Comparison of the Antimicrobial Activity ofHibiscus sabdariffaCalyx Extracts, Six Commercial Types of Mouthwashes, and Chlorhexidine on Oral Pathogenic Bacteria, and the Effect ofHibiscus sabdariffaExtracts and Chlorhexidine on Permeability of the Bacterial Membrane

Abstract

To determine and compare the antimicrobial effect of Hibiscus sabdariffa calyx extracts, six types of commercial mouthwashes, and chlorhexidine on Streptococcus mutans, Streptococcus sanguinis, Capnocytophaga gingivalis, and Staphylococcus aureus. Two varieties of H. sabdariffa cultivated in Mexico were used. Aqueous, methanolic, ethanolic, acetonic, and ethyl acetate extracts were obtained from H. sabdariffa calyces. Six different types of mouthwash (Astringosol^®, Colgate plax-ice-infinity^®, Crest pro-health^®, Dental max^®, Equate^®, and Listerine zero^®) and chlorhexidine (0.12%) were purchased at a pharmacy. The antimicrobial activity of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine was determined by the agar disc diffusion technique. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of all solutions were determined by the broth dilution method and the pour plate technique, respectively. Also, the effect of H. sabdariffa extracts and chlorhexidine on permeability of the bacterial membrane was determined by the violet crystal assay. All H. sabdariffa calyx extracts and chlorhexidine showed antibacterial activity against all oral pathogenic bacteria. The mouthwashes showed lower antibacterial effect than H. sabdariffa extracts and chlorhexidine. Dental max showed no antibacterial effect. The MICs and MBCs, respectively, for H. sabdariffa extracts were between 5–20 and 10–20 mg/mL; and for chlorhexidine, between 3–4 and 3–5 mg/mL. For the Listerine^®, the MIC and MBC values were between 20–25 and 25–33 mg/mL, respectively. The results of the crystal violet test indicate that H. sabdariffa calyx extracts and chlorhexidine alter the permeability of the bacterial membrane. All H. sabdariffa extracts and chlorhexidine showed significantly greater antimicrobial effect than mouthwashes. This is the first report in which the antimicrobial effect of the H. sabdariffa calyx extracts, mouthwashes, and chlorhexidine is compared.