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  • Author: J. Csöllei x
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Relationship between chemical structure, binding affinity and selectivity towards α1-adrenoceptors in the group of substituted n-phenylpiperazines. Part 2*. compounds containing ethane-1,2-diyl connecting chain

The N-phenylpiperazine structures exhibit very extensive multiple receptor activities including the influencing of α1-adrenoceptors (α1-AR). Their antagonistic activity towards α1-AR is intensively applied in the therapy of cardiovascular system diseases - e. g. hypertension as well as in the treatment of benign prostatic hyperplasia. The limited ratio of selective effect on the specific subtypes of the α1-AR by certain drugs used in the practice (azosine-type structures) leads to multiple side effects which includes postural hypotension, syncope or first dose phenomena. The existence of multiple α1-AR subtypes holds promise for the discovery, projection and development of more specific selective drug molecules targeting only one α1-adrenoceptor subtype and making them free from side effects. Towards this aim wide-ranging modifications have been reported in the literature on the "basic" structure of the N-phenylpiperazine-based molecules. The present paper deals with the affinity features of (substituted) N-phenylpiperazines towards α1-ARs in which the structure is a connecting chain formed by (unsubstituted) ethane-1,2-diyl moiety bonded through certain atom or group (S, O, NH, NHCO-fragment, respectively) at the lipophilic part of the molecule.

The efficacy of newly synthesised agent and natural antioxidant treatment in diabetic and hypertensive rats

Hypertension that develops as the result of cardiovascular damage in diabetes is one of the serious complications of diabetes. The aim of this study was to evaluate the changes in levels of oxidative stress and in endothelial NO synthase (eNOS) and heat shock protein 90 (Hsp90) expressions after the treatment of diabetic rats with a newly synthesised heteroarylaminoethanolic derivative 4/1E with potentially beta-adrenergic blockade effects and a strong antioxidant Pycnogenol®. The treatment of 6-weeks duration was indicated in the group of diabetic Wistar rats (DL; streptozotocin (STZ) 3×25 mg/kg i.p.) and hypertensive rats (HL, STZ) with 4/1E in the dose 10 mg/kg i.p. or with Pycnogenol® (DP, HP) in the dose 20 mg/kg p.o. Animals in control groups (C, H, D) received vehiculum. The levels of oxidative stress were assessed in kidney andliver as the activity of N-acetyl-β-D-glucosaminidase (NAGA) and the levels of thiobarbituric acid reactive substances (TBARs). The expression of eNOS and Hsp90 was assessed from the hearts of all animals using SDS-Page and Western blotting.

In our study the effects of newly synthesised drug 4/1E and Pycnogenol® on the levels of oxidative stress were comparable only in diabetic animals. The expression of eNOS was decreased in diabetic, but not hypertensive animals. The treatment with 4/1E did not affect the expression of eNOS unlike the treatment with Pycnogenol® after which the expression was significantly increased. The expression of Hsp90 was increased in both hypertensive and diabetic animals. The treatment with 4/1E was more effective in decreasing Hsp90 expression in both groups of animals than the treatment with Pycnogenol®.

Study of stability of potential betaadrenolytics, derivatives of the [(arylcarbonyl)oxy]aminopropanol by kinetics of alkaline hydrolysis

This work deals with the study of the stability of six derivatives of the [(arylcarbonyl)oxy]amino propanol with carbamate substitution on the benzene ring. The studied compounds are different in the substitution on the amine group in the side chain as well as in the substitution on the carbamate functional group. The hydrolysis of compounds was measured in the aqueous-ethanol sodium hydroxide solution (0.1 mol.l-1) at 25, 37, 45 and 60°C spectrophotometrically in the ultraviolet and visual regions. The studied compounds possess two functional groups, which undergo hydrolysis. The pseudo-first order rate constants of hydrolysis for individual reaction steps were determined. The ester functional group of compounds hydrolyses very quickly in this medium. The compounds possessing the tertiary substitution on the amino group are less stable toward alkaline hydrolysis. The course of hydrolysis of compounds was also investigated by thin layer chromatography (TLC).

Abstract

The aim of this paper is the study of physico-chemical properties of the chosen compounds, derivatives of 2-hydroxy-3-[2-(4-methoxyphenyl) ethylamino]propyl-4-[(alkoxycarbonyl)amino]benzoates and 2-hydroxy-3-[2-(2-methoxyphenyl)ethylamino]propyl-4-[(alkoxycarbonyl) amino]benzoates with potential ultra-short beta-adrenolytic activity. The studied compounds are different in the position of the substituent on the benzene ring in the side chain as well as in the aromatic ring in position 4 with alkyl- (methylto butyl-) carbamate. The physico-chemical characteristics, for example, lipophilicity, surface activity, adsorbability, acidobasic properties etc., are very important for the explanation of the relationship between structure and biological activity of the drug. These parameters serve as the base of quantitative structure-activity study. The goal of this work is to establish the spectral characteristics of studied compounds in UV-area, pKa values, the parameters of lipophilicity (the values of Rf and RM from thin layer chromatography, retention time t´R and capacity factor k´ from liquid chromatography and experimental partition coefficients log P´ values), surface tension, critical micelle concentrations, the adsorbability of compounds expressed by percent of adsorbed compound on active charcoal β% as well as by Freundlich adsorption isotherms. The obtained values are correlated with the parameters characterising the size of molecule, for example, the number of carbon atoms on carbamate functional group.

Abstract

The aim of this work is the study of stability and kinetics of hydrolysis of the chosen compounds, derivatives of 2-hydroxy-3-[2-(4-methoxyphenyl)ethylamino]propyl-4- [(alkoxycarbonyl)amino]benzoates and 2-hydroxy-3-[2-(2-methoxyphenyl)ethylamino] propyl-4-[(alkoxycarbonyl)amino]benzoates with potential ultra-short beta-adrenolytic activity. The studied compounds are different in the position of the substituent on the benzene ring in the side chain as well as in the aromatic ring in position 4 with alkyl- (methyl- to butyl-) carbamate. Thin layer chromatography and UV-area spectrophotometry are used in order to establish the stability of these potential pharmaceuticals. The stability studies of the compounds were examined in acidic and alkaline media, in buffers and due oxidation at room and at elevated temperature chromatographically, and Rf values of incipient products and degradation products were detected. Kinetics of acid and base hydrolysis in various solutions at temperatures 80 °C and 100 °C were examined through UV-area spectrophotometry. Kinetic parameters such as rate constant k, half-life period t1/2 and usable life t90 were determined.