ABSTRACT
Objective To determine the cytotoxicity, reduction in nitric oxide production and anti-oxidative activity of the aqueous leaf extract from Tithonia diversifolia (T. diversifolia) in an in vitro model. Methods Leaves of T. diversifolia were collected from natural habitats and extracted with distilled water using the decoction method. The cytotoxic effect of the extract in terms of cell viability was determined using RAW264.7 cells and human peripheral blood mononuclear cells (PBMCs) via the mitochondrial respiration method using the MTT reagent. The effect of the extract on lipopolysaccharide (LPS)-induced nitric oxide production in RAW264.7 cells was measured using the Griess reagent. The chemical antioxidant was evaluated by ABTS- and DPPH-radical scavenging assays. Results The half-maximal cytotoxic concentration values were 145.87 μg/mL and 73.67 μg/mL for human PBMCs and RAW264.7 cells, respectively. In the presence of phytohemagglutinin-M, the IC