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Azoloazines possess a wide spectrum of biological activity. For the analysis of new drugs of the azoloazine series, reliable methods of identification and quantitative analysis are necessary. Mass spectrometry is one of the main methods for the analysis of drugs and their metabolites in a biological matrix. Information about the main fragmentation pathways of these substances favors their reliable identification. In this study, fragmentation pathways of the protonated molecule of triazavirin, which is an antiviral agent from the azoloazine series, are studied. The experiments are carried out using high resolution tandem mass spectrometry with an electrospray ionization source. The directions of fragmentation of the compound in the collision cell are confirmed by pseudo-MS.sup.3 experiments, which are possible due to dissociation in the ion source, and by comparative data analysis of triazavirin analogs labeled with stable isotopes. It is found that, during dissociation in the ion source, two types of ions associated with the loss of the nitro group are formed, in contrast to fragmentation in the collision cell. The formation of basic product ions occurs due to the loss of substituents in the heterocyclic structure with the release of neutral molecules or radicals, and also as a result of reactions affecting the integrity of the triazolotriazine heterocyclic system. The information presented in this work may be also useful in the study of structurally similar compounds., Author(s): T. V. Klimova [sup.1] , V. A. Shevyrin [sup.1] , A. V. Ivanova [sup.1] , A. N. Kozitsina [sup.1] , S. L. Deev [sup.1] , V. L. Rusinov [sup.1] [...]

Nucleoside reverse transcriptase inhibitors (NRTI) require intracellular phosphorylation, which involves multiple enzymatic steps to inhibit the human immunodeficiency virus type 1 (HIV-1). NRTI-triphosphates (NRTITP) compete with endogenous 2'-deoxyribonucleosides5'-triphosphates (dNTP) for incorporation by the HIV-1 reverse transcriptase (RT). Thus, a highly sensitive analyrical methodology capable of quantifying at the low femtomoles/[10.sup.6] cells level was necessary to understand the intracellular metabolism and antiviral activity of NRTIs in human peripheral blood mononuclear (PBM) cells and in macrophages. A novel, rapid, and a reproducible ion-pair chromatography-tandem mass spectrometry (MS/MS) method was developed to simultaneously quantify the intracellular phosphorylated metabolites of abacavir, emtricitabine, tenofovir disoproxil fumarate, amdoxovir, and zidovudine, as well as four natural endogenous dNTP. Positive or negative electrospray ionization was chosen with specific MS/ MS transitions for improved selectivity on all the compounds studied. The sample preparation, the ion-pair reagent concentration, and buffer composition were optimized, resulting in the simultaneous quantification of 13 different nucleotides in a total run time of 30 min. This novel method demonstrated optimal sensitivity (limit of detection 1-10 nM for various analytes), specificity, and reproducibility to successfully measure NRTI-TP and dNTP in human PBM cells and macrophages. 10.1021/ac902737j

A high-flux screen of 2,000 compounds obtained from a chemical library resulted in the identification of alpha-anilinophenylacetamide(alpha-APA) derivatives as potent inhibitors of human immunodeficiency virus type 1 (HIV-1) replication. These inhibitors apparently target the viral reverse transcriptase and are effective at nanomolar concentrations. One of thederivatives, R 89439, has good oral availability, favorable pharmacokinetics and can be easily synthesized.