Discovery and structural optimization of 1-phenyl-3- （1-phenylethyl）urea derivatives as novel inhibitors of CRAC channel

• Published in: 中国药理学报：英文版 2015 (9), p.1137-1144
• Main Author: Hai-zhen ZHANG Xiao-lan XU Hua-yan CHEN Sher ALI Dan WANG Jun-wei YU Tao XU Fa-jun NAN
• Format: Article
• Language: English
• Subjects: HEK293细胞; Jurkat细胞; 吸电子基团; 抑制剂; 结构优化; 脲衍生物; 苯基; 通道
• ISSN: 1671-4083; 1745-7254

Aim： Ca^2＋-release-activated Ca^2＋ （CRAC） channel, a subfamily of store-operated channels, is formed by calcium release-activated calcium modulator 1 （ORAl1）, and gated by stromal interaction molecule 1 （STIM1）. CRAC channel may be a novel target for the treatment of immune disorders and allergy. The aim of this study was to identify novel small molecule CRAC channel inhibitors. Methods： HEK293 cells stably co-expressing both ORAI1 and STIM1 were used for high-throughput screening. A hit, 1-phenyl-3-（1- phenylethyl）urea, was identified that inhibited CRAC channels by targeting ORAl1. Five series of its derivatives were designed and synthesized, and their primary structure-activity relationships （SARs） were analyzed. All derivatives were assessed for their effects on Ca^2＋ influx through CRAC channels on HEK293 cells, cytotoxicity in Jurkat cells, and IL-2 production in Jurkat cells expressing ORAl 1-SS-eG FP. Results： A total of 19 hits were discovered in libraries containing 32 000 compounds using the high-throughput screening. 1-Phenyl-3- （1-phenylethyl）urea inhibited Ca^2＋ influx with IC50 of 3.25±0.17 pmoVL. SAR study on its derivatives showed that the alkyl substituent on the o-position of the left-side benzylic amine （R1） was essential for Ca^2＋ influx inhibition and that the S-configuration was better than the R-configuration. The derivatives in which the right-side R3 was substituted by an electron-donating group showed more potent inhibitory activity than those that were substituted by electron-withdrawing groups. Furthermore, the free N-H of urea was not necessary to maintain the high potency of Ca2＋ influx inhibition. The N,N＇-disubstituted or N＇-substituted derivatives showed relatively low cytotoxicity but maintained the ability to inhibit IL-2 production. Among them, compound 5b showed an improved inhibition of IL-2 production and low cytotoxicity. Conclusion： 1-Phenyl-3-（1-phenylethyl）urea is a novel CRAC channe chemical scaffold for design and development of CRAC channel inh low cytotoxicity. inhibitor that specifically targets ORAI1. This study provides a new bitors with improved Ca^2＋ influx inhibition, immune inhibition and