title: Inhibition of Na+,K(+)-ATPase by flavonoids and their inotropic effect. Investigation of the structure-activity relationship.
abstract: The relationship between the structures of 39 natural flavonoids (including flavones, flavonols, flavonones, and isoflavones) and their inhibitory and positive inotropic effects have been found. It is shown that flavonoids considerably inhibit the activity of the purified preparation of pig kidney medulla Na+,K(+)-ATPase with Ki = 1.4-22.2 microM and some of the flavonoids studied exert positive inotropic effect on the papillary muscle. Flavones and flavonols, containing hydroxyl groups inside the phenyl radical in ortho- and vicinal positions, exhibit high inhibitory and positive inotropic effects. The inhibitory and positive inotropic effects of flavonoid glycosides and methoxyflavonoids are less pronounced. The presence of dimethylallyl groups in flavonones leads to the increase in the inhibitory and positive activities. Isoflavones produced virtually no effect on the enzyme and the isolated heart muscle. The effect of quercetin on the structure of Na+,K(+)-ATPase was studied by the fluorescence method.
authors.affiliation: Department of Biophysics, Faculty of Biology, Tashkent University, Republic Uzbekistan.
authors.forename: F T
authors.initials: FT
authors.lastname: Umarova
authors.forename: Z A
authors.initials: ZA
authors.lastname: Khushbactova
authors.forename: E H
authors.initials: EH
authors.lastname: Batirov
authors.forename: V M
authors.initials: VM
authors.lastname: Mekler
mesh_terms: D000818:Animals; D002316:Cardiotonic Agents / Q000737:chemistry / Q000494:pharmacology*; D004353:Drug Evaluation, Preclinical; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry / Q000494:pharmacology*; D007679:Kidney Medulla / Q000187:drug effects* / Q000201:enzymology; D007700:Kinetics; D015394:Molecular Structure; D009124:Muscle Proteins / Q000037:antagonists & inhibitors; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013329:Structure-Activity Relationship; D013552:Swine
chemical_list: D002316:Cardiotonic Agents; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009124:Muscle Proteins; D000254:Sodium-Potassium-Exchanging ATPase