Inhibition photosensitized oxidation

The first demonstration that /3-carotene could inhibit photosensitized oxidation and was, therefore, an efficient quencher of O was reported by Foote and Denny (1968). Wilkinson and Ho (1978) showed that quenching by electron exchange energy transfer to produce the carotenoid triplet state ( CAR) is the principal mechanism of carotenoid photoprotection against O ... 

Figure 3.7. Inhibition of photosensitized oxidation by earotene and toeopherol.

The inhibition of photosensitized oxidation by j8-carotene is complicated because it is highly susceptible to autoxidation and is quickly destroyed in the presence of free radicals or hydroperoxides. To be effective in unsaturated... 

Table 3.4. Inhibition of photosensitized oxidation of methyl linoleate by different carotenoids ...

Quercetin and rutin suppressed photosensitized hemolysis of human erythrocytes with ho values equal to 40 p.mol l-1 and 150 jjlmt>I I 1, respectively [139]. Suppression of photohemolysis was accompanied by inhibition of lipid peroxidation. Morin inhibited oxygen radical-mediated damage induced by superoxide or peroxyl radicals to the human cells in the cardiovascular system, erythrocytes, ventricular myocytes, and saphenous vein endothelial cells [140]. Rutin protected against hemoglobin oxidation inside erythrocytes stimulated by prooxidant primaquine [141],... 

Sortino et al. reported the use of light irradiation on SAMs supporting the anticancer drug flutamide to study its photoreactivity and product release of nitric oxide. The authors were able to conduct studies in the absence of noxious side effects such as singlet-oxygen photosensitization and observed that nitric oxide production halted when the light was turned off [103], Another photoactive molecule, azobenzene, has recently been exploited in the SAM community to aid in studies on cell adhesion and enzyme inhibition [104], Pearson and coworkers described the use of photoisomerizable SAMs of azobenzene to conduct a series of serine and cysteine protease inhibition experiments. When light of 340-380 nm is used, the... 

On the other hand, inhibiting effect of nitroxylic radical at irradiation is not observed owing to its strong action as photosensitizer. Photosensitization is absent after irradiation in dark reaction and nitroxylic radical displays its inhibiting action. That is why oxidation after irradiation (post-effect) is not observed (Figure 2.7, curve 2). 

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