Antimicrobial potential of aqueous and ethanol extracts of unripe Carica papaya L.

Abstract

Papaya (Carica papaya L.) is valued in tropical and subtropical regions for its nutraceutical and medicinal properties. This study evaluated the antibacterial activity of aqueous and ethanolic extracts of unripe papaya fruit against microbial isolates. Extracts were obtained via maceration, and their antimicrobial activities were assessed using agar dilution and agar well diffusion techniques. Gas chromatography-mass spectrometry (GC-MS) was employed to identify bioactive compounds in the extracts. The extracts were tested against Salmonella typhi, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans. Both extracts demonstrated significant antimicrobial activity, with the aqueous extract showing the highest efficacy. However, S. aureus was resistant to the ethanol extract, while S. typhi was resistant to the aqueous extract. The optimal concentration for inhibition was 200 mg/mL for both extracts. The aqueous extract exhibited minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of 12.5 mg/mL against S. aureus, B. subtilis, K. pneumoniae, and C. albicans. The ethanol extract had MICs of 50 mg/mL for B. subtilis, 25 mg/mL for S. typhi, and 12.5 mg/mL for K. pneumoniae and C. albicans. GC-MS analysis identified key bioactive compounds, including hexamethylcyclotrisiloxane, dodecamethylcyclohexasiloxane, and dihydroxyphenylglycol, contributing to the extracts’ antimicrobial properties. These findings support the traditional use of C. papaya as a natural antimicrobial agent and highlight its potential as a complementary treatment for antimicrobial-resistant infections. Further studies on its pharmacodynamics are recommended.