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Biomedical subjects

M Tabak

Publications and source records attributed to M Tabak.

76 records · Page 5Linked to original sources
PubMedDate not supplied

Binding of the Mn(III) complex of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin to DNA. Effect of ionic strength.

Interactions of the water-soluble Mn(III) complex of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin (Mn(III)TMPyP) with DNA in aqueous solutions at low (0.01 M) and high (0.2 M) ionic strengths have been studied by optical absorption, resonance light scattering (RLS) and 1H NMR spectroscopies. Optical absorption and RLS measurements have demonstrated that in DNA solutions at low ionic strength the Mn(III)TMPyP form aggregates, which are decomposed at DNA excess. At high ionic strength the aggregation was not observed. We explain this effect by assuming that upon increase in ionic strength, Mn(III) TMPyP dislocates from the DNA sites, which produces better conditions for the porphyrin aggregation, to sites where the aggregation is hindered. The 1H NMR data demonstrated that the aggregation observed at low ionic strength reduces the paramagnetism of Mn(III)TMPyP. This phenomenon was not observed at the high ionic strength in the absence of aggregation.

Animals↗
PubMedDate not supplied

[The mechanism of metabolic denitration of nitroheterocyclic compounds].

It has been found that denitration of nitroheterocyclic drugs (NHCC) in mouse liver homogenate is one of the pathways of their biotransformation. This process is accompanied by the release of NO and NO-heme iron complex formation. The yield of complex increases linearly with time of NHCC incubation with liver homogenate and depends on NHCC structure. The ESR spectrum of the complex represents a superposition of spectra of NO with hemoglobin and NO with the other heme-containing proteins. NHCC denitration is inhibited by metyrapone, which is an evidence of cytochrome P-450 involvement in their metabolic denitration.

Animals↗
PubMedDate not supplied

Binding and location of dipyridamole derivatives in micelles: the role of drug molecular structure and charge.

Binding and localization of the vasodilator and antitumor drug coactivator dipyridamole (DIP) and of its three derivatives, RA14, RA47 and RA25 (DIPD), to cationic (cetyltrimethylammonium chloride), anionic (sodium dodecylsulfate), zwitterionic (N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate), and neutral (t-octylphenoxypolyethoxyethanol) micelles was studied using fluorescence, optical absorption and 1H NMR spectroscopy. The analysis of NMR, optical absorption and fluorescence data indicates that the depth of localization of the drugs in the micelles from the surface decreased in the order DIP > RA14 > RA47 > RA25. The binding constants for the neutral drug forms change in the same order in the range of 1400-3100 M-1 for DIP to 80-300 M-1 for RA25. This order is identical with the reported biological activity of DIPD. For the protonated drugs in zwitterionic or neutral micelles the binding constants are reduced by a factor of 20-75.

Binding Sites↗