Antimicrobial activities of Carica papaya and Nicotiana tabacum leaf extracts against fungal isolates of stored local rice in Abeokuta, Ogun State, Nigeria

Abstract

Ofada” is a type of local unpolished brown rice grown mostly in Ogun State, Southwest Nigeria. The fungal attack poses a major threat to its storage. The efficacy of ethanoic and distilled water extracts (crude extracts) of Carica papaya and Nicotiana tabacum leaves were tested on the isolated fungal species using the pour plate method. Antimicrobial activities of N. tabacum and C. papaya leaf extracts on fungal isolates were evaluated using the agar well diffusion method. One-way analysis of variance was used in this study to compare antimicrobial activities (dependent variable) with respect to extract concentrations (factor). Results revealed a total of seven (7) fungal species, from four different genera- Aspergillus spp, Trichothecium spp, Rhizopus spp, and Fusarium spp. The ethanol extract of C. Papaya leaf has the ability to inhibit the growth of T. roseum, A. niger, and A. flavus better than the control antibiotics. Similarly, ethanol extract of N.tabacum also compares well with the control antibiotics in the antifungal activity against the isolated test fungal species (T. roseum, A. niger and A. flavus). Also, the crude extract of both C. papaya and N. tabacum showed high antifungal activity against T. roseum, A. niger and A. flavus. Based on the findings of this study, both the ethanolic and water extracts of C. papaya and N. tabacum leaves could be used as a natural fungicide in the storage of local Ofada rice.