Gynura procumbens which is locally known as 'Sambung nyawa' in Malay and 'Feng Wei Jian' in Chinese, belongs to the botanical family of Compositae. In this study, antioxidant property of G. procumbens extracts was evaluated using DPPH radical scavenging, metal chelating and β-carotene bleaching assays. To the best of our knowledge, this is the first report that evaluated the cytotoxicity of G. procumbens extracts on human colon cancer cells (HT-29, HCT 116, HCT-15, SW480, Caco-2) and human normal colon cells (CCD-18Co). The results showed that ethyl acetate extract contained the highest total phenolic content (172.68 mg of GAEs/g of extract) compared to methanol, hexane and water extracts. Methanol extract possessed better overall antioxidant activities while ethyl acetate extract demonstrated better cytotoxic activity. At 24 h treatment, ethyl acetate extract demonstrated selective cytotoxicity against HT-29 and HCT 116 cells with IC50 values of 35.7 and 42.6 μg/mL, respectively. In addition, methanol extract showed negligible level of toxicity when administered orally. All the results indicated that G. procumbens may provide benefits in prevention and treatment of cancer.
The methanol and fractionated extracts (hexane, ethyl acetate and water) of Alpinia mutica (Zingiberaceae) rhizomes were investigated for their cytotoxic effect against six human carcinoma cell lines, namely KB, MCF7, A549, Caski, HCT116, HT29 and non-human fibroblast cell line (MRC 5) using an in vitro cytotoxicity assay. The ethyl acetate extract possessed high inhibitory effect against KB, MCF7 and Caski cells (IC₅₀ values of 9.4, 19.7 and 19.8 µg/mL, respectively). Flavokawin B (1), 5,6-dehydrokawain (2), pinostrobin chalcone (3) and alpinetin (4), isolated from the active ethyl acetate extract were also evaluated for their cytotoxic activity. Of these, pinostrobin chalcone (3) and alpinetin (4) were isolated from this plant for the first time. Pinostrobin chalcone (3) displayed very remarkable cytotoxic activity against the tested human cancer cells, such as KB, MCF7 and Caski cells (IC₅₀ values of 6.2, 7.3 and 7.7 µg/mL, respectively). This is the first report of the cytotoxic activity of Alpinia mutica.