Acylated anthocyanins: A review on their bioavailability and effects on postprandial carbohydrate metabolism and inflammation.

Anthocyanins, the natural red and purple colorants of berries, fruits, vegetables, and tubers, improve carbohydrate metabolism and decrease the risk factors of metabolic disorders, but their industrial use is limited by their chemical instability. Acylation of the glycosyl moieties of anthocyanins, however, changes the chemical properties of anthocyanins and provides enhanced stability. Thus, acylated anthocyanins are more usable as natural colorants and bioactive components of innovative functional foods. Acylated anthocyanins are common in pigmented vegetables and tubers, the consumption of which has the potential to increase the intake of health-promoting anthocyanins as part of the daily diet. For the first time, this review presents the current findings on bioavailability, absorption, metabolism, and health effects of acylated anthocyanins with comparison to more extensively investigated nonacylated anthocyanins. The structural differences between nonacylated and acylated anthocyanins lead to enhanced color stability, altered absorption, bioavailability, in vivo stability, and colonic degradation. The impact of phenolic metabolites and their potential health effects regardless of the low bioavailability of the parent anthocyanins as such is discussed. Here, purple-fleshed potatoes are presented as a globally available, eco-friendly model food rich in acylated anthocyanins, which further highlights the industrial possibilities and nutritional relevance of acylated anthocyanins. This work supports the academic community and industry in food research and development by reviewing the current literature and highlighting gaps of knowledge.

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.

Metabolomic discrimination of the edible mushrooms Kuehneromyces mutabilis and Hypholoma capnoides (Strophariaceae, Agaricales) by NMR spectroscopy.

Two edible, cultivable mushroom species of the family Strophariaceae, Kuehneromyces mutabilis (sheathed woodtuft) and Hypholoma capnoides (conifer tuft), were studied using proton nuclear magnetic resonance metabolomic approach. The variation in the metabolites of the two species and their metabolic behaviour regarding caps and stipes and different collection sites were analysed by multivariate analysis methods. Altogether 169 cap and stipe samples of the mushrooms were investigated. The clearest difference between the species was in the sugar composition, which was more diverse in H. capnoides. When mushroom samples collected from different locations were compared, more variance was found in H. capnoides, whereas K. mutabilis appeared more homogeneous as a species. As far as the caps and stipes were concerned, in both species the amount of α-α-trehalose was clearly higher in the stipes, and the caps contained a larger proportion of the amino acids and organic acids.

NMR metabolome of Borrelia burgdorferi in vitro and in vivo in mice.

Lyme borreliosis (LB), caused by bacteria of the Borrelia burgdorferi sensu lato (Borrelia) species, is the most common tick-borne infection in the northern hemisphere. LB diagnostics is based on clinical evaluation of the patient and on laboratory testing, where the main method is the detection of Borrelia specific antibodies in patient samples. There are, however, shortcomings in the current serology based LB diagnostics, especially its inability to differentiate ongoing infection from a previously treated one. Identification of specific biomarkers of diseases is a growing application of metabolomics. One of the main methods of metabolomics is nuclear magnetic resonance (NMR) spectroscopy. In the present study, our aim was to analyze whether Borrelia growth in vitro and infection in vivo in mice causes specific metabolite differences, and whether NMR can be used to detect them. For this purpose, we performed NMR analyses of in vitro culture medium samples, and of serum and urine samples of Borrelia infected and control mice. The results show, that there were significant differences in the concentrations of several amino acids, energy metabolites and aromatic compounds between Borrelia culture and control media, and between infected and control mouse serum and urine samples. For example, the concentration of L-phenylalanine increases in the Borrelia growth medium and in serum of infected mice, whereas the concentrations of allantoin and trigonelline decrease in the urine of infected mice. Therefore, we conclude that Borrelia infection causes measurable metabolome differences in vitro and in Borrelia infected mouse serum and urine samples, and that these can be detected with NMR.