New lignans, sesquiterpenes and other constituents from twigs and leaves of Rhododendron micranthum

Abstract

Rhododendron micranthum is used traditionally as a remedy for the treatment of chronic bronchitis in China. To clarify the chemical basis and provide a reference for the rational use of this medicinal plant, a phytochemical study was carried out on the twigs and leaves of R. micranthum, which afforded eight new compounds (1–8) and eight known compounds (9–16). Their structures were rigorously determined by comprehensive HRESIMS, NMR and electronic circular dichroism (ECD) analyses. The anti-inflammatory activities of these compounds were evaluated. Compounds 3, 13, and 14 suppressed the transcription of the NF-κB-dependent reporter gene in LPS-induced 293T/NF-κB-luc cells at 10 μM, while no effect on cell viability was observed.