Triterpenoid Saponins from Metadina trichotoma

Two new 27-nor-triterpene glycosides, pyrocincholic acid 3β -O-β -D-glucopyranosyl-(1→4)- β -D-quinovopyranosyl-28-O-β -D-glucopyranoside (Metatrichoside A, 1), pyrocincholic acid 3β -O-β -D-glucopyranosyl-(1→4)-β -D-quinovopyranosyl-28-O-β -D-glucopyranosyl-(1→6)-β -Dglucopyranoside (Metatrichoside B, 2), together with pyrocincholic acid 3β -O-β -D-quinovopyranosyl- 28-O-β -D-glucopyranoside (3), pyrocincholic acid 3β -O-β -D-quinovopyranosyl-28-O-β -Dglucopyranosyl-( 1→6)-β -D-glucopyranoside (4), quinovic acid 3β -O-β -D-quinovopyranoside (5), quinovic acid 3β -O-β -D-quinovopyranosyl-28-O-β -D-glucopyranoside (6), quinovic acid 3β -O- β -D-glucopyranoside (7) and quinovic acid 3β -O-β -D-glucopyranosyl-28-O-β -D-glucopyranoside (8) were isolated from the barks of Metadina trichotoma. Their structures were mainly determined by mass spectrometric and 1D and 2D NMR spectroscopic methods. Compound 5 and 6 showed cytotoxic activities towards the A549 non-small-cell lung cancer cell line (IC50 = 8.43 and 6.06 μm), and the methanol extract inhibited the activity of cathepsin B with an IC50 value of 0.77 μg mL−1.