ANTIMICROBIAL ACTIVITIES OF EXTRACTS FROM CARICA PAPAYA ON SOME SELECTED FUNGI, AND ANTIBIOTIC RESISTANT PATHOGENIC BACTERIA.

Abstract

The development of multiple antibiotic resistant organisms has constituted a global problem in the treatment of some infectious diseases. Natural products of plants may possess a new source of antimicrobial agents and possibly a novel mechanism of action. Gram positive, Gram negative and Fungal isolates, were obtained from State Specialist Hospital Akure, Don Dosco Hospital Akure, Federal Medical Centre Owo, and the Department of Microbiology, Faculty of Science, Obafemi Awolowo University, Ile-Ife. Susceptibility of the bacterial and fungal isolates to antibiotics and antifungal drugs respectively was carried out using the agar well and disk diffusion method. Resistant bacterial isolates were molecularly identified and subjected to plasmid profiling. Extracts were obtained from the leaves and unripe pulp of Carica papaya using hot water, cold water, methanol and petroleum ether. Qualitative and quantitative phytochemical analysis of the extracts was carried out. The potency of the extracts on the bacterial and fungal isolates was determined. The extracts were purified, and subjected to infrared (IR) analysis to obtain the functional groups in the bioactive components. Results of the susceptibility test revealed that typed isolates were more susceptible to the antibiotics than the clinical isolates, with the highest level of resistance observed to cotrimoxazole, ceftriaxone, gentamicin, amoxicillin, and chloramphenicol. The plasmid profile of the resistant bacteria revealed that Staphylococcus aureus and Bacillus subtilis had more than one plasmid, and post plasmid curing showed that they are still resistant to some antibiotics. Phytochemical analysis revealed the presence of alkaloids, cardiac glycosides, saponins, tannins, phenols, flavonoids, and terpenoids. The hot water extracts showed the highest antimicrobial potency. Its leaf extracts inhibited Shigella sonnei and Candida albicans with zones of inhibition values 42.33 mm and 52.67 mm respectively, while its unripe pulp extracts inhibited Serratia marcescens and Candida albicans with zones of inhibition values 43.33 mm and 58.00 mm. However, the methanol, cold water and petroleum ether extracts inhibited the organisms with zones of inhibition ranging from 4.67 mm by methanol leaf extract on Bacillus subtilis to 32.67 mm by petroleum ether leaf extract on Serratia marcescens. Column fractions 2 (leaf extract) and 1(pulp extract) produced the highest inhibitory zones of 25.31 mm (Staphylococcus aureus) and 26.20 mm (Pseudomonas aeruginosa) respectively. The Infra-Red spectroscopy showed the presence of alkene, alkyne, hydroxyl group, aldehyde, unsaturated ester, aliphatic ether and carboxylic acid group. It can be inferred that extracts from the leaf and unripe pulp of Carica papaya contain bioactive components that are potent against human pathogenic fungi and multiple drug resistant pathogenic bacteria of medical importance.