Steroidal Glycosides from the Aerial Parts of L. and Their Cytotoxic Activity

Twelve steroidal glycosides (-) were isolated from the aerial parts of L. (Poaceae). Among the isolated compounds, was directly isolated from the plant for the first time, and - were new steroidal glycosides. The structures of - were determined by analysis of their spectroscopic data, chemical transformations, and chromatographic and spectroscopic analyses of the hydrolyzed products. Compounds and were novel steroidal glycosides with a B-ring contracted skeleton (B-nor steroid). Compounds , , , and were cytotoxic to HL-60 human promyelocytic leukemia cells, MIA PaCa-2 human pancreatic carcinoma cells, and A549 human lung adenocarcinoma cells with IC values ranging from 0.79 to 13.5 μM. HL-60 cells treated with exhibited apoptotic characteristics, namely, condensed nuclear chromatin, accumulation of sub-G1 cells, and activation of caspase-3. Additionally, the loss of the mitochondrial membrane potential and the release of cytochrome into the cytoplasm in -treated HL-60 cells suggested that induced apoptosis through a mitochondrial-dependent apoptotic pathway.