Use of Bis-Alkaloid Derivatives of Dicarboxylic Acids on the Basis of Lupinine, Anabasine and Cytisine as Reversible Inhibitors of Cholinesterases of Different Origin

Comparative study was carried out on action of a group of bis-alkaloid derivatives (on the basis of lupinine, anabasine, and cytosine, and their iodomethylates) of dicarboxylic acids (succinic, glutaric, azelaic, sebacic) on activity of cholinesterase of optical ganglia of the Commander squid Berryteuthis magister from different zones of habitation in the northwest part of the Pacific Ocean as well as human erythrocyte acetylcholinesterase and horse serum butyrylcholinesterase. These compounds turned out to be potent reversible inhibitors with specificity of action with respect both of sensitivity of the studied enzymes to them and of the type of their inhibitory action. The studied inhibitors can be used as tools in biochemical taxonomy to determine populational structure of such a marketing species as the Commander squid Berryteuthis magister.     

Comparative Study of Reversible Organofluorine Ammonium Inhibitors of Cholinesterases of Different Animals

A group of organofluorine ammonium compounds, trimethyltrifluoromethylammonium, diethylmethyltrifluoromethylammonium, hexa(difluoromethylene)-bis(trimethylammonium), their non-substituted analogs as well as bis-onium organosilicone, phenyliodonium, and triphenylphosphonium derivatives were tested as reversible inhibitors of acetylcholinesterase of human erythrocytes, butyrylcholinesterase of horse blood serum, cholinesterase of brain of the frog Rana temporaria and cholinesterases of optic ganglion of the Pacific squid Todarodes pacificus. By the method of molecular mechanics, differences were revealed in conformational mobility of interonium chain and in geometric parameters of the studied compounds. It was shown that introduction of fluorine atoms into the inhibitor molecule affected only their interaction with the Pacific squid cholinesterase. It was possible to separate effects of the onium atom nature and of the interonium chain structure in the inhibitor molecule on the anticholinesterase potency.     

Ammonium Compounds with Localized and Delocalized Charge as Reversible Inhibitors of Cholinesterases of Different Origin

Five derivatives of benzimidazole, compounds with delocalized charge in cationic group, are studied and turned out to be reversible inhibitors of hydrolysis of acetylthiocholine under action of acetylcholinesterase from human erythrocytes, butyrylcholinesterase from horse blood serum, and cholinesterases from brain of the brown frog Rana temporaria and from optical ganglion of the Pacific squid Todarodes pacificus. It was only for acetylcholinesterase from erythrocyte as well as (with propyonylthiocholine as substrate) from squid that sensitivity to the studied benzimidazole derivatives correlated with degree of localization of the charge in the cationic group; this confirms the current concepts of functioning of the enzyme active center. A comparative study of 9 ammonium inhibitors with localized cation in their molecules, including the complete sterical analogue of the benzimidazole derivatives, benzimidazolinium iodide, has revealed both quantitative and qualitative differences.     

Effect of the substrate structure on the mechanism of reversible inhibition of cholinesterases of different origin

The mechanism of reversible inhibition of human erythrocyte acetylcholinesterase, horse blood serum butyrylcholinesterase, cholinesterase from optical ganglia of the squids, PacificTodarodes pacificus and CommodoreBerryteuthis magister, from different zones of habitation area is studied in the presence of substrates of various structures (acetylcholine, butyrylcholine, acetylthiocholine, butyrylthiocholine, phenylacetate, indophenylacetate, 2,6-dichlorophenylindophenylacetate). Tested as reversible inhibitors were tetramethylammonium iodide, tetraethylammonium iodide, choline iodide, and two derivatives of α,ω-bis(trimethylammoniommethyl)oligodimethylsiloxane dichloride. It has been revealed that the mechanism of the reversible anticholinesterase action depends essentially both on the enzyme nature and on the structures of substrate and inhibitor. The transfer from cation-containing to hydrophobic substrates increased essentially the contribution of uncompetitive component of the inhibitory constant. In the presence of butyric acid esters (butyrylcholine, butyrylthiocholine), the potency of inhibitors was lower than at hydrolysis of the corresponding acetates. The effect of the substrate structure on the mechanism of reversible inhibition was revealed to a greater extent in reactions with participation of squid cholinesterases.     

Alkylammonium chlorobenzoates are a new group of ester-containing reversible inhibitors of cholinesterases of different animals

Interaction with cholinesterases (ChEs) of nine specially synthesized derivatives of dimethylaminoalkyl esters of 2-chloro-and 2,4-dichlorobenzoic acids and their iodoalkylates is studied. Used as enzyme sources were partially purified preparations of acetylcholinesterase (AChE) from human erythrocytes and butyrylcholinesterase (BChE) from horse blood serum, as well as water homogenates of the frog Rana temporaria brain and of the Pacific squid Todarodes pacificus optical ganglia. The studied benzoates failed to be hydrolyzed by the studied ChEs at the enzyme concentrations exceeding 10 times those used for determination of the acetylthiocholine hydrolysis rate. These compounds have turned out to be reversible inhibitors of ChEs of the mixed-noncompetitive type of action. Effects on the anticholinesterase activity of such structural elements of the inhibitors as the acidic part of the benzoate molecule, length of polymethylene chain in the molecule alcoholic part, and the structure of ammonium group are studied. This study has allowed revealing some peculiarities of the reaction capability of vertebrate and invertebrate ChEs.     

The specificity of the interaction of the cholinesterases in Far Eastern squid and certain vertebrates with reversible inhibitors

Studies have been made of the effect of three groups of ammonia reversible inhibitors on the activity of erythrocyte acetylcholinesterase, serum butyrylcholinesterase, cholinesterase from frog brain, as well as cholinesterases from the optical ganglia of the Pacific and three populations of the commander squids. Determination of kinetic parameters of the reversible inhibition of these enzymes revealed differences resulting from the specific structure of their catalytic centers. Tetramethylammonium assay confirmed different properties of cholinesterases in individuals of the commander squid from various habitats in the Bering Sea; this finding may be taken as an indication of intraspecific differentiation of these cephalopods. Certain similarity was noted in the inhibitory specificity of cholinesterases from the Pacific and "southern" commander squids with the overlapping habitats.     

Comparative-enzymological study of cholinesterases from optic ganglia of the Commander squid Berryteuthis magister individuals inhabiting different zones of the species area

In this review a comparative analysis is performed of enzymological characteristics of cholinesterase (ChE) from optic ganglia of individuals of the Commander squid Berryteuthis magister caught in 8 zones of its habitation area in the northern-western Pacific aquatorium, of ChE of the Pacific squid Todarodes pacificus as well as of the “standard” acetylcholinesterase from human erythrocytes and butyrylcholinesterase from horse blood serum. By the method of the substrate-inhibitor analysis there was shown homogeneity of ChE preparations from the B. magister individuals from different habitation zones. Kinetic parameters of the enzymatic hydrolysis of 8 ester substrates are presented as well as the data on study of identity of ChE properties in the B. magister individuals from different habitation zones. Study of the process of the ChE reversible inhibition from the Commander squid individuals under action of 57 mono- and bisonium inhibitors has revealed differences in ChE properties in squid individuals from isolates in different zones of the habitation area, which argues in favor of the existence of intraspecies groups of the Commander squid B. magister.     

Organosilicon reversible inhibitors of cholinesterases of different animals

The review presents data on cholinesterase effects of 28 specially synthesized organosilicon compounds (monoonium, organoelement, and bisonium derivatives) studied as reversible inhibitors of acetylcholinesterase (acetyl-ChE) of human erythrocytes, butyryl-ChE of horse blood serum, ChE of brain of common frog Rana temporaria, ChE of the optical ganglia tissue of Pacific squid Todarodes pacificus and of individuals of Commandor squid Berryteuthis magister from various habitats in the Northwestern aquatoria of the Pacific ocean. Among the tested compounds, there are revealed highly specific inhibitors of mammalian ChE as well as of ChE of the B. magister individuals from various habitats.     

Inhibition of Human Blood Acetylcholinesterase and Butyrylcholinesterase by Some Alkaloids

A comparative study has been carried out on effects of berberine (diisoquinoline alkaloid) and sanguinarine and chelidonine (benzophenanthridine alkaloids( on erythrocyte acetylcholinesterase and serum butyrylcholinesterase from human blood. The studied alkaloids have been shown to be strong reversible inhibitors of the cholinesterase activity. Acetylcholinesterase is more sensitive to their action, than butyrylcholinesterase. The type of reversible inhibition was determined, and inhibitor constants were calculated. It is revealed that the character of inhibition is identical for the both cholinesterases. Berberine and sanguinarine are competitive-noncompetitive inhibitors, whereas chelidonine, a competitive inhibitor.     

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.     

Comparative-enzymological study of cholinesterases from optic ganglia of the Commander squid Berryteuthis magister individuals inhabiting different zones of the species areal

In this review a comparative analysis is performed of enzymological characteristics of cholinesterase (ChE) from optic ganglia of individuals of the Commander squid Berryteuthis magister caught in 8 zones of its habitation areal in the northern-western Pacific aquatorium, of ChE of the Pacific squid Todarodes pacificus as well as of the "standard" acetylcholinesterase from human erythrocytes and butyrylcholinesterase from horse blood serum. By the method of the substrate-inhibitor analysis there was shown heterogeneity of ChE preparations from the B. magister individuals from different habitation zones. Kinetic parameters of the enzymatic hydrolysis of 8 ester substrates are presented as well as the data on study of inhibitory specificity with use of 20 irreversible organophosphorus inhibitors, which show identity of ChE properties in the B. magister individuals from different habitation zones. Study of the process of the ChE reversible inhibition from the Commander squid individuals under action of 57 mono- and bisonium inhibitors has revealed differences in ChE properties of squid individuals from isolates in different zones of the habitation areal, which argues in favor of the existence of intraspecies groups of the Commander squid B. magister.     

Siliconorganic reversible inhibitors of cholinesterases of various animals

The review present data on cholinesterase effects of 28 specially synthesized siliconorganic compounds (monoonium, clementorganic, and bisonium derivatives) studied as reversible inhibitors of acetylcholinesterase (acetyl-ChE) of human erythrocytes, butyryl-ChE of horse blood serum, ChE of brain of common frog Rana temporaria, ChE of the optical ganglia tissue of Pacific squid Todarodes pacificus and of individuals of Commandor squid Berryteuthis magister from various habitats in the Northwestern aquatoria of the Pacific ocean. Among the tested compounds, there are revealed highly specific inhibitors of mammalian ChE as well as of ChE of the B. magister individuals from various habitats.     

Quaternary phosphonium reversible inhibitors of cholinesterases of different animals

The quaternary phosphonium compounds were found to be reversible inhibitors of cholinesterases of different animals and showed species-specificity of action depending on their inhibitor structure. We have revealed difference in the inhibitory specificity of various acetylcholinesterase preparations. A difference has been shown in inhibitory parameters of optic ganglia of individuals of the squid Berryteuthis magister from different habitat areas. For the first time in comparing phosphonium and ammonium isologues-tetrabutyl- and tributylhexyl derivatives, it has been shown that they are agents practically similar by the character of the anticholinesterase action.     

