In vitro antioxidant and nephroprotective properties of Polyalthia longifolia: A traditional medicinal plant

Polyalthia longifolia (Sonn.) Thwaites is a traditional medicinal plant with diverse medicinal properties including kidney protection. The present investigation was aimed to assess the phytochemical content, antioxidant activity and evaluate nephroprotective activity of Polyalthia longifolia (PL) 70% ethanolic leaf extract against cisplatin and gentamicin-induced toxicity on HEK293 cell line. Phytochemical analysis confirmed the presence of flavonoids, reducing sugars, tannins, coumarin, saponins, alkaloids, and glycosides, as well as the abundant total phenolic and total flavonoid content in the PL leaf extract. The extract exhibited significant free radical scavenging activity (p<0.001) in ABTS (IC50 224 μg/mL), DPPH (IC50 150.1 μg/mL) and H2O2 (IC50 271.1 μg/mL) assays. In vitro MTT assay validated remarkable cytoprotective activity (p<0.001) of PL leaf extract at three concentrations (125 μg/mL, 250 μg/mL, 500 μg/mL) against cisplatin and gentamicin treated HEK293 cell line in dose dependent manner with 70% cell viability (IC50 312.6 µg/mL) and 72% cell viability (IC50 307.3 µg/mL), respectively, at PL dose 500 μg/mL. The cytotoxicity assay also confirmed no adverse effect of PL leaf extract on cell viability in the HEK293 and considered as nontoxic when compared with normal control group. The present study revealed that Polyalthia longifolia leaf extract has remarkable antioxidant activity and nephroprotective properties against cisplatin and gentamicin induced nephrotoxicity in in vitro model which might be due the presence of free radical scavenging phytochemicals.