Antimicrobial and antibiofilm activities of Casearia sylvestris extracts and fractions from distinct Brazilian biomes against Streptococcus mutans and Candida albicans

Author(s)

Sabrina Marcela Ribeiro

• Document type: Master's Dissertation
• Press: Araraquara. 2019-07-16.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Odontologia. Araraquara
• Defense date: 2019-07-05
• Advisor: Marlise Inêz Klein; Alberto José Cavalheiro

Abstract

Dental caries is a worldwide public health problem caused by an interaction between a diet rich in sugar and microorganisms in dental biofilms. Approaches to control these microorganisms in biofilms are necessary. Therefore, the objective of this study was to evaluate the antimicrobial (planktonic) and antibiofilm potential of twelve Casearia sylvestris extracts (0.50 mg/mL) from different Brazilian biomes (Atlantic Forest, Cerrado, Caatinga, Pampa and Pantanal) and variety (sylvestris, lingua and intermediate) against two species found in cariogenic biofilms (Streptococcus mutans and Candida albicans). The chemical characterization of crude extracts was done via chromatography. The antimicrobial activity was determined by the viable microbial population (CFU/mL) and the antibiofilm activity by the viable microbial population (CFU/mL) and biomass of the biofilms treated. For the extracts active for S. mutans, the effect on the initial formation of the glucan matrix (GtfB activity), the release after adhesion of this bacterium to the salivary film and the initial matrix of glucans and cytotoxicity via the MTT assay was evaluated. In addition, the antimicrobial potential against S. mutans of three fractions (methanol, ethyl acetate and hexane, 0.25 mg/mL) from the twelve extracts was also evaluated. Three extracts of the Atlantic Forest biome and sylvestris variety reduced the counts of viable S. mutans cells (vs. vehicle, p <0.0001) by >50% (or >3 logs), while two extracts belonging to the same biome variety, also decreased ≅50% the viable cell counts of C. albicans (vs. vehicle, p <0.0001). For S. mutans biofilms, three extractsreduced biomass by >90% (vs. vehicle; p >0.0001), of which two reduced in 100% of the microbial population and one in ≅50% (vs. vehicle; p<0.0001). However, for the fungal biofilm, two extracts promoted a >50% reduction in viable (vs. vehicle; p <0.0001) and none reduced biomass. The extracts with higher antimicrobial activity and antibiofilm presented higher content of clerodanic diterpenes and lower content of glycosylated flavonoids in relation to the less active extracts. Among the four promising extracts, three reduced the amount of glucans formed by GtfB (vs. vehicle, p <0.0136) and none significantly reduced the removal of adhered cells to the film (vs. vehicle; p> 0.05). However, a larger number of S. mutans cells were removed after adhesion to the glucan matrix when treated by these extracts (vs. vehicle, p <0.0031). The extracts were cytotoxic against NOK-si lineage cells after 1 h exposure (vs. viability control); however, there was no difference when the extracts were compared with the vehicle control (p >0.999). Of the three fractions evaluated for each extract, only the ethyl acetate fractions reduced the microbial population of S. mutans (vs. vehicle; p <0.0001), except one (p >0.05). Of these, three caused the reduction of the microbial population in >80%, the three fractions belong to var.lingua, two include the Cerrado biome and one, the Ecotone biome (Cerrado/Caatinga). Therefore, extracts of C. sylvestris from the Atlantic Forest and var. sylvestris and ethyl acetate fractions of the Cerrado and Ecotone biome; var. lingua can be used as a therapeutic strategy against microorganisms involved in the pathogenesis of dental caries. (AU)

• FAPESP's process: 17/07408-6 - Evaluation of antimicrobial and antibiofilm activities of extracts and fractions from plants against oral pathogenic microorganisms
• Grantee: Sabrina Marcela Ribeiro
• Support Opportunities: Scholarships in Brazil - Master