ASSESSMENT OF ANTIMICROBIAL POTENTIALS AND MINIMUM INHIBITORY CONCENTRATION (MIC) OF EXTRACTS OF DRY carica papaya SEEDS ON MULTIDRUG RESISTANT (MDR) CLINICAL MICROBIAL ISOLATES

Abstract

Background: Infections caused by drug-resistant microorganisms are usually more difficult to treat, require longer hospital stays, and are associated with higher mortality rates. Researchers and scientists have begun using medicinal plants as alternatives to synthetic drugs. Various parts of medicinal plants including carica papaya are being examined.

Aim: This study aimed to investigate the antimicrobial activities of aqueous and 40% ethanolic extracts of dry carica papaya seeds against some clinical isolates, the Minimum Inhibitory Concentration (MIC) and the median lethal dose (LD50) of the extracts.

Methods: Both extracts were tested at 10mg/ml (5%), 50mg/ml (25%), 100mg/ml (50%) and 200mg/ml (100%) on the bacterial and fungal isolates. The in-vitro antibacterial and antifungal activities of the aqueous and 40% ethanolic extracts were determined using Disc diffusion technique. Test organisms were obtained from the laboratory, resuscitated in peptone water, sub-cultured into nutrient agar for the bacteria test organisms and Sabouraud dextrose agar (SDA) for the fungi test organisms and incubated at 370C for 24hours. The test organisms were standardized by matching with the appropriate McFarland’s standard. LD50 was ascertained using modified Lorke’s method (Lorke 1983) using 26 Wistar rats (Rattus norvegicus).

Results: Both extracts had antimicrobial activities of varying degrees based on Clinical Laboratory Standards Institute (CLSI) interpretive criteria (CLSI, 2012). The 40% ethanolic extract gave a higher antibacterial activity on the test organisms than the aqueous extract. MIC of 12.5mg/ml was observed from the 40% ethanolic extract. LD50 for both extracts was found to be greater than 5000mg/kg.

Conclusion: It can be inferred that extracts of dry Carica papaya seeds have antibacterial and antifungal potential.