Determinação dos mecanismos de ação envolvidos nas atividade antiulcerogenica e antioxidantes de Rhizophora mangle L / Determination of the mechanisms of action in the antiulcerogenic and antioxidant activities of Rhizophora mangle L

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The pharmacological research has been focusing on the folk medicine knowledge in order to establish the scientific basis of their pharmacological effects. Nowadays, tannins play a prominent role because of its high antioxidant capacity and, due to the progress made in the analysis and identification of these compounds and their therapeutic possibilities. Among the many natural sources of these compounds, highlighted in this work a well known plant in coastal environments, the Rhizophora mangle L., belonging to the family RHIZOPHORACEAE. The genus includes five species of Rhizophora in equatorial, tropical and subtropical regions in both hemispheres. It is one of the most important sources of tannin (15 to 36% of the dry bark weight) in industrial use. Rhizophora mangle is well known in the Caribbean folk medicine for its anti-inflammatory, antifungal, antibacterial, anti-ulcer, anti-hypertensive and antioxidant properties. This study aimed to evaluate the antioxidant and anti-ulcer activities of R. mangle, and to elucidate the chemical compounds present in its barks. For both evaluations chemical and pharmacological assays with the crude extract (acetone: water 7:3) and their organic fractions (aqueous - fr-aq, ethyl acetate - fr-EtOAc and butanolic - fr-BuOH) were performed. The analysis of anti-ulcer activity of the extract and fractions showed that fr-BuOH was more effective at a dose of 0,5 mg.Kg-1. This fraction also showed significant antioxidant activity. It was found the presence of high concentrations of polyphenolic compounds in the chemical assay performed for both the crude extract and its fractions. The pharmacological experiments were carried out to determine the mechanisms by which the compounds present in fr-BuOH exert their antiulcer and antioxidant activities. It was concluded that the fr-BuOH has antioxidant activity linked to the concentration of polyphenolic compounds, which were able to scavenge free radicals, maintain the levels of GSH, reduce the MPO activity and LPO levels and maintain or increase the antioxidant enzymatic activities of GR, GPx and SOD. Moreover, the antiulcer activity of fr-BuOH is mediated by several mechanisms including: antioxidant action; involvement of GSH and NO; anti-secretory properties; increase of mucus and PGE2 synthesis, and expression of COX-2, EGF, HSP-70 and PCNA on gastric mucosa. Chemical study revealed that the major compounds are heteroside catechins, gallotannins and "tannin complexes"

ASSUNTO(S)

gastric ulcer antioxidants ulcera gastrica taninos antioxidantes tannins

ACESSO AO ARTIGO

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