Abstract
Antibiotic resistance in bacterial species is opening new avenues to search for alternative modes of antimicrobial treatment, medicinal plant extracts being one among them. The aim of this study was to access the possibility of medicinal plant extract from Shih in the manufacture of pharmaceutical preparations for oral hygiene specifically for the prevention and treatment of dental caries due to Streptococcus mutans. Antimicrobial effects of crude organic extract of Shih on S. mutans isolated from the saliva were examined by taking S. mutans with culture media only (-ve control); S. mutans treated with the antibiotic gentamicin (+ve control) and S. mutans treated with Shih. Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) were Determination by Iodonitrotetrazolium chloride (INT) colorimetric assay Time-kill dynamic assay was performed using broth microdilution method. The metabolic reason behind the bacteriostatic and bactericidal effect were studied by measuring the glucose utilization by the microbes, pH as a measure of acid production, nucleic acids quantitation to check the DNA status and inhibition of water-insoluble glucan synthesis were undertaken. Shih MIC for S. mutans was at 2.5 mg/ml and MBC was 4 mg/ml. S. mutans bacterial population started reclining within 60 min of incubation with Shih at MBC. Utilization of added glucose was very high at MIC due to bacteria overcoming the stress, whereas at MBC its utilization was less. Accordingly pH also became acidic to 2.9 with MIC and 4.03 with MBC. There was a great degree of inhibition in the formation of nucleic acids indicating this crude extract interferes with DNA replication. Inhibition of glucan synthesis was to the tune of 45% as compared to control. Thus we conclude that Shih has potentially effective antibacterial activity hence it can be proposed as a potentially effective antiplaque and anticariogenic agent in the form of mouth wash or gum paint. However, the cytotoxicity of the extract needs to be evaluated in in-vitro and in-vivo conditions before it is considered as a safe antiplaque and anticariogenic agent.