Antitumor and antioxidant activity of Polyalthia longifolia stem bark ethanol extract

In the present study, the ethanol extract of stem bark of Polyalthia longifolia Benth. and Hook (Annonaceae) was screened for its in vitro and in vivo antitumor activity. In vitro cytotoxicity of P. longifolia extract was assessed in murine cancer cells and in human cancer cells by Trypan blue exclusion assay and MTT assay, respectively. P. longifolia extract showed concentration-dependent cytotoxicity in Ehrlich's ascites carcinoma (EAC) and Dalton's ascites lymphoma (DLA) cells with IC₅₀ values of 45.77 and 52.52 μg/mL, respectively. In the MTT assay, the IC₅₀ values of P. longifolia extract against HeLa and MCF-7 cells were 25.24 and 50.49 μg/mL, respectively. In vivo antitumor activity against Ehrlich's ascites tumor and Dalton's solid tumor models was assessed by administering 50 and 100mg/kg of P. longifolia extract, i.p., for 7 consecutive days. P. longifolia extract, at a dose of 100mg/kg, significantly enhanced mean survival time (MST) and marginally improved hematological parameters when compared to EAC control mice. And the same dose significantly reduced the tumor volume as compared to control DLA inoculated mice. Positive control, cisplatin (3.5mg/kg, i.p., single dose), significantly enhanced MST and improved hematological parameters when compared to EAC and significantly reduced the tumor volume when compared to DLA control. In vitro antioxidant potential of P. longifolia extract was also determined owing to the role of reactive oxygen species in tumor initiation and progression. P. longifolia extract scavenged DPPH radicals, reduced ferric ions and inhibited lipid peroxidation with IC₅₀ values of 18.14, 155.41 and 73.33 μg/mL, respectively.