LAUSR

Cosmetically, hyperpigmentation is an important issue and the most prominent target for inhibiting hyperpigmentation is, tyrosinase, the rate-limiting enzyme in melanogenesis. Therefore, in this research, we have screened several medicinal plants collected from Bangladesh for their anti-tyrosinase activity and found that roots of Persicaria orientalis have potent inhibitory activity. Nine compounds, including five phenylpropanoid sucrose esters (1–5), were isolated from the EtOH extract of P. orientalis roots. The chemical structures were determined based on spectroscopic methods. All the tested compounds (1–5), significantly reduced extracellular melanin formation in B16 melanoma cells and inhibited tyrosinase monophenolase and diphenolase activity in a dose dependent manner. Compound 4 was twice as effective as kojic acid, when l-DOPA was used as the substrate. Compound 1 and 4 showed better inhibitory activity (>59%) on melanin synthesis at a treated concentration of 50 µM compare with arbutin (730 µM). At 6.25 µM concentration, compounds 2 and 5, inhibited extracellular melanin production by 53.1% and 40.2%, respectively. Structure-activity-relationship suggested that both the feruloyl (C-6′) and acetyl (C-2′/ C-4′) groups in sucrose moiety is essential for cytotoxicity. Our finding indicated the roots of P. orientalis is a potential source of natural compounds that could be used in dermatological and cosmetological research. To the best of our knowledge, this is the first study to report the potential melanogenesis inhibitory activity of phenylpropanoid sucrose esters.