Cytotoxic Evaluation of Clinacanthus nutans Extracts

Since the previous study [18 (link)] established that the extracts at 100 μg/mL did not induce significant cytotoxicity on human embryonic kidney cells and macrophage, this indicated that the extracts may not have any cytotoxic effect to non-cancerous cells. Hence, concentrations used were up to 100 μg/mL. Cells were plated in 384-well plates for 24 h followed by LP, LN, SP and SN treatment at 1-100 μg/mL for 72 h incubation as per established in previous studies [11 (link)]. As a comparison, we also tested vitexin and isovitexin (Sigma Aldrich, USA), the pure compounds that were commonly isolated Clinacanthus nutans extracts [13 (link)]. CellTitre-Glo® Luminescent Cell Viability Assay kit (Promega, USA) was used to quantify the cell viability based on the luminescence readings recorded using SpectraMax M3 Multi-Mode Microplate Reader (Radnor, USA). IC₅₀ values were calculated based on the dose-response curve generated. The experiments were validated using with 100 μg/mL gemcitabine and 5-fluorouracil, the first line clinically used anti-cancer agents.