Resumo:
Dental caries is an infectious oral disease that has as one of the most important etiological agents Streptococcus mutans. Proven, plant species have been isolation of important compounds with antimicrobial activity, which have greater acceptance because it is of natural origin and has little or no adverse effect. Among the antioxidant compounds that has been highlighted today, Gallic acid and its derivatives, which are among the largest phenolic antioxidants found in wines and green tea. This phytochemical acid is well known for its antioxidant, antimicrobial, anti-inflammatory, antimutagenic, anticarcinogenic, antiviral and analgesic properties. This work was developed with the objective of identifying and purifying the bioactive compounds of the gallate obtained through sterification of gallic acid and to evaluate their antimicrobial activity on Streptococcus mutans ATCC 700610. Butyl Gallate (BG), Propyl Gallate (PG), Methyl Gallate (MG) and Sec-Butyl Gallate (SBG) were tested in the determination of minimal inhibitory concentration (MIC) and bactericide (MBC), inhibition of cell adherence (MICA) with planktonic cells of S. mutans. The sterification reaction was proven by Gas Chromatography Coupled to the Mass Spectrum (GC-MS). BG antimicrobial activity was evaluated in vitro regarding the inhibition of biofilm formation, inhibition of glycolytic pathway (polysaccharide formation), inhibition of acid production (pH drop), inhibition of acidicity (permeability to protons). BG presented CIM - 62.5 μg/ml, MBC - 250 μg/and PG was the most bioactive fraction MIC - 31, 25 μg/ml, MBC - 250 μg/ml. BG, SBG, PG and MG did not present activity on the inhibition of cell adhesion (up) at the highest tested concentrations. BG 6.25 mg/mL demonstrated bactericidal activity (decrease in CFU/biofilm), reduction in the production of soluble and insoluble glucans, BG (62.5 mg/mL) reduced the acid production of S. mutans biofilm in the period from 15 to 120 min compared to the vehicle (p < 0.05). The final pH at 120 min was 6.07 for chlorhexidine, 5.85 for GB and 4.94 for vehicle. GB (6.25 mg/mL) reduced the proton permeability of the S. mutans cell membrane at 80, 82, 90, 110 and 120 min compared to the vehicle (p < 0.05).
