Biochemistry Division, Department of Chemistry, Faculty of Arts and Sciences, Aksaray University, 68100 Aksaray, Turkey.
Appl Biochem Biotechnol. 2012 Nov;168(6):1540-8. doi: 10.1007/s12010-012-9876-4. Epub 2012 Sep 13.
Human serum paraoxonase 1 (PON1; EC 3.1.8.1) is a high-density lipoprotein associated, calcium-dependent enzyme that hydrolyses aromatic esters, organophosphates and lactones and can protect the low-density lipoprotein against oxidation. In this study, in vitro inhibition effect of some dihydroxy coumarin compounds namely 6,7-dihydroxy-3-(2-methylphenyl)-2H-chromen-2-one (A), 6,7-dihydroxy-3-(3-methylphenyl)-2H-chromen-2-one (B) and 6,7-dihydroxy-3-(4-methylphenyl)-2H-chromen-2-one (C) on purified PON1 were investigated by using paraoxon as a substrate. PON1 was purified using two-step procedures, namely ammonium sulphate precipitation and Sepharose-4B-L-tyrosine-1-naphthylamine hydrophobic interaction chromatography. The purified enzyme had a specific activity of 11.76 U/mg. The dihydroxy coumarin derivatives of A and B compounds inhibited PON1 enzyme activity in a noncompetitive inhibition manner with K(i) of 0.0080±0.256 and 0.0003±0.018 mM values, respectively. C compound exerted an uncompetitive inhibition of PON1 enzyme activity with K(i) of 0.0010±0.173 mM. Moreover, dihydroxy coumarin derivatives of A, B and C compounds were effective inhibitors on purified human serum PON1 activity with IC(50) of 0.012, 0.022 and 0.003 mM values, respectively. IC(50) value of unsubstituted 6,7 dihydroxy coumarin was found as 0.178 mM. The present study has demonstrated that PON1 activity is very highly sensitive to studied coumarin derivatives.
人血清对氧磷酶 1（PON1；EC 3.1.8.1）是一种与高密度脂蛋白相关的、依赖钙的酶，可水解芳香酯、有机磷酸酯和内酯，并能保护低密度脂蛋白免受氧化。在这项研究中，使用对氧磷作为底物，研究了一些二羟基香豆素化合物，即 6,7-二羟基-3-(2-甲基苯基)-2H-色烯-2-酮（A）、6,7-二羟基-3-(3-甲基苯基)-2H-色烯-2-酮（B）和 6,7-二羟基-3-(4-甲基苯基)-2H-色烯-2-酮（C）对纯化的 PON1 的体外抑制作用。使用两步程序，即硫酸铵沉淀和 Sepharose-4B-L-酪氨酸-1-萘胺疏水性相互作用色谱法纯化 PON1。纯化的酶具有 11.76 U/mg 的比活性。二羟基香豆素衍生物 A 和 B 化合物以非竞争性抑制方式抑制 PON1 酶活性，K(i)值分别为 0.0080±0.256 和 0.0003±0.018 mM。C 化合物对 PON1 酶活性表现出竞争性抑制，K(i)值为 0.0010±0.173 mM。此外，二羟基香豆素衍生物 A、B 和 C 化合物对纯化的人血清 PON1 活性均具有抑制作用，IC(50)值分别为 0.012、0.022 和 0.003 mM。未取代的 6,7-二羟基香豆素的 IC(50)值为 0.178 mM。本研究表明，PON1 活性对所研究的香豆素衍生物非常敏感。
