Nicole H. P. Cnubben

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In vitro studies were performed to elucidate the human cytochrome P450 enzymes involved in the bioactivation of methyleugenol to its proximate carcinogen 1'-hydroxymethyleugenol. Incubations with Supersomes, expressing individual P450 enzymes to a high level, revealed that P450 1A2, 2A6, 2C9, 2C19, and 2D6 are intrinsically able to 1'-hydroxylate(More)
The regioselectivity of phase II conjugation of flavonoids is expected to be of importance for their biological activity. In the present study, the regioselectivity of phase II biotransformation of the model flavonoids luteolin and quercetin by UDP-glucuronosyltransferases was investigated. Identification of the metabolites formed in microsomal incubations(More)
In the present study, the effects of a large series of flavonoids on multidrug resistance proteins (MRPs) were studied in MRP1 and MRP2 transfected MDCKII cells. The results were used to define the structural requirements of flavonoids necessary for potent inhibition of MRP1- and MRP2-mediated calcein transport in a cellular model. Several of the(More)
The potential benefits of a high fruit and vegetable intake on the antioxidant status and on relevant biomarkers of oxidative damage to lipids, proteins and DNA and on (functional) markers of oxidative stress were evaluated. A randomized, free living, open placebo-controlled cross-over trial of 3 wk, with a 2-wk washout period between treatments, was(More)
BACKGROUND Low-grade chronic inflammation in overweight subjects is thought to play an important role in disease development. OBJECTIVE It was hypothesized that specific dietary components are able to reduce low-grade inflammation as well as metabolic and oxidative stress. DESIGN Dietary products [resveratrol, green tea extract, alpha-tocopherol,(More)
The human multidrug resistance protein MRP1 mediates transport of organic substrates conjugated to glutathione, glucuronide, or sulfate. The naturally occurring prostaglandins A1 and A2 can form two diastereomeric glutathione S-conjugates, and it has been speculated that these might be substrates for MRP1. Here we present evidence that polarized MDCKII(More)
Natural antioxidants like vitamin C, vitamin E, carotenoids, and polyphenols like flavonoids, are at present generally considered to be beneficial components from fruit and vegetables. The anti-oxidative properties of these compounds are often claimed to be responsible for various beneficial health effects of these food ingredients. Together these studies(More)
This review summarizes current knowledge on glutathione (GSH) associated cellular processes that play a central role in defense against oxidative stress. GSH itself is a critical factor in maintaining the cellular redox balance and has been demonstrated to be involved in regulation of cell signalling and repair pathways. Enhanced expression of various(More)
In vitro and in vivo skin absorption of the pesticide propoxur (2-isopropoxyphenyl N-methyl carbamate, commercially Baygon(TM) and Unden (TM); log Po/w 1.56, MW 209.2) was investigated. In vivo studies were performed in rats and human volunteers, applying the test compound to the dorsal skin and the volar aspect of the forearm, respectively. In vitro(More)
The objective of this study was to investigate the structural requirements necessary for inhibition of glutathione S-transferase P1-1 (GSTP1-1) and GS-X pump (MRP1 and MRP2) activity by structurally related flavonoids, in GSTP1-1 transfected MCF7 cells (pMTG5). The results reveal that GSTP1-1 activity in MCF7 pMTG5 cells can be inhibited by some flavonoids.(More)