Antibacterial Activity of Aqueous and Ethanol Fruit Extracts of <i>Cucumis sativus</i> Linn. Against Selected Microorganisms at the University of Maiduguri Teaching Hospital, Maiduguri

Abstract

Cucumber (Cucumis sativus Linn) [Cucurbitaceae] is a famous vegetable crop used for food since ancient times but little is known of its antibacterial potential. This study investigated the phytochemical constituents and antibacterial activities of the aqueous and ethanol fruit extracts of the plant against some clinical isolates (Escherichia coli, Salmonella typhi, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus pyogenes, Bacillus subtilis and Corynebacterium spp) using the disc diffusion method. The qualitative phytochemical screening revealed the presence of carbohydrates, cardiac glycosides, terpenoids, cardenolites and flavonoids. Corynebacterium spp was the most susceptible (with maximum inhibition zone of 30.00±0.00 mm). The two extracts had varied antibacterial activity at the same level. At the concentration of 400mg/ml, aqueous extract inhibited S. aureus, Corynebacterium spp, E. coli and K. pneumoniae, while ethanol extract inhibited S. aureus, S. pyogenes, S. typhi and Corynebacterium spp. B. subtilis was inhibited only at the highest (significant) concentration of 600mg/ml (7.00±0.00 mm) [p<0.05]. The MIC value for both extracts against Corynebacterium spp was 25mg/ml. The MBC value against Corynebacterium spp was observed at 50mg/ml and 25mg/ml for the aqueous and ethanol extract respectively. The results suggest that the ethanol extract was bactericidal at low concentration while the aqueous extract was bacteriostatic at low concentration and bactericidal at high concentration against Corynebacterium spp. The difference between the MBC for the two extracts was significant (p<0.05). In conclusion, the results of this study showed that extract of C. sativus could be a potential source of natural antibacterial agent.