Bi-aryl analogues of salicylic acids: Design, synthesis and SAR study to ameliorate endoplasmic reticulum stress

Abstract

Ye Eun Kim,1,* Dong Hwan Kim,1,* Ami Choi,1,* Seoul Jang,1 Kwiwan Jeong,2 Young-mi Kim,1 Tae-gyu Nam1 1Department of Pharmacy and Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Gyeonggi-do, 15588, Republic of Korea; 2Gyeonggi Bio-Center, Gyeonggido Business & Science Accelerater, Suwon, Gyeonggi-do, 16229, Republic of Korea*These authors contributed equally to this workCorrespondence: Young-mi Kim; Tae-gyu Nam Tel +82-31-400-5815; +82-31-400-5807Fax +82-31-400-5958Email ymikim12@hanyang.ac.kr ; tnam@hanyang.ac.krIntroduction: Endoplasmic reticulum (ER) stress condition is characterized as the accumulation of misfolded or unfolded proteins in lumen of ER. This condition has been implicated in various diseases and pathologies including β-cell apoptosis, Alzheimer’s disease and atherosclerosis. We have reported that hydroxynaphthoic acids (HNA), naphthalene analogues of salicylic acid (SA), reduced ER stress. In this study, we explored structural modification to bi-aryl analogues of SA.Methods: Palladium-catalyzed cross-coupling was applied to synthesize bi-aryl analogues of SA. Anti-ER stress activity was monitored by using our cell-based assay system where ER stress is induced by tunicamycin. To monitor ER stress markers, ER stress was induced physiologically relevant palmitate system.Results: Many analogues decreased ER stress signal induced by tunicamycin. Compounds creating dihedral angle between Ar group and SA moiety generally increased the activity but gave some cytotoxicity to indicate the crucial role of flat conformation of aromatic region. The best compound (16e) showed up to almost 6-fold and 90-fold better activity than 3-HNA and tauro-ursodeoxycholic acid, positive controls, respectively. ER stress markers such as p-PERK and p-JNK were accordingly decreased in Western blotting upon treatment of 16e under palmitate-induced condition.Conclusion: Anti-ER stress activity and toxicity profile of bi-aryl analogues of SA could provide a novel platform for potential therapy for protein misfolding diseases.Keywords: endoplasmic reticulum stress, aryl-substituted salicylate, protein misfolding, biaryl group