Potencial bioativo de extratos de plantas utilizadas em medicina popular no estado de Pernambuco

Abstract

Bioactive compounds extracted from plants with biological activity, such as antimicrobial and antioxidant, may be the key to the prevention and/or treatment of several diseases, for this reason, the present work aimed to evaluate the antimicrobial, antibiofilm, antioxidant and cytotoxic potential of extracts and fractions of plants used in folk medicine, in the state of Pernambuco. Ten plants were collected and identified, these being, amora (Morus alba), aroeira (Schinus terebinthifolius), cajueiro-roxo (Anacardium occidentale), capim limão (Cymbopogon citratus), gengibre (Zingiber officinale), mandacaru (Cereus jamacaru), pitanga (Eugenia uniflora), sambacaitá (Hyptis pectinata), unha-de-gato (Uncaria tomentosa) and uxi-amarelo (Endopleura uchi). Then, ethanol extracts of these plants were prepared, as well as their aqueous, chloroform and hexane fractions. The extracts and fractions were tested against Gram-positive and Gram-negative bacteria. The isolates were tested for their antimicrobial susceptibility profile by diffusion tests in wells, at concentrations of 10 and 20 mg.mL-1, Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), at concentrations from 0.195 to 25 mg.mL-1. The quantification of the content of phenolic compounds, by the Folin-Ciocalteu assay and flavonoids by the colorimetric method with aluminum chloride, also evaluated the antioxidant potential by the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging methods. and 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), determination of antibiofilm activity with crystal violet dye and cell cytotoxicity test quantified by the MTT method, of plants with greater antimicrobial potential. It was observed, by the diffusion test in wells, that the ethanolic extracts with greater activity were aroeira and pitangueira, with inhibition zones of 21.33 for E. faecalis and 18.33 for B. subitilis, respectively, at 20 mg.mL-1. It was possible to identify which aroeira ethanolic extract showed better activity by the MIC test, for all strains tested, especially for Bacilus subtilis, Enterococcus faecalis, Listeria monocytogenes, Staphylococcus aureus, Escherichiacoli and Klebsiella pneumoniae with values of MIC ranging from 0.78 to 1.56 mg.mL-1. The quantitative analysis of the content of total phenolic compounds reveals their greater presence in the aqueous fractions and then in the ethanolic extracts, since the content of total flavonoids was more expressive for the ethanolic extracts, for both plants. By the ABTS and DPPH tests, the highest percentage of elimination occurred at the lowest concentration, 0.195 mg.mL-1, both for the ethanolic extract, 92.04% and 80.42%, and for the aqueous fraction, 93.73% and 86.63% of S. terebinthifolius, respectively. With the ethanolic extract and aqueous fraction of E. uniflora leaves, the mean elimination of ABTS was 93.33 and 92.29% and the mean elimination of DPPH was 83.29% and 87.55%, respectively, at 0.195 mg.mL-1. Biofilm reduction was identified for the E. uniflora ethanolic extract up to 87.08%. It can be concluded that the ethanolic extracts and aqueous fractions of both plants have excellent content of phenolic compounds and flavonoids. For most Gram-positive and Gram-negative strains tested, S. terebinthifolius shows moderate activity, highlighting a possible potential for its role as a broad-spectrum antimicrobial. Antibiofilm potential was identified for both plants. The ethanolic extract and the aqueous fraction of the leaves of S. terebinthifolius and E. uniflora have high antioxidant potential, when analyzed by ABTS and DPPH methods. This demonstrates that both plants can serve as raw materials for the pharmaceutical industry, since they have bioactive compounds with biological activity such as antimicrobial and/or antioxidant, as well as justifying their vast popular use.