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

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.