Comparative Evaluation of Phytochemicals, Antioxidant and Antimicrobial Activity of Four Medicinal Plants Native to Northern Nigeria.

Abstract

The evaluation of secondary metabolites in four Nigerian native plants; Cissampelos owarensis, Tacca leontopetaloides, Euphobia hirta and Euphobia thymifolia. Reveals the presence of alkaloids, tannins, saponins, triterpenes, flavonoids, glycosides and carbohydrates. Cissampelos owarensis contains all the metabolites while Tacca leontopetaloides contain all the metabolites except flavonoids; Euphobia hirta contains all the metabolites except anthraquinones. Euphobia thymifolia contains all the metabolites except cardiac glycosides. The result of antimicrobial activities of the plants extract on the clinical isolates; Staphylococcus aureus, Streptococcus pyogene, Salmonella typhi, Escherichia coli, Shigellia dysenteriae, Proteus vulgaris and Candida albicans showed zones of inhibition ranging from 18-27 mm. The result of the minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) showed that all the plants’ extract inhibited and completely killed S. aureus and E. coli at a concentration range of 6.25-50 mg/mL and 25-100 mg/mL respectively. The Percentage antioxidant (AA %) activity of the plants extract showed a dose dependant increase, C. owariensis had the highest percentage antioxidant activity at 125 µg/mL (91 %) while the least results was recorded for T. leontopetaliodes at 125 µg/mL (86 %). The results of the reducing potential and Total Phenolic content express in terms of Gallic acid equivalent (GAE) showed that C. owariensis possesses the highest reducing potential and total phenolic content (0.703nm, 12.4 mg), E. thymifolia (0.482nm, 7.46 mg), E. hirta (0.451nm, 7.00 mg) and T. leontopetaliodes showed the least reducing potential (0.217nm, 6.90 mg), when compared with Gallic acid standard (1.268nm). These observations showed that the plants have reducing characteristics hence can act as good antioxidants.