Kalgutkar A S, Kozak K R, Crews B C, Hochgesang G P, Marnett L J
A. B. Hancock, Jr., Memorial Laboratory for Cancer Research, Departments of Biochemistry and Chemistry, Center in Molecular Toxicology and The Vanderbilt Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
J Med Chem. 1998 Nov 19;41(24):4800-18. doi: 10.1021/jm980303s.
All of the selective COX-2 inhibitors described to date inhibit the isoform by binding tightly but noncovalently at the substrate binding site. Recently, we reported the first account of selective covalent modification of COX-2 by a novel inactivator, 2-acetoxyphenyl hept-2-ynyl sulfide (70) (Science 1998, 280, 1268-1270). Compound 70 selectively inactivates COX-2 by acetylating the same serine residue that aspirin acetylates. This paper describes the extensive structure-activity relationship (SAR) studies on the initial lead compound 2-acetoxyphenyl methyl sulfide (36) that led to the discovery of 70. Extension of the S-alkyl chain in 36 with higher alkyl homologues led to significant increases in inhibitory potency. The heptyl chain in 2-acetoxyphenyl heptyl sulfide (46) was optimum for COX-2 inhibitory potency, and introduction of a triple bond in the heptyl chain (compound 70) led to further increments in potency and selectivity. The alkynyl analogues were more potent and selective COX-2 inhibitors than the corresponding alkyl homologues. Sulfides were more potent and selective COX-2 inhibitors than the corresponding sulfoxides or sulfones or other heteroatom-containing compounds. In addition to inhibiting purified COX-2, 36, 46, and 70 also inhibited COX-2 activity in murine macrophages. Analogue 36 which displayed moderate potency and selectivity against purified human COX-2 was a potent inhibitor of COX-2 activity in the mouse macrophages. Tryptic digestion and peptide mapping of COX-2 reacted with [1-14C-acetyl]-36 indicated that selective COX-2 inhibition by 36 also resulted in the acetylation of Ser516. That COX-2 inhibition by aspirin resulted from the acetylation of Ser516 was confirmed by tryptic digestion and peptide mapping of COX-2 labeled with [1-14C-acetyl]salicyclic acid. The efficacy of the sulfides in inhibiting COX-2 activity in inflammatory cells, our recent results on the selectivity of 70 in attenuating growth of COX-2-expressing colon cancer cells, and its selectivity for inhibition of COX-2 over COX-1 in vivo indicate that this novel class of covalent modifiers may serve as potential therapeutic agents in inflammatory and proliferative disorders.
迄今为止所描述的所有选择性环氧化酶 -2（COX -2）抑制剂都是通过在底物结合位点紧密但非共价地结合来抑制该同工型。最近，我们报道了一种新型失活剂2 - 乙酰氧基苯基庚 -2 - 炔基硫醚（70）对COX -2进行选择性共价修饰的首次报道（《科学》，1998年，第280卷，第1268 - 1270页）。化合物70通过乙酰化与阿司匹林乙酰化相同的丝氨酸残基来选择性地使COX -2失活。本文描述了对初始先导化合物2 - 乙酰氧基苯基甲基硫醚（36）进行的广泛构效关系（SAR）研究，这些研究促成了70的发现。用更高的烷基同系物延长36中的S - 烷基链导致抑制效力显著增加。2 - 乙酰氧基苯基庚基硫醚（46）中的庚基链对COX -2抑制效力而言是最佳的，并且在庚基链中引入三键（化合物70）导致效力和选择性进一步提高。炔基类似物比相应的烷基同系物是更有效的和选择性更高的COX -2抑制剂。硫化物比相应的亚砜、砜或其他含杂原子的化合物是更有效的和选择性更高的COX -2抑制剂。除了抑制纯化的COX -2外，36、46和70还抑制小鼠巨噬细胞中的COX -2活性。对纯化的人COX -2显示出中等效力和选择性的类似物36是小鼠巨噬细胞中COX -2活性的有效抑制剂。用[1 - 14C - 乙酰基] - 36处理后的COX -2的胰蛋白酶消化和肽图谱分析表明，36对COX -2的选择性抑制也导致了Ser516的乙酰化。用[1 - 14C - 乙酰基]水杨酸标记的COX -2的胰蛋白酶消化和肽图谱分析证实了阿司匹林对COX -2的抑制是由Ser516的乙酰化引起的。硫化物在抑制炎症细胞中COX -2活性方面的功效、我们最近关于70在减弱表达COX -2的结肠癌细胞生长方面的选择性的结果以及其在体内对COX -2的抑制相对于COX -1的选择性表明，这类新型共价修饰剂可能作为炎症和增殖性疾病中的潜在治疗药物。
