Evaluation of cytotoxic and apoptotic activities of Clinacanthus nutans (Burm. f.) Lindau leaves against D24 human melanoma cells

Abstract

The leaves of Clinacanthus nutans have been increasingly used as an adjuvant treatment for cancers. Infusion of the dried leaves in water is the traditional and preferred method of preparation by cancer patients for consumption. Traditionally, this medicinal plant is brewed in boiling water before consumption as a tea but little is known about the effect of preparation temperature for optimal anticancer activity. Therefore, the present study assessed the effect of preparation temperature (hot or cold) of crude aqueous extracts of C. nutans leaves on the cytotoxicity of D24 melanoma cells using a colorimetric WST-8 assay. Apoptotic cell death was detected by a cytofluorometric double staining method. Biochemical and morphological changes in the treated cells were examined by fluorescence and transmission electron microscopy techniques, respectively, to further verify the type of cell death. The cold aqueous extract was the most cytotoxic against D24 melanoma cells with an EC50 of 163 μg/mL at 72 h. The extract also predominantly induced apoptosis in these cells according to cytofluorimteric, confocal and transmission electron microscopic analyses. This study provides important information on the preparation of C. nutans and its effectiveness as an anticancer concoction for regular consumption.