Potencial antimicrobiano de extratos vegetais e frações químicas de Sideroxylon obtusifolium T.D. Penn sobre microrganismos bucais

Abstract

This study aimed to evaluate the in vitro antimicrobial activity of plant extracts and chemical fractions from Sideroxylon obtusifolium T.D. Penn on Streptococcus mutans (ATCC 27175), Streptococcus oralis (ATCC 10557), Streptococcus salivarius (ATCC 7073), Streptococcus parasanguinis (ATCC 903) and Candida albicans (ATCC 10231), as well as to identify the bioactive chemical substances contained in the extracts with the best antimicrobial activity. Lyophilized extracts of leaf and bark (LL and LB) and ethanol extracts of leaf and bark (EL and EB) of S. obtusifolium T. D. Penn were tested for their antimicrobial potential by determining their Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Minimum Fungicidal Concentration (MFC). Tests were performed in triplicate by the microdilution method in three independent experiments. Phytochemical characterization was performed by measuring the content of total polyphenols, total flavonoids and condensed tannins. The EB extract of S. obtusifolium T. D. Penn showed bacteriostatic and bactericidal activity against Streptococcus mutans (MIC = 1000 µg/ml, MBC = 1000 µg/ml); the other streptococci strains were found to be resistant to the extract concentrations tested; all extracts (ethanol and lyophilized, from leaf and bark) showed inhibitory activity on Candida albicans (MIC = 500 µg/ml); the dichloromethane and n-butanol fractions of LL extract showed higher antifungal potential than the crude LL extract (MIC = 250 µg/ml; CFM = 500 µg/ml). Phytochemical characterization revealed predominance of polyphenol compounds (EB = 29.23%, LB = 25.98%), followed by condensed tannins (LB = 38.84%, LB = 17.78%). According to the results, it is suggested that Sideroxylon obtusifolium T. D. Penn has antifungal activity on C. albicans and antibacterial activity on S. mutans, possibly due to the presence of total polyphenols and condensed tannins.