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Huang S, Xiang H, Lv J, Zhu D, Yu L, Guo Y, Xu L. Au nanozyme-based colorimetric sensor array integrates machine learning to identify and discriminate monosaccharides. J Colloid Interface Sci 2024; 672:200-208. [PMID: 38838628 DOI: 10.1016/j.jcis.2024.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/18/2024] [Accepted: 06/02/2024] [Indexed: 06/07/2024]
Abstract
As different monosaccharides exhibit different redox characteristics, this paper presented a novel colorimetric sensor array based on the glucose oxidase-like (GOx-like) activity of Au nanoparticles (NPs) for monosaccharides identification. AuNPs can use O2, ABTS+•, or [Ag(NH3)2]+ as an electron acceptor to catalyze the oxidation of monosaccharides in different velocity, resulting in cross-responsive signals. The current sensor array can distinguish between different monosaccharides or their mixtures through linear discriminant analysis (LDA) and hierarchical clustering analysis (HCA). Moreover, the glucose and fructose concentrations can be estimated simultaneously using a neural network regression model based on the sensor array. This method shows potential for monosaccharide detection in industrial, medical, and biological applications.
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Affiliation(s)
- Sijun Huang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Henglong Xiang
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Jiachen Lv
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Dongwei Zhu
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Liqiang Yu
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China
| | - Yi Guo
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China.
| | - Li Xu
- Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, National Engineering Laboratory for AIDS Vaccine, School of Life Sciences, Jilin University, Changchun, China.
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2
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Farazi M, Houghton MJ, Nicolotti L, Murray M, Cardoso BR, Williamson G. Inhibition of human starch digesting enzymes and intestinal glucose transport by walnut polyphenols. Food Res Int 2024; 189:114572. [PMID: 38876610 DOI: 10.1016/j.foodres.2024.114572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 05/26/2024] [Accepted: 05/26/2024] [Indexed: 06/16/2024]
Abstract
One approach to controlling type 2 diabetes (T2D) is to lower postprandialglucose spikesby slowing down the digestion of carbohydrates and the absorption of glucose in the small intestine. The consumption of walnuts is associated with a reduced risk of chronic diseases such as T2D, suggested to be partly due to the high content of (poly)phenols. This study evaluated, for the first time, the inhibitory effect of a (poly)phenol-rich walnut extract on human carbohydrate digesting enzymes (salivary and pancreatic α-amylases, brush border sucrase-isomaltase) and on glucose transport across fully differentiated human intestinal Caco-2/TC7 monolayers. The walnut extract was rich in multiple (poly)phenols (70 % w/w) as analysed by Folin-Ciocalteau and by LCMS. It exhibited potent inhibition of both human salivary (IC50: 32.2 ± 2.5 µg walnut (poly)phenols (WP)/mL) and pancreatic (IC50: 56.7 ± 1.7 µg WP/mL) α-amylases, with weaker effects on human sucrase (IC50: 990 ± 20 µg WP/mL), maltase (IC50: 1300 ± 80 µg WP/mL), and isomaltase (IC25: 830 ± 60 µg WP/mL) activities. Selected individual walnut (poly)phenols inhibited human salivary α-amylase in the order: 1,3,4,6-tetragalloylglucose > ellagic acid pentoside > 1,2,6-tri-O-galloyl-β-D-glucopyranose, with no inhibition by ellagic acid, gallic acid and 4-O-methylgallic acid. The (poly)phenol-rich walnut extract also attenuated (up to 59 %) the transfer of 2-deoxy-D-glucose across differentiated Caco-2/TC7 cell monolayers. This is the first report on the effect of (poly)phenol-rich extracts from any commonly-consumed nut kernel on any human starch-digesting enzyme, and suggests a mechanism through which walnut consumption may lower postprandial glucose spikes and contribute to their proposed health benefits.
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Affiliation(s)
- Mena Farazi
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Level 2, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168 Australia
| | - Michael J Houghton
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Level 2, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168 Australia
| | - Luca Nicolotti
- The Australian Wine Research Institute, Adelaide, SA 5064, Australia; Metabolomics Australia, The Australian Wine Research Institute, Adelaide, SA 5064, Australia
| | - Margaret Murray
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Department of Health Sciences and Biostatistics, Swinburne University of Technology, John St, Hawthorn, VIC 3122, Australia
| | - Barbara R Cardoso
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Level 2, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168 Australia
| | - Gary Williamson
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Level 2, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168 Australia.
