Phenolic Metabolites in the Urine and Plasma of Healthy Men After Acute Intake of Purple Potato Extract Rich in Methoxysubstituted Monoacylated Anthocyanins.

SCOPE: Structurally stable acylated anthocyanins have potential in various food applications but the effects of acylation and methoxysubstitution on anthocyanin metabolism are poorly understood. This is the first study thoroughly investigating phenolic metabolites, their time-wise changes, and pharmacokinetics following an acute intake of methoxysubstituted monoacylated anthocyanins. METHODS AND RESULTS: Healthy male volunteers (n = 17) consumed a yellow potato meal with and without purple potato extract rich in acylated anthocyanins (152 mg) and hydroxycinnamic acid conjugates (140 mg). Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) is used for identification and quantification of metabolites from serially collected urine and plasma. While the parent anthocyanins are not detected, 28 phenolic metabolites from urine and 14 from plasma are quantified, including hydroxybenzoic and hydroxycinnamic acids and protocatechuic acid sulfates and glucuronides; three (catechol, gallic acid-4-O-glucuronide, and 2-methoxybenzoic acid) are detected for the first time after anthocyanin-rich food. Urinary hippuric acid is the most abundant with an increase of 139 µM mM-1 creatinine after the treatment. A large additional set of tentatively identified phenolic metabolites are detected. Late urinary peak time values suggest colonic degradation. CONCLUSION: Acylated anthocyanins are more bioavailable than earlier reported after extensive degradation in human and/or colonial metabolism to phenolic metabolites, which may be further conjugated and demethylated.

Effects of Anthocyanin Extracts from Bilberry (Vaccinium myrtillus L.) and Purple Potato (Solanum tuberosum L. var. 'Synkeä Sakari') on the Plasma Metabolomic Profile of Zucker Diabetic Fatty Rats.

This study compared the effects of the nonacylated and acylated anthocyanin-rich extracts on plasma metabolic profiles of Zucker diabetic fatty rats. The rats were fed with the nonacylated anthocyanin extract from bilberries (NAAB) or the acylated anthocyanin extract from purple potatoes (AAPP) at daily doses of 25 and 50 mg/kg body weight for 8 weeks. 1H NMR metabolomics was used to study the changes in plasma metabolites. A reduced fasting plasma glucose level was seen in all anthocyanin-fed groups, especially in the groups fed with NAAB. Both NAAB and AAPP decreased the levels of branched-chain amino acids and improved lipid profiles. AAPP increased the glutamine/glutamate ratio and decreased the levels of glycerol and metabolites involved in glycolysis, suggesting improved insulin sensitivity, gluconeogenesis, and glycolysis. AAPP decreased the hepatic TBC1D1 and G6PC messenger RNA level, suggesting regulation of gluconeogenesis and lipogenesis. This study indicated that AAPP and NAAB affected the plasma metabolic profile of diabetic rats differently.

Anthocyanin-rich extract from purple potatoes decreases postprandial glycemic response and affects inflammation markers in healthy men.

Our recent clinical study suggested that polyphenol-rich purple potatoes lowered postprandial glycemia and insulinemia compared to yellow potatoes. Here, 17 healthy male volunteers consumed yellow potatoes with or without purple potato extract (PPE, extracted with water/ethanol/acetic acid) rich in acylated anthocyanins (152 mg) and other phenolics (140 mg) in a randomized cross-over trial. Ethanol-free PPE decreased the incremental area under the curve for glucose (p = 0.019) and insulin (p = 0.015) until 120 min after the meal, glucose at 20 min (p = 0.015) and 40 min (p = 0.004), and insulin at 20 min (p = 0.003), 40 min (p = 0.004) and 60 min (p = 0.005) after the meal. PPE affected some of the studied 90 inflammation markers after meal; for example insulin-like hormone FGF-19 levels were elevated at 240 min (p = 0.001). These results indicate that PPE alleviates postprandial glycemia and insulinemia, and affects postprandial inflammation.