Ethanolic extract of Nymphaea lotus L. (Nymphaeaceae) leaves exhibits in vitro antioxidant, in vivo anti-inflammatory and cytotoxic activities on Jurkat and MCF-7 cancer cell lines

Abstract Background Nymphaea lotus L. (N. lotus) is an aquatic plant with anecdotal reports suggesting its use in the traditional management of cancer. However, there is a paucity of data on the antioxidant, anti-inflammatory and cytotoxic properties of N. lotus in relation to its phytochemical and elemental contents. This study aimed at determining the antioxidant, anti-inflammatory and cytotoxic properties of the hydro-ethanolic extract of N. lotus leaves (NLE), and its phenolic, flavonoid and elemental constituents. Methods The antioxidant property of NLE was determined using total phenolic and flavonoid, DPPH radical scavenging, lipid peroxidation and reducing power assays. The anti-inflammatory activity of NLE (100–250-500 mg/kg), diclofenac and hydrocortisone (positive controls) were determined by paw oedema and skin prick tests in Sprague Dawley rats. Also, the erythrocyte sedimentation rate (ESR) was determined by Westergren method. The macro/micro-elements content was determined by the XRF method. The cytotoxic property of NLE was determined by the MTT assay, on two cancer cell lines (MCF-7 and Jurkat) and compared to a normal cell line (Chang liver). Inhibitory concentrations were determined as IC50 values (±SEM). Results The extract had appreciable levels of phenolic and flavonoids compounds and was two-fold more potent in scavenging DPPH radicals than Butylated hydroxytoluene (BHT). However, NLE was three- and six-fold less potent than ascorbic acid and BHT, respectively, in reducing Fe3+ to Fe2+. The extract was six-fold more potent than gallic acid in inhibiting lipid peroxidation. The extract caused a dose-dependent decrease in rat paw oedema sizes, comparable to diclofenac, and a significant decrease in wheel diameters and ESR. The elemental analysis revealed relevant concentrations of Mg2+, P2+, S2+, K2+, Mn+, Fe+, Cu+, Zn+ and Cd+. The extract exhibited cytotoxic activity on both MCF-7 (IC50 = 155.00 μg/ml) and Jurkat (IC50 = 87.29 μg/ml), with higher selectivity for Jurkat cell line. Interestingly, the extract showed low cytotoxicity to the normal Chang liver cell line (IC50 = 204.20 μg/ml). Conclusion N. lotus leaves extract exhibited high antioxidant, anti-inflammatory and cancer-cell-specific cytotoxic properties. These aforementioned activities could be attributed to its phenolic, flavonoid and elemental constituents. Graphical abstract