Preliminary Study on the Antibacterial Activity of Six Medicinal Plants against Two Naso-Pharyngeal Pathogens—<i>Streptococccus pyogenes</i> and <i>Pseudomonas aeruginosa</i>

Abstract

Objective: The objective is to study the antibacterial activity of six medicinal plants against two naso-pharyngeal pathogens and determination of total phenol contents in ethanol extracts of those plants. Methods: Different serial concentrations (0.05 g/mL, 0.1 g/mL, 0.2 g/mL, 0.4 g/mL) of ethanolic and acetone extracts of Piper nigrum L. ( Piperaceae ), Ocimum sanctum Linn., Plectranthus amboinicus L. ( Lamiaceae ), Ayapana triplinervis M.Vahl. ( Asteraceae ), Cinnamomum zeylanicum L. ( Lauraceae ), Allium schoenoprasum Linn. ( Liliaceace ) were evaluated for the antibacterial activity using disc diffusion method against gram positive Streptococcus pyogenes and gram negative Pseudomonas aeruginosa . The extracts were prepared from different parts of the plants. The total phenol content was estimated using folin-ciocaltau reagent in catechol equivalents. Results: Majority of the extracts had inhibitory effect against the tested bacteria at different concentrations. In ethanol extracts, Plectranthus amboinicus exhibited the maximum zone of inhibition (14 mm) at 0.05 g/mL concentration against Streptococcus pyogenes , and Ocimum sanctum showed highest zone of bacterial inhibition (19 mm) at 0.05 g concentration against Pseudomonas aeruginosa . In acetone extracts, Piper nigrum had the maximum zone of bacterial inhibition (17 mm) in 0.4 g/mL concentration against Streptococcus pyogenes and Cinnamomum zeylanicum and Allium schoenoprasum exhibited the highest zone of bacterial inhibition (0.4 g/mL) against Pseudomonas aeruginosa . The ethanol extract of Plectranthus amboinicus contained the highest amount of phenol (0.8 mg/mL) and Allium schoenoprasum contained the lowest amount (0.62 mg/mL). In acetone, Cinnamomum zeylanicum contained highest phenol content (0.78 mg/mL). Conclusion: All these investigations pave way to the molecular modeling of the lead phyto compounds present in the studied plants, and also in finding out their biochemical action in various metabolic pathways and reactions of infection.