Phytochemical Screening and in vitro Antimicrobial Activity of Cyperus rotundus Leaf Extracts

Abstract

Cyperus rotundus, a member of family Cyperaceae is a perennial, stoloniferous herb. The study investigated the secondary metabolites present in the leaf of Cyperus rotundus and antimicrobial activities of the hexane, ethyl acetate and methanol extracts. Phytochemical analysis revealed the presence of saponins, alkaloids, phenolic compounds, tannins, steroids, flavonoids, cardiac glycosides and terpenoids. The qualitative test of the extracts show the presence of steroid only in the hexane extract; flavonoid, cardiac glycoside in both the ethyl acetate and methanol extracts; saponin and tannin and phenolics in just the methanol extract. While alkaloid was present in all the extracts, terpenoid was absent in all. Antimicrobial activity of plant extracts were monitored using the agar disk-diffusion method against strains gram-positive bacterial: Staphylococcus aureus, Pseudomonas aeruginosa; and gram-negative bacteria: Escherichia coli, Salmonela typhi, and strains of fungi: Candida albicans and Aspergillus niger. The antimicrobial activity of the extracts was monitored at different concentrations of 50, 25, 12.5 and 6.25 mg/mL prepared from the stock concentration (100mg/mL) by serial dilution; with standard drugs: ciprofloxacin and fluconazole. The inhibition of the test organisms were concentration dependent. The methanol extract showed significantly higher Inhibition Zone (IZ) and Activity Index (AI) against the microbes at all concentrations compared to the ethyl acetate and hexane extracts due to the much phytochemicals (saponins, tanins, phenols, flavonoids, cardiac glycocides and alkaloids) found present in its extract. The overall study results signify the potential of Cyperus rotundus as a source of therapeutic agents. The methanol extract showed the best activity against both bacterial and fungal pathogens at the highest concentration of 100 mg/mL, especially the most susceptible bacteria: Staphylococcus aureus (IZ of 25.0±1.5; AI of 0.96) and Candida albicans (IZ of 25.5±0.5; AI of 0.91). At MIC, MBC and MFC of 6.25 mg/mL and 12.5 mg/mL, the plant extracts showed effective bactericidal and fungicidal effect against the test microbes.