Dendrobine-type alkaloids and bibenzyl derivatives from Dendrobium findlayanum

Five previously undescribed compounds, including two dendrobine-type alkaloids (1 and 2), three bibenzyl derivatives (3-5), along with six known compounds were isolated from orchids Dendrobium findlayanum. The structures and absolute configurations of the undescribed compounds were elucidated on the basis of HR-ESIMS, NMR spectroscopy, optical rotation value, as well as electronic circular dichroism (ECD) calculations. The cytotoxic effects of the isolated compounds on three human tumour cell lines (A172, SHSY5Y, and Hela) were evaluated by the MTT assay. Compound 6 showed excellent inhibitory activities against three human tumour cell lines with IC₅₀ ranging from 1.65 μM to 3.77 μM. All these compounds were assessed for their activity of promoting the gastrointestinal motility of zebrafish treated with Nile red. Compound 6 have excellent activity to promote the gastrointestinal motility of zebrafish at the concentration of 0.3 μM.