Correlation between the structure and inhibiting activity of phenosan derivatives

Sterically hindered phenolic antioxidants (AOs) of the IKhFAN family are characterized as inhibitors of initiated oxidation of methyl oleate in homogeneous chlorobenzene solutions and in aqueous emulsions in the presence of dodecyl sulfate. The IKhFANs inhibit oxidation by scavenging peroxo radicals and by decomposing hydroperoxides to yield molecular products. The effect of an IKhFAN is governed by its chemical structure and by oxidation conditions. The IKhFANs slow down methyl oleate oxidation in lipid solution more effectively than comparable concentrations of -tocopherol, dibunol, phenosan K, or phenosan ester. The most effective is IKhFAN-10, in which the R³ radical is the shortest (CH₃). The inhibiting effect of the AOs weakens markedly with increasing chain length of R³. The specific features of the observed oxidation kinetics are explained by the formation of microheterogeneous systems involving AOs. In these systems, the phenolic OH groups are directed to the micelle center and, as a consequence, can hardly react with RO₂^· radicals. In the IKhFAN group in which R³ ranges from C₈H₁₇ to C₁₆H₃₃, the induction period grows in proportion to the number of carbon atoms. In an aqueous emulsion, the overall inhibiting effects of structurally different IKhFANs are similar and weaker than effects in homogeneous solution.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 863–871Original Russian Text Copyright © 2004 by Storozhok, Perevozkina, Nikiforov, Rusina, Burlakov.     

Synthesis and inhibiting activity of functional derivatives of 2,6-di-tert-butylphenol

Conclusions Methods were developed for the synthesis of 2,6-di-tert-butylphenols that are substituted in the 4 position by HOCH₂CH₂CH₂ and XCH₂CH₂ groups, where X = OH, COOH, CONH₂, CONHR, CONR₂, CONHNH₂, and HOCH₂CH₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1174–1177, May, 1976.     

Temperature and concentration dependence of the activity of quinones of presumed inhibiting action

The inhibiting properties of a series of organic compounds with a quinonoid structure have been electrochemically studied. The effect of the area and the structure of the organic molecule on the activity of the quinones has been followed. The compounds studied inhibit mild steel's corrosion in model cooling water and prove to be inhibitors of a cathodic type. The degree of corrosion inhibition is a function of the temperature, the concentration and the nature of the substance. The protective effect of the quinones is explained with their adsorption on the corroding surface. The adsorption itself is facilitated by the presence of π-electron systems and conjugated bonds in the molecules as well as by the increase of the molecule's size. Some differences in the behaviour of the p- and o-compounds studied are observed.     

Cycloadducts of fullerene C60 with trolox and tocopherol diazo derivatives: synthesis and antioxidant activity

The antioxidant activity of new cycloadducts, [2H-chromen-2″-yl]carbonylmethano-fullerenes, obtained from fullerene C₆₀ and diazo ketones was quantitatively studied with initiated cumene oxidation as a model reaction.     

DAPY类化合物抑制野生型HIV-1活性的QSAR研究

应用分子力学、半经验量子化学RM1方法优化了32个抗野生型HIV-1病毒毒株的二芳基嘧啶类(DAPYs)化合物分子结构,从分子构象模型中提取了多种参数并结合疏水性参数与指示性参数建立QSAR多元线性回归方程.回归方程显示:分子体积V的增大会降低其抑制活性,而左苯环与嘧啶环间二面角θ增大可以提高抑制活性.同时指示性参数I表明左苯环CN基团加入可以明显增加抑制活性,嘧啶环上R1位置苯基与硝基的加入可以极大降低抑制活性.     

Study of the electrospray ionization mass spectrometry of the proton pump inhibiting drug Omeprazole

A detailed analysis of the product ion spectrum generated from the protonated molecule under ESI-MS/MS conditions using a triple quadrupole mass spectrometer is reported for the gastrointestinal proton pump inhibitor Omeprazole. Unambiguous molecular composition data of the fragment ions were obtained with the aid of regioselectively 14C-, 34S- and 18O-labeled analogs. Attempts have been made to provide rational pathways for the formation of the fragment ions from four protonated omeprazole species. These results will facilitate the characterization of the complex metabolic fate of Omeprazole in humans, which involves the excretion of at least 50 metabolites.     

A physiological examination of the antioxidant ability of super tocopherol derivatives

Structural Chemistry - A quantum-chemical study on some super tocopherol derivatives and their heavier chalcogen derivatives has been undertaken to evaluate the antioxidant abilities through...     

