PHOTOOXIDIZED PSORALEN INDUCES Conversions of oxyhemoglobin

E. P. Lysenko*, S. Wunderlich**, F. Pliquett**, U. Neitz**, R. A. Ionina*, R. E. Mollaev*, and

A. Ya. Potapenko*

* Department of Medical and Biological Physics, Russian State Medical University, Moscow, Russia

**Institute of Medical Physics and Biophysics, Leipzig University, Germany

Keywords: psoralen, photooxidized psoralen, oxyhemoglobin oxidation, methemoglobin, hemihrome, hydrogen peroxide.

Abbreviations: Ps - psoralen, PUVA - psoralen combined with UV-A irradiation, POP - photooxidized psoralen, POP_eth - photooxidized ethanol solution of psoralen, POP_aq - photooxidized aqueous solution of psoralen, ROS - reactive oxygen species, DOPA - 3,4-dihydroxyphenylalanine, PBS - phosphate buffered saline, ChL - chemiluminescent method, PBN - C-phenyl-N-tert-butyl-nitrone, DTH-reaction - delayed type hypersensitivity reaction, A - absorbance, OxyHb - oxyhemoglobin, MetHb - methemoglobin, c_oxyHb - concentration of oxyhemoglobin, c_metHb - concentration of methemoglobin, c_hemichr - concentration of hemichrome.

The corresponding author: Eugene P. Lysenko.

Department of Medical and Biological Physics, Russian State Medical University, Ostrovityanova Str. 1, 117869 Moscow, Russia, Tel. 434 66 76 (office); 954 53 79 (home);

FAX: (095) 245 12 20; e-mail: apotap@mx.iki.rssi.ru (after 1 December 1997)

or:

Institute of Med.Physics and Biophysics, Leipzig University, Liebig str.27, 04103 Leipzig, Germany,

FAX: (0341) 971 57 09; e-mail: plif@server3.medizin.uni-leipzig.de (till 30 November 1997)

Abstract. It is known that photooxidized psoralen comprises a large number of biologically active photoproducts. Earlier we have found that some of psoralen photooxidation products (POP-products) were readily reduced by Fe(II)-ions with the formation of more reactive species (free radicals, electonically excited products). It is shown, that UV-A irradiated (366 nm) in air ethanol and aqueous solutions of psoralen (10^-4 M) induce quick (in some min) and irreversible oxidation of Fe-containing protein oxyhemoglobin (OxyHb) mainly into ferric methemoglobin (MetHb) and to a lesser extent into hemichrome. POP-induced conversions of OxyHb were registered by spectrophotometry method in fresh human blood hemolisate (0.8 - 3.4 mM of Hb). Psoralen irradiated without oxygen (under nitrogen atmosphere) did not induce conversions of OxyHb.It was found, that oxidation of OxyHb was induced by those POP-products, which could be stored for several hours without loss of their activity. These reactive POP-species were also thermostable, and they did not hydrolized. At all investigated fluences of psoralen preirradiation (0 -300 kJ.m^-2) decomposition of OxyHb increased with the increase of irradiation fluence. POP-induced conversions of OxyHb were similar to well known H₂O₂-induced oxidation of OxyHb. It may be proposed, that hydrogen peroxide play role of an intermediate in the process of POP-induced conversions of OxyHb, or it can be formed during psoralen oxidation as one of POP-products.