6-Bromo-8-(4-[3H]methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic Acid: A Powerful Tool for Studying Orphan G Protein-Coupled Receptor GPR35

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• 作者：Dominik Thimm ; Mario Funke ; Anne Meyer ; Christa E. M眉ller
• 刊名：Journal of Medicinal Chemistry
• 出版年：2013
• 出版时间：September 12, 2013
• 年：2013
• 卷：56
• 期：17
• 页码：7084-7099
• 全文大小：573K
• 年卷期：v.56,no.17(September 12, 2013)
• ISSN：1520-4804

文摘

The potent and selective GPR35 agonist 6-bromo-8-(4-methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic acid (12) was obtained in tritium-labeled form, designated [³H]PSB-13253, with a specific activity of 36 Ci (1.33 TBq)/mmol. Radiolabeling was achieved by methylation of ethyl 6-bromo-8-(4-((tert-butyldimethylsilyl)oxy)benzamido)-4-oxo-4H-chromene-2-carboxylate (19) with [³H]methyl tosylate followed by ester hydrolysis. The radioligand was characterized by kinetic, saturation, and competition assays at membrane preparations of Chinese hamster ovary cells recombinantly expressing the human GPR35. [³H]12 labeled the receptor with high affinity (K_D = 5.27 nM). Binding was saturable (B_max = 12.6 pmol/mg of protein) and reversible. Affinities of selected standard ligands and a library of amidochromen-4-one-2-carboxylates were determined. Binding data mostly correlated with potencies determined in 尾-arrestin assays. On the basis of the test results, several new fluorine-substituted 6-bromo-8-benzamidochromen-4-one-2-carboxylic acids were obtained, which represent the most potent GPR35 agonists known to date. 6-Bromo-8-(2,6-difluoro-4-methoxybenzamido)-4-oxo-4H-chromene-2-carboxylic acid (83; K_i = 0.589 nM, EC₅₀ = 5.54 nM) showed the highest affinity with a K_i value in the subnanomolar range.