Free radical scavengers from dendrobium secundum

Abstract

Phytochemical study of the MeOH extract of Dendrobium secundum (Blume) Lindl. (Orchidaceae) led to the isolation of a new bibenzyl derivative named 4,5,4′-trihydroxy-3,3′-dimethoxybibenzyl, along with four known compounds which included brittonin A, moscatilin, syringaresinol and ferulic acid. Their structures were determined by spectroscopic analysis (NMR, MS, IR and UV) and by comparison with previously reported data. These compounds were evaluated for scavenging activity against DPPH (2,2-diphenyl-1-picryhydrazyl) and superoxide radicals. All compounds, except for brittonin A, exhibited moderate DPPH free radical scavenging activity. In addition, moscatilin and syringaresinol showed superoxide radical scavenging activity.