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It was found that irradiation of the solution of 4,4"-diazidodiphenyl in ethyl alcohol with UV-light at a wavelength longer than 280 nm in the presence of dissolved oxygen resulted in appearance of post-luminescence. The luminescence intensity increases with increasing the oxygen concentration; the luminescence virtually disappears after purging the solution with argon. The observed emission of light was attributed to chemiluminescence of the products of photooxidation of 4,4"-diazidodiphenyl. The rate dependence of the afterglow shows two maxima. The first is observed immediately after cessation of the UV irradiation of the solution and its transfer to a photometric cell. The intensity of the corresponding chemiluminescence decreases by an exponential law with τe= 5 s. The second maximum appears after a certain time interval after the first one. Addition of a triplet sensitizer (Michler's ketone) to the reaction mixture results in quenching of the chemiluminescence from the photooxidation products, whereas the addition of substances that stabilize electrophilic species in the singlet state leads to an increase in the chemiluminescence intensity. It was suggested that the chemiluminescence resulted from reactions involving the singlet nitrene adduct with oxygen.

The review deals with photosensitizing properties of drugs and plant extracts. Some compounds are able to cause side effects such as phototoxicity and photoallergy. Revealing and study of harmful photosensitizers is actual problem in connection with changing photoecological situation.

The photosensitizing properties of eight N-alkylated phenothiazine neuroleptic drugs were studied. The experiments were carried out in a model system based on photooxidative chemiluminescence of Gly-Trp peptide in aqueous solution. Under irradiation with light longer than 280 nm, all the studied phenothiazine derivatives decrease the chemiluminescence intensity at low concentrations and enhance it at high concentrations. Phenothiazine derivatives is likely to be due to superoxide and/or Gly-Trp free peroxide radicals. Photosensitization begins to dominate over protection at concentrations which are different for various phenothiazine derivatives compounds and lie in the range 10(-6)-10(-5) M. The photosensitizing efficiency decreases in the order: Thioproperazine, Trifluoperazine Hydrochloride, Alimezine, Thioridazine Hydrochloride, Levomepromazine Hydrochloride, Promethazine Hydrochloride, Periciazine, Chlorpromazine Hydrochloride. It was shown that photooxidation of Gly-Trp sensitized by phenothiazine derivatives occurs via singlet oxygen formation.

Photosensitizing and photoprotecting efficiency of about a hundred of compounds, mainly drugs, was studied. The method based on chemiluminescence occurred along with photooxidation of glycyltryptophan under irradiation in UVB range in solution was used for testing. As a measure of photosensitizing efficiency the concentration of photosensitizer which induced two-fold increase of chemiluminescence intensity was chosen. The most effective photosensitizers are riboflavin, FAD, furagin, psoralene, vicasol, benzobarbital, mydocalm, angelicyn, furadonin, ethacridin, diazolin, folic acid. With regard to pharmacological doses of drugs in organism more dangerous sensitizers (in descending order) are p-aminosalicylic acid, furagin, riboflavin, benzobarbital, thiopental, chloramphenicol, nicodin, mydocalm, furadonin, oxolonic acid, furazolidone, psoralene, nicotinamide and diazolin. Photoprotecting effect was described by the concentration at which chemiluminescence intensity decreased twice. The most effective photoprotectors are etamsilat, quercetin, ftivazid, chlorpromazine, diprazine, thioridazine, aminophenazone, oxaphenamide. Concentration dependence for some of these drugs (etamsilat, chlorpromazine, diprazine, thioridazine) is non-monotonous: they inhibit photooxidation in low concentration (about 10(-7)-10(-6) M), but at higher concentrations (10(-5)-10(-4) M) photosensitization dominates over photoprotection.

Photosensitizing effect of antimicrobial drug nitrofuran derivative--furagin N-(5-nitro-2-furil)-allylidencamino-hydantoin) under irradiation with light longer than 280 nm was found. The method of investigation is based on photochemiluminescence of Gly-Trp peptide in aqueous solution. Maximum photosensitizing efficiency was observed at the furagin concentration 0.08 mM when chemiluminescence yield was 33 times greater than photochemiluminescence of Gly-Trp peptide in absence of drug. It was shown that photochemiluminescence sensitized by furagin occurred via free radical way. Life time of the triplet state of furagin determined by flash photolysis was 40 microseconds. A comparison of experimental data with kinetic calculation allowed us to estimate the rate constant of triplet quenching by oxygen ((2.2 +/- 0.3)10(8) M-1.s-1) and the total rate constants of physical quenching and chemical reaction with Gly-Trp peptide ((2.0 +/- 0.4)10(8) M-1.s-1). It was also found in experiments with photochemiluminescence of Gly-Trp peptide sensitized by riboflavin (irradiation with monochromatic light 436 nm) that furagin possesses antioxidant properties twice reducing the intensity of chemiluminescence at the drug concentration 0.029 mM.