reaction mixture was removed to obtain 121.3 mg of esculin lipoic acid ester (78.14% yield).

[Example 3]
Preparation of esculin lipoate

  100 mg (0.29 mmol) of esculin and 78.7 mg (0.38 mmol) of lipoic acid were placed in a 100 mL reactor. 60 mL of acetonitrile was added to form a reaction mixture. Then 61.9 mg (0.3 mmol) of DCC and 3.5 mg of thionyl chloride were added to the reaction mixture. The reaction mixture was sonicated and heated at 55 ° C. under a nitrogen atmosphere for 3 hours. The reaction mixture was cooled to room temperature, concentrated under reduced pressure, filtered, and dried over sodium sulfate. Next, the solvent in the reaction mixture was removed to obtain 129.3 mg of esculin lipoic acid ester (83.26% yield).

[Example 4]
Preparation of esculin lipoate

  100 mg (0.29 mmol) of esculin and 66.6 mg (0.32 mmol) of lipoic acid were placed in a 100 mL reactor. 60 mL of acetonitrile was added to form a reaction mixture. Then 61.9 mg (0.3 mmol) of DCC and 3.5 mg of thionyl chloride were added to the reaction mixture. The reaction mixture was heated at 30 ° C. for 3 hours under sonication and nitrogen atmosphere. The reaction mixture was cooled to room temperature, concentrated under reduced pressure, filtered, and dried over sodium sulfate. Then, the solvent in the reaction mixture was removed to obtain 124.4 mg of esculin lipoate (yield: 80.11%).

[Example 5]
Preparation of esculin lipoate

  100 mg (0.29 mmol) of esculin and 66.6 mg (0.32 mmol) of lipoic acid were placed in a 100 mL reactor. 60 mL of acetonitrile was added to form a reaction mixture. Then 61.9 mg (0.3 mmol) of DCC and 6.7 mg of benzyltriethylammonium chloride (TEBAC) were added to the reaction mixture. The reaction mixture was heated at 50 ° C. for 4 hours under sonication and nitrogen atmosphere. The reaction mixture was cooled to room temperature, concentrated under reduced pressure, filtered, and dried over sodium sulfate. Thereafter, the solvent in the reaction mixture was removed to obtain 130.9 mg of esculin lipoate (84.28% yield).

[Example 6]
Antioxidant activity of esculin lipoate as measured by DPPH radical scavenging activity assay

2,2-Diphenyl-1-picrylhydrazyl (DPPH) is an organic compound composed of stable organic radicals. In the DPPH molecule, nitrogen free radicals are stabilized by the presence of a plurality of electron-withdrawing NO ₂ and a large π bond of a benzene ring. The methanol solution is purple and has a maximum absorption peak at 517 nm. After addition of the antioxidant, DPPH captures electrons that are paired with free electrons, and the purple color fades to a yellow substance. The absorption at 517 nm disappears and the degree of fading is quantitatively related to the number of electrons it captures. Based on this principle, a spectrophotometer can be used to detect changes in DPPH radicals and the absorbance of the sample solution and determine the ability of the sample to supply hydrogen atoms and remove free radicals.

<< Preparation of DPPH solution >>
An accurate amount of 2,2-diphenyl-1-picrylhydrazyl (DPPH) is measured, dissolved in methanol to prepare a 0.2 mmol / L DPPH solution, and stored at 0 ° C. in a dark place.

<< Preparation of sample solution >>
The sample solution to be tested is prepared by diluting the esculin lipoate with acetonitrile in a gradient of 1.82, 7.28, 24.2, 48.4, 72.6, 96.8, 242, 484, 726 and 968 ppm. Was prepared. Control samples (vitamin C, esculin, lipoic acid, a mixture of esculin and lipoic acid) were similarly diluted with methanol at the same concentration gradient to obtain four corresponding groups of control solutions.

<< Specific process: Measurement of scavenging activity of sample solution >>
2 mL of the sample solution was taken at each concentration gradient, 2 mL of a 0.2 mmol / L DPPH solution was added, the mixture was mixed, allowed to react at room temperature for 30 minutes in the dark, and then methanol was added to adjust the final volume. The absorbance _{A i} was measured at 517nm. 2 mL of the control solution and 2 mL of methanol were mixed, and the absorbance _Aj was measured. Mixing the DPPH solution 2mL methanol 2mL, and the absorbance was measured _{A 0.} The scavenging activity of the sample solution and the control solution is calculated according to the following formula.
Scavenging activity (%) = 100 × [1- (A _i -A _j ) / A ₀ ]

  The scavenging activity is shown in Table 1 and FIG. In FIG. 1, the X-axis represents the concentration of the sample and the control solution (PPM), and the Y-axis represents the scavenging activity.

Table 1: Scavenging activity

  The test results show that the antioxidant activity of esculin lipoate is similar to that of vitamin C, and that free radical clearance rates of more than 90% can be achieved at lower concentrations, due to esculin, lipoic acid, and esculin And a mixture of lipoic acid, showing significantly higher. Esculin lipoate can be used as an antioxidant additive for food and cosmetics and has widespread application prospects.

  It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (4)

A compound of the following formula I:

2. A method for preparing a compound according to claim 1, comprising reacting a compound of formula II with a compound of formula III to obtain said compound of formula I.

Wherein the reaction of the compound of Formula II with the compound of Formula III comprises:
Disposing the compound of the formula II and the compound of the formula III in a reactor in a molar ratio of 1: 1 to 1: 1.3,
Adding an organic solvent, N, N′-dicyclohexylcarbodiimide, and a catalyst to obtain a reaction mixture; and
Heating the reaction mixture under sonication at 30-55 ° C for 3-4 hours.   The method according to claim 3, wherein the organic solvent is acetonitrile or THF, and the catalyst is benzyltriethylammonium chloride or thionyl chloride.

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