3-(Fur-2-yl)-10-(2-phenylethyl)-[1,2,4]triazino[4,3-a]benzimidazol-4(10H)- one, a novel adenosine receptor antagonist with A_2A-mediated neuroprotective effects

In this study, compound FTBI (3-(2-furyl)-10-(2-phenylethyl)[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one) was selected from a small library of triazinobenzimidazole derivatives as a potent A_2Aadenosine receptor (AR) antagonist and tested for its neuroprotective effects against two different kinds of dopaminergic neurotoxins, 1-methyl-4-phenylpyridinium (MPP+) and methamphetamine (METH), in rat PC12 and in human neuroblastoma SH-SY5Y cell lines. FTBI, in a concentration range corresponding to its affinity for A_2AAR subtype, significantly increased the number of viable PC12 cells after their exposure to METHand, to a similar extent, to MPP+, as demonstrated in both trypan blue exclusion assay and in cytological staining. These neuroprotective effects were also observed with a classical A_2AAR antagonist, ZM241385, and appeared to be completely counteracted by the AR agonist, NECA, supporting A_2AARs are directly involved in FTBI-mediated effects. Similarly, in human SH-SY5Y cells, FTBI was able to prevent cell toxicity induced by MPP+ and METH, showing that this A_2AAR antagonist has a neuroprotective effect independently by the specific cell model. Altogether these results demonstrate that the A_2AAR blockade mediates cell protection against neurotoxicity induced by dopaminergic neurotoxins in dopamine containing cells, supporting the potential use of A_2AAR antagonists in dopaminergic degenerative diseases including Parkinson's disease.