Investigação da ação antimicrobiana de três espécies vegetais da Amazônia contra leveduras patogênicas

Abstract

Several species of medicinal plants are a source of compounds with therapeutic potential for treating diseases of microbial origin, including filamentous and unicellular fungi (yeasts). This study aimed to evaluate the antimicrobial action of organic extracts from three plant species Pleonotoma jasminifolia, Mansoa alliacea and Solanum sessiliflorum against opportunistic pathogenic yeasts Candida albicans DPUA 1340, Candida tropicalis DPUA 023, Trichosporon beemeri DPUA 213, and Trichosporon beigelii DPUA 208, as well as to select a source of biocompounds with antimicrobial action for future industrial application. For the extraction of biocompounds, the leaves of the plant species were subjected to extraction by maceration assisted by ultrasonic bath with organic solvents of increasing polarity [hexane, ethyl acetate, and methanol], followed by filtration and concentration in a rotary evaporator under reduced pressure. The test yeasts were reactivated on Sabouraud Agar supplemented with 5% (w/v) yeast extract and maintained at 37°C for 72 hours. Authentication was performed using conventional methods such as colony morphology, chlamydospore production, and pseudohyphae. The evaluation of antimicrobial activity was performed by the agar diffusion method, determination of the minimum inhibitory concentration (MIC), and by bioautography. The results showed that the organic extracts of P. jasminifolia, M. alliacea, and S. sessiliflorum present a source of biocompounds with antimicrobial action against the tested yeasts, except for T. beigelii. The hexane extracts of the three plant species showed the broadest spectrum of action (22.3 to 23.6 nm), with T. beemeri being the most sensitive yeast. Next, the Minimum Inhibitory Concentration (MIC) of the hexane extracts was obtained; the MIC results showed weak activity for P. jasminifolia and moderate activity for M. alliacea and S. sessiliflorum. Bioautographic analysis of the hexane extracts showed inhibitory action of biocompounds with Rf (Retention factor) between 0.6 to 0.93, in addition to the presence of phytochemical classes such as alkaloids, terpenes, and flavonoids revealed with Dragendorff, NP-PEG, and sulfuric anisaldehyde solutions, respectively. The results of the analyses indicate that these organic extracts present a potential source of biocompounds with anti-yeast activity; however, further analyses must be performed to enable the industrial application of these biocompounds.