| Gray hair is caused by several factors. Some problems were the destruction of melanocyte by free radicals oxidation and the reduction of tyrosinase enzyme activity in the melanin synthesis pathway. The objective of this study was to investigate for antioxidative activities and stimulating activity of tyrosinase enzyme of five Thai traditional medicinal plants used in gray hair treatment such as; Centella asiatica (L.) Urb. Clitoria ternatea, Morus alba L., Tiliacora triandra (Colebr.) Diels, and Pueraria candollei Grah. They were extracted by aqueous, methanol, ethyl acetate and hexane. These extracts were examined for antioxidant activity by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assay, FRAP (Ferric reducing antioxidant power) assay, ABTS (2,2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) cation radical scavenging assay and total phenolic compound by Folin-Ciocalteu assay.
The results showed that aqueous extract of Tiliacora triandra (Colebr.) Diels had strong antioxidant activity with the EC50 of 53.02 μg/ml (DPPH assay), the FRAP value of 588.75+21.8 mM (FRAPassay) and the TEAC and VEAC of 1.17+0.14 and 4.3+0.3 (ABTS assay), respectively. It also had the highest quantity of total phenolic compound with the amount of 340+11.41 μg GAE/ml dry mass. The tyrosinase enzyme stimulating activities were determined by Modified Dopachrome assay.The results exhibited that methanol extract of Centella asiatica (L.) Urb. had the strongest activity with % stimulation of 97.02%. |