Water-in-stable L-ascorbic acid derivative and a method for preparation thereof, and a skin-whitening cosmetic composition containing the same

DETAILED DESCRIPTION OF THE INVENTION L-ascorbic acid derivative provided by the present invention is 2-(3-Aminopropane phosphoric acid)-L-ascorbate represented by a following general formula (I): ##STR3## L-ascorbic acid derivative (I) (thereinafter, this compound will be referred to "AsA-APPA", which is an abbreviated name for ascorbic acid--aminopropanol phosphoric diester) is a compound where 3-aminopropane phosphoric acid is combined to 2-hydroxyl group of ascorbic acid by phosphoric ester bond.
This compound is very stable without any discoloration and reduction of activity by oxidation in an aqueous base, and has a good solubility in water not to cause any precipitation.
Further, it can be easily percutaneously penetrated by the phosphoric group, and once absorbed compound can be easily decomposed by a hydrolytic enzyme to release ascorbic acid and 3-aminopropane phosphoric acid.
As a result, this compound can provide an activity for inhibiting melanin-formation by ascorbic acid and an activity for deferring skin-aging by 3-aminopropane phosphoric acid.
According to the present invention, the method for preparing AsA-APPA represented by the formula (I) partially comprises a method for preparing 3-aminopropane phosphoric acid(3-APPA) disclosed in U.
S.
Pat.
No.
5,723,645.
The disclosed preparation method of 3-APPA is simple and economic because it employs two-step process and inexpensive phosphorus oxychloride, thereby can be advantageously applied to an industrial scale.
In detail, the method for preparing L-ascorbic acid derivative (I) according to the present invention comprises steps of: (1) reacting 3-amino-1-propanol with phosphorus oxychloride in an equivalent ratio of 1:1.
about.
1.
3, in presence of an organic base, in an organic solvent, at a temperature of about 0.
about.
5.
degree.
C.
for about 1.
about.
2 hours, to produce 2-chlorotetrahydro-2H-1,3,2-oxazaphosphorin P-oxide represented by following general formula (II): ##STR4## (2) reacting said compound (II) of said step (1) with 5,6-hydroxyl groups-protected L-ascorbic acid, in presence of an organic base, in an organic solvent, to produce L-ascorbic acid derivative represented by following general formula (III): ##STR5## (3) hydrolyzing the L-ascorbic acid derivative (III) of said step (2) by adding distilled water thereto, at a temperature of about 5