Estudo da composição fitoquímica e avaliação da actividade farmacológica e antimicrobiana de extractos de vernonia polyanthes

Abstract

The chemical compounds found in plants reveal high diversity in terms of structure and of chemical-biological properties, many of them constituting models for the synthesis of a large number of drugs. The aim of this work was to determine the phytochemical composition and evaluate the activity antimicrobial, antipyretic, analgesic and antitripanosome extracts from Vernonia polyanthes (Funguza). Crude extracts of the bark of the stem of Vernonia polyanthes were prepared by maceration with 70% ethanol, distilled water and by Soxhlet extraction with 90% ethanol. The extracts obtained were submitted to phytochemicals identification tests, having been found compounds such as saponins, tannins, steroids / triterpenoids, flavonoids and anthraquinones. The extracts were used to measure antimicrobial, antipyretic, analgesic and antitripanosome. In testing for antimicrobial activity, extracts in the concentrations of 125 mg.mL-1, 250 mg.mL-1 and mg.mL-1a showed greater inhibition of bacterial growth Gram + (Staphylococcus aureus and Bacillus cereus), less inhibition of bacterial growth Gram- (Escherichia coli and Pseudomonas aeruginosa) and did not exhibit any inhibition of fungal growth (Candida sp). Regarding antipyretic activity, ethanolic extracts at a dose of 500 mg.kg-1 revealed an antipyretic effect comparable to that of paracetamol at a dose of 120 mg.kg-1. In analgesic activity the aqueous extract and ethanolic extracts at a dose of 500 mg.kg-1 showed a significant increase in the response time to the thermal nociceptive stimulus, compared to paracetamol, used as a standard pain reliever. In antitrypanosomal activity, the ethanolic extract obtained by the method of maceration in the dose 500 mg.kg-1 did not show any effect against Congolese Trypanossoma. The results of this study corroborate the traditional use of Vernonia polyanthes (Funguza) and constitute an important contribution to scientific validation and to the elaboration of recommendations for the safe use of medicines based on this plant, particularly for the treatment of bacterial infections, pain and fever.