ANTICARIOGENIC POTENTIAL OF TANNINS OF FOREST SPECIES
natural tannins, bioactive substances, antimicrobial activity, dental caries, cariogenics bacterias.
Studies on compounds from secondary plant metabolism may increase our ability to understand the pharmaceutical potential of tropical flora. The presence of substances such as tannins arouses pharmaceutical interest in several plant species, based on the principle of popular use, and their antimicrobial, antioxidant, antiviral and anti-tumor properties of tannins, which are already well known and documented. The aim of this study is to extract, chemically characterize the tannins of Acacia mangium Willd., Azadirachta indica A. Juss Mimosa tenuiflora Willd, Mimosa caesalpiniifolia Benth ,. and to verify antibacterial activity of these tannins against strains of cariogenic bacteria. The content of tannins present in bark of trees from commercial plantations with 4 years of age, located in an experimental area in the municipality of Macaíba, State of Rio Grande do Norte, was analyzed. The extractions were performed in hot water. Total solids content (TST), Stiasny index (IS) and condensed tannin content (TTC) were determined. The chemical characterization of tannic extracts was carried out using infrared spectrometry with Fourrier transform. The evaluation of the antibacterial activity of the tannins was performed by means of the Minimum Inhibitory Concentration (MIC) test for the species Streptococcus mutans (UA159), Lactobacillus acidophilus (ATCC IAL523), Lactobacillus casei (ATCC 193) and Candida albicans (SC5314). The quantification of the extracts showed that M. tenuiflora and A. mangium presented higher percentages of TTC (23.40% and 12.41%, respectively), indicating the potential for tannin production on an industrial scale. Although M. caesalpiniifolia had a low TTC (8.38%), this species had a high IS (91.27%), characterized by a high degree of pure tannins. Regarding chemical characterization, the tannins of all species showed very similar spectra, with strong OH elongation in the range of 3,439 to 3,418 cm-1. No evaluated extract showed inhibitory activity against the tested microorganisms (MIC> 2500 µg / mL).