Unravelling mechanisms of dietary flavonoid-mediated health effects: effects on lipid metabolism and genotoxicity
| Jazyk: | angličtina |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
mice
Novel Foods & Agrochains BU Toxicologie Toxicology flavanoids liver Novel Foods & Agroketens genotoxiciteit fatty acids quercetin body weight flavonolen lipid metabolism quercetine heterocyclic compounds flavanoïden Toxicologie VLAG lichaamsgewicht hart- en vaatziekten BU Toxicology genotoxicity lipidenmetabolisme health flavonols lever adipose tissue cardiovascular diseases nutrition muizen vetweefsel Human and Animal Physiology vetzuren flavonoids Fysiologie van Mens en Dier flavonoïden gezondheid voeding |
| Popis: | Summary Consumption of foods containing flavonoids is associated with a reduced risk of cardiovascular diseases (CVD), possibly by lipid-lowering effects. On the other hand, for one of these flavonoids, quercetin, also genotoxicity was shown especially in in vitro bioassays. Therefore, the first aim of this thesis was to identify mechanisms underlying potential beneficial health effects of flavonoids. The focus was on hepatic lipid metabolism and circulating lipids and a molecular and physiological approach was used. Secondly, we aimed to study the potential in vivo genotoxic effects of quercetin by transcriptome analyses in liver and small intestine, since these represent the tissues of first contact exposed to relatively high levels upon oral intake of flavonoids. Circulating lipids are important CVD-related risk markers, which are in general determined with commercially available enzyme-based assays. However, the usual enzyme in these assays, peroxidase, has previously been reported to be inhibited by flavonoids. Therefore, we have studied in chapter 2 whether these assays can adequately be used in flavonoid research. We observed that various flavonoid aglycones interfere with peroxidase used in triglycerides (TG) and free fatty acids (FFA) enzymatic assays, reporting incorrect lower TG and FFA levels than actually present. Furthermore, addition of metabolites such as isorhamnetin or quercetin-3-O-glucuronide, the major metabolite of quercetin in human and rat plasma, to murine serum also resulted in a significant reduction of the detected TG levels, while a trend was seen towards reduced FFA levels. It can be concluded that when applying these biochemical assays, vigilance is needed and alternative analytical methods assessing FFA or TG levels should preferably be applied for studying the biological effects of flavonoids on TG and FFA levels. In chapter 3 mechanistic and physiological effects of quercetin on hepatic lipid metabolism were studied. C57BL/6JOlaHsd male adult mice received a mild high-fat (30 en%) diet without or with supplementation of 0.33% (w/w) quercetin for 12 weeks. Gas chromatography and 1H-NMR were used to quantitatively measure serum lipid profiles. Whole genome microarray analysis of liver tissue was used to identify potential mechanisms underlying altered circulating lipid levels by quercetin supplementation. Body weight, energy intake and hepatic lipid accumulation did not differ significantly between the quercetin and the control group. In serum of quercetin-fed mice, TG levels were decreased by 14% (p |
| Databáze: | OpenAIRE |
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