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

Abstract

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 2A adenosine 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 2A AR subtype, significantly increased the number of viable PC12 cells after their exposure to METH and, 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 2A AR antagonist, ZM241385, and appeared to be completely counteracted by the AR agonist, NECA, supporting A 2A ARs 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 2A AR antagonist has a neuroprotective effect independently by the specific cell model. Altogether these results demonstrate that the A 2A AR blockade mediates cell protection against neurotoxicity induced by dopaminergic neurotoxins in dopamine containing cells, supporting the potential use of A 2A AR antagonists in dopaminergic degenerative diseases including Parkinson's disease.

The 1,2,4-Triazolo[4,3-a]pyrazin-3-one as a Versatile Scaffold for the Design of Potent Adenosine Human Receptor Antagonists. Structural Investigations to Target the A2A Receptor Subtype

“…All pharmacological data are presented in Tables and . The selected derivative 12 was also profiled for its protective effect against MPP + neurotoxicity in cultured human neuroblastoma SH-SY5Y cell lines, a widely used cellular PD model. , The results of these experiments are reported in Figures –.…”

“…To verify that the protective effect of 12 was due to the selective blockade of the A 2A AR, we compared the effects of the compound with those of the well-known selective hA 2A AR antagonist 4-(2-[7-amino-2-(2-furyl­[1,2,4]-triazolo­[2,3- a ]­[1,3,5]­triazin-5ylamino]­ethyl)­phenol 72 (ZM241385) and we evaluated the effects of 12 in the presence of the selective hA 2A AR agonist 2-[ p -(2-carboxyethyl)­phenethylamino]-5′- N -ethylcarboxamido adenosine 73 (CGS21680) . As shown in Figure A, the hA 2A AR antagonist 72 , used at the concentration of 0.5 nM, presented a neuroprotective effect on SH-SY5Y cells, thus counteracting MPP + toxicity. To validate the involvement of the A 2A AR in the neuroprotective activity of 12 against MPP + toxicity, we evaluated the ability of the hA 2A AR agonist 73 to reverse the effects of compound 12 .…”