D.A. Kostina - Post-graduate, Departament of Biochemistry, Samara State University O.S. Fedotkina - Ph.D. (Chem.), Departament of organical, bioorganical and medicinal chemistry, Samara State University N.A. Klenova - Dr. Sc. (Biol.), Professor, Deptartament. of Biochemistry, Samara State University P.P. Purygin - Dr.Sc. (Chem.), Professor, Departament of organical, bioorganical and medicinal chemistry, Samara State University A.K. Buryak - Dr.Sc. (Chem.), Institute of Physical Chemistry and Electrochemistry A.N. Frumkin RAS E.G. Litvinova - Ph.D. (Biol.), Senior Research scientist, Institute of Theoretical and Experimental Biophysics, RAS

The aim of this work was to study the influence of a derivative of a toxic xenobiotic acetone-dimethylhydrazone (ADMH) on the content and antibacterial properties of antibacterial peptides in hemolymph of Galleria mellonella larvae. It has been shown that ADMH promotes increase of the amount of peptides in hemolymph fractions and enhancement of antimicrobial activity of the fractions. Besides the known peptides (cecropin-D-like peptide, defensin and Proline-rich antimicrobial peptide-2 the hemolymph of hydrazone-treated larvae contained previously uncharacterized peptides (1662, 2537 and 3481 Da) with antimicrobial activity. Antimicrobial activity of the hemolymph fraction, which contained these peptides, was significantly higher as compared to the hemolymph fractions containing other antibacterial peptides. All peptide fractions, caused disturbances of metabolic processes in bacterial cells. Peptides from different fractions had different effects on activity of the E. coli enzymes, leading to reduction or increase in activity of dehydrogenases. Thus, nonspecific stimulation by a xenobiotic leads to activation of insects - immune system in the absence of real threat of bacterial infection, which might subsequently result in immunity exhaustion and weakening of antibacterial protection.