Biomimetic chemical, and spectroscopic evaluations for the radiosensitizing potential of N1- and N2-substituted derivatives of 3-Nitro-1,2,4-Triazole toward hypoxic cells in the radiotherapy: Remarkably different substitution effect

Decomposition of triazole and 3-nitrotriazole upon low-energy electron attachment

Compounds based on nitrotriazole have been studied for their application as potential radiosensitizers for the treatment of tumors and as energetic materials. In the former application, the initial reduction of the compounds may serve as a mechanism which leads to the formation of tumor-active species. In this study, we investigated the fundamental properties of anion formation in isolated 3-nitro-1,2,4-triazole (3NTR) molecules upon attachment of low-energy electrons. The resulting product anions formed were detected via mass spectrometry. Quantum chemical calculations were performed to study the dissociation pathways and to derive the threshold energies. We also studied the attachment of electrons to the native 1H-1,2,4-triazole (TR) molecule, revealing the influence of the nitro group on anion formation. Comparing the results for these two systems, we computationally observed a considerable more stable parent anion for 3NTR, which results in significantly more effective degradation of the molecule at lower electron energies. Although characteristic fragmentation reactions in the presence of the nitro group were observed (like formation of NO2- or the release of an OH radical), the main dissociation channel for the 3NTR anion turned out to be the direct dissociation of a hydrogen radical by a single bond cleavage, which we also observed for TR as the main channel. Thus, the triazole ring shows a pronounced stability against electron attachment-induced cleavage compared, for example, to the imidazole ring, which is found in common nitroimidazolic radiosensitizers.

[Development of new reactions and their pharmaceutical application based on the molecular structure characteristics]

The author and his group have been developing new reactions based on molecular structure characteristics; sigma-symmetric bifunctional molecules, dipole-dipole repulsion, active amide structures, latent active species, orbital-orbital interactions, nonbonded interactions, strained structures, allenic structures, etc. Various new reactions such as asymmetric aminolyses and Dieckmann-type cyclizations of prochiral sigma-symmetric dicarboxylic diamides, asymmetric aldol-type reactions onto gamma-hydroxybutenolides and asymmetric imine alkylations onto omega-acetoxy lactams using chiral Sn(II) enolates, asymmetric Pummerer-type reactions, cascade reactions and endo-mode cyclizations exploiting alpha,beta-unsaturated allenic esters and ketones, base- and palladium-promoted ring-expansion reactions, and syntheses of alpha-substituted serines and 1-azabicyclo [1.1.0] butane have been achieved. These new reactions were applied to the synthetic development of new seed and lead compounds (SH-enzyme inhibitors, tumor inhibitors, and antibiotics) with the aim of synthesizing new drugs. Asymmetric syntheses of (+)-Prelog-Djerassi lactonic acid methyl ester, (+)-carbacyclin, ISP-I (myriocin), (+)-conagenin, Geissman-Waiss lactone, biapenem (a new carbapenem antibiotic), thienamycin-like gamma-lactam, and bicyclic alkaloids were also achieved by utilizing these reactions. Evaluation and molecular design of the seed and model compounds for angiotensin II receptor antagonists, tumor inhibitors, and antibiotics have been investigated on the basis of QRSA and/or nonbonded S...X (X=O, N, S, halogens) interaction concepts.