Cyclic Adenosine Diphosphate Ribose Analogues

A compound having formula (1) where at least one of X<3> and X<7> is CR and any remaining X<3> or X<7> is N; Y is halo, C1-C20 hydrocarbon, NR2, OR, SR, nitro or carboxyl; R is H or C1-C20 hydrocarbon and R groups can be the same or different; and one or each Z represents H or one Z is a cageing group. The compound 7-deaza-8-bromo-cyclic adenosine 5'-diphosphate ribose has been shown to be a stable hydrolysis-resistant cADPR antagonist.