In vitro antioxidant, cytotoxic and phytochemical studies of Clinacanthus nutans Lindau leaf extracts

An increasing demand for natural additives has drawn more interest from consumers due to their relatively safe and wide acceptance. The present work examines the potential of different solvent system of Clinacanthus nutans Lindau leaves as a source of natural antioxidant. We also screened for its phytochemical constituents and cytotoxicity toward breast cancer cell. In vitro antioxidant activity of the n-hexane, dichloromethane, ethyl acetate, and ethanol extracts were assessed via 1,1-diphenyl-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorbance capacity and s-carotene bleaching activity assays, whereas the cytotoxic effect was tested on tumorigenic breast cancer estrogen positive cell (MCF-7) and normal fibroblast cell (3T3) using the tetrazolium assay. Liquid chromatography mass spectrometry equipped with an electrospray ionization source liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI/MS) was used to analyze the amount of targeted phenolic and fatty acids in ethanol and ethyl acetate extracts. Several phenolic compounds and fatty acids were identified and quantified from ethanol and ethyl acetate extracts of this plant. Ethanol and ethyl acetate extracts demonstrated stronger antioxidant activity than n-hexane and dichloromethane extracts (p<0.05). Thus, ethanol and ethyl acetate extracts of C. nutans may be explored as new sources of antioxidants in herbal medicines research.   Key words: Cytotoxicity, polyphenols, polyunsaturated fatty acid (PUFA), Sabah snake grass, anticancer.