- Synthesis and biological evaluation of new imidazole, pyrimidine, and purine derivatives and analogs as inhibitors of xanthine oxidase
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Several derivatives of 4,5-disubstituted imidazole, 2,4,5-trisubstituted pyrimidine, 2-substituted purine, thiazolo[3,2-a]purine, [1,3]thiazino[3,2- a]purine, thiazolo[2,3-i]purine, [1,3]thiazino-[2,3-i]purine, and 6- substituted pyrazolo[3,4-d]pyrimidine were synthesized and tested as inhibitors of the xanthine oxidase enzyme. Of those, some 4-(acylamino)-5- carbamoylimidazoles and 2-thioalkyl-substituted purines exhibited very good inhibitory activity, being at least 500 times more effective than allopurinol. The ineffectiveness of 6-n-alkylpyrazolo[3,4-d]pyrimidines is imputable to the alkyl chain which could hinder the coordination with molybdenum according to the known mechanism for the binding of the inhibitor allopurinol; the effectiveness of imidazole derivatives, by contrast with the ineffectiveness of 4,5-diamino-2-(thioalkyl)-6-hydroxypyrimidines, indicates the relative importance of the five-membered ring in the interaction with the enzyme. Moreover, the marked effectiveness of the angularly-cyclized [1,3]thiazino[2,3-i]purinones, which constitute an interesting new class of inhibitors, together with the weak activity of linearly-cyclized derivatives, allowed us to characterize more precisely the lipophilic region of the enzyme facing the N(1)-C(2) positions of the substrate hypoxanthine.
- Biagi, Giuliana,Costantini, Alberto,Costantino, Luca,Giorgi, Irene,Livi, Oreste,Pecorari, Piergiorgio,Rinaldi, Marcella,Scartoni, Valerio
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p. 2529 - 2535
(2007/10/03)
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