Phytochemical and in vitro anti-bacterial properties of Hibiscus sabdariffa L (Roselle) juice

The anti-bacterial properties of aqueous and ethanol extracts of the calyces of Hibiscus sabdariffa on five bacteria genera, namely, Escherichia coli, Staphylococcus aureus, Salmonella typhi, Shigella  dysenteriae and Streptococcus mutans were evaluated using agar well and disc diffusion methods. Six bioactive compounds were identified from phytochemical analysis of the juice extract of H. sabdariffa. Analysis revealed the presence of the following in the water and ethanol extracts: saponins (1.46%), alkaloids (0.09%), tannins (0.19%), total phenols (0.07%), flavonoids (2.41%) and glycosides (0.13%). The results revealed that both water and ethanol extracts had significant anti-bacterial effects (P ≤ 0.05) against the tested pathogenic bacteria genera with the ethanol extract of Roselle having higher anti-bacterial effects against all the pathogens. S. aureus and E. coli were the most sensitive to Roselle juice extract (47.9 and 45. 8 mm zones of inhibition, respectively). The minimum inhibitory concentration (MIC) for the ethanol extract of H. sabdariffa was between 0.26 and 1.03 mg/ml. The results observed in this study contribute to scientific baseline data on the anti-bacterial activities of H. sabdariffa juice extract. Key words: Antimicrobial activity, minimum inhibitory concentration, pathogenic bacteria, phytochemical, Hibiscus sabdariffa.