Nègre-Salvayre A, Salvayre R
Department of Biochemistry, Faculty of Medicine in Rangueil, University Paul Sabatier, Toulouse, France.
Free Radic Biol Med. 1992;12(2):101-6. doi: 10.1016/0891-5849(92)90002-x.
Low-density lipoproteins oxidized by ultraviolet radiations constitute a useful model system for studying their cytotoxic effect on cultured cells. Polyphenolic flavonoids were able to inhibit the peroxidation of low-density lipoproteins (IC50; 10-20 microM for quercetin or rutin) and their subsequent cytotoxicity. The inhibition of the cytotoxic effect was well correlated with that of TBARS formation. Our most important and novel conclusion is that quercetin and rutin are able to prevent directly at the cellular level the cytotoxic effect of oxidized LDL, since cells preincubated with polyphenolic flavonoids were protected against the cytotoxic effect of previously oxidized low-density lipoprotein (IC50; 0.1 and 3 microM with quercetin and rutin, respectively). In contrast, flavone was completely inefficient. In conclusion polyphenolic flavonoids can protect cells against the injury due to oxidation of low-density lipoproteins by constituting two lines of defence: (1) at high concentrations, antioxidant effect inhibiting the lipoprotein oxidation and the subsequent cytotoxicity; (2) at low concentrations, direct protection of cells against the cytotoxic effect of oxidized low-density lipoproteins.
经紫外线辐射氧化的低密度脂蛋白构成了一个用于研究其对培养细胞细胞毒性作用的有用模型系统。多酚类黄酮能够抑制低密度脂蛋白的过氧化作用（半数抑制浓度；槲皮素或芦丁为10 - 20微摩尔）及其随后的细胞毒性。细胞毒性作用的抑制与硫代巴比妥酸反应物（TBARS）形成的抑制密切相关。我们最重要且新颖的结论是，槲皮素和芦丁能够在细胞水平直接预防氧化型低密度脂蛋白的细胞毒性作用，因为预先用多酚类黄酮孵育的细胞对先前氧化的低密度脂蛋白的细胞毒性作用具有保护作用（槲皮素和芦丁的半数抑制浓度分别为0.1和3微摩尔）。相比之下，黄酮则完全无效。总之，多酚类黄酮可以通过构建两道防线来保护细胞免受因低密度脂蛋白氧化而导致的损伤：（1）在高浓度时，具有抗氧化作用，抑制脂蛋白氧化及随后的细胞毒性；（2）在低浓度时，直接保护细胞免受氧化型低密度脂蛋白的细胞毒性作用。
