Resumo

SANCHEZ CALERO, Janet; MARTINEZ SANCHEZ, Gregorio  e  FAURE GARCIA, Roberto. Protective effect of polyphenols from Rhizophora mangle L. on oxidative damage to proteins and DNA. Rev Cubana Plant Med [online]. 2011, vol.16, n.1, pp. 1-12. ISSN 1028-4796.

Introduction: the aqueous extract from Rhizophora mangle (L.) bark has demonstrated a broad spectrum of medicinal uses; for example, in treating bovine mastitis, wound healing, uterine infections and gastroduodenal ulcers, due to its antiseptic, healing, anti-inflammatory and antioxidant properties. However, the antioxidant activity in its whole complexity has not been fully studied in order to elucidate the mechanisms of action involved in this pharmacological effect. Objective: to determine if R. mangle bark aqueous extract and its polyphenolic fraction protect the main biomolecules from oxidative damage. Methods: the antioxidant activity of R. mangle extract and its polyphenolic fraction on the main biomolecules was determined by the following methods: oxidative damage trial on bovine serum albumin exposed to hydroxyl radicals generated in the Fenton system and the bleomycin-Fe³⁺ system-induced DNA oxidative degradation trial. Results: the R. mangle bark extract and its polyphenolic fraction, at the highest tested concentration, reduced the sulfhydryl group oxidation by 87,3 % and 89,1 % and they also inhibited the DNA degradation by 98.4 % and 91.9 % respectively. The regression analysis demonstrated that both effects depended on tannin concentration in the extract and its fraction. The comparison of regression lines revealed that the extract and its fraction were equally effective in protecting bovine serum albumin from oxidation by hydroxyl radicals; however, the extract was more effective when protecting DNA from oxidative degradation than its fraction. Conclusions: the R. mangle aqueous extract showed a protective effect on the main biomolecules from the oxidative damage, evidenced by inhibiting loss of sulfhydryl group in bovine serum albumin and decreasing the DNA degradation. At the same time, it was shown that polyphenolic compounds present in the extract were the main responsible for the antioxidant effects observed in this study.

Palavras-chave : hydroxyl radicals; bleomycin; biomolecules; polyphenolic compounds; Rhizophora mangle (L.); antioxidant activity.

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