Antioxidative Activity of Ferrocenes Bearing 2,6-Di-Tert-Butylphenol Moieties

The antioxidative activity of ferrocenes bearing either 2,6-di-tert-butylphenol or phenyl groups has been compared using DPPH (1,1-diphenyl-2-picrylhydrazyl) test and in the study of the in vitro impact on lipid peroxidation in rat brain homogenate and on some characteristics of rat liver mitochondria. The results of DPPH test at 20°C show that the activity depends strongly upon the presence of phenolic group but is improved by the influence of ferrocenyl fragment. The activity of N-(3,5-di-tert-butyl-4-hydroxyphenyl)iminomethylferrocene (1), for instance, was 88.4%, which was higher than the activity of a known antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) (48.5%), whereas the activity of N-phenyl-iminomethylferrocene 2 was almost negligible −2.9%. The data obtained demonstrate that the compounds with 2,6-di-tert-butylphenol moiety are significantly more active than the corresponding phenyl analogues in the in vitro study of lipid peroxidation in rat brain homogenate. Ferrocene 1 performs a promising behavior as an antioxidant and inhibits the calcium-dependent swelling of mitochondria. These results allow us to propose the potential cytoprotective (neuroprotective) effect of ditopic compounds containing antioxidant 2,6-di-tert-butylphenol group and redox active ferrocene fragment

Mathematical retroreflectors

Retroreflectors are optical devices that reverse the direction of incident beams of light. Here we present a collection of billiard type retroreflectors consisting of four objects; three of them are asymptotically perfect retroreflectors, and the fourth one is a retroreflector which is very close to perfect. Three objects of the collection have recently been discovered and published or submitted for publication. The fourth object - notched angle - is a new one; a proof of its retroreflectivity is given.Comment: 32 pages, 19 figure

Derivatives of 9-phosphorylated acridine as butyrylcholinesterase inhibitors with antioxidant activity and the ability to inhibit β-amyloid self-aggregation: potential therapeutic agents for Alzheimer’s disease

We investigated the inhibitory activities of novel 9-phosphoryl-9,10-dihydroacridines and 9-phosphorylacridines against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carboxylesterase (CES). We also studied the abilities of the new compounds to interfere with the self-aggregation of β-amyloid (Aβ42) in the thioflavin test as well as their antioxidant activities in the ABTS and FRAP assays. We used molecular docking, molecular dynamics simulations, and quantum-chemical calculations to explain experimental results. All new compounds weakly inhibited AChE and off-target CES. Dihydroacridines with aryl substituents in the phosphoryl moiety inhibited BChE; the most active were the dibenzyloxy derivative 1d and its diphenethyl bioisostere 1e (IC50 = 2.90 ± 0.23 µM and 3.22 ± 0.25 µM, respectively). Only one acridine, 2d, an analog of dihydroacridine, 1d, was an effective BChE inhibitor (IC50 = 6.90 ± 0.55 μM), consistent with docking results. Dihydroacridines inhibited Aβ42 self-aggregation; 1d and 1e were the most active (58.9% ± 4.7% and 46.9% ± 4.2%, respectively). All dihydroacridines 1 demonstrated high ABTS•+-scavenging and iron-reducing activities comparable to Trolox, but acridines 2 were almost inactive. Observed features were well explained by quantum-chemical calculations. ADMET parameters calculated for all compounds predicted favorable intestinal absorption, good blood–brain barrier permeability, and low cardiac toxicity. Overall, the best results were obtained for two dihydroacridine derivatives 1d and 1e with dibenzyloxy and diphenethyl substituents in the phosphoryl moiety. These compounds displayed high inhibition of BChE activity and Aβ42 self-aggregation, high antioxidant activity, and favorable predicted ADMET profiles. Therefore, we consider 1d and 1e as lead compounds for further in-depth studies as potential anti-AD preparations

Dimebon Attenuates the Aß-Induced Mitochondrial Permeabilization

The currently available experimental data supports the hypothesis that the neuroprotective effect of dimebon is related to the protection of the brain-mitochondria from neurodegeneration. In this study, the influence of dimebon on mitochondria was investigated to gain a better understanding of the neuroprotective effects of this drug. Here, we demonstrate that dimebon enhances the resistance of the isolated rat brain and liver mitochondria to the induction of mitochondrial permeability transition (MPT) by calcium ions even in the presence of atractyloside, a MPT pore (MPTP) opener, but is ineffective against atractyloside-induced mitochondria swelling. Unlike cyclosporine A (CsA), a MPTP inhibitor, Dimebon does not influence the adenine nucleotide translocase (ANT) conformational changes and is not able to prevent the MPT of de-energized mitochondria. Using three different assays, and using amyloid-ß peptide for inducing mitochondrial toxicity, we show that the influence of dimebon on the calcium retention capacity (CRC) of mitochondria depends on the mode of calcium addition. No obvious influence of dimebon on CRC was observed under the conditions of calcium infusion in the pump mode but the increase of CRC of rat brain mitochondria was observed when calcium was added in the bolus mode; the addition of calcium in the single pulse mode led to the increase of the lag period of calcium efflux from mitochondria. From these studies it is shown that dimebon is effective against amyloid-ß (Aß) potentiated mitochondrial swelling and decrease of calcium retention capacity (CRC) of the brain mitochondria

Ion assisted deposition of titanium chromium nitride

Chromium titanium nitride films with different content of Cr and Ti were deposited on a silicon substrate by ion beam assisted deposition and characterised by Rutherford Backscattering Spectroscopy, X-ray Diffraction, X-ray Photoelectron Spectroscopy (XPS), Cross-sectional Transmission Electron Microscopy and nanoindentation testing. All of the samples except for the pure Cr2N coating have a structure similar to the fcc form of TiN (111). XPS data showed that the films contained a small amount of oxygen. The dependence of hardness on film composition was observed. Maximum hardness at about 30 GPa was for coatings containing 15 at.% Ti and 35 at.% Cr. The high hardness in the ternary compound is thought to be attributed to high energy of dislocation propagation. It has been shown that chromium nitride formed in the absence of atomic nitrogen always grows as Cr2N. The addition of atomic nitrogen using an ion assisting beam promotes growth of CrN. The presence of a relatively low amount of Ti in the Ti–Cr–N film was seen to promote a significant increase in the number of Cr–N bonds. Preferential sputtering of nitrogen from the film during Ar ion cleaning for XPS analysis shows that composition analysis by XPS can be unreliable and should be done with great care