RESUMO
Flavonoids are natural products commonly found in the human diet that show antioxidant, anti-inflammatory and anti-hepatotoxic activities. These nutraceutical properties may relate to the electrochemical activity of flavonoids. To increase the understanding of structure-electrochemical activity relations and the inductive effects that OH substituents have on the redox potential of flavonoids, we carried out square-wave voltammetry experiments and ab initio calculations of eight flavonoids selected following a systematic variation in the number of hydroxyl substituents and their location on the flavan backbone: three flavonols, three anthocyanidins, one anthocyanin and the flavonoid backbone flavone. We compared the effect that the number of -OH groups in the ring B of flavan has on the oxidation potential of the flavonoids considered, finding linear correlations for both flavonols and anthocyanidins ( R 2 = 0.98 ). We analyzed the effects that position and number of -OH substituents have on electron density distributions via ab initio quantum chemical calculations. We present direct correlations between structural features and oxidation potentials that provide a deeper insight into the redox chemistry of these molecules.
Assuntos
Técnicas Eletroquímicas/métodos , Flavonoides/química , Humanos , OxirreduçãoRESUMO
UNLABELLED: We assessed the anti-fibrotic effects of methanolic black bean extract antioxidants in a carbon tetrachloride (CCl4) liver injury model in rats. Experimentally intoxicated animals received CCl4 for eight weeks, the reference and test groups received daily intragastric quercetin or daily intragastric black bean extract. Liver fibrosis was assessed and quantified using morphometric analysis. Expression of fibrosis related genes was measured by real time RT-PCR. Qualitative and quantitative histological analysis showed that administration of 70 mg/kg b.w. of black bean extract reduced hepatic fibrosis index by 18% compared to positive controls (P 0.006), as a result of a decrease in type I (44.3% less, P 0.03) and type IV (68.9% less, P 0.049) collagen gene expression compared to CCl4-injured and Quercetin treated rats. In conclusion, we provide evidence that this methanol black bean extract ameliorates liver fibrosis and types I and IV collagen gene expression, in the animal model used. PRACTICAL APPLICATIONS: The compounds contained in this black bean extract exhibited strong antifibrotic effects in the CCl4 chronic liver injury model used; considering that this compounds are contained in a leguminous that has been used in human diet for a long time, their toxic potential should be very low, and this characteristic should favor their potential use in some other chronic or degenerative states that include an increase in inflammation and oxidative burst in their pathogenesis. Another possible application of this kind of extract could be its use as an antimicrobial or even antiparasitic therapeutic agent, although it is purely speculative.