Avaliação de atividades farmacológicas e toxicidade de plantas medicinais do semiárido do Nordeste brasileiro

Abstract

This study combines one ethnopharmacological approach within the traditional use of species such as screening, in association with phylogenetic aspects, considering the scientific evidences regarding the chemical composition and pharmacological activities in other species within the same genus. This is associated with assessments of antioxidant and hepatoprotective activities already performed in previous studies from the research group using the crude extract of Spondias mombim×S. tuberosa and Turnera ulmifolia Linn. var. elegans, which indicated a positive therapeutic effect, as well as the importance of a toxicological evaluation, other pharmacological activities and the elucidation of the major compounds present in crude extracts and fractions of Licania tomentosa Benth. Fritsch, C. impressa Prance, L. rigida Benth., S. mombim×S. tuberosa and Turnera ulmifolia Linn. var. elegans. Thus, leaf extracts and their fractions relating to the above mentioned species were characterized for chemical composition, pharmacological activities by in vitro and ex vivo assays, as well as the in vivo evaluation of toxicity. The chemical composition of crude extracts and fractions were evaluated by a validated chromatographic procedure and spectrometric techniques, which enabled the identification and/or characterization of compound majority. This analysis pointed that extracts and their fractions are a source of phenolic compounds, especially flavonoids and their glycosides such as flavonls-3-O-glicosilates. In the leaf extract of S. mombim×S. tuberosa and its rich in flavonoids fraction, called FRF, was isolated and characterized rutin as major compound of this species. Regarding the antioxidant activity, only the methanol S. mombim×S. tuberosa leaf extract and its FRF showed a marked DPPH free radical scavenging capacity, while FRP was only one able to protect the erythrocyte integrity by preventing its hemolysis by inhibiting lipid lipoperoxidation and maintaining the GSH levels. The other extracts induced hemolysis. This antioxidant effect is associated to chemical composition in all extracts and fractions. The antimicrobial activity assessment showed just a moderate bactericidal effect in the presence of the S. mombim×S. tuberosa extract and its FRP. The toxicological assessment of all extracts in a murine model, using a single dose of the extract at a concentration of 2000 mg / kg, showed no toxic effect. Therefore, the results described herein promote a complementary scientific knowledge, enabling the use of these plant species leaves as a therapeutic resource, allowing the rational use of the same, and control the indiscriminate extraction due to medical uses no scientifically validated, here in Northeastern Brazil and worldwide.