A. Yu. Perchenok

New Acylate and Thioacylate Effectors of Mammalian Cholinesterases Based on Cyclic Ammonium Alcohols Containing Elements of the Anabasine Structure

We report a pioneering analysis of the interaction between mammalian cholinesterases and 36 acylates and thioacylates of ammonium alcohols with different structure of an alkyl chain between ammonium and etheric atoms and with different structure of a cyclic ammonium group. Among these ethers, which were both substrates and reversible inhibitors of erythrocyte cholinesterase and serum butyrylcholinesterase, specific effectors of both enzymes were identified.

Substrate Specificity of Cholinesterases in Various Representatives of the Animal Kingdom

This review summarizes the literature data as well as experimental results obtained at our Institute over a period of 50 years on the substrate specificity of cholinesterases–acetylcholine acetylhydrolases (EC 3.1.1.7) and acylcholine acylhydrolases (EC 3.1.1.8). The parameters of enzymatic hydrolysis of oxo- and thiocholine and β-methylcholine esters in different organs and tissues were analyzed in 66 animal species including 22 chordate, 20 insect, 1 mite, 17 mollusk, 4 nematode, and 2 flatworm species. Our substrate specificity studies and extensive data on the inhibitory specificity obtained using irreversible organophosphorous inhibitors and reversible effectors unequivocally indicate that the cholinesterase family is characterized by a clear-cut species and tissue specificity.

Activities of Tetramethylene-Bis-Onium Reversible Cholinesterase Inhibitors as Influenced by the Nature of the Onium Atom

Inorganic tetramethylene bis-onium compounds were studied as reversible inhibitors of various cholinesterases (ChE), i.e., human erythrocyte acetyl-ChE, horse blood serum butyryl-ChE, grass frog Rana temporaria brain ChE, and Pacific squid Todarodes pacificus and commander squid Berryteuthis magister visual ganglia ChE from various habitats in the northwest Pacific Ocean, in order to study the influence of the nature of the onium atom on their anti-ChE activities. bis-Phosphonium inhibitors turned out to be significantly more potent effectors than bis-ammonium compounds, which may actually have been due to the significant increases of size and hydrophobicity of the onium groups. The bis-ammonium organosilicon compound and its monoammonium analog turned out to be equally active as reversible ChE inhibitors in mammals. The bis-phenyliodonium derivative was studied for the first 7time, was characterized by significantly increased hydrophobicity due to introduction of F atoms into the tetramethylene spacer in the onium chain, and exhibited marked anti-ChE activity with respect to mammalian ChE.

Tetramethonium derivatives as reversible inhibitors of various cholinesterases

To study the effect of the onium atom nature on anticholinesterase efficiency, we tested elementorganic derivatives of tetramethylenbisonium compounds as reversible inhibitors of the following cholinesterases (ChE): acetyl-ChE from human erythrocytes, butyryl-ChE from horse serum, ChE from the brain of the grass frog Rana temporaria, ChEs from visual ganglia of the Pacific squid Todarodes pacificus, and ChE from visual ganglia of the commander squid Berryteuthis magister from different habitats in the Northwestern Pacific Ocean. Bisphosphonium inhibitors were found to be much stronger effectors than bisammonum compounds, although this may be due to a significantly increased size and hydrophobicity of their onium groups. Bisammonium organosilicon compound and its monoammonium analog were equally active as reversible ChE inhibitors in mammals. The first studied bis(phenyliodonium) derivative, which is characterized by a significantly increased hydrophobicity due to the introduction of fluorine atoms to the interonium tetramethylene chain, also exhibited a pronounced anticholinesterase effect on mammalian ChE.

