Bioactive chemical constituents, acute toxicity and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of Polyalthia longifolia root

Polyalthia  longifolia (masquerade tree) is a plant which is believed to possess varied pharmacological and therapeutic values among different populations. The present report investigated the phytochemical composition, proximate, acute toxicity and antioxidant potential of P. longfolia root. All analyses were carried out using established methods; the antioxidant activity of the crude methanol extract and its fractions (n-hexane and ethyl acetate) were examined using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay while the total phenolic and flavonoid contents were assessed using the Folin-Ciocalteu and the aluminum chloride calibration methods respectively. The phytochemical analysis revealed the presence of alkaloids, carbohydrate, reducing sugars, tannins, saponins, flavonoids, phenolic compounds and protein in aqueous extract. The proximate analysis showed moisture content, total ash, alcohol extractive value, water extractive value, acid insoluble ash and water soluble ash at 8.80, 9.35, 3.28, 3.29, 2.27 and 7.29% respectively. The ethyl acetate fraction showed the highest antioxidant property compared to the n-hexane fraction and crude methanol extract in all assays conducted. Also, the methanol fraction was found to have the highest flavonoids and phenolic content among the extract and fractions. Oral administration of crude methanol extract of P. longifolia to Swiss mice was relatively non-toxic at a maximum dose of 5000 mg/kg. The root extract and fractions of P. longifolia indicated moderately high level of some phytochemicals with outstanding radical scavenging activity, and therefore substantiate its use as a conventional and comparatively non-toxic plant antioxidant.