Antiulcerogenic activity of crude extracts, fractions and active compound from the species Vernonia polyanthes e Vernonia ferruginea / Atividade antiulcerogenica de extratos brutos, frações semi-purificadas e substancia ativa de duas especies do genero Vernonia : Vernonia polyanthes e Vernonia ferruginea

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The genus Vernonia (Asteraceae), which includes about 1.000 species, figures as the most representative from its family. From a systematic point of view, Vernonia is one of the most complex genus of its family, mainly because of its diverse biological forms, from small herbs through big trees. This genus possesses a great pharmacological potential and is always mentioned by ethnopharmacological works. Evidence for the interest in this genus is the number of citations in the database Pubmed. This exceeds 126 for the keyword Vernonia , as of December, 2006. In the present work, the antiulcerogenic effect of two species from genus Vernonia (Vernonia polyanthes Less. and Vernonia ferruginea Less.) was evaluated. Both species are found predominately in Brazilian savannah, although they are widespread over Brazilian territory. They are used in traditional medicine for the treatment of bronchitis, cough, asthma and renal calculus. Initially, phytochemical and pharmacological assays were done with the crude methanolic and chloroformic extracts from each species. Flavonoids and terpenoids were identified in both species, and all crude extracts presented an antiulcerogenic effect. Soon afterward we evaluated some of the action mechanisms from the most effective crude extracts, the methanolic extract from V. ferruginea (EMVF), a flavonoid rich extract, and the chloroformic extract from V. polyanthes (ECVP), a terpenoid rich extract. They both presented an increase in gastric mucus content, and depended in part of the nitric oxide (NO) and sulfhydryls (SHs) presence. ECVP was then fractionated in a chloroformic (FCVP) and methanolic fraction (FMVP), while EMVF was partitioned in an acetate fraction (FAVF) for pharmacological approaches in chronic and acute models. FMVP, the most effective fraction, had its majority compound identified. Lupeol, a lupane pentacyclic triterpene, was identified as the active compound from V. polyanthes, and new assays were done to evaluate its action mechanisms. Lupeol increased gastric mucus content in rats, probably mediated by NO presence. It also presented anti-inflammatory properties in gastric mucosa, reducing PGE2 production and neutrophil infiltration. On its effective dose, it didnt decreased the gastric acid output. On the other hand, Lupeol showed on a chronic model of ulcer induction a great healing effect with no toxicity in vivo, probably not related to the presence of Heat Shock Protein 70 (HSP70) and cellular proliferation (PCNA) on the ulcer border. In the present work, in a biomonitored fractionation process of the species V. polyanthes and V. ferruginea, we identified the antiulcerogenic compound lupeol. Its high gastroprotective effect allied to its low toxicity in vivo, turns it a potential drug for treating gastric ulcers.

ASSUNTO(S)

vernonia polyanthes ulcera gastrica lupeol vernonia ferruginea lupeol vernonia polyanthes vernonia ferruginea gastric ulcer

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