| Summary: | Scope: Insulin-regulated glucose metabolism in cells is critical for proper metabolic functioning, and insulin resistance leads to type 2 diabetes. We performed a human study to assess the availability of structurally related dietary flavonols and tested their ability to affect cellular glucose uptake, metabolism, and glucose transporter gene expression in a liver HepG2 cell model. Methods and results: Eight healthy volunteers consumed a meal containing galangin, kaempferol, quercetin, and myricetin. In plasma, myricetin was absent, but the others were present, mostly as conjugates. In HepG2 cells, a combination of galangin, kaempferol, and quercetin (5 μM each) for 12 h increased the acute uptake of [U-14C]-glucose and 2-[U-14C]-deoxyglucose by almost 100 and ∼10%, respectively. All of the combinations increased glucose metabolism, but the effect on transport was less pronounced and mixed. A mixture of all flavonols significantly increased mRNA expression of the main glucose transporter Glut1 in HepG2 cells. Conclusion: These results for the first time show the presence of galangin conjugates in human plasma, and allow direct comparison between absorption of flavonols. A combination of flavonols has the potential to modulate sugar metabolism, both uptake into cells as evident from effects on deoxyglucose, and also further cellular glucose metabolism. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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