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1. Carbohydrate Hydrolase-Inhibitory Activity of Juice-Based Phenolic Extracts in Correlation to Their Anthocyanin/Copigment Profile

Author

Kirsten Berger, Johanna Josefine Ostberg-Potthoff, Tamara Bakuradze, Peter Winterhalter, and Elke Richling

Subjects
α-amylase, α-glucosidase, inhibition, red fruits, anthocyanins, phenolic compounds, Organic chemistry, QD241-441
Abstract

Red fruits and their juices are rich sources of polyphenols, especially anthocyanins. Some studies have shown that such polyphenols can inhibit enzymes of the carbohydrate metabolism, such as α-amylase and α-glucosidase, that indirectly regulate blood sugar levels. The presented study examined the in vitro inhibitory activity against α-amylase and α-glucosidase of various phenolic extracts prepared from direct juices, concentrates, and purees of nine different berries which differ in their anthocyanin and copigment profile. Generally, the extracts with the highest phenolic content—aronia (67.7 ± 3.2 g GAE/100 g; cyanidin 3-galactoside; chlorogenic acid), pomegranate (65.7 ± 7.9 g GAE/100 g; cyanidin 3,5-diglucoside; punicalin), and red grape (59.6 ± 2.5 g GAE/100 g; malvidin 3-glucoside; quercetin 3-glucuronide)—showed also one of the highest inhibitory activities against α-amylase (326.9 ± 75.8 μg/mL; 789.7 ± 220.9 μg/mL; 646.1 ± 81.8 μg/mL) and α-glucosidase (115.6 ± 32.5 μg/mL; 127.8 ± 20.1 μg/mL; 160.6 ± 68.4 μg/mL) and, partially, were even more potent inhibitors than acarbose (441 ± 30 μg/mL; 1439 ± 85 μg/mL). Additionally, the investigation of single anthocyanins and glycosylated flavonoids demonstrated a structure- and size-dependent inhibitory activity. In the future in vivo studies are envisaged.

Published
2020
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2. Activity-Guided Fractionation of Red Fruit Extracts for the Identification of Compounds Influencing Glucose Metabolism

Author

Johanna Josefine Ostberg-Potthoff, Kirsten Berger, Elke Richling, and Peter Winterhalter

Subjects
aronia, pomegranate, red grape, polyphenols, HPLC-PDA-MS/MS, α-amylase, α-glucosidase, high-performance countercurrent chromatography (HPCCC), Nutrition. Foods and food supply, TX341-641
Abstract

An activity-guided search for compounds influencing glucose metabolism in extracts from aronia (Aronia melanocarpa, A.), pomegranate (Punica granatum L., P.), and red grape (Vitis vinifera, RG) was carried out. The three extracts were fractionated by means of membrane chromatography to separate the anthocyanins from other noncolored phenolic compounds (copigments). In addition, precipitation with hexane was performed to isolate the polymers (PF). The anthocyanin and copigment fractions (AF, CF) of aronia, pomegranate, and red grape were furthermore fractionated with high-performance countercurrent chromatography (HPCCC) and the subfractions were characterized by HPLC-PDA-MS/MS analyses. Each of the (sub-)fractions was examined by in vitro-tests, i.e., the inhibition of the activity of α-amylase and α-glucosidase. On the basis of this screening, several potent inhibitors of the two enzymes could be identified, which included flavonols (e.g., quercetin), ellagitannins (e.g., pedunculagin), and anthocyanins (e.g., delphinidin-3-glucoside and petunidin-3-glucoside). In the α-glucosidase assay all of the examined fractions and subfractions of the fruit extracts were more active than the positive control acarbose.

Published
2019
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3. Blood Glucose Lowering Effect by an Extract from Aronia (Aronia melanocarpa) - A Pilot Intervention Study

Author

Johanna Josefine Ostberg Potthoff, Tamara Bakuradze, Kirsten Berger, Elke Richling, and Peter Winterhalter

Subjects
Cultural Studies, Glucose lowering, Linguistics and Language, History, Traditional medicine, business.industry, Anthropology, Aronia melanocarpa, Medicine, Aronia, business, Intervention studies, Language and Linguistics
Abstract

Background: The polyphenols from red fruits exhibit protective effects against degenerative diseases, such as diabetes mellitus type 2, cardiovascular disease and others. Objective: In this small pilot intervention study with only ten volunteers, we investigated the influence of phenolic extracts prepared from an aronia juice, and a red grape juice concentrate on peripheral glucose, blood glucose, and insulin after the intake of a drink containing these extracts plus maltodextrin and water. Method: Maltodextrin in water served as control; additionally, phenolic extracts from aronia or grape juice were added. Blood samples were taken before ingestion of the bolus drink, and 30, 60, 90, 120, 180, 240, and 360 min after. Additionally, the peripheral glucose was measured continuously using a commercially available sensor system. Results: In all ten volunteers, the intake of aronia extract (100 mg) reduced both, the peripheral glucose and the blood glucose levels significantly (p≤0.05) in comparison to the control. Blood insulin levels were not affected. Whereas the intake of red grape extract (120 mg) did not reduce the glucose levels, but increased the insulin levels significantly. Conclusion: Our pilot study showed that even low amounts of a phenolic aronia extract could lower the glucose absorption. Thus, due to the blood glucose lowering effects of aronia phenolics in healthy volunteers, these preliminary results warrant further investigation in the frame of a follow- up study with larger number of volunteers.

Published
2021

4. Carbohydrate Hydrolase-Inhibitory Activity of Juice-Based Phenolic Extracts in Correlation to Their Anthocyanin/Copigment Profile

Author

Peter Winterhalter, Johanna Josefine Ostberg-Potthoff, Elke Richling, Kirsten Berger, and Tamara Bakuradze

Subjects
Hydrolases, Cyanidin, Pharmaceutical Science, phenolic compounds, 01 natural sciences, Analytical Chemistry, chemistry.chemical_compound, Drug Discovery, blood glucose, Food science, Chromatography, High Pressure Liquid, Pigmentation, food and beverages, Malvidin, anthocyanins, Hydrolyzable Tannins, inhibition, Fruit and Vegetable Juices, Chemistry (miscellaneous), ddc:540, Molecular Medicine, Quercetin, α-glucosidase, Chlorogenic Acid, Carbohydrates, Article, lcsh:QD241-441, Inhibitory Concentration 50, Chlorogenic acid, lcsh:Organic chemistry, Glycoside Hydrolase Inhibitors, Physical and Theoretical Chemistry, Flavonoids, Phenol, Plant Extracts, 010405 organic chemistry, Punicalin, 010401 analytical chemistry, Organic Chemistry, fungi, Polyphenols, alpha-Glucosidases, Carbohydrate, 0104 chemical sciences, red fruits, α-amylase, chemistry, Polyphenol, Anthocyanin, alpha-Amylases
Abstract

Red fruits and their juices are rich sources of polyphenols, especially anthocyanins. Some studies have shown that such polyphenols can inhibit enzymes of the carbohydrate metabolism, such as &alpha, amylase and &alpha, glucosidase, that indirectly regulate blood sugar levels. The presented study examined the in vitro inhibitory activity against &alpha, glucosidase of various phenolic extracts prepared from direct juices, concentrates, and purees of nine different berries which differ in their anthocyanin and copigment profile. Generally, the extracts with the highest phenolic content&mdash, aronia (67.7 &plusmn, 3.2 g GAE/100 g, cyanidin 3-galactoside, chlorogenic acid), pomegranate (65.7 &plusmn, 7.9 g GAE/100 g, cyanidin 3,5-diglucoside, punicalin), and red grape (59.6 &plusmn, 2.5 g GAE/100 g, malvidin 3-glucoside, quercetin 3-glucuronide)&mdash, showed also one of the highest inhibitory activities against &alpha, amylase (326.9 &plusmn, 75.8 &mu, g/mL, 789.7 &plusmn, 220.9 &mu, 646.1 &plusmn, 81.8 &mu, g/mL) and &alpha, glucosidase (115.6 &plusmn, 32.5 &mu, 127.8 &plusmn, 20.1 &mu, 160.6 &plusmn, 68.4 &mu, g/mL) and, partially, were even more potent inhibitors than acarbose (441 &plusmn, 30 &mu, 1439 &plusmn, 85 &mu, g/mL). Additionally, the investigation of single anthocyanins and glycosylated flavonoids demonstrated a structure- and size-dependent inhibitory activity. In the future in vivo studies are envisaged.

Published
2020

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