COMPARATIVE PHYTOCHEMICAL AND IN VITRO ANTIMICROBIAL STUDIES OF AQUEOUS LEAVES EXTRACTS OF COLOCASIA ESCULENTA, AZADIRACHTA INDICA AND MORINGA OLEIFERA

Terngu Paul Ugoso, Apeyuan Kparev-Wua David, Ornguga Terlumum Timothy

The growing resistance of pathogenic microorganisms to synthetic antibiotics has necessitated renewed interest in medicinal plants as potential sources of novel antimicrobial agents. This study comparatively evaluates the phytochemical composition and antimicrobial activities of aqueous leaves extracts of Colocasia esculenta, Azadirachta indica, and Moringa oleifera. Standard phytochemical screening revealed the presence of alkaloids, flavonoids, saponins, tannins, terpenoids, steroids, glycosides, and phenolics in varying concentrations across the three species. Quantitative analysis indicated that Moringa oleifera exhibited the highest total phenolic and flavonoids contents (82.46 mg GAE/g and 59.23 mg QE/g) respectively. Colocasia esculenta showed significantly higher saponins (10.36 mg/g) and terpenoid, while Azadirachta indica recorded the highest terpenoids concentration (11.84 mg/g). Antimicrobial activity was determined using the disc method against Aspergillus niger, Aspergillus flavus, Botryodiplodia theobromae, Fussarium oxysporum and Myrothecium verrucaria as well as Klebsiella oxytoca, Serratia marcescens, Pseudomonas aeruginosa, Escherichia coli and Erwinia carotovora. M. oleifera demonstrated the highest inhibitory zones, followed by A. indica and C. esculenta. Among the test organisms, Erwinia carotovora and Escherichia coli were the more susceptible isolates. A Minimum Inhibition Concentration (MIC) of 12.50 mg/mL was recorded for Moringa oleifera and 25.00 mg/mL against Azadirachta indica and Colocaisa esculenta. The results suggest that these plants possess broad-spectrum antimicrobial potential, with M. oleifera showing the greatest potency. The findings support the ethnomedicinal use of these plants and potential application in the development of plant-based antimicrobials.