JPH0739578B2 - Antioxidant - Google Patents

Description

Detailed Description of the Invention

[0001]

This invention relates to antioxidants.

[0002]

2. Description of the Related Art Ascorbic acid has an antioxidant effect and is used for the purpose of preventing browning of food, maintaining flavor and freshness. However, ascorbic acid is susceptible to decomposition in an aqueous solution, and it may be difficult to achieve the above effects for a long period of time.

Therefore, in order to improve the stability of ascorbic acid, various ascorbic acid derivatives have been synthesized.
For example, we have the general formula

[Chemical 2] (Wherein R is a group selected from the group consisting of an alkyl group, a heterocycle-containing alkyl group, an aralkyl group, a hydroxycarbonylalkyl group, an alkoxycarbonylalkyl group, an alkylcarbonylalkyl group and an arylcarbonylalkyl group). Ascorbic acid derivative,
They have found that they are more stable than ascorbic acid, have radical scavenging ability, and are preferably used as antioxidants, and have filed a patent application for an invention of the use of antioxidants composed of this ascorbic acid derivative (Japanese Patent Application No. Sho 63-63). -552
89, JP-A-1-228977).

In the above-mentioned Japanese Patent Application No. 63-55289, among the ascorbic acid derivatives of the above general formula (II),
As the ascorbic acid derivative in which R is an alkyl group, only an ascorbic acid derivative in which the alkyl group is an alkyl group having 4, 8, 12 or 18 carbon atoms is exemplified. And the above C ₄ , C ₈ , C ₁₂ or C ₁₈ of ascorbic acid
Although the alkyl ester has excellent antioxidant ability as described above, it has a low solubility in water and has a problem when it is to be formulated using water or an aqueous solvent.

[0005]

OBJECTS OF THE INVENTION Therefore, the object of the present invention is to provide a Japanese Patent Application No. 63-5.
The above-mentioned drawbacks of the ascorbic acid derivative specifically described in No. 5289 are solved, and an antioxidant comprising an ascorbic acid derivative having excellent stability and antioxidant ability and also having excellent solubility in water is provided. Especially.

[0006]

[Means for Achieving the Object] As a result of various studies for achieving the above-mentioned object, the present inventors have found that the above-mentioned Japanese Patent Application No. 63-
The compound is conceptually included in the ascorbic acid (R = alkyl group) of the formula (II) described in JP-A-55289, but the compound name, the synthesis example, etc. are not disclosed in the specification.

[Chemical 3] It was found that 3-O-ethylascorbic acid represented by the formula (1) has surprisingly excellent stability and antioxidant ability, and has extremely high solubility in water as compared with long-chain alkylascorbic acid. Was achieved.

Accordingly, the present invention provides the formula

[Chemical 4] The gist is an antioxidant characterized by containing an ascorbic acid derivative represented by. The antioxidant of the present invention contains the ascorbic acid derivative of the above formula (I). That is, the antioxidant of the present invention may be composed of the ascorbic acid derivative of formula (I) alone, or may be composed of the ascorbic acid derivative of formula (I) and one or more second components. Is also good. As the second component, various substances are used depending on the use, such as ascorbic acid, erythorbic acid, B
HT, BHA, tocopherols, gallic acid and its esters, nordihydroguaiaretic acid (NDG
A), sesamol, phosphoric acid, maleic acid, malonic acid, citric acid, pyruvic acid, succinic acid, fumaric acid, aconitic acid and the like.

In the antioxidant of the present invention, the ascorbic acid derivative of the formula (I), which is a constituent thereof, has stability, antioxidant ability,
Since it has excellent solubility in water, it is preferably used for applications such as pharmaceuticals, food antioxidants, whitening cosmetics, and additives for pharmaceuticals, baits, general cosmetics and the like. Test Example 4 described below
As is clearer, when the antioxidant of the present invention is added to Japanese tea in a small amount (for example, 0.01 to 1% by weight),
It can retain the color and aroma of Japanese tea for a long time.

The ascorbic acid derivative of the formula (I), which constitutes the antioxidant of the present invention, has the formula:

[Chemical 5] It can be obtained by treating the compound represented by with an acid to open the dioxolane ring to form a vic-glycol group.

The acid used in this reaction is hydrochloric acid,
Examples thereof include acetic acid, sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid and camphorsulfonic acid. The reaction is also preferably carried out in one or more organic solvents selected from methanol, ethanol, dioxane, tetrahydrofuran and 1,2-dimethoxyethane.

The starting material of the formula (III) is obtained by ketalizing ascorbic acid by a conventional method,

[Chemical 6] After obtaining 5,6-O-isopropylideneascorbic acid represented by the following formula, this is reacted with an ethyl halide represented by the general formula C ₂ H ₅ X (wherein X is a halogen atom) to obtain a compound represented by the formula ( Obtained by ethyl etherifying the hydroxyl group at the 3-position of the compound of IV). This dehydrohalogenation reaction may be carried out according to the well-known Williamson reaction, or may be carried out in an organic layer-water phase system using a phase transfer catalyst.

