[Antioxidant properties of some sulfur-containing substances].

The antioxidant properties of sulfur-containing substances have been experimentally studied in vitro. Unithiol exhibits a wide spectrum us radicals. For this reason, unithiol can be considered, along with ascorbic acid, as a universal drug for the reduction of free radical reactions.

[Biochemical characteristics of aminostigmine--a new anticholinesterase agent]. / Biokhimicheskaia kharakteristika aminostigmina--novogo lekarstvennogo antikholinésteraznogo sredstva.

The properties of aminostigmine in comparison with those of other carbamate inhibitors of cholinesterases have been studied in vitro using potentiometric titration and Ellman methods. The bimolecular constants of the inhibition rate of acetyl-, butyryl- and propionylcholinesterase were found to be equal to (8.0-14.0).10(5) (3.8-7.7).10(5) and 11.0.10(5) M-1.min-1, respectively. In terms of inhibitory activity, aminostrigmine is comparable to neostigmine methylsulphate, being inferior to physostigmine and superior to pyridistigmine. The rate of decarbamylation of acetylcholinesterase inhibited by aminostigmine measured by the dilution method, by creating excessive acetylcholine and by dialysis is characterized by k2c constants equal to (1.1-1.6).10(-2), (2.5-2.8).10(-2) and 0.025.10(-2) min-1, respectively. On the whole, aminostigmine belongs to slowly reversible inhibitors. Being carbamylated by aminostigmine, the enzyme is resistant to reactivation by TMB-4 and HI-6. At (4-6).10(-7) M aminostigmine prevents by 50% the irreversible binding of cholinesterase by certain organophosphate inhibitors of cholinesterase when the latter are used at concentrations needed to inhibit the enzymatic activity by 85-90%.

[Trial of cholinesterase reactivators as proserine antagonists]. / Ispytanie reaktivatorov kholinésterazy kak antagonistov prozerina.

HI-6 and TMB-4 were the most effective and safe of 7 cholinesterase reactivators tested as agents for the prophylaxis of proserine poisoning of male mice. The reactivator HI-6 strongly potentiated the prophylactic efficacy of a mixture of atropine and arpenal administered in the doses sufficient for the blockade of both the m- and h-cholinoreactive systems of mice. As demonstrated by experiments in vitro, HI-6 and TMB-4 did not reacivate proserine-inhibited cholinesterase. The natural anticholinesterase activity of HI-6 was negligible. Based on the correlation of the data obtained to the reported data indicating that HI-6 has a low ganglioblocking activity it is inferred that the direct effect on the receptor is of no importance for the potentiating effect. It is assumed that HI-6 modulates the cholinoreactive systems, which leads to a dramatic increase of the efficacy of cholinolytics.

[Effect of reversible inhibitors on the reaction capacity of functional portions of the active center of acetylcholinesterase]. / Vliianie obratimykh ingibitorov na reaktsionnuiu sposobnost' funktsional'nykh uchastkov aktivnogo tsentra atsetilkholinésterazy.

The effect of galanthamine, tacrine, and oxazyl (ambenomum) on human red cells acetylcholinesterase phosphorylation by armine and Gd-42 (o-ethyl-s-beta-ethylthioethyl ester of methylthiophosphinic acid) was studied. In the presence of galanthamine phosphororganic inhibitors interacted only with the active center of the enzyme, the anionic site of which was not occupied by the reversible inhibitor. Tacrine and oxazyl decreased the reactivity of the free enzyme and the rate of its phosphorylation.