Fawzy A A, Vishwanath B S, Franson R C
Department of Biochemistry and Molecular Biophysics, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0614.
Agents Actions. 1988 Dec;25(3-4):394-400. doi: 10.1007/BF01965048.
The interaction of retinoids and flavonoids with phospholipases A2 (PLA2) was studied to assess the mechanism of inhibition. Retinoids, such as retinal, retinol, retinoic acid and retinol acetate, and flavonoids, such as quercetin, rutin, morin and sciadopitysin, inhibit Ca2+-dependent PLA2 activity of human synovial fluid (HSF) in vitro in a dose-dependent fashion; ID20S ranged from 2-8 microM. Retinal inhibited neutral active Ca2+-dependent PLA2S from human platelets, human plasma, human polymorphonuclear leukocytes and Naja mossambica mossambica venom in a dose-dependent manner while quercetin inhibits extracellular PLA2 activities of human plasma, HSF and N. m. mossambica venom in a dose-dependent manner but not PLA2 activity derived from human platelets and polymorphomonuclear leukocytes. Inhibition of PLA2 activity by both flavonoid and retinoids were independent of Ca2+ or Na+. Increasing substrate concentration (9-144 nmols) relieved the inhibition of HSF-PLA2 activity by quercetin indicating probable interaction with the substrate. The inhibition by retinal is independent of substrate concentration suggesting that inhibition by retinal is probably due to direct interaction with the enzyme. both retinal and quercetin quenched the relative fluorescent intensity of N. m. mossambica PLA2 and in a dose-dependent manner in the same concentration range at which they inhibit in vitro PLA2 activity. Retinal and quercetin shift the thermotropic phase transition of distearoylphosphatidylethanolamine (DSPE) liposomes. Both compounds broadened the transition peak, shifted the Tm to lower temperature, and decreased enthalpy significantly. These findings indicate that inhibition of non-pancreatic human PLA2S by retinoids and flavonoids can be mediated by interaction with enzyme and/or substrate.
研究了类视黄醇和黄酮类化合物与磷脂酶A2（PLA2）的相互作用，以评估其抑制机制。类视黄醇，如视黄醛、视黄醇、视黄酸和醋酸视黄醇，以及黄酮类化合物，如槲皮素、芦丁、桑色素和穗花杉双黄酮，在体外以剂量依赖方式抑制人滑液（HSF）的钙依赖性PLA2活性；半数抑制剂量（ID20S）范围为2-8微摩尔。视黄醛以剂量依赖方式抑制来自人血小板、人血浆、人多形核白细胞和莫桑比克射毒眼镜蛇毒液的中性活性钙依赖性PLA2S，而槲皮素以剂量依赖方式抑制人血浆、HSF和莫桑比克射毒眼镜蛇毒液的细胞外PLA2活性，但不抑制来自人血小板和多形核白细胞的PLA2活性。黄酮类化合物和类视黄醇对PLA2活性的抑制均与钙或钠无关。增加底物浓度（9-144纳摩尔）可减轻槲皮素对HSF-PLA2活性的抑制，表明可能与底物相互作用。视黄醛的抑制与底物浓度无关，表明视黄醛的抑制可能是由于与酶的直接相互作用。视黄醛和槲皮素均使莫桑比克射毒眼镜蛇PLA2的相对荧光强度猝灭，且在抑制体外PLA2活性的相同浓度范围内呈剂量依赖方式。视黄醛和槲皮素改变了二硬脂酰磷脂酰乙醇胺（DSPE）脂质体的热致相变。两种化合物均使转变峰变宽，将熔点（Tm）移至较低温度，并显著降低焓。这些发现表明，类视黄醇和黄酮类化合物对非胰腺人PLA2S的抑制可通过与酶和/或底物的相互作用介导。
