13171-43-2Relevant academic research and scientific papers
Reactive nitrogen oxygen species metabolize N-acetylbenzidine
Lakshmi,Fong Fu Hsu,Davis,Zenser
, p. 312 - 318 (2001)
A close association has been reported for certain types of cancers influenced by aromatic amines and infection/inflammation. Reactive nitric oxygen species (RNOS), components of the inflammatory response, are bactericidal and tumoricidal, and contribute to the deleterious effects attributed to inflammation on normal tissues. This study assessed the possible transformation of the aromatic amine N-acetylbenzidine (ABZ) by RBOS. RNOS were generated by various conditions to react with ABZ, and samples were evaluated by HPLC. Conditions which generate nitrogen dioxide radical (NO2- + myeloperoxidase + H2O2, ONOO-, and NO2- + HOCI) produced primarily a single new product termed 3′-nitro-ABZ. The myeloperoxidase-catalyzed reaction with 0.3 mM NO2- was completely inhibited by 1 mM cyanide, and not effected by 100 mM chloride with or without 1 mM taurine. In contrast, conditions which generate N2O3, such as spermine NONOate, did not produce 3′-nitro-ABZ, but rather two compounds termed 4′-OH-AABP and AABP. 1H NMR and mass spectrometry identified 3′-nitro-ABZ as 3′-nitro-N-acetylbenzidine, 4′-OH-AABP as 4′-OH-4-acetylaminobiphenyl, and AABP as 4-acetylaminobiphenyl. Human polymorphonuclear neutrophils incubated with [3H]-ABZ and stimulated with β-phorbol 12-myristate 13-acetate produced 3′-nitro-ABZ in the presence of NO2- (0.1-1 mM). Neutrophil 3′-nitro-ABZ formation was verified by mass spectrometry and was consistent with myeloperoxidase oxidation of NO2-. The results demonstrate that ABZ forms unique products in the presence of nitrosating and nitrating RNOS, which could influence the carcinogenic process and serve as biomarkers for these reactive species.
Catalysis of the Photo-Fries Reaction: Antibody-Mediated Stabilization of High Energy States
Dickerson, Tobin J.,Tremblay, Martin R.,Hoffman, Timothy Z.,Ruiz, Diana I.,Janda, Kim D.
, p. 15395 - 15401 (2007/10/03)
A conformationally constrained hapten is presented that is capable of catalyzing the first antibody-mediated photo-Fries rearrangement. In this reaction, absorption of light energy by a diphenyl ether substrate results in homolytic C-O bond cleavage followed by recombination to yield biphenyl-derived products. The most proficient antibody studied converts 4-phenoxyaniline 15 into 2-hydroxy-5-aminobiphenyl 16 under high-intensity irradiation at a rate of 8.6 μM/min. These results support a recent hypothesis stating that immunization with conformationally constrained haptens provides higher titers for the acquisition of simple binding antibodies; however, in this case, conformational constraint does not ensure the development of more efficient catalysts. Using the obtained antibodies, the presence of products resulting from escape of free radicals from the solvent cage can be suppressed, altering the excited state energy surface such that free radicals are funneled into the formation of the desired biphenyl product. However, studies also show the inactivation of the antibodies as a result of photodecay of the biphenyl product. Using an isocyanate scavenging resin, the photodecay product could be removed and the inactivation of the antibody drastically reduced. Furthermore, despite the observed photodecay, turnover of the antibody was present; this represents the first case in which true turnover of a photochemical reaction using a catalytic antibody could be observed.
