title: Xanthine oxidase (XO): relative configuration of complexes formed by the enzyme, 2- or 8-n-alkyl-hypoxanthines and 2-n-alkyl-8-azahypoxanthines. XII.
abstract: Several 2- or 8-n-alkyl-hypoxanthines and a 2,8-di-n-pentyl-hypoxanthine were synthesized and tested as substrates or inhibitors of Xanthine Oxidase (XO). 8-Alkyl derivatives showed a substrate behaviour, whereas 2-alkyl substituted compounds were non-substrates and inhibitors. 2,8-di-n-pentyl-hypoxanthine was ineffective as inhibitor. The comparison between their activity allowed us to conclude that the complexes formed by the enzyme and the cited n-alkylhypoxanthines or 2-n-alkyl-8-azahypoxanthines involve their N(3) and N(9) positions in all the cases. The position of the n-alkyl chain determines the disposition of the molecule inside the complex: 2-n-alkyl-hypoxanthines and 2-n-alkyl-8-azahypoxanthines gave complexes with the same orientation of heterocyclic moieties, opposite that given by 8-n-alkyl-hypoxanthines.
authors.affiliation: Istituto di Chimica Farmaceutica e Tossicologica, Facoltà di Farmacia, Pisa.
authors.forename: G
authors.initials: G
authors.lastname: Biagi
authors.forename: I
authors.initials: I
authors.lastname: Giorgi
authors.forename: O
authors.initials: O
authors.lastname: Livi
authors.forename: V
authors.initials: V
authors.lastname: Scartoni
authors.forename: I
authors.initials: I
authors.lastname: Tonetti
authors.forename: A
authors.initials: A
authors.lastname: Lucacchini
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D007042:Hypoxanthines / Q000138:chemical synthesis* / Q000494:pharmacology; D007700:Kinetics; D008892:Milk / Q000201:enzymology; D008968:Molecular Conformation; D010944:Plants / Q000201:enzymology; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism
chemical_list: D007042:Hypoxanthines; D014969:Xanthine Oxidase