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Visvanathan R, Houghton MJ, Barber E, Williamson G. Structure-function relationships in (poly)phenol-enzyme binding: Direct inhibition of human salivary and pancreatic α-amylases. Food Res Int 2024; 188:114504. [PMID: 38823880 DOI: 10.1016/j.foodres.2024.114504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 05/04/2024] [Accepted: 05/07/2024] [Indexed: 06/03/2024]
Abstract
(Poly)phenols inhibit α-amylase by directly binding to the enzyme and/or by forming starch-polyphenol complexes. Conventional methods using starch as the substrate measure inhibition from both mechanisms, whereas the use of shorter oligosaccharides as substrates exclusively measures the direct interaction of (poly)phenols with the enzyme. In this study, using a chromatography-based method and a short oligosaccharide as the substrate, we investigated the detailed structural prerequisites for the direct inhibition of human salivary and pancreatic α-amylases by over 50 (poly)phenols from the (poly)phenol groups: flavonols, flavones, flavanones, flavan-3-ols, polymethoxyflavones, isoflavones, anthocyanidins and phenolic acids. Despite being structurally very similar (97% sequence homology), human salivary and pancreatic α-amylases were inhibited to different extents by the tested (poly)phenols. The most potent human salivary α-amylase inhibitors were luteolin and pelargonidin, while the methoxylated anthocyanidins, peonidin and petunidin, significantly blocked pancreatic enzyme activity. B-ring methoxylation of anthocyanidins increased inhibition against both human α-amylases while hydroxyl groups at C3 and B3' acted antagonistically in human salivary inhibition. C4 carbonyl reduction, or the positive charge on the flavonoid structure, was the key structural feature for human pancreatic inhibition. B-ring glycosylation did not affect salivary enzyme inhibition, but increased pancreatic enzyme inhibition when compared to its corresponding aglycone. Overall, our findings indicate that the efficacy of interaction with human α-amylase is mainly influenced by the type and placement of functional groups rather than the number of hydroxyl groups and molecular weight.
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Affiliation(s)
- Rizliya Visvanathan
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Michael J Houghton
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Elizabeth Barber
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Gary Williamson
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia; Victorian Heart Institute, Monash University, Victorian Heart Hospital, 631 Blackburn Road, Clayton, VIC 3168, Australia.
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4
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Farazi M, Houghton MJ, Cardoso BR, Murray M, Williamson G. Inhibitory effect of extracts from edible parts of nuts on α-amylase activity: a systematic review. Food Funct 2024; 15:5209-5223. [PMID: 38717256 DOI: 10.1039/d4fo00414k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2024]
Abstract
Elevated blood glucose concentration is a risk factor for developing metabolic dysfunction and insulin resistance, leading to type 2 diabetes and cardiovascular diseases. Nuts have the potential to inhibit α-amylase activity, and so lower postprandial glucose, due to their content of polyphenols and other bioactive compounds. We conducted a systematic literature review to assess the ability of extracts from commonly consumed edible parts of nuts to inhibit α-amylase. Among the 31 included papers, only four utilised human α-amylases. These papers indicated that polyphenol-rich chestnut skin extracts exhibited strong inhibition of both human salivary and pancreatic α-amylases, and that a polyphenol-rich almond skin extract was a potent inhibitor of human salivary α-amylase. The majority of the reviewed studies utilised porcine pancreatic α-amylase, which has ∼86% sequence homology with the corresponding human enzyme but with some key amino acid variations located within the active site. Polyphenol-rich extracts from chestnut, almond, kola nut, pecan and walnut, and peptides isolated from cashew, inhibited porcine pancreatic α-amylase. Some studies used α-amylases sourced from fungi or bacteria, outcomes from which are entirely irrelevant to human health, as they have no sequence homology with the human enzyme. Given the limited research involving human α-amylases, and the differences in inhibition compared to porcine enzymes and especially enzymes from microorganisms, it is recommended that future in vitro experiments place greater emphasis on utilising enzymes sourced from humans to facilitate a reliable prediction of effects in intervention studies.
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Affiliation(s)
- Mena Farazi
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
- Victorian Heart Institute, Monash University, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Michael J Houghton
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
- Victorian Heart Institute, Monash University, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Barbara R Cardoso
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
- Victorian Heart Institute, Monash University, 631 Blackburn Road, Clayton, VIC 3168, Australia
| | - Margaret Murray
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
- School of Health Sciences, Swinburne University of Technology, John St, Hawthorn, VIC 3122, Australia
| | - Gary Williamson
- Department of Nutrition, Dietetics and Food, Monash University, BASE Facility, Level 1, 264 Ferntree Gully Road, Notting Hill, VIC 3168, Australia.