Alpha-lipoic acid inhibits matrix metalloproteinase-9 expression by inhibiting NF-kappaB transcriptional activity

The migration of vascular smooth muscle cells (VSMCs) into the intima, an important step in injury-induced neointimal hyperplasia, requires the activation of nuclear factor-kappaB (NF-kappaB) and the consequent up-regulation of matrix metalloproteinase-9 (MMP-9). This study was undertaken to test for a possible effect of alpha-lipoic acid (ALA), a potent inhibitor of NF-kappaB, on MMP-9 expression. ALA inhibited high-glucose- and TNF-alpha-stimulated VSMC migrations in vitro. It also inhibited high-glucose- and TNF-alpha-induced increases in MMP-9 expression. The activity of MMP-9-promoter constructs with mutations in the NF-kappaB binding site was not inhibited by ALA, indicating an involvement of the NF-kappaB signaling pathway in the ALA-specific inhibition of MMP-9. These data suggest the possibility that ALA may be useful for the prevention of neointimal hyperplasia after angioplasty, by inhibiting the NF-kappaB/MMP-9 pathway, especially with hyperglycemia.     

Target-triggered inhibiting oxidase-mimicking activity of platinum nanoparticles for ultrasensitive colorimetric detection of silver ion

A facile colorimetric method for sensitive and selective detection of Ag⁺ is successfully developed based on the excellent oxidase-like activity of chitosan-stabilized platinum nanoparticles and the strong metallophilic Pt²⁺-Ag⁺ interactions.     

Target-triggered inhibiting oxidase-mimicking activity of platinum nanoparticles for ultrasensitive colorimetric detection of silver ion

The development of efficient methods for the detection of hazardous and toxic elements is extremely important for environmental security and public health. In this work, we developed a facile colorimetric assaying system for Ag⁺ detection in aqueous solution. Chitosan-stabilized platinum nanoparticles (Ch-PtNPs) were synthesized and severed as an artificial oxidase to catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) and generate color signal. In the presence of Ag⁺, due to the strong metallophilic interactions between Ag⁺ and Pt²⁺ on the surface of Ch-PtNPs, Ag⁺ can weaken the affinity to the substrates and inactivate the catalytic activity of Ch-PtNPs, leading to decreased absorbance signal to varying degrees depending on Ag⁺ amount. Combing the specific binding between Ch-PtNPs and Ag⁺ with signal amplification procedure based on the Ch-PtNPs-catalyzed TMB oxidation, a sensitive, selective, simple, cost-effective, and rapid detection method for Ag⁺ can be realized. Ag⁺ ions in tap and lake waters have been successfully detected. We ensured that the proposed method can be a potential alternative for Ag⁺ determination in environmental samples.     

A catalytic antibody against a tocopherol cyclase inhibitor

The cyclic ammonium cation 5 and its guanidinium analogue 4 are inhibitors of tocopherol cyclase. Monoclonal antibodies were raised against protein conjugates of the haptens 1-3 and screened for catalytic reactions with alkene 8, a short chain analogue of the natural substrate phytyl-hydroquinone 6, and its enol ether analogues 10a,b. Antibody 16E7 raised against hapten 3 was found to catalyze the hydrolysis of Z enol ether 10a to form hemiacetal 12 with an apparent rate acceleration of k(cat)/k(uncat)=1400. Antibody 16E7 also catalyzed the elimination of Kemp's benzisoxazole 59. The absence of cyclization in the reaction of enol ether 10a was attributed to the competition of water molecules for the oxocarbonium cation intermediate within the antibody binding pocket. Hapten and reaction design features contributing to this outcome are discussed. Antibody 16E7 provides the first example of a carboxyl group acting both as an acid in an intrinsically acid-catalyzed process and as a base in an intrinsically base-catalyzed process, as expected from first principles. In contrast to the many examples of general-acid-catalyzed processes known to be catalyzed by catalytic antibodies, the specific-acid-catalyzed cyclization of phytyl-hydroquinone 6 or its analogue 8 still eludes antibody catalysis.     

Study of the stabilization of cis-hexadec-11-enal — The main component of the sex pheromone of the cotton boll worm — By tocopherol

The stabilization of cis-hexadec-11-enal — the main component of the sex pheromone of the boll worm — by additions of tocopherol has been studied by UV spectroscopy. It has been shown that the addition of 2–2.5% of tocopherol considerably increases the stability of the attractant.