Interaction of plant polyphenols with lipids and proteins

(1)测量掺入脂质体的量以确定异黄酮的亲脂性。在双链结构中，A环5-位上的羟基和B环4 ′-位上的甲氧基的存在增加了掺入量。通过V79细胞的集落形成试验研究了阿托伐他汀的细胞毒性。细胞毒活性的构效关系反映了掺入量。(2)（+）-儿茶素衍生物的抗菌活性随着烷基链长度的增加而增加。具有三个碳或更多碳链的衍生物对脂质体膜表现出较强的亲和力。链长超过5个碳的衍生物破坏了膜。这些结果表明，（+）-儿茶素衍生物的亲脂性和对脂质体膜的破坏能力参与了其抗菌活性。(3)在H_2O_2和高铁肌红蛋白存在下，通过监测亚油酸胶束中O_2的消耗，研究了酚酸类化合物咖啡酸、对香豆酸和阿魏酸的抗氧化作用。酚酸的主要抗氧化作用归因于铁酰肌红蛋白在pH 7.4下的还原和在pH 3.4下在第二相中胶束内部发生的链反应的抑制。(4)用固体~ 1H NMR和~ 1H NMR研究了儿茶素表没食子儿茶素没食子酸酯（EGCg）与二肉豆蔻酰磷脂酰胆碱（DMPC）模型膜的相互作用<31>。DMPC<31>磷酸基团的^ P化学位移各向异性随着EGCg的加入而降低。DMPC脂质体中[4-^2H]EGCg的^2H NMR谱显示氘核的四极分裂比固相中的小得多。这些观察结果提供了直接的实验证据表明，EGCg分子与脂质双层相互作用。

(1) The amount of incorporated into liposomes was measured to determine lipophilicity of isoflavonoids. The presence of a hydroxyl group at 5-position of the A-ring and a methoxyl group at 4'-position of the B-ring in the isoflavonoid structure increased the amount incorporated. The cytotoxicity of isoflavonoids was investigated by a colony-formation assay with V79 cells. The structure-activity relationship of the cytotoxic activity reflected the amount incorporated.(2) The antibacterial activity of (+)-catechin derivatives increased with elongation of the alkyl chain length. The derivatives with a chain of three carbons or more showed strong affinity for the liposome membrane. The derivatives with chains longer than five carbons destroyed the membrane. These results implied that the lipophilicity and disrupting ability of the (+)-catechin derivatives to the liposome membrane participate in their antibacterial activity.(3) Antioxidant effects of the phenolic acids, caffeic acids, p-coumaric acid, and ferulic acid, were investigated by monitoring O_2 consumption in the linoleic acid micelles in the presence of H_2O_2 and metmyoglobin. The main antioxidant effects of the phenolic acids was ascribed to reduction of ferrylmyoglobin at pH 7.4 and inhibition of the chain reaction occurring inside of the micelles in the second phase at pH 3.4.(4) The interaction of a tea catechin, epigallocatechin gallate (EGCg), with the model membrane of dimyristoylphosphatidylcholine (DMPC) was studied by solid-state ^<31>P and ^2H NMR. The ^<31>P chemical shift anisotropy of the DMPC phosphate group decreased on addition of EGCg. The ^2H NMR spectrum of [4-^2H]EGCg in the DMPC liposomes gave deuterium nuclei with much smaller quadrupole splittings than those in the solid phase. These observations provide direct experimental evidence that the EGCg molecule interacts with the lipid bilayers.