Trifluoromethylated cyclic-ADP-ribose mimic: synthesis of 8-trifluoromethyl-N1-[(5′′-O-phosphorylethoxy)methyl]-5′-O-phosphorylinosine-5′,5′′-cyclic pyrophosphate (8-CF3-cIDPRE) and its calcium release activity in T cells

A convenient trifluoromethylation method was firstly applied to the synthesis of 8- CF3-purine nucleosides. On the basis of this method, new protection and deprotection strategies were developed for the successful synthesis of the trifluoromethylated cyclic-ADP-ribose mimic, 8-CF3-cIDPRE 1. Using intact, fura-2-loaded Jurkat T cells compound 1 and 2′,3′-O-isopropylidene 8-CF3-cIDPRE 14 were characterized as membrane-permeant cADPR agonists. Contrary to the 8-substituted cADPR analogues that mainly act as antagonists of cADPR in cells, 8-substituted cIDPRE derivatives were shown to be Ca2+ mobilizing agonists. Here we report that even compound 1, the 8-substituted cIDPRE with the strong electron withdrawing CF3 group, behaves as an agonist in T cells. Interestingly, also the partially protected 2′,3′-O-isopropylidene 8-CF3-cIDPRE activated Ca2+ signaling indicating only a minor role for the hydroxyl groups of the southern ribose of cADPR for its biological activity. To our knowledge 8-CF3-cIDPRE 1 is the first reported fluoro substituted cADPR mimic and 8-CF3-cIDPRE 1 and compound 14 are promising molecular probes for elucidating the mode of action of cADPR.