[Conjugate of podophyllotoxin with chlorambucil: synthesis, biological testing and molecular modeling]. / Kon"iugat podofillotoksina s khlorambutsilom: sintez, biotestirovanie i molekuliarnoe modelirovanie.

In the present work we have studied a novel conjugate of the DNA alkylating agent chlorambucil with podophyllotoxin, a ligand of the colchicine binding site in tubulin. The target compound was obtained by Steglich esterification of podophyllotoxin with the percentage yield of 41%. Results of biotesting carried out on the carcinoma A549 cell line revealed that at a concentration of 2 µM the conjugate caused full depolymerization of microtubules without any other effect on free tubulin. The conjugate inhibited proliferation (IC50=135±30 nM) and growth (EC50=240±30 nM) of A549 cells. The data of computer molecular docking of the novel compound into the 3D model of the colchicine binding site in α,ß-tubulin and molecular dynamics modelling allowed to explain the observed difference in effects of chlorambucil-podophyllotoxin and chlorambucil-colchicine conjugates on microtubules.

[Podophyllotoxin analogue with bicyclo[3.2.1]octane moiety annelated with indole: synthesis, molecular modeling, and biological testing]. / Analog podofillotoksina s bitsiklo[3.2.1]oktanovoi gruppirovkoi, annelirovannoi s indolom: sintez, molekuliarnoe modelirovanie i biotestirovanie.

C4-Ester derivatives of the anticancer agent podophyllotoxin with bridged moieties can either inhibit polymerization of alpha,beta-tubulin with the formation of microtubules (analogously to the parent molecule) or cause an unusual effect of "curling and shortening" of the microtubules (MT). In order to predict the effect of bridged podophyllotoxin derivatives on the MT network using computer molecular modeling it is desirable to enhance the structural diversity of their bridged substituents. In the present work we synthesized novel podophyllotoxin ester with bicyclo[3.2.1]octane moiety annelated with indole core. The target compound was obtained by Steglich esterification of podophyllotoxin by rac-exo-(indolo[2,3-b])bicyclo[3.2.1]oct-2-ene-6-carboxylic acid as diastereomeric (6RS,8SR,9RS) mixture, which could not be separated by thin layer or preparative column chromatography on silica gel. Results of biotesting of 4-O-{(6R,8S,9R)-5,6,7,8,9,10-hexahydro-6,9-methanocyclohepto[b]indol-8-ylcarbonyl}-Lpodophyllotoxin on the carcinoma A549 cells proved its ability to cause full depolymerization of microtubules without curling effect at a concentration 10 µM. Cytotoxicity value of the compound estimated in MTT test was in a high nanomolar concentration interval (EC50=710±30 nM). Computer molecular docking of both isomers of novel compound and earlier synthesized podophyllotoxin esters with bridged moieties into the 3D model of the colchicine domain in alpha,beta-tubulin revealed the difference in positions of the bridge moieties of new compound and MT-curling ligands and allowed to hypothesize that the atypical action on MT might be caused by positioning of their bridge groups near the GTP binding site in alpha-tubulin.

[Preparation and characteristics of immobilized collagenase isolated from crab Paralithodes camtschatica]. / Poluchenie i svor'stva preparatov immobilizovannoi' kollagenoliticheskoi' proteazy iz gepatopankreasa kraba Paralithodes camtshatica.

Collagenolytic protease from hepatopancreas of king crab was immobilized on water-soluble reactive polymers containing N-succinimide units and possessing different hydrophobicity-hydrophilicity balance. The immobilized enzyme displayed higher heat stability, but its proteolytic activity decreased with the increase in the number of the copolymer hydrophobic groups. Highly active thermostable preparations of collagenolytic protease were obtained by copolymerization. The copolymerization did not affect the enzyme activity and increased the protease heat stability to the formation of pseudocross-links of protein molecules in their associates.

[Oxidase activity of horseradish peroxidase in oxidation of the bilirubin-albumin complex]. / Oksidaznaia aktivnost' peroksidazy khrena v okislenii kompleksa bilirubin-al'bumin.

The catalytic activity of horseradish peroxidase was investigated upon oxidation of the bilirubin-albumin complex (10(-5)-10(-4) M; BR: SA = 1: 1.5 mol/mol) by dissolved oxygen to biliverdin and other components. The process can be described by the Michaelis-Menten equation with Km = 14.4 microM and Vmax = 0.12 microM/min, if HRP = 3.1 x 10(-8) M. Oxidation is supposed to proceed in the triple complex--peroxidase: albumin: bilirubin.