Quinic acid esters from Erycibe obtusifolia with antioxidant and tyrosinase inhibitory activities

Abstract

A new quinic acid derivative, 3-O-syringoylquinic acid methyl ester (1), along with eight known quinic acid derivatives (2-9), three coumarins (10-12), one phenylpropanoid (13), three feruloyltyramine derivatives (14-16), one lignan (17) and two isoflavones (18-19) were isolated from an ethyl acetate-soluble fraction of the roots and stems of Erycibe obtusifolia. The structure was elucidated on the basis of spectroscopic methods such as 1D and 2D-NMR, including HR-ESI-MS spectrometry. All of these compounds were investigated for their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and inhibitory effects on mushroom tyrosinase. Compounds 2–9, quinic acid derivatives with caffeoyl moiety, showed significant DPPH radical scavenging activity. Moreover, compounds 2 and 5–10 showed weak mushroom tyrosinase inhibitory effects.