There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Mannich bases in medicinal chemistry and drug design.

To develop a simple, relatively noninvasive small-animal model of reversible regional cerebral ischemia, we tested various methods of inducing infarction in the territory of the right middle cerebral artery (MCA) by extracranial vascular occlusion in rats. In preliminary studies, 60 rats were anesthetized with ketamine and different combinations of vessels were occluded; blood pressure and arterial blood gases were monitored. Neurologic deficit, mortality rate, gross pathology, and in some instances, electroencephalogram and histochemical staining results were evaluated in all surviving rats. The principal procedure consisted of introducing a 4-0 nylon intraluminal suture into the cervical internal carotid artery (ICA) and advancing it intracranially to block blood flow into the MCA; collateral blood flow was reduced by interrupting all branches of the external carotid artery (ECA) and all extracranial branches of the ICA. In some groups of rats, bilateral vertebral or contralateral carotid artery occlusi...

Reversible middle cerebral artery occlusion without craniectomy in rats.

Stable thermo-responsive hydrogel nanofibres have been prepared by electrospinning of commercial poly(N-isopropylacrylamide) (PNIPAM) in the presence of a polyhedral oligomeric silsesquioxane (POSS) possessing eight epoxide groups and of an organic-base catalyst, followed by a heat curing treatment. The nanofibres showed excellent hydrogel characteristics with fast swelling and de-swelling responses triggered by temperature changes. They were also morphologically robust as their physical integrity was preserved upon repeated hydration/dehydration cycles and exposure to solvents.

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Fast responsive and morphologically robust thermo-responsive hydrogel nanofibres from poly(N-isopropylacrylamide) and POSS crosslinker

Organic radicals originating from phenolic compounds have been known for decades. The most well-known of these radical species are the phenoxyl-radical and the galvinoxyl-radical. Those radicals are characterized by the unpaired electron at a formerly phenolic oxygen-atom. In natural systems phenolic radicals are often found as intermediate products or as part of antioxidant and radical-scavenging processes. Tyrosyl-radicals or tocopherol-radicals represent typical examples. More reactive radicals like the hydroxyl-radical come in contact with these compounds and react to harmless water, while the radical is passed to the phenolic compound. Other radical scavengers in biological systems are, e.g., flavonoid molecules like catechin, luteolin and quercetin as well as resveratrol, vanillin or neurotransmitters like dopamine and epinephrine. In organic radical batteries phenoxyl-radicals or galvinoxyl-radicals can play a pivotal role as electroactive material to store electric energy. They are also often investigated for their magnetic properties, or their redox-activity when used in metal-complexes. From the tyrosyl-radical as part of enzymes to galvinoxyl as dopant in organic solar cells phenolic radicals display great versatility in structure and function. This review summarizes the application of phenol-based radicals in biological as well as artificial materials and systems over the last years.

Application of phenolic radicals for antioxidants, as active materials in batteries, magnetic materials and ligands for metal-complexes

Antioxidant activity of terpene-substituted phenols and their aminomethyl derivatives as compared to the activity of standard antioxidants, ionol and trolox, has been studied by spectrophotometry (by the ability to react with the stable radical of 2,2-diphenyl-1-picrylhydrazyl) and coulometry (by the ability to react with a bromine radical).

Antioxidant properties of terpene-substituted phenols

We studied the effects of novel sterically hindered phenol, 4-methyl-2,6-diisobornyl phenol (dibornol) on the rheological properties of the blood in the model of myocardial ischemia/reperfusion. Dibornol (100 mg/kg intraperitoneally for 3 days before and 5 days after ischemia/reperfusion) decreased blood viscosity by 9-25% in comparison with that in sham-operatedanimals by modulating cellular (erythrocyte deformability and aggregation) and plasma (plasma viscosity) rheological parameters. Normalization of blood rheology under the influence of dibornol increased the availability of oxygen to tissues at high shear rates by 9-18% after acute ischemia/reperfusion in rats.

Hemorheologic Effects of Dibornol in a Model of Myocardial Ischemia/Reperfusion

New 2,6-diisobornylphenol derivatives having formyl, hydroxymethyl, and carboxy groups in the para position with respect to the hydroxy group were synthesized. 4-Hydroxy-3,5-diisobornylbenzoic acid was obtained in a moderate yield through intermediate ortho ester and methyl ester.

Synthesis of new 2,6-diisobornyl-4-methylphenol derivatives

The stoichiometric factors of inhibition and the rate constants (k
 7) were measured for the reaction of isobornylphenols with peroxy radicals of ethylbenzene. The values of k
 7 of the compounds under study increase with an increase in the amount of alkyl substituents and OH groups on the aromatic ring. The introduction of the oxygen atom between the o-isobornyl substituent and the aromatic ring decreases k
 7 by a factor of 6.5. The inhibiting action of binary mixtures of sterically hindered phenols with 2-isobornyl-4-methylphenol and 2,6-diisobornyl-4-methylphenol in the initiated oxidation of ethylbenzene is close to additive.

Kinetic parameters of the reaction of isobornylphenols with peroxy radicals

The membrane protective and membrane active properties and the antioxidative activity of new semisynthetic antioxidants—isobornylphenols were studied. The presence of oxidant and cytotoxic properties of the compounds were evaluated considering the degree of hemolysis of erythrocytes, either spontaneous or induced by hydrogen peroxide. All the studied compounds were found to have significant antioxidative activity in certain conditions. But their capacity to protect membrane erythrocytes from oxidative stress substantially depended on the structure and concentration of the compound. The highest membrane protective activity was observed for 2,6-diisobornyl-4-methylphenol, which has isobornyl in both of its ortho-positions. Scanning electron microscopy of blood erythrocyte surface architectonics confirmed the ability of the studied compounds to interact with the cell membrane and to change its structure. A relationship between erythrocyte morphological transformation according to bilayer-couple hypothesis depending on isobornylphenols membrane behavior and the cytotoxic effect of certain compound high concentrations reflected in low membrane protective activity in the model cell system was shown. The data obtained allow us to conclude that the biological activity of isobornylphenols is due to both their antioxidative properties and their ability to interact with the cell membranes.

I. Yu. Chukicheva

Papers

Antioxidant properties of terpene-substituted phenols

Hemorheologic Effects of Dibornol in a Model of Myocardial Ischemia/Reperfusion

Synthesis of new 2,6-diisobornyl-4-methylphenol derivatives

Kinetic parameters of the reaction of isobornylphenols with peroxy radicals

Membrane-protective properties of isobornylphenols-a new class of antioxidants