Boranophosphate Isoster Controls P2Y-Receptor Subtype Selectivity and Metabolic Stability of Dinucleoside Polyphosphate Analogues

Dinucleoside polyphosphates, NpnN', exert their physiological effects via P2 receptors (P2Rs). NpnN' are attractive drug candidates as they offer better stability and specificity compared to nucleotides, the most common P2R ligands. To further improve the agonist properties of NpnN', we synthesized novel isosters of dinucleoside polyphosphates where N and N' are A or U and where the P alpha or P beta phosphate groups are replaced by boranophosphate, denoted as Np-n(alpha-B)N' or Np-n(beta-B)N' (n = 3, 4), respectively. The potency of Np-n(alpha/beta-B)N'. analogues was evaluated at tP2Y(1), hP2Y(2), hP2Y(4), and rP2Y(6) receptors. The most potent P2Y(1)R and P2Y(6)R agonists were the Up(4)(beta-B)A (A isomer, EC50 of 0.5 mu M vs 0.004 mu M for 2-SMe-ADP) and Up(3)(alpha-B)U (B isomer, EC50 of 0.3 mu M vs 0.2 mu M for UDP), respectively. The receptor subtype selectivity is controlled by the position of the borano moiety on the NpnN' polyphosphate chain and the type of the nucleobase. In addition, Np-n(alpha/beta-B)N' proved similar to 22-fold more resistant to hydrolysis by e-NPP1, as compared to the corresponding NpnN' analogues. In summary, Up(4)(beta-B)A and Up(3)(alpha-B)U are potent, stable, and highly selective P2Y(1) and P2Y(6) receptor agonists, respectively.