Bioactive constituents from the leaves of Metapanax delavayi with anti-benign prostatic hyperplasia activities

In the course of our continuing search for biologically active compounds from medicinal sources, we further investigated the aqueous extract of Metapanax delavayi (Franch.) J. Wen & Frodin (Araliaceae) leaves. Five undescribed terpene glycosides, liangwanosides B-F referring to two megastigmane glycosides, one monoterpene glycoside, and two sesquiterpene glycosides, together with seven known compounds were isolated. Their chemical structures were elucidated by detailed spectroscopy (1D/2D NMR), HRESIMS data analysis, hydrolysis, and comparison of experimental and calculated electronic circular dichroism (ECD) data. The biological evaluation of benign prostate hyperplasia (BPH) inhibition revealed that some compounds, including liangwanosides B-D, benzyl-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranoside, methyl 2-O-β-D-glucopyranosylbenzoate, and 3,4-dihydroxybenzaldehyde, exhibited moderate inhibitory activity against BPH-1 cells with inhibition rates ranging from 13.8% to 23.8% at 100 μM. Among them, liangwanoside B showed the comparable effect to positive control (finasteride) at 100 μM, and its possible mechanism was then explored by molecular docking studies.