Photoprotective effect

As has been shown above photorotective effects are most expressed in long-chain Ca-AR and C12-AR. However, some technological aspects are determined by low C12-AR solubilization in water, demanded its preliminary dissolution in ethanol that gave additional difficulties for AR addition into different media for electrophoresis. For this reason, in the current paragraph of the study Ce-AR was used, photoprotective effects of wich were compared with Ci-AR, C3-AR and C5-AR. 

Study of the action of AR on . coli precA luxCDABE-Anvp has confirmed it photoprotective effects and has shown features of such activity in live systems. Surprising was the interrelation between preservation of viability of AR-processed bacterial cells in the conditions of a long and intensive UV-irradiation and depression of activity their reparing SOS-systems. It has assumed AR action and the SOS-answer as alternative "passive" and "active" mechanisms for protection of bacterial cells DNA at various intensivity of UV-irradiation. 

Bissett DL, Chatterjee R, Hannon DP (1990) Photoprotective effect of superoxide-scavenging antioxidants against ultraviolet radiation-induced chronic skin damage in the hairless mouse. Photodermatol Photoimmunol Photomed 7 56-62... 

Photoageing at X>300 nm. The good photoprotective effect of polyoctenamer (VEST) grafted with PPA and St-NO has been reported elsewhere13. 

A study on the photoprotective effect of the topical application of 2% vitamin E and 5% vitamin C in humans showed no effect with the application of each substance alone, but an enhanced photo-protective effect after applying vitamins E and C combined, which was attributed to the regeneration of vitamin E by vitamin C.20 This enhanced effect has also been shown with the topical application of a combination of 15% ascorbic acid and 1% a-tocopherol to porcine skin.21 The combined systemic supplementation of vitamins C and E was similarly able to reduce sunburn reactions22 and to increase the minimal erythema dose (MED), a measure for individual photosensitivity, more than supplementation with either vitamin E or vitamin C alone.23,24 An oral supplementation with an anti-oxidative combination of carotenoids (P-carotene and lycopene), vitamin C, vitamin E, selenium, and proanthocyanidins (Seresis , Pharmaton SA, Lugano, Switzerland) also reduced the development and grade of UVB-induced erythema 25... 

Khettab, N., Amory, M.C., Briand, G., Bousquet, B., Combre, A., Forlot, P., and Barey, M. (1988) Photoprotective effect of vitamins A and E on polyamine and oxygenated free radical metabolism in hairless mouse epidermis, Biochemie 70, 1709-1713. 

The photoprotective effect of the foil was demonstrated in studies using the highly photosenstive riboflavine solution. In spite of intense photo exposure, no photodegradation of the aluminum-wrapped riboflavine solution was detectable (35). 

The photoprotective effect of pigments depends on their particle size, which in turn affects their radiation absorption and scattering properties. For example, the optimum particle diameter for titanium dioxide is about 200 nm according to the manufacturer (16). A point that has to be considered in this context is that a loss of the photoprotective properties of the pigments may result from secondary agglomeration. Consequently, pigments are most effective if they are evenly distributed over the surface of the individual photosensitive drug particles in the tablet (Thoma K, Aman W. In preparation) (4). 

Investigations, related to the photoprotection of nifedipine tablets using films containing titanium dioxide and/or tartrazine, revealed that the photoprotective effect of a film could be evaluated by using its concentration of colorant (C) and thickness (L) value. This value is the product of concentration of the colorant C and the film thickness L. Tablets coated with films having the same CL value had the same photodegradation rates. Degradation rates were found to be proportional to the CL value for every colorant system tested (18). 

The photoprotecting effect of opacifiers is based primarily upon their total absorption and/or reflection of incident radiation. Another approach to predict the photostabilizing effect of a film is therefore to determine its opacity. 

