INHIBITION THE RAT CYTOPLASMATIC ALCOHOL DEHYDROGENASE BY SUBSTITUTED BENZOIC ACID AMIDES OF RATS’ LIVER

Abstract

The main purpose of this work was to investigate the influence of substituted benzoic acid amides on the activity of NAD+ dependent alcohol dehydrogenase in vitro, to study the kinetic nature of the  effective  inhibitors  interaction  with  the  enzyme,  to  establish  the  relationship  between  the  chemical structure of compounds and their influence on the rate of the enzymatic reaction. The  studies were  carried  out  using rat  liver  cytoplasmic  alcohol  dehydrogenase, which  was  obtained  by  differential  centrifugation.  The  enzyme  activity  was  determined  by spectrophotometric method. To study the kinetic nature of the enzyme interaction with inhibitors, solutions of
substituted  benzoic  acid  amides  at  concentrations  of  12.5-100  μM  were  used.  The  obtained  data  were presented in double reciprocal coordinates using the Lineweaver-Burk and Yoshino-Murakami methods.   Findings. An effective reversible inhibitor of cytoplasmic ADH was revealed among the studied
substituted benzoic acid amides.  2.4-dichloro-5-methylbenzamide inhibited the enzyme activity up to 60%.  It exhibited a mixed character of inhibition in relation to ethanol at saturating concentrations of NAD+. An in-depth study of this process showed that the amide inhibited the enzyme activity in a non-competitive type at  low  ethanol  concentrations  (up  to  2  mM)  with  an  inhibition  constant  of  35  μM.  When  the  alcohol concentration  was increased, the character of inhibition became uncompetitive.   Originality.  The  kinetic  type  of  the  interaction  between  the  NAD+  -  dependent  alcohol dehydrogenase and the new inhibitor of its activity was investigated.   Practical value. The new ADH inhibitor has been identified. It can be used as a potential antidote for poisoning with toxic alcohols and their biotransformation products.