DNA-hydrolyzing autoantibodies

Catalysis by antibodies could be a frequent phenomenon if the immune system generates a sufficiently diverse number of antibodyactive sites, some of which may possess catalytic activity. A catalytic antibody can be expected to do more damage than one that simply binds antigen. The best biochemical marker of systemic lupus erythematosus (SLE) is presence of autoantibodies to DNA. In the present article, we describe the DNA-hydrolyzing activity of DNA-binding autoantibodies purified from SLE patients. The substrates employed were supercoiled plasmid, radiolabeled plasmid fragments, and oligonucleotides. Hydrolysis of DNA by the antibodies was indicated by the appearance of fragments visualized by ethidium bromide staining of agarose gels or autoradiography of polyacrylamide gels. Changes in linear dichroism values were also indicative of DNA hydrolysis. The antibody activity was purified by protein A-sepharose chromatography, high-performance liquid chromatography gel filtration, and DNA-affinity chromatography. Scrupulous control studies were done to demonstrate that DNA-hydrolyzing activity really belongs to the antibodies. Purified Fab fragments showed hydrolyzing activity, whereas the Fc fragment was inactive. The specificity of DNA cleavage was investigated, and the rate parameters of hydrolysis by antibodies and conventional nucleases were compared.     

Cardiac glycosides of Erysimum contractum

The cardenolide composition ofErysimum contractum Somm. et Lew. familyBrassicaceae (Cruciferae) has been investigated. The seeds of this plant have yielded strophanthidin, erysimin, erysimoside, erycordin, and new cardiac glycoside which has been called nigrescigenin digitoxoside. It has mp 141–145°C, []_D ²⁰+16.0±2° (c 0.75; methanol), C₂₉H₄₂O₁₀. On the basis of chemical transformations and spectral investigations it has been established that the new glycoside is 3--D-digitoxopyranosyloxy-5,11,14-trihydroxy-19-oxo-5,14-card-20(22)-enolide. The total content of cardiac glycosides in the seeds of this plant amounted to 3.2%, including 1.26% of erysimoside.All-Union Scientific-Research Institute of the Chemistry and Technology of Drugs, Kharkov. G. S. Skovroda Kharkov State Pedagogic Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 58–62, January–February, 1991.     

Cardiac glycosides of Erysimum crepidifolium

Summary Four cardiac glycosides have been isolated from the leaves ofErysimum crepidifolium Rchb. Three of them have been identified as erysimin, erysimoside, and erycordin. The fourth glycoside, which has been named glucostrophalloside, is new, and it consists of strophanthidin 3-O-[4-O--D-glucopyranosyl--D-allomethylopyranoside].Khar'kov Scientific-Research Institute of Pharmaceutical Chemistry. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 611–614, September–October, 1974.     

19-Norcardenolides

The products of the autooxidation of the cardenolides strophanthidin and erysimin in solutions have been studied. It has been established that the autooxidation of 19-oxocardenolides forms, together with 19-carboxylic acids, a complex mixture of 19-norcardenolides. The bulk of them consists of 10-OH compounds and a smaller proportion of 10-H compounds. Autooxidation affects both the functional group at C-10 and its transformation and also other groupings and bonds in ring A and, to some extent, in ring B, including the oxidation of the 3-OH group, degradation of the 5-OH group, and cleavage of the C₅-C₁₀ bond with the formation of 5,10-seco-19-norcardenolides. A possible mechanism of the formation of 19- norcardenolides is discussed.All-Union Scientific-Research Institute of Drug Chemistry and Technology, Khar'kov. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 71–76, January–February, 1985.     

Effect of compatibilizer additives on the technological and performance characteristics of biodegradable materials based on starch-filled polyethylene

The deformation and strength characteristics, as well as rheological properties and biodegradability of film materials prepared by hot pressing and slot extrusion methods from polyethylene-plasticized starch-compatibilizer blends were examined. Polyethylene with grafted itaconic acid served as compatibilizer. The formulation and technological parameters of preparation of biodegradable film materials were optimized to meet the technical performance criteria.     

Thermal tranformation of cardiac glycosides

The thermal transformations of cardiac glycosides in neutral alcoholic solutions have been investigated. The kinetics of their acidless hydrolysis at 100 and 142°C and the activation energy of the process have been studied. The possibility has been shown of the stepwise hydrolysis of natural trisdigitoxosides with the production of difficulty available mono- and bisdigitoxosides. The following were used as the objects of investigation: convallatoxin, glucostrophanthidin, cheirotoxin, desglucocheirotoxin, erycordin, erysimin, erysimoside, digitoxin, and cymarin.All-Union Scientific-Research Institute of Drug Chemistry and Technology, Kharkov. Kharkov State Pharmaceutical Institute. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 62–64, January–February, 1991.