Эффективность применения антиоксидантов группы пространственно затрудненных фенолов при фотодегенерации сетчатки

Renoprotective effect of antioxidants from group sterically hindered phenols (thiophane, dibornol) in white nondescript male rats (n = 55) subjected to influence of light intensity level 6 000 lx during 6 h was demonstrated. Course intragastric administration of thiophane limited of destructive changes in the retina, but didn’t bring to disappearance of lesion focuses. Dibornol prevented progression of local changes in the retina, contributed to decrease destruction of neurosensory cells, pigment epithelium and neurons of internal layer.На 55 белых половозрелых беспородных крысах-самцах, подвергнутых световому воздействию интенсивностью 6 000 лк в течение 6 ч, показан ретинопротекторный эффект антиоксидантов группы пространственно затрудненных фенолов — тиофана и диборнола. Курсовое введение тиофана ограничивает деструктивные изменения в сетчатке, однако не приводит к исчезновению очагов поражения. Диборнол при курсовом введении препятствует развитию очаговых изменений сетчатки, способствует снижению деструкции нейросенсорных клеток, пигментного эпителия и нейронов внутренних слоев

Antiradical Activity of Porphyrins with a Diisobornylphenol Fragment at the Macrocycle Periphery

This article focuses on the antiradical activity of a number of 2,6-diisobornylphenol-porphyrin conjugates with various spacers between the porphyrin and phenolic fragments in the model reaction of ethylbenzene oxidation initiated by azoisobutyric acid dinitrile. The study has shown that the electronic effects of the groups directly related to the 2,6-diisobornylphenol fragment exert the predominant influence both on the reactivity of the phenolic hydroxyl group in interaction with free radicals and on the antiradical activity of the molecule as a whole. The antiradical activity of the molecule is generally less affected by the nature of the substituents in the porphyrin macrocycle, mainly due to a change in the stoichiometric inhibition coefficient in the presence of relatively easily oxidizable groups. It was found that the length of the spacer between the porphyrin and phenolic fragments does not affect the antiradical activity of the conjugate

Isobornyl and Isocamphyl Photostabilizers in Poly(lactic acid)-Based Electrospun Fibers

In this work, electrospun polylactide fibers with new photostabilizing additives, 4-methyl-2,6-diisobornylphenol (DIBP) and N-isocamphylaniline (NICA), have been tested under the influence of UV-C radiation (254 nm). The changes in the polymers’ chemical structure under UV-C radiation were revealed through the increase in absorption in the 3600–3100 cm−1 region in regard to the FTIR spectra. In the samples that were irradiated for 1 h, the stabilizing effect of the photoprotectors became most noticeable as the difference in the content of the hydroxyl groups in stabilized and the pure PLA reached a maximum. The TG–DSC method revealed that the most sensitive indicator of the irradiation effect was the glass transition temperature (Tg), which persisted after 2 h of irradiation when using photostabilizers and their combinations. The PLA/DIBP(1) and PLA/NICA(1) samples showed the best results in protecting PLA from UV-C radiation based on the Tg values; although, the mixture of DIBP and NICA was not as effective. The chemical structure of the photostabilized PLA samples was studied using NMR, GPC, and Py–GC/MS analysis. The electrospun polylactide fibers were mechanically tested and the effects of the electrospun samples on cell viability were studied

Tailoring Photoprotection of Polylactide with New Isobornyl Derivatives of Phenol and Aniline

This article is devoted to the development of new photostabilizers for polylactide (PLA), a polymer that is an environmentally friendly alternative to polymers and is based on fossil raw materials. We have elucidated the role of the reaction center of two potential PLA photoprotectors: N-isobornylaniline and 2-isobornylphenol, in reactions occurring in a polymer matrix under the action of UV-C radiation. PLA samples with the photostabilizers were irradiated under a wavelength of 253.7 nm for 4, 8 and 12 h. The effectiveness of the photostabilizers was evaluated based on FTIR spectrometric data, 1H and 13C NMR, scanning electron microscopy and simultaneous thermal analysis (TG-DSC). Both stabilizers led to the protection of ester bonds between monomer units of PLA. However, 2-isobornylphenol proved to be more effective at a concentration of 0.05 wt.%, while the optimal concentration of N-isobornylaniline was 0.5 wt.% by weight. TG-DSC showed that the addition of N-isobornylaniline led to an increase in PLA resistance to thermal decomposition; the temperature of the onset of weight loss increased by 2.8 °C at 0.05 wt.% and by 8.1 °C at 0.5 wt.% of N-isobornylaniline. The photoprotector 2-isobornylphenol, on the contrary, reduced the thermal stability of PLA