There are many different kinds of phenolic compounds in plants. Their antioxidation capacity has been studied in many research recently. Tyrosinase is the key of enzyme to catalyze reaction of melanin, inhibition of tyrosinase is an important issue in whitening. The purposes of this study is to find out the antioxidation capacity and effects of tyrosinase inhibition of plant phenolic compounds from winery solid waste.
The samples were treated by organic acids and blanching in order to preserve the phenolic compounds in them. The samples treated by 0.1% citric acid have highest total phenolic compound and flavonoids content. The drying test were followed, results show that the highest total phenolic (1.77mg/g) and flavonoid (5.94mg/g) content were found under under 65˚C drying.
Ethanolic extract was further divided into ethyl acetate and water fractions by a liquid-liquid partition procedure. The ethyl acetate and water subfraction were further fractionated by Sephadex LH-20 column. Then we had eight subfractions E1~E4 and W1~W4. Sephadex LH-20 was then used in solvent elution scheme for separating non-polymeric and polymeric phenols. Then, we compared anti-oxidation and inhibition of tyrosinase in each sections. DPPH radical scavenging test, ABTS radical scavenging test, FRAP total antioxidant were conducted to survey the antioxidation capacity of each fraction. The results show that the fraction of ethyl acetate (E2) is the most prominent in anti-oxidation tests. At 0.05 mg/ml, DPPH radical scavenging was 99.88% ; ABTS radical scavenging was 99.57%. At 1 mg/ml, FRAP total antioxidant capacity of is 5.017 FRAP value. The effect of tyrosinase inhibition was 94.79% for E2 fraction at concentration of 0.01mg / ml, which is higher than the effect of kojic acid in tyrosinase inhibition.
The phenolic compounds can be preserved by the treatments of organic acids and blanching procedures. And the partition procedure could further increase the antioxidation capacity and the effects of tyrosinase inhibition. According the the results, winery solid waste could be a potential raw material in replacing artificial antioxidants or in cosmetic products.
