Elemental Analysis and Bioactivities of Ripe and Unripe Pericarp of Polyalthia longifolia (Annonaceae)

Abstract

Polyalthia longifolia (Annonaceae) is an ornamental street tree having several medicinal values. The plant is used in traditional systems of medicine. The present study was conducted with an aim of estimating the content of minerals and determining bioactivities viz., antibacterial, cytotoxic and larvicidal activity of ripe and unripe pericarp of P. longifolia. The content of major and minor elements in powdered ripe and unripe pericarp was estimated by ICP-OES after microwave digestion using nitric acid. The pericarp powders were extracted using methanol and the extracts were subjected to preliminary phytochemical analysis. Antibacterial activity of pericarp extracts was determined against two Gram positive and three Gram negative bacteria by agar well diffusion assay. Cytotoxic potential of pericarp extracts was determined against two cell lines viz., HT-29 and MDA-MB-231 by MTT assay. Insecticidal activity, in terms of larvicidal activity of pericarp extracts was tested against II instar larvae of Aedes aegypti. The content of all elements except copper was highest in ripe pericarp. The content of potassium and iron was highest among major and minor elements respectively. Pericarp extracts caused dose dependent inhibition of test bacteria. Extract of ripe pericarp caused higher inhibition of test bacteria than extract of unripe pericarp. Both extracts showed concentration dependent cytotoxic effect. The cytotoxic effect of both the extract was pronounced against HT-29 than MDA-MB-231. The extracts exhibited dose dependent larvicidal effect. Among extracts, potent larvicidal activity was observed in case of ripe extract. Preliminary phytochemical analysis revealed the presence of flavonoids, tannins, saponins, steroids and glycosides in both the extracts. In conclusion, the ripe and unripe pericarp extracts of P. longifolia were found to contain various minerals in an appreciable quantity. The observed dose dependent bioactivities viz., antibacterial, cytotoxic and larvicidal activities might be ascribed to the presence of phytoconstituents. There is a great potential for the development of therapeutic agents from ripe and unripe pericarp. Further studies on isolation of active principles from pericarp extracts and their bioactivity determinations are under progress.

Keywords: Polyalthia longifolia; Pericarp; Minerals; ICP-OES; Agar well diffusion; MTT;Larvicidal