Steroidal glycosides from Convallaria majalis whole plants and their cytotoxic activity

Abstract

Phytochemical examination of Convallaria majalis (Liliaceae) whole plants yielded 15 steroidal glycosides (1-15), including nine new compounds (4-6, 10-15) with a lycotetrose unit. The structures of the new compounds were determined using two-dimensional Nuclear magnetic resonance (NMR) analyses and chemical methods. The isolated compounds were evaluated for cytotoxicity against HL-60 human promyelocytic leukemia cells, A549 human lung adenocarcinoma cells, and HSC-4 and HSC-2 human oral squamous cell carcinoma cell lines. Of these, (25S)-spirost- 5-en-3β-yl O-β-D-glucopyranosyl-(1→2)-O-[β-D-xylopyranosyl-(1→3)]-O-β-D-glucopyranosyl- (1→4)-β-D-galactopyranoside (1) exhibited cytotoxic activity against HL-60, A549, HSC-4, and HSC-2 cells with IC50 values ranging from 0.96 to 3.15 µM. The corresponding furostanol glycoside of 1, (25S)-26-[(β-D-glucopyranosyl)oxy]-22α-hydroxyfurost-5-en-3β-yl O-β-D-glucopyranosyl-(1→2)-O- [β-D-xylopyranosyl-(1→3)]-O-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (8), was cytotoxic to the adherent cell lines of A549, HSC-4, and HSC-2 cells with IC50 values of 2.97, 11.04, and 8.25 µM, respectively. The spirostanol lycotetroside (1) caused necrotic cell death in A549 cells in a dosedependent manner. Alternatively, the furostanol lycotetroside (8) induced apoptotic cell death in A549 cells in a time-dependent manner, as was evident by morphological observations and flow cytometry analyses.