Skin Lightening / Whitening Potential

Skin Lightening / Whitening Potential of DiHyrdrooxyresveratrol

Comparison of the skin lightening /brightening/whitening experiments were done on dihydrooxyresveratrol with other skin lightening compounds popularly used skin in creams, lotions and serum.

For the evaluation of tyrosinase inhibitory activity, assays were performed with L-dopa as the substrate and using kojic acid-, a well-known strong tyrosinase inhibitor-, as the positive control.
Table 1 summarizes the percentages of inhibition and the IC50 values of 1–4, as compared with kojic acid. Oxyresveratrol (1) was earlier reported to be stonger tyrosinase inhibitor from natural sources.

Table 1. Tyrosinase inhibition in 300 _M and 60 _M, and IC50 values of compounds isolated from Morus alba wood.

Compound	Tyrosinase Inhibition
Compound	% +STD (300 _M)	% +STD (60 _M)	IC50 +STD (_M) *
1. Oxyresveratrol	97.8 +0.1	93.1 +0.1	1.7 +0.04
2. Di hydro oxyresveratrol	98.2 +0.5	97.6 +0.2	0.3 +0.05
3. Kojic acid	96.0 +0.2	94.2 +0.2	40.0 +1.4
4. Moracin M	87.2 +0.5	61.3 +1.2	8.0+ 0.6

Figure 1. Dose-dependent inhibitory effects on mushroom tyrosinase by (1) oxyresveratrol (2),Dihydrooxyresveratrol (3) and kojic acid. Samples shown are oxyresveratrol (circle ), Dihydrooxyresveratrol(triangle), and kojic acid (diamond).

The compound Dihydrooxyresveratrol, a bibenzyl derivative prepared from Oxyresveratrol,, showed more inhibitory activity than did the parent compound, being about 8- fold stronger in view of the IC50 value. Analysis of the data obtained for Dihydrooxresveratrol indicated that this compound, as well as Oxyresveratrol and kojic acid, inhibited the enzyme in a dose-dependent manner .

Dihydrooxyresveratrol , which loses the double bond between the two aromatic rings in contrast to Oxyresveratrol, showed 8-fold more diphenolase inhibitory activity toward mushroom tyrosinase than its analog, oxyresveratrol . It is suggested that the higher tyrosinase inhibitory activity of dihydrooxyresveratrol was probably due to its bibenzyl structure, which gave more flexibility and thus allowed the phenolic groups to interact with the enzyme more effectively.

A Comparison of the skin whitening activity of selected popular products in skin lightening/ Skin whitening formulations

Compound	Onset	Significant Whitening	Optimum / Maximum	Maximum Whitening Effect
HYDROQUINONE	3 to 5 Weeks	8 Weeks	8 to 12 Weeks	2%
KOJIC ACID	4 to 6 Weeks	6 Weeks	12 Weeks	2.20%
LICORICE EXTRACT	4 to 6 Weeks	10 Weeks	12 Weeks	1.70%
OXYRESVERATROL	2 to3 Weeks	3 Weeks	4 Weeks	2.78%
Dihydrooxy- resveratrol	Less than 2 weeks	3 weeks	Less than 4 weeks	3.0%

Table 1 summarizes the percentages of inhibition and the IC50 values of 1–4, as compared with kojic acid. Oxyresveratrol (1) was earlier reported to be stonger tyrosinase inhibitor from natural sources.

Table 1. Tyrosinase inhibition in 300 _M and 60 _M, and IC50 values of compounds isolated from Morus alba wood.

Compound	Tyrosinase Inhibition
Compound	% +STD (300 _M)	% +STD (60 _M)	IC50 +STD (_M) *
1. Di hydro oxyresveratrol	98.2 +0.5	97.6 +0.2	0.3 +0.05
2. Oxyresveratrol	97.8 +0.1	93.1 +0.1	1.7 +0.04
3. Kojic acid	96.0 +0.2	94.2 +0.2	16.1 +1.4
4. Moracin M	87.2 +0.5	61.3 +1.2	8.0+ 0.6

SKIN LIGHTENING / SKIN WHITENING AGENTS IN THE TREATMENT OF HYPERPIGMENTATION

COMMON SKIN WHITENING AGENTS USED IN DERMATOLOGICAL PREPARATIONS AND COSMETIC FORMULATIONS

	Active Compound	IC50	Optimum Conccentration	Side Effects	Current Status
1st Generation	Hydroquinon	72 μm	2 to 5%	Very High	Banned in cosmetic formulations
2nd Generation	Kojic acid	40.0 μm	1 to 3%	Side effects reported	Banned in many Countries.
3rd Generation	GLABREDIN (Licorice Extract)	12 μm	0.3 to 0.5%	No side effects reported	Highly in Use
4th Generation	OXYRESVERATROL	1.7 μm	0.2 to 0.30 %	No side effects reported	Very high use expected
Latest	Dihydrooxyresveratrol	0.3 μm	0.1 to 0.25%	No side effects Reported	Very high use expected

Table 1. Tyrosinase inhibition in 300 _M and 60 _M, and IC50 values of compounds isolated from Morus alba wood.

Compound	Tyrosinase Inhibition
Compound	% +STD (300 _M)	% +STD (60 _M)	IC50 +STD (_M) *
1. Di hydro oxyresveratrol	98.2 +0.5	97.6 +0.2	0.3 +0.05
2. Oxyresveratrol	97.8 +0.1	93.1 +0.1	1.7 +0.04
3. Kojic acid	96.0 +0.2	94.2 +0.2	16.1 +1.4
4. Moracin M	87.2 +0.5	61.3 +1.2	8.0+ 0.6

DiHydrooxyresveratrol