Phytochemical and Antioxidant Screening of Seed Extracts of Kenyan Custard Apple (Annona squamosa)

Abstract

Medicinal plants have been the mainstay of traditional herbal medicine amongst rural dwellers worldwide since antiquity for their preventive and curative properties. Investigation of plants for phytochemicals and medicinal activities is imperative for the discovery of prospective novel molecules for medicinal use. This current analysis was aimed at screening the seed extracts of Annona squamosa for the presence of phytochemicals and their antioxidant activities. Extraction of the active components was through organic solvents; methanol, dichloromethane and methanol: dichloromethane blend in Soxhlet extractor and concentrated in a rotary evaporator. Investigation of phytochemicals was through standard qualitative screening procedures while antioxidant activities of the extract were evaluated through the radical scavenging effect of DPPH, H2O2 and the FRAP assay. Methanol was the most effective solvent in capturing phytochemicals including tannins, alkaloids, flavonoids, fixed oils and phenols. Dichloromethane captured only alkaloids and fixed oils. The antioxidant data obtained was assayed against that of the standard (Ascorbic acid). The methanolic extract was found to be the most potent extract with highest antioxidant activities followed by methanol: dichloromethane blend while dichloromethane portrayed the least potency. The highest DPPH radical scavenging was at 500mg/ml, while for H2O2 was at 1mg/ml while the highest FRAP activity was at 1mg/ml. Methanolic extracts were the most potent while dichloromethane extracts showed the least DPPH and H2O2 radical scavenging activities. Phenols appear have significantly contributed towards the antioxidant activity of the methanolic extracts and the alkaloids in dichloromethane extracts. Most of the inedible parts of commonly consumed fruits have not been studied for their antioxidant activity but the current assay demonstrates that seeds may be a promising source of antioxidants. This study shows that the seed extracts of Annona squamosa may be utilised therapeutically in the management of oxidative stress related disorders.

Keywords:Annona squamosa, Phytochemical, Antioxidant, Radical Scavenging, diphenyl-picrylhydrazyl (DPPH), Hydrogen Peroxide (H2O2) and Ferrous Reducing Antioxidant Power (FRAP)