title: Potential of pyrazolooxadiazinone derivatives as serine protease inhibitors.
abstract: As a part of an investigation on molecular hybrids as new serine protease inhibitors, the pyrazolo [4,3-c][1,2,5]oxadiazin-3(5H)-one ring system was selected as a model of potential mechanism-based inhibitors. Due to the inherent reactivity of this system an optimal balance between susceptibility to nucleophilic attack and stability in solvents was sought prior to development as therapeutic agents. Substitutions on N5 and C7 of the supporting pyrazole ring with either aliphatic or aromatic groups (compounds 2 a-m) and the replacement of the carbonyl oxygen on the reactive oxadiazinone ring with sulfur (compounds 3a,i) were explored. Two members (2i and 2k) of this class of inhibitors displayed time-dependent inhibition of HLE suggesting mechanism-based inhibition. The observation that HLE generated a product(s) from compound 2i which displayed an identical UV-Visible spectrum to that observed during non-enzymatic hydrolysis further supports this proposal. FlexX-based docking of these compounds into a model of the human leukocyte elastase (HLE) active site produced a molecular model of the inhibitor-enzyme interaction.
authors.affiliation: Dipartimento di Scienze Farmaceutiche, Università di Ferrara, Italy.
authors.forename: C B
authors.initials: CB
authors.lastname: Vicentini
authors.forename: M
authors.initials: M
authors.lastname: Guarneri
authors.forename: V
authors.initials: V
authors.lastname: Andrisano
authors.forename: S
authors.initials: S
authors.lastname: Guccione
authors.forename: T
authors.initials: T
authors.lastname: Langer
authors.forename: R
authors.initials: R
authors.lastname: Marschhofer
authors.forename: R
authors.initials: R
authors.lastname: Chabin
authors.forename: A M
authors.initials: AM
authors.lastname: Edison
authors.forename: X
authors.initials: X
authors.lastname: Huang
authors.forename: W B
authors.initials: WB
authors.lastname: Knight
authors.forename: P
authors.initials: P
authors.lastname: Giori
mesh_terms: D001665:Binding Sites; D056649:Cathepsin G; D002403:Cathepsins / Q000037:antagonists & inhibitors; D002851:Chromatography, High Pressure Liquid; D002918:Chymotrypsin / Q000037:antagonists & inhibitors; D004355:Drug Stability; D006801:Humans; D019272:Leukocyte Elastase / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D012697:Serine Endopeptidases; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D015842:Serine Proteinase Inhibitors; D002403:Cathepsins; D012697:Serine Endopeptidases; D002918:Chymotrypsin; C534094:CTSG protein, human; D056649:Cathepsin G; D019272:Leukocyte Elastase