Minor terpenoids from the stems and twigs of Rhododendron ovatum

Four minor undescribed terpenoids, including a monoterpenoid (1) and three triterpenoids (3, 6 and 7), together with 26 known terpenoids were isolated from the stems and twigs of Rhododendron Ovatum. Their structures were identified by extensive spectroscopic analyses and electronic circular dichroism (ECD) techniques. Compound 10 showed excellent cytotoxicity against human colon cancer cell (HCT-116) with IC50 value of 2.56 mu M. Compounds 9 and 19 exhibited partly inhibitory effects on nitric oxide production stimulated by lipopolysaccharide-induced neuroinflammation in microglia cells at 10 mu M with inhibition ratios of 39.70% and 28.08%, respectively.

Automated summary

In this study, four minor undescribed terpenoids and 26 known terpenoids were isolated and identified from the stems and twigs of Rhododendron ovatum. Compound 10 exhibited excellent cytotoxicity against human colon cancer cells, while compounds 9 and 19 showed inhibitory effects on nitric oxide production in microglia cells.