- Victorian Heart Institute, Monash University, 631 Blackburn Road, Clayton, VIC 3168, Australia
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Gupta A, Jamal A, Jamil DA, Al-Aubaidy HA. A systematic review exploring the mechanisms by which citrus bioflavonoid supplementation benefits blood glucose levels and metabolic complications in type 2 diabetes mellitus. Diabetes Metab Syndr 2023; 17:102884. [PMID: 37939436 DOI: 10.1016/j.dsx.2023.102884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 10/10/2023] [Accepted: 10/12/2023] [Indexed: 11/10/2023]
Abstract
BACKGROUND Citrus bioflavonoids are polyphenolic compounds that are derived from citrus fruits and vegetables. Although they are well known for their powerful antioxidant properties, their effects on glycemic control are not well understood. This review aims to highlight the potential benefits of using citrus bioflavonoids in patients with type 2 diabetes mellitus and its metabolic complications, as well as the medicinal effects of known subclasses of naturally occurring citrus bioflavonoids. METHODS In this systematic review, a survey of studies was conducted from January 2012 to February 2023 using various databases (PubMed, Medline, Google Scholar, and Scopus) to determine the effects of citrus bioflavonoid supplementation on reducing oxidative stress, improving lipid profiles, and glycemic index in patients with diabetes mellitus, as well as the proposed mechanisms of action. RESULTS The results of the survey indicate that citrus bioflavonoids may have a positive impact on reducing oxidative stress levels in patients with type 2 diabetes mellitus. In addition to reducing oxidative stress, citrus bioflavonoids may also have a positive impact on other markers of diabetes. For example, studies have shown that they can reduce non-enzymatic protein glycation, which is a process that occurs when glucose molecules bind to proteins in the body. CONCLUSION The reduction in oxidative stress that can be achieved using citrus bioflavonoids may help to maintain antioxidant levels in the body, thereby reducing the severity of diabetes and its complications. These findings suggest that citrus bioflavonoids may be a useful complementary therapy for patients with diabetes.
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Affiliation(s)
- Ankit Gupta
- School of Medicine, University of Tasmania, Hobart, TAS, 7000, Australia
| | - Abdulsatar Jamal
- Department of Microbiology, Anatomy, Physiology and Pharmacology & Centre for Cardiovascular Biology and Disease Research, School of Agriculture, Biomedicine & Environment, La Trobe University, Bundoora, VIC, 3086, Australia
| | - Dina A Jamil
- Department of Microbiology, Anatomy, Physiology and Pharmacology & Centre for Cardiovascular Biology and Disease Research, School of Agriculture, Biomedicine & Environment, La Trobe University, Bundoora, VIC, 3086, Australia; New Medical Education Australia, Brisbane, QLD, 4007, Australia
| | - Hayder A Al-Aubaidy
- School of Medicine, University of Tasmania, Hobart, TAS, 7000, Australia; Department of Microbiology, Anatomy, Physiology and Pharmacology & Centre for Cardiovascular Biology and Disease Research, School of Agriculture, Biomedicine & Environment, La Trobe University, Bundoora, VIC, 3086, Australia; New Medical Education Australia, Brisbane, QLD, 4007, Australia.
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6
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Zulfiqar S, Blando F, Orfila C, Marshall LJ, Boesch C. Chromogenic Assay Is More Efficient in Identifying α-Amylase Inhibitory Properties of Anthocyanin-Rich Samples When Compared to the 3,5-Dinitrosalicylic Acid (DNS) Assay. Molecules 2023; 28:6399. [PMID: 37687228 PMCID: PMC10490044 DOI: 10.3390/molecules28176399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 08/12/2023] [Accepted: 08/25/2023] [Indexed: 09/10/2023] Open
Abstract
The inhibition of carbohydrate digestion by plant bioactive compounds is a potential dietary strategy to counteract type 2 diabetes. Indeed, inhibition of α-amylase, a key enzyme that carries out the bulk of starch digestion, has been demonstrated for a range of bioactive compounds including anthocyanins; however, sample pigmentation often interferes with measurements, affecting colorimetric assay outcomes. Therefore, the present study compared the performance of a direct chromogenic assay, using 2-chloro-4 nitrophenyl α-D-maltotrioside (CNPG3) as a substrate, with the commonly used 3,5-dinitrosalicylic acid (DNS) assay. The direct chromogenic assay demonstrated a 5-10-fold higher sensitivity to determine α-amylase inhibition in various samples, including acarbose as a reference, pure anthocyanins, and anthocyanin-rich samples. The IC50 values of acarbose presented as 37.6 μg/mL and 3.72 μg/mL for the DNS assay and the direct chromogenic assay, respectively, whereas purified anthocyanins from blackcurrant showed IC50 values of 227.4 µg/mL and 35.0 µg/mL. The direct chromogenic assay is easy to perform, fast, reproducible, and suitable for high-throughput screening of pigmented α-amylase inhibitors.
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Affiliation(s)
- Sadia Zulfiqar
- School of Food Science and Nutrition, Faculty of Environment, University of Leeds, Leeds LS2 9JT, UK; (S.Z.); (C.O.); (L.J.M.)
| | - Federica Blando
- Institute of Sciences of Food Production (ISPA), National Research Council (CNR), Via Prov.le Lecce-Monteroni, 73100 Lecce, Italy;
| | - Caroline Orfila
- School of Food Science and Nutrition, Faculty of Environment, University of Leeds, Leeds LS2 9JT, UK; (S.Z.); (C.O.); (L.J.M.)
| | - Lisa J. Marshall
- School of Food Science and Nutrition, Faculty of Environment, University of Leeds, Leeds LS2 9JT, UK; (S.Z.); (C.O.); (L.J.M.)
| | - Christine Boesch
- School of Food Science and Nutrition, Faculty of Environment, University of Leeds, Leeds LS2 9JT, UK; (S.Z.); (C.O.); (L.J.M.)
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Nag S, Majumder S. Starch, gallic acid, their inclusion complex and their effects in diabetes and other
diseases—A
review. Food Sci Nutr 2022; 11:1612-1621. [PMID: 37051339 PMCID: PMC10084954 DOI: 10.1002/fsn3.3208] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/29/2022] Open
Abstract
Starch is the most important energy-providing component of food. It is useful for maintaining the structural and rheological consistency of food, ad thus, in turn, is responsible for maintaining the freshness of food. Polyphenols are present in plant products in huge amounts as secondary metabolites. Gallic acid, one of the potent plant polyphenols, has been reported to have excellent anti-inflammatory, antioxidative, anticarcinogenic, microbicidal, and antidiabetic properties. Till date, very few articles on the starch-polyphenol inclusion complex are present. Quite a few hypotheses have been proposed as to how the formation of an inclusion complex of starch with polyphenol can slower the digestion or the hydrolysis of starch. The efficient qualities of starch-polyphenol systems, such as reduced starch digestion, lower blood glucose and preserving food freshness, have formed a necessity for investigation in this area. The focus of this review centers on the recent research on starch-polyphenol interactions and starch-gallic acid inclusion complexes in native and extruded food systems, as well as how the production of these complexes can aid in the treatment of diseases, particularly diabetes mellitus.
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Affiliation(s)
- Sayoni Nag
- Department of Biotechnology Brainware University Barasat India
| | - Suman Majumder
- Department of Biotechnology Brainware University Barasat India
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8
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Barber E, Houghton MJ, Visvanathan R, Williamson G. Measuring key human carbohydrate digestive enzyme activities using high-performance anion-exchange chromatography with pulsed amperometric detection. Nat Protoc 2022; 17:2882-2919. [PMID: 36180531 DOI: 10.1038/s41596-022-00736-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 06/17/2022] [Indexed: 11/09/2022]
Abstract
Carbohydrate digestion in the mammalian gastrointestinal tract is catalyzed by α-amylases and α-glucosidases to produce monosaccharides for absorption. Inhibition of these enzymes is the major activity of the drugs acarbose and miglitol, which are used to manage diabetes. Furthermore, delaying carbohydrate digestion via inhibition of α-amylases and α-glucosidases is an effective strategy to blunt blood glucose spikes, a major risk factor for developing metabolic diseases. Here, we present an in vitro protocol developed to accurately and specifically assess the activity of α-amylases and α-glucosidases, including sucrase, maltase and isomaltase. The assay is especially suitable for measuring inhibition by compounds, drugs and extracts, with minimal interference from impurities or endogenous components, because the substrates and digestive products in the enzyme activity assays are quantified directly by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD). Multiple enzyme sources can be used, but here we present the protocol using commercially available human α-amylase to assess starch hydrolysis with maltoheptaose as the substrate, and with brush border sucrase-isomaltase (with maltase, sucrase and isomaltase activities) derived from differentiated human intestinal Caco-2(/TC7) cells to assess hydrolysis of disaccharides. The wet-lab assay takes ~2-5 h depending on the number of samples, and the HPAE-PAD analysis takes 35 min per sample. A full dataset therefore takes 1-3 d and allows detection of subtle changes in enzyme activity with high sensitivity and reliability.
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Affiliation(s)
- Elizabeth Barber
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, Victoria, Australia
| | - Michael J Houghton
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, Victoria, Australia
| | - Rizliya Visvanathan
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, Victoria, Australia
| | - Gary Williamson
- Department of Nutrition, Dietetics and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, Victoria, Australia.
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Williamson G. Effects of Polyphenols on Glucose-Induced Metabolic Changes in Healthy Human Subjects and on Glucose Transporters. Mol Nutr Food Res 2022; 66:e2101113. [PMID: 35315210 PMCID: PMC9788283 DOI: 10.1002/mnfr.202101113] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 02/14/2022] [Indexed: 12/30/2022]
Abstract
Dietary polyphenols interact with glucose transporters in the small intestine and modulate glucose uptake after food or beverage consumption. This review assesses the transporter interaction in vitro and how this translates to an effect in healthy volunteers consuming glucose. As examples, the apple polyphenol phlorizin inhibits sodium-glucose linked transporter-1; in the intestinal lumen, it is converted to phloretin, a strong inhibitor of glucose transporter-2 (GLUT2), by the brush border digestive enzyme lactase. Consequently, an apple extract rich in phlorizin attenuates blood glucose and insulin in healthy volunteers after a glucose challenge. On the other hand, the olive phenolic, oleuropein, inhibits GLUT2, but the strength of the inhibition is not enough to modulate blood glucose after a glucose challenge in healthy volunteers. Multiple metabolic effects and oxidative stresses after glucose consumption include insulin, incretin hormones, fatty acids, amino acids, and protein markers. However, apart from acute postprandial effects on glucose, insulin, and some incretin hormones, very little is known about the acute effects of polyphenols on these glucose-induced secondary effects. In summary, attenuation of the effect of a glucose challenge in vivo is only observed when polyphenols are strong inhibitors of glucose transporters.
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Affiliation(s)
- Gary Williamson
- Department of Nutrition, Dietetics, and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health SciencesMonash UniversityBASE Facility, 264 Ferntree Gully RoadNotting HillVIC 3168Australia
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10
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Miller N, Joubert E. Critical Assessment of In Vitro Screening of α-Glucosidase Inhibitors from Plants with Acarbose as a Reference Standard. PLANTA MEDICA 2022; 88:1078-1091. [PMID: 34662924 DOI: 10.1055/a-1557-7379] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Postprandial hyperglycemia is treated with the oral antidiabetic drug acarbose, an intestinal α-glucosidase inhibitor. Side effects of acarbose motivated a growing number of screening studies to identify novel α-glucosidase inhibitors derived from plant extracts and other natural sources. As "gold standard", acarbose is frequently included as the reference standard to assess the potency of these candidate α-glucosidase inhibitors, with many outperforming acarbose by several orders of magnitude. The results are subsequently used to identify suitable compounds/products with strong potential for in vivo efficacy. However, most α-glucosidase inhibitor screening studies use enzyme preparations obtained from nonmammalian sources (typically Saccharomyces cerevisiae), despite strong evidence that inhibition data obtained using nonmammalian α-glucosidase may hold limited value in terms of identifying α-glucosidase inhibitors with actual in vivo hypoglycemic potential. The aim was to critically discuss the screening of novel α-glucosidase inhibitors from plant sources, emphasizing inconsistencies and pitfalls, specifically where acarbose was included as the reference standard. An assessment of the available literature emphasized the cruciality of stating the biological source of α-glucosidase in such screening studies to allow for unambiguous and rational interpretation of the data. The review also highlights the lack of a universally adopted screening assay for novel α-glucosidase inhibitors and the commercial availability of a standardized preparation of mammalian α-glucosidase.
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Affiliation(s)
- Neil Miller
- Department of Food Science, Stellenbosch University, South Africa
- Plant Bioactives Group, Post-Harvest & Agro-Processing Technologies, Agricultural Research Council (ARC) Infruitec-Nietvoorbij, Stellenbosch, South Africa
| | - Elizabeth Joubert
- Department of Food Science, Stellenbosch University, South Africa
- Plant Bioactives Group, Post-Harvest & Agro-Processing Technologies, Agricultural Research Council (ARC) Infruitec-Nietvoorbij, Stellenbosch, South Africa
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11
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Wang X, Ren Y, Wang Y, Li H, Huang J, Wang Z, Yue T, Gao Z. Changes in the physicochemical composition of Auricularia auricula during growth stages and control of endogenous formaldehyde. J Food Compost Anal 2022. [DOI: 10.1016/j.jfca.2021.104336] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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12
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Zhang Y, Chen Y, Chen J. The starch hydrolysis and aroma retention caused by salivary α-amylase during oral processing of food. Curr Opin Food Sci 2022. [DOI: 10.1016/j.cofs.2021.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Impact of time and temperature on the physicochemical, microbiological, and nutraceutical properties of laver kombucha (Porphyra dentata) during fermentation. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2021.112643] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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14
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Visvanathan R, Williamson G. Citrus polyphenols and risk of type 2 diabetes: Evidence from mechanistic studies. Crit Rev Food Sci Nutr 2021; 63:2178-2202. [PMID: 34496701 DOI: 10.1080/10408398.2021.1971945] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Citrus fruits are a rich source of (poly)phenols, a group of dietary bioactive compounds that protect against developing type 2 diabetes. Our review critically evaluates how experimental in vitro and animal models have elucidated some of the underlying mechanisms on how citrus (poly)phenols affect the markers of type 2 diabetes. According to animal studies, the beneficial effects derived from consuming citrus compounds appear to be related to long-term effects, rather than acute. There are some notable effects from citrus (poly)phenol metabolites on post-absorptive processes, such as modulation of hepatic glucose metabolism and insulin sensitivity in target tissues, but with a more modest effect on digestion and sugar absorption within the gut. Experimental studies on cells and other systems in vitro have indicated some of the possible mechanisms involved, but ∼70% of the studies utilized unrealistically high concentrations and forms of the compounds, compromising physiological relevance. Future studies should discuss the relevance of concentration used in in vitro experiments, relative to the proposed site of action, and also examine the role of catabolites produced by the gut microbiota. Finally, it is important to examine the relationship between the gut microbiota and bioavailability on the action of citrus (poly)phenols.
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Affiliation(s)
- Rizliya Visvanathan
- Department of Nutrition, Dietetics, and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, VIC, Australia
| | - Gary Williamson
- Department of Nutrition, Dietetics, and Food, School of Clinical Sciences at Monash Health, Faculty of Medicine, Nursing and Health Sciences, Monash University, BASE Facility, Notting Hill, VIC, Australia
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Visvanathan R, Williamson G. Effect of citrus fruit and juice consumption on risk of developing type 2 diabetes: Evidence on polyphenols from epidemiological and intervention studies. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.06.038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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16
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Barber E, Houghton MJ, Williamson G. Flavonoids as Human Intestinal α-Glucosidase Inhibitors. Foods 2021; 10:foods10081939. [PMID: 34441720 PMCID: PMC8392382 DOI: 10.3390/foods10081939] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/15/2022] Open
Abstract
Certain flavonoids can influence glucose metabolism by inhibiting enzymes involved in carbohydrate digestion and suppressing intestinal glucose absorption. In this study, four structurally-related flavonols (quercetin, kaempferol, quercetagetin and galangin) were evaluated individually for their ability to inhibit human α-glucosidases (sucrase, maltase and isomaltase), and were compared with the antidiabetic drug acarbose and the flavan-3-ol(−)-epigallocatechin-3-gallate (EGCG). Cell-free extracts from human intestinal Caco-2/TC7 cells were used as the enzyme source and products were quantified chromatographically with high accuracy, precision and sensitivity. Acarbose inhibited sucrase, maltase and isomaltase with IC50 values of 1.65, 13.9 and 39.1 µM, respectively. A similar inhibition pattern, but with comparatively higher values, was observed with EGCG. Of the flavonols, quercetagetin was the strongest inhibitor of α-glucosidases, with inhibition constants approaching those of acarbose, followed by galangin and kaempferol, while the weakest were quercetin and EGCG. The varied inhibitory effects of flavonols against human α-glucosidases depend on their structures, the enzyme source and substrates employed. The flavonols were more effective than EGCG, but less so than acarbose, and so may be useful in regulating sugar digestion and postprandial glycaemia without the side effects associated with acarbose treatment.
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