Antibacterial activity of Cyperus esculentus (Tiger nut) and Cucumis sativus (Cucumber) against multiresistant bacteria isolates

Abstract

The increase in antimicrobial resistance has become a great threat in the treatment of common infections. Antimicrobial resistance has direct and severe consequences on both morbidity and mortality rates of humans and animals: healing process is delayed; surgical operations and other medical procedures are endangered due to microbial infections and treatment costs increase. The ethanolic and aqueous extracts of Cyperus esculentus and Cucumis sativus were investigated against Staphylococcus aureus, Listeria ivanovii, Bacillus cereus, Serratia marcescens, Pseudomonas aeruginosa and Escherichia coli. The results revealed that the ethanolic and aqueous extracts of Cucumis sativus contain more bioactive components than ethanolic and aqueous extracts of Cyperus esculentus. The phytochemical analysis of the Cucumis sativus extracts showed the presence of flavonoids, saponins, alkaloids and steroids, while Cyperus esculentus showed the presence of alkaloids, resins, saponins, tannins and steroids. The aqueous extract of Cucumis sativus pulp had a high antibacterial activity against Staphylococcus aureus (IZD = 27 ± 0.27 mm) and Bacillus cereus (IZD = 26.5 ± 0.41 mm) at the 50 mg/ml concentration. Also, the ethanolic extract of Cucumis sativus pulp showed good activity at the same concentration against Bacillus cereus (IZD 18.5 ± 0.49 mm) and Serratia marcescens (IZD 16 ± 0.00 mm). In contrast, both the ethanolic and aqueous extracts of C. sativus and C. esculentus peels only showed very negligible activities against the test bacterial isolates. Also, the minimum inhibitory concentration (MIC) of the ethanolic and aqueous extracts of C. sativus pulp was lower (1.53 mg/ml) against Bacilius cereus and Listeria ivanovii than other bacteria. The minimum bactericidal concentration (MBC) of the extracts was only observed against Staphylococcus aureus (6.13 mg/ml) and Listeria ivanovii (3.06 mg/ml). These findings revealed that the ethanolic and aqueous extracts of Cucumis sativus pulp may have potential applications in the phytomedicine for treating human infections.