紅景天與 tyrosol 及其類緣物對淡化色素沉澱作用及機轉探討

Abstract

Melanin is responsible for skin color. Melanogenesis is mainly regulated by tyrosinase taking part in the rate-limiting steps. Developing skin hypopigmenting agents are thought based on down-regulating melanin synthesis by inhibiting the activity of tyrosinase and melanin formation. Rhodiola rosea (R. rosea) belongs to the family Crassulaceae with phenolic components, exerting antioxidant activity. Melanogenesis is an oxidative process. In addition, previous study has showed aglycone has superior biological activity to its glycoside. As a results, we examined the hypopigmentation effect of R. rosea extract, hydrolysate and the constitutents of R. rosea such as salidroside and its aglycone, tyrosol and its analogues on hypopigmentation. The results indicated R. rosea extract inhibit cAMP response element binding protein (CREB) phospharylation, activation of AKT and glycogen synthase kinase 3beta (GSK3β), and inhibition of microphthalmia-associated transcription factor (MITF), tyrosinase and tyrosinase-related protein 1 (TRP-1). R. rosea hydrolysate exerted the inhibition of CREB phospharylation, activation of AKT and GSK3β, and inhibition of MITF and tyrosinase. Tyrosol, 4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 2-hydroxyphenylacetic acid could suppress the expression of tyrosinase and TRP-1. Salidroside would inhibit the amount of tyrosinase in B16 cells. R. rosea extract below 1000 μg/mL and R. rosea hydrolysate below 60 μg/mL showed no cytotoxity. Furthermore, tyrosol, 4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid and 2-hydroxyphenylacetic acid below 4 mM and salidroside below 0.5 mM also showed no cytotoxity. R. rosea extract did not show the irritation on skin and eyes. Our results suggested that R. rosea extract, hydrolysate, tyrosol, 4-hydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 2-hydroxyphenylacetic acid, and salidroside had potential for developing hypopigmenting agents.