Cyclodextrins can form inclusion complexes with some drugs, modifying their physical and chemical properties. Because cyclodextrins are mainly used to increase the solubility of poorly soluble drugs, most investigations in this field focus on photostability of drugs in solution. Here, the positive effect of cyclodextrins on the photostability of colchicine (36), emetine and cephaeline (37) could be shown. However, these results show that the photoprotective effect depends on the particular cyclodextrin used. For some forms of cyclodextrin, an increase of the photodegradation rate can be obtained, as the example of molsidomine shows (13). 

As can be expected from the principle of spectral overlay, all sunblockers exhibit a photoprotective effect (Fig. 22). The remaining content after two hours can... 

Uric acid in very low concentrations, very strongly absorbs UV radiation and for this reason, has been used to protect various FD C colors against fading when they will be probably exposed to direct sunlight (112). Uric acid has been found to enhance the photostability of solutions of colchicine (70) and FD C Blue No. 2 (82,113). Sodium urate, the neutral salt of uric acid, has a photoprotective effect on solutions of metronidazole (68), doxorubicin hydrochloride (77), and physostigmine sulfate (108). In addition to its photon-absorbing property, uric acid has been reported to also possess antioxidant quality (114). 

A quantum chemical study of the mechanism of the cis-trans photochemical isomerization in retinal like protonated Schiff bases uses the model compound 1-imino-2.3-pentadiene23. The lowest excited state is B like but the second A like state is particularly labile photochemically. The photoisomerization of all trans-retinal has been studied in a variety of organic solvents and organized media232 The structure of the isomers involved in the photoisomerization of retinoic acid and photoprotective effects in model physiological solutions have been determined233. picosecond time-resolved absorption study of... 

Normally ferric chloride is a strong oxidative agent for cellulosic textiles (150) however, a photoprotective effect was observed with wood treated with ferric chloride solution similar to those treated with chromic acid. Similar photoprotective effects of ferric chloride were observed with thermomechanical pulp fibers (151). 

Substitution of hydrogen for alkyl residue in heteroatom of carbazole cycle causes high level photoprotective effect even at 0,5% stabilizer cocentration in polymer, the more so, this effect doesn t change considerably with futher increasing of concentration (Table 20 XXVI and XXIII compounds). 

Fortunately, substituted BQ or QM do not diminish the activity of HAS 28 (R = H, CH3) in thermal or sensitized photo-oxidation of heptane [263,264]. On the contrary, 3,5,3 5 -tetra- erf-butyl-4,4 -stilbenquinone 164, the most common QM derived from hindered phenols, enhanced the photoprotective effect of 28. The light screening ability of 164 is favourably cooperating in the model system. 

Glaser DA. Anti-aging products and cosmeceuticals. Facial Plast Smg Clin North Am 2004 12 363-72. Elmets CA, Vargas A, Oresajo C. Photoprotective effects of sunscreens in cosmetics on sunburn and Langerhans cell photodamage. Photodermatology. PkofoimmHWcl Photomed 1992 9 113-20. 

E. Ruszova, S. Pavek, V. Hajkova, S. JcUidovci, V. Velebny, I. Papezflcova, L. Kubala, Photoprotective effects of glucomaimcui isolated from Candida utilis, Carbohydr. Res., 343, 501-511,2008. 

The mechanistic basis of these photoprotective effects was investigated using the DPPH and FRAP assays. From these results it was concluded that any antioxidant abilities of 9, 43 and 44 are not due to radical scavenging and/or reducing actions. 

The development of metal complexes, particularly those based on nickel, resulted in compounds which exhibited relatively low extinction coefficients in the near ultraviolet region and yet in many instances were found to be superior in performance to the currently available ortho-hydroxyaromatic compounds [3,5]. This finding resulted in a search for some other feasible mechanistic function. As carbonyl photolysis was considered to be an important initiation process which gives rise to both free radicals and backbone cleavage, then deactivation or quenching of the excited-state precursor should prove an effective means of photoprotection. Effective structures in this respect were tris(dibenzoylmethanato) chelates of Fe and Cr (Structure 5), nickel oxime chelates (Structure 6), and the nickel complex of Structure 7, nick-el(ii) 2,2 -thiobis(4-f-octylphenolato)- -butylamine. 

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