Inhibitory effects of Rhodiola plants and their oligomeric proanthocyanidins on tyrosinase and Aβ42 aggregation

Tyrosinase is a key enzyme related to skin pigmentation disorders of elderly people, while self-aggregation of the amyloid-β peptide, Aβ42, has been considered as a key event in the pathogenesis of Alzheimer’s disease (AD).  The present study was undertaken to investigate the inhibitory effects of 20 samples from Rhodiola species on tyrosinase and Aβ42 aggregation, and to isolate their corresponding bioactive components.  The results demonstrated that the oligomeric proanthocyanidins (OPCs) commonly found in Rhodiola species were the major bioactive components corresponding to their anti-tyrosinase and anti-Aβ42 aggregation bioactivities.  Salidroside, a representative compound of Rhodiola plants, proved not to be active in the present studies.