COUMARIN DERIVATIVES ENHANCE THE CHEMILUMINESCENCE ACCOMPANYING LIPID-PEROXIDATION

The effect of laser dyes, derivatives of 1,2-benzopyrone (coumarin), o n the chemiluminescence (CL) accompanying Fe2+-induced lipid peroxidat ion (LPO) in liposomes prepared from egg yolk phospholipids has been i nvestigated. It was found that quinolizin (9a,9,1-gh)-substituted coum arins enhanced CL at the stages of ''fast'' and ''slow'' hashes (abbre viated as FF and SF, respectively), which are known to accompany lipid hydroperoxide decomposition (FF) and chain LPO reaction development ( SF). On the other hand, these compounds did not virtually change the s hape of CL curve (in particular, lag phase duration) and accumulation of the LPO products reacting with 2-thiobarbituric acid (TEARS). The d ependences of FF and SF amplitudes on the concentration of coumarins e xhibited for some compounds an effect of saturation with subsequent de crease of CL at high concentrations of the dyes. The highest degree of CL amplification was reached with the compound etrahydro-9-(2'-benzoi midazolyl)-quinolizin-(9,9a, I-gh)coumarin (C-525), which enhanced CL at the stages of FF and SF by a factor 1600 at a dye concentration of 8 nmoles/mg of phospholipid. On the other hand, C-525 did not increase the intensity of CL associated with the decomposition of H2O2 by Fe2 ions (Fenton's reaction). Apparently, these coumarin sensitizers may be used for selective enhancement of CL associated with LPO both in ex perimental and clinical investigations.