Sub-acute Toxicity Assessment of Methanol Leaf Extract of Polyalthia longifolia (Sonn.) Thwaites on Haematological and In Vivo Antioxidant Parameters in Wistar Rats

Polyalthia longifolia is an ornamental plant, which has been reported to possess various ethnomedicinal applications. However, there is a dearth of information on the toxicity profile in the administration of the plant extract. The study evaluates the impact of sub-acute administration of methanol leaf extract of P. longifolia on haematological and in vivo antioxidant parameters. The powdered dried leaves of the plant were extracted with methanol at room temperature. Single oral doses, 200, 400, 800 and 1600 mg/kg respectively, of the extract, were administered daily to four groups of adult Wistar rats repeatedly for 28 days. Distilled water served as the control. Immediately following the treatment period, blood samples were collected from all the animals and analyzed for levels of haematological and in vivo antioxidant indices. The results obtained from this study showed that levels of total protein, catalase and glutathione peroxidase in all treatments were not significantly different (P>0.05) from the control group. However, malondialdehyde increased (0.05 ± 0.01[10-3 ] U/mg of protein) significantly (P<0.05) at the highest dose of extract (1600 mg/kg) compared with the control. Also, among all the heamatological indices analyzed, only the mean corpuscular volume was elevated (56.67 ± 1.58 fl) significantly at the highest dose of treatment compared with the control. It can be inferred from this study that repeated oral administration of methanol leaf extract of P. longifolia is relatively safe and tolerable within the lower test doses, with possible contraindications at the highest dose (1600 mg/kg).