Efeitos do extrato aquoso de folhas de Syzygium cumini sobre a oxidação e glicação de liporoteínas de baixa densidade

Abstract

Structural modifications of low density lipoproteins (LDL) are considered one of the main causes to atherosclerosis development. Among these modifications, highlights the modifications caused by oxidation and/or glycation, the latter being favored in diabetic subjects due to the hyperglycemia status and consequent increased availability of glucose, making diabetes mellitus one of the risk factors of atherosclerosis. Considering the relationships established between atherosclerosis and hyperglycemia, as well as the role of oxidative stress in both conditions, this work aimed to evaluate the effect in vitro of the Syzigium cumini aqueous-leaf extract (S.cExt), a plant popularly used to treat diabetes, on parameters of oxidation and glycation in low density lipoproteins isolated from human plasma. The results obtained demonstrated that S.cExt exhibited a potent antioxidant effect on CuSO4-induced lipid peroxidation in human LDL, serum and plasma assayed by conjugated dienes formation and thiobarbituric acid reactive substances (TBARS) production. Besides the antioxidant activity exhibited against lipid peroxidation, the assay of loss of tryptophan fluorescence showed that S.cExt is also able to diminish the oxidative damage caused by CuSO4 in the protein moiety of LDL. In contrast to oxidation parameters, S.cExt did not modify the LDL glycation induced by methylglyoxal (MG), which was evaluated by eletrophoretic mobility in agarose gel eletroforesis and by the fluorimetric analysis of the formation of advanced glycation end products (AGEs). In general, the data obtained here suggest that S.cExt can be considered a promising antiatherogenic agent due its antioxidant activity on LDL oxidation in vitro.