title: Oxidative modifications of kynostatin-272, a potent human immunodeficiency virus type 1 protease inhibitor: potential mechanism for altered activity in monocytes/macrophages.
abstract: Previous studies have indicated that human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs) are less active at blocking viral replication in HIV-1 infected peripheral blood monocytes/macrophages (M/M) than in HIV-1-infected T cells. We explored the hypothesis that oxidative modification and/or metabolism of the PIs in M/M might account for this reduced potency. We first tested the susceptibility of several PIs (kynostatin-272 [KNI-272], saquinavir, indinavir, ritonavir, or JE-2147) to oxidation after exposure to hydrogen peroxide (H(2)O(2)): only KNI-272 was highly susceptible to oxidation. Treatment of KNI-272 with low millimolar concentrations of H(2)O(2) resulted in mono-oxidation of the sulfur in the S-methyl cysteine (methioalanine) moiety, as determined by reversed-phase high-performance liquid chromatography and mass spectrometry (RP-HPLC/MS). Higher concentrations of H(2)O(2) led to an additional oxidation of the sulfur in the thioproline moiety of KNI-272. None of the PIs were metabolized or oxidized when added to T cells and cultured for up to 12 days. However, when KNI-272 was added to M/M, the concentration of the original KNI-272 steadily decreased with a corresponding increase in the production of three KNI-272 metabolites as identified by RP-HPLC/MS. The structures of these metabolites were different from those produced by H(2)O(2) treatment. The two major products of M/M metabolism of KNI-272 were identified as isomeric forms of KNI-272 oxidized solely on the thioproline ring. Both metabolites had reduced capacities to inhibit HIV-1 protease activity when tested in a standard HIV-1 protease assay. These studies demonstrate that antiviral compounds can be susceptible to oxidative modification in M/M and that this can affect their antiviral potency.
authors.affiliation: HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. dadavis@helix.nih.gov
authors.forename: David A
authors.initials: DA
authors.lastname: Davis
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Read-Connole
authors.forename: Kara
authors.initials: K
authors.lastname: Pearson
authors.forename: Henry M
authors.initials: HM
authors.lastname: Fales
authors.forename: Fonda M
authors.initials: FM
authors.lastname: Newcomb
authors.forename: Jackob
authors.initials: J
authors.lastname: Moskovitz
authors.forename: Robert
authors.initials: R
authors.lastname: Yarchoan
mesh_terms: D004305:Dose-Response Relationship, Drug; D016333:HIV Protease / Q000187:drug effects / Q000378:metabolism*; D017320:HIV Protease Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D066298:In Vitro Techniques; D008264:Macrophages / Q000378:metabolism*; D009000:Monocytes / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism* / Q000494:pharmacology; D010084:Oxidation-Reduction; D013601:T-Lymphocytes / Q000378:metabolism; D013997:Time Factors
chemical_list: D017320:HIV Protease Inhibitors; D009842:Oligopeptides; D006861:Hydrogen Peroxide; D016333:HIV Protease; C077822:kynostatin 272