Structure-activity relationships of pyrimidine nucleotides containing a 5′-α,β-methylene diphosphonate at the P2Y6 receptor

The Gq-coupled P2Y6 receptor (P2Y6R) is a component of the purinergic signaling system and functions in inflammatory, cardiovascular and metabolic processes. UDP, the native P2Y6R agonist and P2Y14R partial agonist, is subject to hydrolysis by ectonucleotidases. Therefore, we have synthesized UDP/CDP analogues containing a stabilizing alpha,beta-methylene bridge as P2Y6R agonists and identified compatible affinity-enhancing pyrimidine modifications. A distal binding region on the receptor was explored with 4-benzyloxyimino cytidine 5 '-diphosphate analogues and their potency determined in a calcium mobilization assay. A 4-trifluoromethyl-benzyloxyimino substituent in 25 provided the highest human P2Y6R potency (MRS4554, 0.57 mu M), and a 5-fluoro substitution of the cytosine ring in 28 similarly enhanced potency, with >175- and 39-fold selectivity over human P2Y14R, respectively. However, 3-alkyl (31-33, 37, 38), beta-D-arabinofuranose (39) and 6-aza (40) substitution prevented P2Y6R activation. Thus, we have identified new alpha,beta-methylene bridged N4-extended CDP analogues as P2Y6R agonists that are highly selective over the P2Y14R.

Automated summary

By synthesizing UDP/CDP analogues with a stabilizing alpha,beta-methylene bridge as P2Y6R agonists, researchers identified pyrimidine modifications that enhance affinity. Among the compounds tested, those with a 4-trifluoromethyl-benzyloxyimino substituent showed the highest human P2Y6R potency, while a 5-fluoro substitution in the cytosine ring increased potency and selectivity over P2Y14R. The study also found certain substitutions prevented P2Y6R activation, leading to the identification of new alpha,beta-methylene bridged N4-extended CDP analogues as highly selective P2Y6R agonists.