Avaliação de bioatividades e da ação dos extratos aquosos de folhas e cascas do caule de Ziziphus joazeiro Mart. (Rhamnaceae) em biofilmes microbianos

Abstract

The use of natural products with a therapeutic focus appears as an alternative against the presence of antimicrobial resistance and the search for new options for the treatment of various microbial infections. Ethnobiological research has become an essential scientific field in identification by active principles, since it is based on popular knowledge and the medicinal use of plants in traditional practices. Ziziphus joazeiro is one of the most exploited endemic plants of the Caatinga, being notorious its therapeutic value in several medicinal practices. One of the main popular uses is in oral hygiene and treatment of gingivitis. Plant parts, mainly peels and against bark of the stem are crushed and used in tooth brushing. However, the incorrect managemant of removing parts of the stem can impede the flow of nutrients, resulting in dehydration of the tissue, besides the attack of pests and microorganisms causing the plant death. In this sense, it is necessary to investigate other parts of Z. joazeiro, for minimize the use of the stem. This work aimed to evaluate in vitro the antimicrobial activity, the action against bacterial and fungal biofilms by the aqueous extracts of leaves and stem bark of Ziziphus joazeiro Mart, comparing the effects of both extracts, as well as with the action of conventional standard drugs. For this, microbial assays for antibacterial and antifungal activity were carried out by the microdilution method in broth. The minimum inhibitory concentration and the modulatory activity against antibiotics and antifungals, the antiparasitic activity against Trypanonoma cruzi (epimastigote) and Leishmania brasiliensis (promastigote), in addition to cytotoxicity, against mammalian cells were determined. The treatment of microbial biofilms was determined by the OD 600 nm absorbance and the crystal violet assay. All the results were compared to each other and to the effects of standard drugs. The chemical composition of the extracts was performed by ultra-high performance liquid chromatography. The extracts did not demonstrate direct antibacterial activity, with MIC ≥ 2048 μg / mL. However, they showed significant modulatory activity when combined with antibiotics. In a comparative evaluation between the extracts, the EACCZJ presented more significant values, regarding antifungal activity (CFM ≥ 8192 μg / mL) and against promastigote forms. On the other hand, the EAFZJ had a highlighted effect when used in combination with fluconazole and an antiparasitic action with no clinical relevance. For microbial biofilms, the EACCZJ presented a more effective treatment than the EAFZJ, presenting some results similar to the standard drugs used. The chemical analysis identified in the EAFZJ the presence of flavonoids, saponins, phenolic acid and nitrogen compound, and in the EACCZJ revealed derivatives of saponins. From the point of view of ethnopharmacological knowledge, the use of the Joazeiro stem bark for dental brushing show scientific basis, proving the antimicrobial effects and treatment of bacterial and fungal biofilms. The same effects were not completely observed in the leaf extracts, reinforcing the stem choice by the population. Finally, in spite of these effects, the presented significant results in relation to the tests performed, the bark extract did not present superior action to the standard reference drugs.