Title:Phenolic Compounds as Antioxidants: Carbonic Anhydrase Isoenzymes Inhibitors
VOLUME: 13 ISSUE: 3
Author(s):Ilhami Gulcin and Sukru Beydemir
Affiliation:Ataturk University, Faculty of Sciences, Department of Chemistry, 25240-Erzurum-Turkey.
Keywords:Antioxidant activity, free radical, phenolic compounds, carbonic anhydrase, CA isoenzymes, enzyme purification,
enzyme inhibition, pH regulation
Abstract:Antioxidant compounds can scavenge free radicals and increase shelf life by retarding the process of lipid
peroxidation, which is one of the major reasons for deterioration of food, medicine and pharmaceutical products during
processing and storage. An antioxidant molecule has been defined as any substance when found in low concentrations
compared to that of an oxidizable substrate significantly delays or inhibits the oxidation. The major antioxidant
compounds are especially phenolics and flavonoids, which are responsible for their health benefits. Carbonic anhydrase
(EC 4.2.1.1., CA) is a pH regulatory/metabolic enzyme in all life kingdoms, being found in organisms all over the
phylogenetic tree. It catalyzes the hydration of carbon dioxide (CO2) to bicarbonate (HCO3
-) and the corresponding
dehydration of HCO3
-in acidic medium with regeneration of CO2. Also, CA isoforms are found in a variety of tissues
where they participate in several important biological processes such as acid-base balance, respiration, carbon dioxide and
ion transport, bone resorption, ureagenesis, gluconeogenesis, lipogenesis and electrolyte secretion. On the other hand, the
phenyl moiety of phenol was found to lay in the hydrophobic part of the CA active site, where CO2, the physiologic
substrate of the CAs, binds in the precatalytic complex, explaining thus the behavior of phenol as a unique CO2
competitive inhibitor. This review consists of two main sections. The first section is devoted to main phenolic antioxidant
compounds in the foodstuffs and beverages. The second general section is about some definitions of CA inhibitory effects
of the main phenolic compounds used for antioxidant activity. The phenolic compounds and acids had marked especially
CA I and CA II inhibitory effects and might be used as leads for generating CA isoenzyme inhibitors. This class of
compounds may lead to isoform-selective inhibitors targeting just one or few of the medicinally relevant CAs. In addition,
there are given some chemical and kinetic basis and technical details related to phenolic antioxidant compounds and
carbonic anhydrase isoenzymes.
