Boranophosphate isoster controls P2Y-receptor subtype selectivity and metabolic stability of dinucleoside polyphosphate analogues

Dinucleoside polyphosphates, Np _nN′, exert their physiological effects via P2 receptors (P2Rs). Np _nN′ 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 Np _nN′, we synthesized novel isosters of dinucleoside polyphosphates where N and N′ are A or U and where the Pα or Pβ phosphate groups are replaced by boranophosphate, denoted as Np _n(α-B)N′ or Np _n(β-B)N′ (n = 3, 4), respectively. The potency of Np _n(α/β-B)N′ analogues was evaluated at tP2Y ₁, hP2Y ₂, hP2Y ₄, and rP2Y ₆ receptors. The most potent P2Y ₁R and P2Y ₆R agonists were the Up ₄(β-B)A (A isomer, EC ₅₀ of 0.5 μM vs 0.004 μM for 2-SMe-ADP) and Up ₃(α-B)U (B isomer, EC ₅₀ of 0.3 μM vs 0.2 μM for UDP), respectively. The receptor subtype selectivity is controlled by the position of the borano moiety on the Np _nN′ polyphosphate chain and the type of the nucleobase. In addition, Np _n(α/β-B) N′ proved ∼22-fold more resistant to hydrolysis by e-NPP1, as compared to the corresponding Np _nN′ analogues. In summary, Up ₄(β-B)A and Up ₃(α-B)U are potent, stable, and highly selective P2Y ₁ and P2Y ₆ receptor agonists, respectively.