Cytotoxic and antioxidant properties of phenolic compounds from Tagetes patula flower

Context: Tagetes patula Linn. (Asteraceae) (French Marigold) flowers are used by local practitioners for cancer treatment; however, it lacks scientific justification. Objective: Identification of bioactive compounds in Tagetes patula flower for cytotoxic and growth inhibition in human cancer cell lines along with its antioxidant properties using chemical and cell based systems. Materials and methods: The Tagetes patula flower methanol extract, its seven fractions, and three phenolic compounds including methyl protocatechuate (1), patuletin (2), and patulitrin (3) were evaluated using sulforhodamine-B assay against HeLa, HT-144, NCI-H460, MCF-7, PC-3, and SF-268 human cancer cell lines. In parallel, antioxidant activity was evaluated using chemical (DPPH, deoxyribose, and lipid peroxidation assays) and cell-based chemiluminescence systems (human neutrophils and mice macrophages). Results: The methanol extract and ethyl acetate insoluble fraction exhibited cytotoxic and growth inhibitory effects against HeLa in which 2 exhibited highest cell growth inhibition (GI(50): 0.6 +/- 0.1 mu g/ml) and cytotoxicity (LC50: 2.5 +/- 0.1 mu g/ml). It also scavenged LOO (IC50: 6.5 +/- 0.7 mu g/ml) and O-2-(center dot) (IC50: 27.5 +/- 1.3 mu g/ml) in chemical systems and human neutrophils, respectively. However, 1 preferably scavenged H2O2-Cl- (IC50: 0.5 +/- 0.01 mu g/ml) in mice macrophages. Discussion and conclusion: Compound 2 from Tagetes patula flower exhibited both growth inhibitory and cytotoxic properties while 1 and 3 were only growth inhibitory against HeLa. 1-3 also displayed antioxidant properties implying its probable role in growth inhibition/cytotoxic action. The present study provides scientific evidence for the use of Tagetes patula flower in cancer treatment by traditional healer.