In vitro effects of myricetin, morin, apigenin, (+)-taxifolin, (+)-catechin, (-)-epicatechin, naringenin and naringin on cytochrome b5 reduction by purified NADH-cytochrome b5 reductase

Celik, Haydar
Kosar, Muberra
Arinc, Emel
The microsomal NADH-dependent electron transport system consisting of cytochrome b5 reductase and cytochrome b5 participates in a number of physiologically important processes including lipid metabolism as well as is involved in the metabolism of various drug and xenobiotics. In the present study, we assessed the inhibitory effects of eight dietary flavonoids representing five distinct chemical classes on cytochrome b5 reduction by purified cytochrome b5 reductase. From the flavonoids tested, myricetin was the most potent in inhibiting cytochrome b5 reduction with an IC50 value of 0.35 mu M. Myricetin inhibited b5 reductase noncompetitively with a K-i of 0.21 mu M with respect to cofactor NADH, and exhibited a non-linear relationship indicating non-Michaelis-Menten kinetic binding with respect to cytochrome b5. In contrast to the potent inhibitory activity of myricetin, (+)-taxifolin was found to be a weak inhibitor (IC50 =.9.8 mu M). The remaining flavonoids were inactive within the concentration range tested (1-50 mu M). Analysis of structure-activity data suggested that simultaneous presence of three OH groups in ring B is a primary structural determinant for a potent enzyme inhibition. Our results suggest that inhibition of the activity of this system by myricetin or myricetin containing diets may influence the metabolism of therapeutic drugs as well as detoxification of xenobiotics. (c) 2013 Elsevier Ireland Ltd. All rights reserved.


Association between polymorphisms of EPHX1 and XRCC1 genes and the risk of childhood acute lymphoblastic leukemia
TÜMER, TUĞBA; Sahin, Gurses; Arinc, Emel (Springer Science and Business Media LLC, 2012-03-01)
Microsomal epoxide hydrolase, EPHX1, plays a central role in the detoxification of potentially genotoxic epoxide intermediates. In this study, we firstly aimed to investigate the relationship between EPHX1 Tyr113His and His139Arg variants, and the risk of incidence of childhood acute lymphoblastic leukemia (ALL) in Turkish population, comprised of 190 healthy controls and 167 ALL patients. In exon 3 Tyr113His polymorphism, 113His/His homozygous mutant genotype with slow activity was 18.6% in ALL patients an...
Effects of diabetes on rabbit kidney and lung CYP2E1 and CYP2B4 expression and drug metabolism and potentiation of carcinogenic activity of N-nitrosodimethylamine in kidney and lung
Arinc, Emel; Arslan, Sevki; Bozcaarmutlu, Azra; Adalı, Orhan (Elsevier BV, 2007-01-01)
There are limited number of studies regarding the influence of diabetes on the regulation of cytochrome P450s and associated drug metabolizing enzyme activities especially in extrahepatic tissues such as kidney. However, there is almost no such study in lung. Alloxan-induced diabetes did not change CYP2B4 expression as measured with immunoblot analysis and associated enzyme, benzphetamine N-demethylase, activity in rabbit kidney and lung. Induction of cytochrome P4502E1 by diabetes was identified by immunoc...
Methicillin-Resistant Bacteria Inhabiting Surface Waters Monitored by mecA-Targeted Oligonucleotide Probes
Seyedmonir, Elnaz; Yılmaz, Fadime; İçgen, Bülent (Springer Science and Business Media LLC, 2016-08-01)
Part of a 20-60 kb staphylococcal chromosome cassette called mecA encodes low-affinity penicillin-binding protein PBP2a and causes methicillin resistance. Among all methicillin-resistant bacteria, methicillin-resistant Staphylococcus aureus is a major pathogen and main concern worldwide. Although the origin of the mecA is not very well-defined, mecA homologues are also ubiquitous in methicillin-resistant non-staphylococcal bacteria. Due to the dissemination of methicillin resistance through the transmission...
Hair arsenic concentrations of residents living in Nevsehir province, Turkey
Altun, Beril; ERTAŞ, Nusret; Alshana, Usama; Hisarli, N. Deniz; Asik, Elif; ÇAKMAK DEMİRCİGİL, GONCA; KADIOĞLU, ELA; Celebi, Celalettin R.; Atabey, Esref; Ataman, Osman Yavuz; Serce, Hakan; Bilir, Nazmi; Tuncer, A. Murat; BURGAZ, SEMA (2013-08-28)
Arsenic-contaminated drinking water affects millions of people worldwide, causing substantial mortality and morbidity from cancers, and cardiovascular and respiratory diseases. Geological studies have recently shown that arsenic (As) levels in drinking water ranged from 11 μg L−1 to 500 μg L−1 in Nevsehir-province. However, little is known about the level of arsenic exposure in this area. This study as a part of ongoing molecular epidemiology research concerning carcinogenic risk related to arsenic exposur...
Differential effects of diabetes on CYP2E1 and CYP2B4 proteins and associated drug metabolizing enzyme activities in rabbit liver
Arinc, E; Arslan, S; Adalı, Orhan (Springer Science and Business Media LLC, 2005-08-01)
The effects of diabetes on cytochrome P450 (CYP)-dependent drug metabolizing enzymes are yet to be clarified. The most widely used animals in these studies have been rats, and information on the effects of diabetes on rabbit liver drug metabolizing enzymes have been unavailable until now. In this study, for the first time, a significant induction of liver CYP2E1 is demonstrated via immunoblot analysis in alloxan-induced rabbits. The CYP2E1 content of diabetic microsomes was highly correlated with the activi...
Citation Formats
H. Celik, M. Kosar, and E. Arinc, “In vitro effects of myricetin, morin, apigenin, (+)-taxifolin, (+)-catechin, (-)-epicatechin, naringenin and naringin on cytochrome b5 reduction by purified NADH-cytochrome b5 reductase,” TOXICOLOGY, pp. 34–40, 2013, Accessed: 00, 2020. [Online]. Available: