Upper Rim Of Macrocycle Research Articles

Calix[4]arene C-90 and its analogs activate ATPase of the myometrium myosin subfragment-1.

Numerous female reproductive abnormalities are consequences of disorders in uterus smooth muscle (myometrium) contractile function. In this work, we described activators of ATPase, which could be used for development of effective treatments for correcting this dysfunction. Myosin ATPase localized in the catalytic domain of myosin subfragment-1 transforms a chemical energy deposited in macroergic bonds of ATP into mechanical movement. It was shown that сalix[4]arene C-90 and its structural analogs functionalized at the upper rim of macrocycle with four or at least two N-phenylsulfonуltrifluoroacetamidine groups, are able to activate ATP hydrolysis catalyzed by myometrium myosin subfragment-1. It was shown with the method of computer modeling that N-phenylsulfonуltrifluoroacetamidine groups of calix[4]arene C-90 interact with responsible for binding, coordination and the hydrolysis of ATP amino acid residues of myosin subfragment-1. The results can be used for further research aimed at using calix[4]arene C-90 and its analogs as pharmacological compounds that can effectively normalize myometrium contractile hypofunction.

The role of preorganization of hydrazone moieties on tetrathiacalix[4]arene platform for their conformational and binding properties from the view of structural investigation

The IR, 1H and 13C NMR data, as well as conformation and dynamic behaviour of tetrathiacalix[4]arenes functionalized by hydrazone fragments are reported. The influence of isomers of thiacalix[4]arenes, the removal of tert-butyl groups from upper rim of macrocycle and the replacement of a phenyl substituents in the hydrazone fragments by 2-pyridyl ones on conformational properties of the compounds are discussed. The structural peculiarities of the cone isomer of 25,26,27,28-tetrakis[N 2-(2-pyridinylmethylidene)hydrazinocarbonylmethyloxy]-2,8,14,20-tetrathiacalix[4]arene and the 1, 3-alternate isomer of 25,26,27,28-tetrakis[N 2-(benzylidene)hydrazinocarbonylmethyloxy]-2,8,14,20-tetrathiacalix[4]arene in solution are compared with their crystal structures obtained by X-ray analysis. The correlation between extraction efficiency data obtained for these compounds earlier and the conformational features of calix[4]arene hydrazone derivatives studied in this work was performed.

Binding of polar organic substrates by amphiphilic calixresorcin[4]arenes in the solution bulk and on the surface of anion-exchange resin

A comparative study is performed on the binding properties of free and immobilized water-soluble calixresorcin[4]arenes with respect to neutral organic molecules, one of which is capable of forming inclusion complexes, while the other possesses a fairly high potential of many-point hydrogen binding with the groups of the upper rim of macrocycle (parent substances of drugs Xymedon® and Dimephosphon®). It is revealed that macrocycle tetraanions present in aqueous solutions can be electrostatically immobilized on anion-exchange resin Amberlite IRA-900 Cl. The immobilization leads to changes in the binding mechanism of studied substrates due to the formation of calixresorcinarene aggregates on the surface of ion-exchange resin. The sorption of individual substrates and their mixtures is considered and models of the structure of immobilized aggregates of macrocycles and the mechanism of the binding of neutral guest molecules by the aggregates are proposed.