Potential effect of Roselle (Hibiscus sabdariffa) ethanol extract against Streptococcus mitis and Streptococcus oralis

Abstract

IntroductionThe use of medicinal plants as natural antimicrobial agents has recently gained popularity. Many naturally occurring compounds found in medicinal plants, herbs, and spices have been shown to possess antimicrobial activity against different pathogenic bacteria. Of these medicinal plants, Hibiscus sabdariffa has been found to have significant antimicrobial properties. This study aimed to investigate the effect of Hibiscus SabdariffaH sabdariffa ethanol extract on Streptococcus Mitismitis and Streptococcus Oralisoralis. MethodsIn vitro antibacterial effects of three types of extracts (ethanol, acidic water, and aqueous) of the dry calyces of H sabdariffa were investigated against S mitis and S oralis. Well diffusion technique was used on solid nutrient agar at different concentrations of these extracts (0.0, 50, 100, 150, 200, and 250) µg/mL. Around 0.2% of chlorhexidine (CHX) was used as positive control. The minimum inhibitory concentration and minimum bactericidal concentration of the plant extracts on the test isolates were determined using the micro broth dilution method. The phytochemical analysis was carried out using standard methods to determine the most effective substances like (glycoside, alkaloids, flavonoids, and phenols). ResultsThe antibacterial activity of the three extracts compared with the positive control (CHX) showed that acidic water and ethanol extracts of calyces of H sabdariffa have strong antibacterial characteristics and are more efficient than CHX. The inhibition rate of CHX was 29.1% in S mitis and 63.23% in S oralis, whereas the inhibition rate reached 91.2% and 92% in S mitis, and 91.34% and 94.53% in S oralis for the ethanol and acidic water extracts, respectively with significant differences (P ≤ 0.05). Phytochemical analyses revealed the presence of flavonoids, glycosides, phenols, and alkaloids. ConclusionThe 70% ethanol extract or acidified aqueous extract had higher antimicrobial activity than the aqueous extract in a concentration-dependent manner.