Evaluation of Phytochemical Contents, Proximate Nutritional Composition and Antimicrobial Activity of the Leaves and Rhizome Extracts of Cyperus rotundus Linn. in Uyo, Akwa Ibom State, Nigeria

Abstract

Background: The leaves and rhizome extracts of Cyperus rotundus Linn. popularly called “Nut grass” in many Nigerian communities have been extensively used in local food preparation and in treatment purposes. Aim: This study aimed to evaluate the phytochemical contents, proximate nutritional composition and antimicrobial activity of the leaves and rhizome extracts of C. rotundus. Methodology: The disease-free plant materials were collected from a farm in Uyo, Akwa Ibom State, Nigeria. Preparation of the plant material, methanolic and aqueous extracts; bacterial culture, isolation, microscopy and biochemical identification; phytochemical screening and proximate nutritional analysis were done according to standard methods, while screening for antimicrobial activity was done by agar well diffusion technique. Results: The preliminary phytochemical analysis of the plant extracts showed the presence of bioactive compounds at varying amounts such as glycosides, tannins, reducing sugars, alkaloids, flavonoids, polyphenols, terpenoids, saponins and phlobatannins. The proximate nutritional and elemental analysis of C. rotundus extracts showed high presence of B-carotene (164.3 ± 0.02), Vitamin A (109.25 ± 0.01) and carbohydrate (59.0 ± 0.01) with moderate content of lipid (24.25 ± 0.02) and moisture (9.10 ± 0.01) as well as contents of some mineral elements such as Ca, K and P occurring in the range literature values in mg per 100 g dry weight of the plant sample. The methanol and aqueous extracts of C. rotundus showed varying diameter of zones of inhibition on the test organism. The observable inhibitory effect of the plant extracts on the test organism was more pronounced with methanol extracts as indicated by the diameter of zones of inhibition in mm in the order of 22.0>14.0>13.0 for P. mirabilis, E. coli and S. aureus, respectively compared to the aqueous extract. Conclusion: The results of this study have shown the antimicrobial, therapeutic and nutritional potential of the leaves and rhizome extracts of C. rotundus. It could possibly find application as a good alternative antibacterial agent, nutraceuticals and dietary supplements.