[0012]

EXAMPLES Examples of the present invention will be described below. Reference Example [Production of 3-O-ethylascorbic acid] (1) Synthesis of L-5,6-O-isopropylidene ascorbic acid 180 g of ascorbic acid was stirred in 750 ml of acetone and heated to 40 ° C. 20 ml of acetyl chloride was added and stirring was continued to form a slurry layer. After 3 hours, the mixture was cooled with ice and the deposited precipitate was collected by filtration. The precipitate was cooled on a funnel with cold acetone-n.
After washing with a mixed solution of hexane (3: 7), it was dried under reduced pressure (silica gel). Recrystallized from acetone and L-
5,6-O-isopropylidene ascorbic acid (melting point 2
(190-208 ° C) was obtained.

(2) L-5,6-O-isopropylidene-
Synthesis of 3-O-ethylascorbic acid 4.32 g of the compound obtained in (1) was dissolved in 30 ml of DMSO, 1.78 g of NaHCO ₃ was added, and the mixture was stirred at room temperature for 30 minutes. Ethyl bromide (3.27 g) was added, and the mixture was heated to 40 ° C and stirred for 7 hours. After cooling, 100 ml of H ₂ O was added, the pH was adjusted to 5 with 4N hydrochloric acid, and the mixture was shaken with ethyl acetate (100 ml × 2). The organic layers were combined, washed with water and saturated aqueous hydrochloric acid, dried over sodium sulfate, and concentrated under reduced pressure. 4.5 g of the obtained residue was subjected to silica gel column chromatography and eluted with a benzene-ethyl acetate mixed solution to give L-5,6.
3.42 g of -O-isopropylidene-3-O-ethylascorbic acid derivative was obtained.

(3) Synthesis of L-3-O-ethylascorbic acid (2) 3.3 g of the obtained compound was dissolved in 40 ml of a tetrahydrofuran-methanol (3: 1) mixed solution, and 10 ml of 2N hydrochloric acid was dissolved.
Was added and stirred at room temperature for 20 hours. The reaction solution was concentrated under reduced pressure, and the residue was recrystallized from ethyl acetate-petroleum ether to give L
-3-O-Ethylascorbic acid was obtained.

Mp 113-114 ° C. H-NMR (MeOH-d ₄ ) δ ppm, 1.36
(3H, t) 3.58 to 3.67 (2H, m) 3.
77-3.85 (1H, m) 4.54 (2H, q)
4.75 (1H, d, 1.3Hz)

Test Example 1 (Antioxidant Effect Investigated Using Stable Radicals) S. Blois Method [Nature 181]
Vol., P. 1199, 1958], the reducing activity of α, α-diphenyl-β-picrylhydrazyl (DPPH), which is a stable free radical, was examined and used as an index of antioxidant action. That is, 0.1 mM DPPH ethanol solution 3
Add the sample to ml, and 20 minutes later, using a spectrophotometer,
Absorbance was measured at a wavelength of 517 nm. Solvent [dimethylformamide (DMF) 0.5% or less] The difference in absorbance from the control was taken as the reduction activity.

The 50% radical scavenging concentration of the test compound (3-O-ethylascosbic acid) was 2.0 × 10 ^-5 M, and this value was 50% radical scavenging of 3-O-octadecylascorbic acid. It was lower than the concentration (3.2 × 10 ⁻⁵ M).

Test Example 2 (Antioxidant action on edible oils and fats) 3-O-ethylalcorbic acid and 3-O-octadecylascorbic acid were dissolved in cottonseed oil to a concentration of 0.02 w / w% to obtain 90 ml / mi
The mixture was heated in an oven maintained at 100 ° C while bubbling n 2 oxygen gas. Sampling was performed at 15 hours and 18 hours, and the peroxide value (PO
V) was measured. The measurement results are shown in Table 1.

[0019]

[Table 1] From Table 1, it was revealed that 3-O-ethylascorbic acid markedly prevented the formation of peroxide in cottonseed oil as compared to 3-O-octadecylascorbic acid.

Test Example 3 (Solubility in water) 10 mg of 3-O-ethylascorbic acid was dissolved in 0.1 ml of water, and the solubility of 3-O-ethylascorbic acid in water was 100 mg / ml. confirmed. On the other hand, 3-O-decyl ascorbic acid and 3-O-octadecyl ascorbic acid required 200 ml or more of water to dissolve 10 mg of each. From these results, it is clear that 3-O-ethylascorbic acid is far superior in solubility to 3-O-decylascorbic acid and 3-O-octadecylascorbic acid.

Test Example 4 (Color and aroma retaining effect in tea) Japanese tea containing 0.1% by weight of 3-O-ethylascorbic acid and Japanese tea to which 3-O-ethylascorbic acid was not added ( (Control) was placed in an airtight container and left at room temperature for 3 months, and changes in color and aroma during that time were observed. The evaluation was carried out by 5 panelists. The results are shown in Table 2.

[0022]

[Table 2]

It can be seen from Table 2 that the color and aroma of Japanese tea can be maintained for a long period of time by adding a small amount of 3-O-ethylascorbic acid to Japanese tea.

[0024]

As described in detail above, according to the present invention,
An antioxidant having excellent stability, antioxidant ability and solubility in water was provided.

Claims (1)

[Claims] 1. The formula: An antioxidant comprising an ascorbic acid derivative represented by: