Synthesis and biological evaluation of novel laropiprant derivatives as potential anti-allergic agents

DP antagonists are claimed to be useful in the treatment of allergic disorders. Laropiprant is a potent and selective DP antagonist to reduce the allergic disorders, especially niacin-induced flushing. In our study, a series of novel laropiprant derivatives (I-1-I-18) were synthesized and characterized by IR, H-1-NMR, C-13-NMR and HRMS spectrum. The potency of these compounds was evaluated in a murine model of niacin-induced flushing. The results indicated that most compounds exhibited faster-acting effect of suppressing vasodilation than laropiprant. Among them, I-1, I-2, I-3, I-9, I-13, I-15 and I-16 exhibited substantial flushing inhibitory effect. Especially, I-1 and I-2 showed higher potency than laropiprant and would be valuable for further investigation.