Anticancer activity of Dioscorea membranacea Pierre extract and its isolated compound (Dioscorealide B) in non-small cell lung carcinoma cells

Abstract

The rhizome of Dioscorea membranacea Pierre (or „Hua-Khao-Yen“ in Thai) has long been used as a common ingredient in Thai traditional anticancer medicines. In this study, we investigated the anti-proliferation effects of the ethanolic extract of this plant on two human non-small cell lung carcinoma (NSCLC) cells (COR-L23 and A549) versus a normal human lung fibroblast cell line (MRC-5) using the sulphorhodamine B (SRB) assay. The results revealed that the plant extract induced a stronger growth inhibition in COR-L23 (IC50 33µg/ml) than in A549 (IC50 51µg/ml) cells, whereas it showed no cytotoxic effect on MRC-5 with a significant difference in the IC50 value (p<0.05). DNA fragmentation assay detected classic DNA ladder patterns in both treated tumor cell lines in a dose- and time-dependent manner, indicating that the plant extract exerts its antitumor activity via the apoptotic process. In addition, we evaluated the growth inhibitory effects of Dioscorealide B, a novel derivative of naphthofuranoxepins isolated from the ethanolic extract of D. membranacea [1]. Dioscorealide B exhibited about 10-times greater cytotoxic activity against COR-L23 than the crude extract (IC50 3.1µg/ml) and the IC50 was significantly different from that of Dioscorealide B-treated normal MRC-5 cells (p<0.05). However, this pure compound displayed cytotoxicity against A549 to the same extent as normal cells. Taken together, D. membranacea crude extract and its pure Dioscorealide B possess potent anticancer properties and are worthy of further investigation for their potential chemotherapy of certain cancers.