Comparative study of cholinergic activity of some tropolone and isoquinoline alkaloids

Comparative study was performed of action of a group of 15 isoquinoline homoproaporphine and homoaporphine alkaloids, 10 tropolone colchicine alkaloids and their lumoderivatives that were isolated from corms of a representative of the lily family, the showy autumn crocus Colchicum speciosum Stev. on activity of mammalian erythrocyte acetylcholinesterase and serum butyrylcholinesterase. The studied compounds have turned out to be moderate-potency reversible inhibitors of the studied cholinesterases and to show to a certain degree some specificity of action towards different enzymes both quantitatively, by the ratio of total inhibitor constant values, and qualitatively, by the type of mechanism of the enzymatic activity inhibition. The overwhelming majority of the studied alkaloids revealed certain specificity towards butyrylcholinesterase. An exception was colchamine.     

Kinetic analysis of the “substrate protective effect” in cholinesterases of different origin

The authors’ own and literature data are summarized on interaction of 17 irreversible organophosphorus inhibitors with different types of cholinesterases (ChE): erythrocyte acetylcholinesterase (AChE), serum butyrylcholinesterase (BuChE), and cholinesterase of the Pacific squidTodarodes pacificus, in the presence of 9 substrates. The kinetic analysis of the “substrate protective effect” based on A.P. Brestkin’s equation is performed, and the current interpretation of individual components of this process is done. An essential effect of the inhibitor structure on individual phases of the reaction is revealed. Among choline substrates, only formylcholine did not show a protective effect. The inability of an uncationic substrate, phenylacetate, to regulate ChE reactivity is confirmed. Among the studied ChE, the highest substrate protective effect was revealed in the Pacific squid ChE.     

Quaternary phosphonium reversibile inhibitors of cholinesterases of different animals

Quaternary phosphonium compounds were found to be reversible inhibitors of cholinesterases of various animals and showed species-specificity of action depending on the inhibitor structure. It became possible to reveal difference in inhibitory specificity of various preparations of acetylcholinesterases. A difference has been shown in inhibitory parameters of the series of phosphonium toward cholinesterase of visual ganglia of individuals of the squid Berryteuthis magister from different zones of the habitat areal. For the first time, when comparing phosphonium and ammonium isologues - tetrabutyl- and tributylhe-xyl derivatives, it has been shown that they are agents practically similar by the character of anticholinesterase action.     

How thionphosphonates inhibit activity of different cholinesterases

Analysis of mechanism of reversible inhibition of human erythrocyte acetylcholinesterase (AChE), of horse serum cholinesterase (ChE), and ChE of optical ganglia tissue of individuals of the Commander squid Berryleuthis magister from various habitat zones was studied under effect of thionphosphonates (P=S), derivatives of piperidine, morpholine, perhydroazepine as well as several heterocyclic model compounds. Data of comparative inhibitory specificity have allowed us to suggest that thionphosphonates are sorbed in the area of cholinesterase esterase center through the phosphoryl part of the inhibitor molecule, rather than through its heterocyclic grouping. An advantage in the antienzyme efficiency of thionphosphonates (P=S) over phosphonates (P=O) is revealed. Effect of the ion strength is used for analysis of contribution of the hydrophobic—hydrophilic interaction in the enzyme—inhibitor system.     

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.     

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.     

Oxidation at C-16 enhances butyrylcholinesterase inhibition in lupane triterpenoids

A set of triterpenoids with different grades of oxidation in the lupane skeleton were prepared and evaluated as cholinesterase inhibitors. Allylic oxidation with selenium oxide and Jones’s oxidation were employed to obtain mono-, di- and tri-oxolupanes, starting from calenduladiol (1) and lupeol (3). All the derivatives showed a selective inhibition of butyrylcholinesterase over acetylcholinesterase (BChE vs. AChE). A kinetic study proved that compounds 2 and 9, the more potent inhibitors of the series, act as competitive inhibitors. Molecular modeling was used to understand their interaction with BChE, the role of carbonyl at C-16 and the selectivity towards this enzyme over AChE. These results indicate that oxidation at C-16 of the lupane skeleton is a key transformation in order to improve the cholinesterase inhibition of these compounds.