Antibacterial Activities of Selected Plant Extracts on Cariogenic Microbes.

PURPOSE: To investigate and compare the antibacterial effect of different botanical (turmeric, miswak, derum) and non-botanical oral hygiene products (toothpaste, mouthwash, activated charcoal, baking soda) on the cariogenic bacteria E. coli, S. aureus, and S. mutans. MATERIALS AND METHODS: Different plant extracts (turmeric, miswak, and derum) and as well as non-botanical substances used in oral hygiene (charcoal, toothpaste, mouthwash, and sodium bicarbonate) were studied for their antibacterial activities against cariogenic model microbes Streptococcus mutans, Staphylococcus aureus, and Escherichia coli using the agar diffusion technique and in-silico molecular docking. Based on LC-MS analysis and literature reviews, linoleic acid - the bioactive fatty acid antimicrobial and anti-biofilm agent present in the studied plants - was selected for molecular docking analysis. RESULTS: Among all tested materials, derum revealed the highest activity against S. mutans (inhibition zone diameter 16 mm2), S. aureus (inhibition zone diameter 14.3 mm2), and E. coli (inhibition zone diameter 14 mm2). The mouthwash and toothpaste inhibited the growth of S. aureus (inhibition zone diameter 15 mm2) and E. coli (14 mm2) but had no or negligible effect on S. mutans (8 mm2) as was the case for all the other substances used in oral hygiene tested here. Liquid chromatography/mass spectrometry revealed the presence of linoleic acid at 279m/z, and in-silico screening demonstrated a possible affinity of linoleic acid for extracellular polysaccharide glucan. Low energy level scores of -1.24 kcal/mol stabilized by four hydrogen bonds between linoleic acid and extracellular alpha (α) 1,3-glucan matrix showed promising potential of linoleic acid in the treatment of S. mutans biofilm. CONCLUSION: Derum sticks showed the highest antibacterial activity against S. mutans, followed by S. aureus, and E. coli. The insights from molecular docking analysis of linoleic acid and glucan may lead to the development of therapeutic agents targeting extracellular polymeric substance (EPS) synthesis, thus helping prevent biofilm formation and improve oral hygiene.