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, (25 S)-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 IC ₅₀ values ranging from 0.96 to 3.15 μM. The corresponding furostanol glycoside of 1, (25 S)-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 IC ₅₀ values of 2.97, 11.04, and 8.25 μM, respectively. The spirostanol lycotetroside ( 1) caused necrotic cell death in A549 cells in a dose-dependent 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.