Free radical scavenging compounds from dendrobium lindleyi

Abstract

Free radicals lead to oxidative stress which plays an important role in the development of many diseases. Dendrobium lindleyi belongs to Dendrobium, a genus the secondary metabolites of which were reported as free radical scavenging compounds. However, the bioactivity of D. lindleyi has never been revealed. In this study, the EtOAc extract of D. lindleyi was fractionated to give five pure compounds identified by spectroscopic techniques as a new constituent named 4,5-dihydroxy-3,3′,4′-trimethoxybibenzyl along with four known compounds including chrysotoxine, gigantol, cypripedin, and moscatilin. DPPH radical, superoxide radical, and ORAC assay were performed to evaluate their radical scavenging activities. Chrysotoxine, gigantol, and moscatilin exhibited comparable activity to Trolox in DPPH assay. In the superoxide radical and ORAC assays, the new compound, chrysotoxine, gigantol, and moscatilin were more potent than Trolox. Conversely, cypripedin was a poor radical scavenger in all tests. These findings encourage further research of the four active components for the treatment of conditions related to oxidative stress.