ABSTRACT

Emilia coccinea is a medicinal plant of African origin that belongs to the family of Asteraceae. This plant has diverse and potential medicinal uses in traditional medicine for treating tumor, inflammation, cough, rheumatism, fever, dysentery, wounds and in preventing miscarriage. This study was undertaken to investigate the bioactive constituents, vitamin content, mineral composition and antibacterial properties of methanolic extract of Emilia coccinea leaf. The quantitative phytochemical screening of the extract revealed the presence of alkaloids (3.87 ± 0.02), phenols (0.43 ± 0.01), flavonoids (0.57 ± 0.01), saponins (0.39 ± 0.02), tannins (0.15 ± 0.01) with alkaloid registering the highest presence. Stigmasterol was isolated from the leaves of E. coccinea and was characterized using ¹H, COSY, DEPT, HMBC and HSQC NMR Spectroscopic techniques. Vitamins detected included thiamin (0.12 ± 0.01 mg/100g), niacin (0.62 ± 0.05 mg/100g), riboflavin (0.34 ± 0.01 mg/100g), ascorbic acid (5.20 ± 0.80 mg/100g) and β-carotene (3.83 ± 0.05 mg/100g), with ascorbic acid and thiamine having the highest and lowest concentrations respectively. Minerals detected included calcium (27.24 ± 0.01 mg/100g), magnesium (5.42 ± 0.01 mg/100g), potassium (430.20± 0.01 mg/100g), phosphorus (140.36 ± 0.03 mg/100g), nitrogen (3.63 ± 0.07 mg/100g). Of the minerals detected, Phosphorus had the highest concentration, while nitrogen was the lowest. E.coccinea leaves extract exhibited significant free radical activity at minimum and maximum concentrations of 2.0 mg/ml and 12.0 mg/ml compared to the ascorbic acid used as a standard free scavenger These components are known to be medicinal as well as exhibiting physiological activities in humans. The antibacterial activity at varying concentrations of 100 mg/ml, 50 mg/ml, 40 mg/ml, 20 mg/ml and 10 mg/ml of the extract was investigated against Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa using agar well diffusion method. The results of the antimicrobial assay showed that the extract inhibited the growth of the test organisms in a concentration dependent manner. The highest growth inhibition was seen against B. subtilis and the lowest growth inhibition was against S. aerus with MIC of 5.00±0.00 mg/ml and 35.07±0.71 mg/ml respectively. Thus, the folkloric usage of this plant for the treatment of microbial infections is justified. The results of this research work revealed that Emilia coccinea has a lot of phytochemicals which could be used as raw material by pharmaceutical industries for drug development. The ability of the extract from this plant to exhibit potent inhibition against these pathogens lends a contributory scientific evidence for the use of this plant in traditional medicine.