Phytochemical Screening and Antimicrobial Activity of Carica papaya Seed Extracts from Edo State

Carica papaya seeds, which are typically discarded as waste during papaya consumption and commercial processing, have received increasing attention as a source of bioactive compounds with antimicrobial, anthelminthic, and antioxidant properties. This study investigated the phytochemical composition and antimicrobial activity of extracts prepared from Carica papaya seeds obtained from farms in Edo State, South South Nigeria. Seeds were extracted sequentially with petroleum ether, chloroform, ethanol, and water. Qualitative and quantitative phytochemical analyses were conducted. Antimicrobial activity was evaluated against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, and Candida albicans by the agar well diffusion method. Minimum inhibitory concentrations were determined by the broth microdilution method. Alkaloids, flavonoids, tannins, saponins, and glucosinolates were identified in the ethanol extract. The ethanol extract exhibited the broadest antimicrobial spectrum, with inhibition zones of 16 to 28 mm. Maximum activity was observed against Staphylococcus aureus and Salmonella typhi. Minimum inhibitory concentrations for the ethanol extract ranged from 3.13 to 12.5 mg/mL. The petroleum ether extract showed strong activity against Candida albicans, consistent with the known antifungal properties of benzyl isothiocyanate derived from glucosinolate hydrolysis in papaya seeds. These findings support the bioprospecting of Carica papaya seeds as a source of natural antimicrobial agents and encourage waste valorisation of papaya seeds in Edo State's food processing sector.

Keywords: Carica papaya seeds, phytochemicals, antimicrobial activity, Edo State, natural antimicrobials