Evaluation of the antimicrobial potential of Annona Muricata seed extracts on resistant bacterial and fungal pathogens of public health importance

Abstract

The use of medicinal plants for treatment of diseases has become a common practice due to the increasing resistance of microbial agents to known antimicrobial drugs. We investigated the antimicrobial effects of Annona muricata on multidrug resistant Corynebacterium renale isolated from bird and a fungal pathogen Candida albicans. The C. renale isolate was characterized using biochemical and morphological methods; and screened for antibiotic susceptibility using a panel of 8 antibiotics. The resistance profile of the C. renale isolate was compared with C. albicans using seed extracts (hexane, ethyl ether and ethanol) of A. muricata at different concentrations. Among the 8 antibiotics tested, only ciprofloxacin showed activity on the C. renale with a zone of inhibition (ZI) of 25.00 mm as against the standard which was ≥21 mm. All the extracts showed appreciable antimicrobial effects in a concentration - dependent manner with the highest inhibition zone recorded at 400 mg/ml. The hexane extract showed no antimicrobial activity on the C. renale at all the tested concentrations. The hexane and ethyl ether extracts showed almost similar activity on the C. albicans isolate at all the tested concentrations. The ethanol extract showed the highest ZI of 17.60 ± 1.67 mm on C. albicans at 400 mg/ml and this was statistically significant (P = 0.05) when compared with the other concentrations. The two control antifungals, voriconazole and fluconazole had higher zones of inhibition of 29.6 ± 1.34 mm and 19.00 ± 2.00 mm respectively than all the extracts. The results suggest that the plant extracts (ethanol and ethyl ether) showed appreciable antimicrobial effects at 400 mg/ml and hence could act as a potential drug for antimicrobial therapy.

Keywords: Annona muricata, antibacterial, antifungal, Candida albicans, Corynebacterium, medicinal plants.