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-(14)C]-glucose and 2-[U-(14)C]-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.
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-(14)C]-glucose and 2-[U-(14)C]-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.
Authors: Elaine A Yu; José O Alemán; Donald R Hoover; Qiuhu Shi; Michael Verano; Kathryn Anastos; Phyllis C Tien; Anjali Sharma; Ani Kardashian; Mardge H Cohen; Elizabeth T Golub; Katherine G Michel; Deborah R Gustafson; Marshall J Glesby Journal: PLoS One Date: 2022-07-08 Impact factor: 3.752