Abstract
Objective: Phytochemical constituents of various solvent extracts of leaf and stem bark of Polyalthia fragrans (Dalz.) Bedd were screened. Antimicrobial and antioxidant activities of the extracts were evaluated.Methods: Crude extracts of methanol, ethyl acetate, chloroform and aqueous of leaf and stem bark were evaluated for antimicrobial activity by disc diffusion method and antioxidant activity by DPPH (diphenyl-2-picrylhydrazyl) radical scavenging and reducing power assay. Quantitative analysis of total phenolics was done by the Folin-Ciocalteau method and total flavonoids by aluminum chloride method.Results: The study revealed the presence of several physiologically active phytochemicals such as alkaloids, phenols, flavonoids and tannins. The highest antibacterial activity of methanol extract of the leaf was observed against Bacillus subtilis with 14.33±0.57 mm inhibition zone and water extract of stem bark against Proteus vulgaris with 17.67±1.52 mm inhibition zone among other extracts. The lowest activity of leaf methanol and leaf water extract was observed against Bacillus subtilis. The IC50 values of 58.18±2.04 µg/ml, 116.58±2.43 µg/ml, 134.78±3.64 µg/ml and 387.28±2.9 µg/ml for DPPH activity were observed in methanol stem bark, ethyl acetate stem bark, methanol leaf and ethyl acetate leaf extracts respectively. The reducing power of extracts was very potent which increased with increasing concentrations of the sample.Conclusion: The results indicate that phytochemicals like alkaloids, phenols, flavonoids and tannins may be responsible for the antimicrobial and antioxidant properties. The results suggest that P. fragrans can be further researched to be used as a natural source of a potent drug by mankind.
Highlights
Plants are usually known to make use of their diverse health benefits through the numerous phytochemicals they contain
The phytochemical screening of the extracts of Polyalthia fragrans revealed the presence of phenols, flavonoids and tannins in all the extracts assessed
The IC50 values of 58.18±2.04 μg/ml, 116.58±2.43 μg/ml and 134.78±3.64μg/ml for DPPH activity were observed in methanol stem bark, ethyl acetate stem bark and methanol leaf extracts respectively
Summary
Plants are usually known to make use of their diverse health benefits through the numerous phytochemicals they contain. According to an estimation of world health organization, about 80% of world’s populations rely on traditional medicine for their primary healthcare needs and the most of this therapy involves the use of plant extracts and their active compounds [2]. Annonaceae, a family of the flowering plant is known as custard apple family which consists of trees, shrubs and rarely lianas. It is the largest family in Magnoliales which includes more than 130 genera and about 2300 to 2500 species [3]. The genus Polyalthia (Annonaceae) distributed in subtropical and tropical regions [4] which consist of about 120 species of shrubs and trees. The plant P. longifolia is used to treat fever, skin diseases, gonorrhea, uterus ailment, leucorrhoea, diabetes, hypertension and helminthiasis [11,12,13,14] and P. simiarum is known to exhibit antimicrobial and cytotoxic [15]
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