Efficacy of Three Tropical Plants for Inhibition of Pathogen Causing Human Diarrhoea

Okigbo Raphael Nnajiofor^* & Ezeaku, Chikaodili Eziamaka

Department of Botany, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria

Okigbo Raphael Nnajiofor, Department of Botany, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.

Keywords: Human Pathogens; Diarrhoea; Psidium; Mangifera; Vernonia

Abstract

The efficacy of three tropical plants that can be used for the inhibition of pathogens causing human diarrhoea was investigated. Ethanol was used as solvent for extraction. Six human pathogens; Escherichia coli, Bacillus subtilis, Salmnonella enterica, Pseudomonas aeruginosa, Staphylococcus citrinum and Aspergillus niger were employed in this study. The inhibitory effects of the ethanol extracts of Psidium guajava L., Mangifera indica L. and Vernonia amygdalina L. on the test organisms were conducted using the agar well diffusion method of antimicrobial assay. Phytochemical screening of the plants was carried out. Antibiotic (Streptomycin) served as the control. Phytochemical screening of the plants revealed the presence of biologically active chemical compounds such as tannins, phenols, saponins, alkaloids, flavonoids and sterols. The quantitative determination of the phytochemicals revealed the different levels of concentrations. The minimum inhibitory concentration(MIC) of the extracts on the organisms ranged between 5.62-15.60 mg/mL for Bacillus subtilis 5.30-16.25 mg/mL for Staphylococcus citrinum, 3.94-12.90 mg/mL for Pseudomonas aeruginosa, 4.85-13.75 for Escherichia coli, 4.50-12.36 mg/mL for Salmonella enteric, 5.40-14.10 mg/mL for Aspergillus niger. The solvent used for extraction varied significantly (P<0>

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