Transferase activity of horse blood serum cholinesterase at hydrolysis of 1-methyl-8-acetoxychinolinium iodide in the presence of aliphatic alcohols

The study was performed to check whether the horse blood serum butyrylcholinesterase expresses transferase activity in the presence of several low-molecular aliphatic alcohols, using chromogenic substrate 1-methyl-8-acetoxychinolium iodide whose phenolic hydrolysis product absorbs intensively at 445 nm, whereas the initial ester practically does not absorb within this spectrum area. This allowed measuring simultaneously accumulation of both products of enzymatic hydrolysis: of acetic acid by the potentiometric, while of phenol—by the colorimetric method. Rates of formation of both products of enzymatic hydrolysis are practically equal in experiments with all studied alcohols. This indicates that horse blood serum butyrylcholinesterase under these experimental conditions does not catalyze the transfer of acetyl residue to the studied aliphatic alcohols, i.e. does not have transferase activity.

How aliphatic alcohols and pH affect reactivity of horse blood serum cholinesterase at its interaction with organophosphorus inhibitors

There was studied action of aliphatic alcohols (ethanol, propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol), and pH on various kinds of serum cholinesterase. At inhibition of the cholinesterase hydrolytic activity under effect of alcohols the key role was played not by the total number of carbon atoms in the alcohol molecule, but by the “efficient length” of the carbohydrate chain. The fact that the presence of alcohols did not affect parameters of reversible inhibition of cholinesterase by onium ions tetramethylammonium and choline allows suggesting the absence of action of solvents on specific sorption of acetylcholine in the enzyme active center. With aid of two sets of hydrophobic organophosphorus inhibitors (OPI) (12 compounds), we have managed to estimate both the degree and the character itself of serum cholinesterase.

Ligands of cholinesterases of ephedrine and pseudoephedrine structure

The paper is a review of literature data on interaction of erythrocytic acetylcholinesterase and of mammalian blood serum butyrylcholinesterase with a group of isomeric complex ester derivatives (acetates, propionates, butyrates, valerates, and isobutyrates) of bases and iodomethylates of ephedrine and its enantiomer pseudoephedrine. For 20 alkaloid monoesters, parameters of enzymatic hydrolysis are determined and their certain specificity toward acetylcholinesterase is revealed, whereas 5 diesters of iodomethylates of pseudoephedrine were submitted to hydrolysis only by butyrylcholinesterase. It turned out that 20 alkaloid diesters and 10 trimethylammonium derivatives were uncompetitive reversible inhibitors of acetylcholinesterase and competitive inhibitors of butyrylcholinesterase. The performed for the first time isomer and enantiomer analysis “structure—efficiency” has shown that in most caes it is possible to state the greater complementarity of catalytical surface of enzymes for ligands of pseudoephedrine structure, such differentiation being more often manifested.

Lupinine and epilupinine derivatives as substrates of Mammalian cholinesterases

Two series of lupinine and epilupinine acetates, the free bases and the N-methyl, N-ethyl, and N-propyl derivatives, were studied. Enzymatic hydrolysis of substrates by human erythrocyte acetylcholinesterase and horse blood serum butyrylcholinesterase was investigated in comparison with the corresponding dimethylalkyl derivatives of acetylcholine. The important role of non-productive substrate binding was taken into account in the data analysis. Additional information for a better understanding of the metabolism of lupinine derivatives in vivo in animals was obtained.

Reversible lupinin inhibitors of cholinesterases of mammalian blood and of optical ganglia of individuals of the Commander squid Berryteuthis magister from different zones of species areal

Arylsulfoesters and carbonic lupinin esters are studied for the first time as reversible inhibitors of mammalian blood cholinesterases. Studied in detail is sensitivity of cholinesterases to mono- and bilupinin inhibitors in Commander squid individuals from different habitation zones.

Comparative analysis of sensitivity of cholinesterases to reversible inhibitors by methods of multidimensional statistics

Using the methods of factor and cluster analysis, the statistical treatment is performed of data on interaction of seven cholinesterases (ChE)—human acetylcholinesterase, horse butyrylcholinesterase, cholinesterases of frog brain and of different squid species (Todarodes pacificus and Berrytheutis magister, in the latter case, individuals from three different habitats are compared)—with 141 reversible inhibitors of various structures. Statistically significant differences between ChE of squids and vertebrates are shown. The previously revealed intraspecies peculiarities of ChE in the Commander squid B. magister are statistically confirmed.