Higher Habitual Flavonoid Intakes Are Associated with a Lower Incidence of Diabetes

A flavonoid-rich diet is associated with lower risk and improved imaging biomarkers of nonalcoholic fatty liver disease: a prospective cohort study

BACKGROUND

Mechanistic studies and short-term randomized trials suggest higher intakes of dietary flavonoids may protect against nonalcoholic fatty liver disease (NAFLD).

OBJECTIVES

We aimed to perform the first population-based study with long-term follow-up on flavonoid consumption, incident NAFLD, and validated NAFLD biomarkers.

METHODS

In a prospective study, we assessed the associations between flavonoid intake based on ≥2 24-h dietary assessments and NAFLD risk among 121,064 adults aged 40-69 y by multivariable Cox regression analyses. We further assessed the associations between flavonoid intake and magnetic resonance imaging-derived liver fat (a subset of n = 11,435) and liver-corrected T1 values (cT1; a subset of n = 9570), a marker of steatosis, more sensitive to inflammatory pathology.

RESULTS

Over 10 y of follow-up, 1081 cases of NAFLD were identified. Participants in the highest quartile (Q4) of the flavodiet score reflecting the consumption of foods high in flavonoids, had a 19% lower risk of NAFLD compared to the lowest quartile (Q1) [hazard ratio (HR) (95% confidence interval (CI): 0.81 (0.67, 0.97), P-trend = 0.02)]. Moreover, participants in the Q4 of the flavodiet score had lower liver fat and cT1 values than those in Q1 (liver fat: relative difference Q1 compared with Q4: -5.28%, P-trend = <0.001; cT1: relative difference Q1 compared with Q4: -1.73%, P-trend = <0.001). When compared to low intakes, high intakes of apples and tea were associated with lower NAFLD risk [apples: HR (95% CI): 0.78 (0.67, 0.92), P-trend = <0.01; tea: HR (95% CI): 0.86 (0.72, 1.02), P-trend = 0.03)]. Additionally, when compared to low intakes, high apple, tea, and dark chocolate intakes were significantly associated with lower liver fat values, whereas high tea and red pepper intakes were significantly associated with lower cT1 values.

CONCLUSIONS

The consumption of flavonoid-rich foods was associated with a reduced risk of NAFLD among middle-aged adults.

Cocoa flavanols rescue stress-induced declines in endothelial function after a high-fat meal, but do not affect cerebral oxygenation during stress in young, healthy adults

Food choices during stressful periods often worsen, which can influence the impact of stress on vascular health. For instance, fat consumption impairs the recovery of endothelial function following mental stress, while flavanols have been shown to enhance recovery. This randomised, counterbalanced, double-blinded, crossover, postprandial intervention study examined whether flavanols consumed in combination with fat can mitigate the negative impact of fat on stress-induced impairments in endothelial function. Twenty-three young, healthy males and females ingested a high-fat meal (56.5 g fat) with high-flavanol (150 mg (-)-epicatechin) or low-flavanol (<6 mg (-)-epicatechin) cocoa 1.5 hours before an 8-minute mental stress task. The primary outcome, brachial flow-mediated dilatation (FMD), was assessed at pre-intervention baseline and 30 and 90 minutes post-stress. Pre-frontal cortical oxygenation was assessed post-meal at rest and during stress. Forearm blood flow (FBF), blood pressure (BP), cardiovascular activity, common carotid artery (CCA) diameter and blood flow and mood were assessed before, during and/or after stress. FMD was impaired at 30 and 90 minutes post-stress after the low-flavanol cocoa. High-flavanol cocoa attenuated FMD impairments at 30 minutes and improved FMD at 90 minutes post-stress. Mental stress induced similar increases in cortical oxygenation, FBF, BP, cardiovascular activity, and disruptions to mood, in both conditions. CCA diameter increased and CCA retrograde blood flow decreased post-stress, with no difference between conditions. In summary, flavanols can counteract declines in endothelial function induced by consuming fat in the context of stress, but do not impact cerebral oxygenation. These findings can have important implications for flavanol-rich dietary choices to protect the vasculature from stress.

Dairy and nondairy proteins as nano-architecture structures for delivering phenolic compounds: Unraveling their molecular interactions to maximize health benefits

Phenolic compounds are recognized for their benefits against degenerative diseases. Clinical and nutritional applications are limited by their low solubility, stability, and bioavailability, compromising their efficacy. Natural macromolecules, such as lipids, polysaccharides, and proteins, employed as delivery systems can efficiently overcome these limitations. In this sense, proteins are attractive due to their biocompatibility and dynamic structure properties, functional adaptability and self-assembly capabilities, offering stability, efficient encapsulation, and controlled release. This review explores the potential use of dairy proteins, caseins, and whey proteins, and, alternatively, nondairy proteins, gelatin, human serum albumin, maize zein, and soybean proteins, in building wall materials for the delivery of phenolic compounds. To optimize performance, aspects, such as protein-phenolic affinity and complex stability/activity, should be considered when designing particle nano-architecture. Molecular interactions between protein-phenolic compound complexes are, thus, further discussed, as well as the effects of temperature and pH and strategies to stabilize and preserve nano-architecture and retain phenolic compound activity. All proteins harbor one or more putative binding sites, shared or not, depending on the phenolic compound. Preservation techniques are still a case-to-case study, as no behavior patterns among different complexes are noted. Safety aspects necessary for the marketing of nanoproducts, such as characterization, toxicity assessments, and post-market monitoring as defined by the European Food Safety Authority and the Food and Drug Administration, are discussed, evidencing the need for a unified regulation. This review broadens our understanding and opens new opportunities for the development of novel protein-based nanocarriers to obtain more effective and stable products, enhancing phenolic compound delivery and health benefits.

The flavonoid Sudachitin regulates glucose metabolism via PDE inhibition

Sudachitin, a member of the flavonoid family, reportedly improves glucose metabolism after long-term administration, but details of the underlying mechanisms are unknown. We found that Sudachitin approximately doubles insulin secretion under high glucose concentrations in mouse pancreatic islets and MIN6 cells. When Sudachitin was orally administered to mice, early-phase insulin secretion was increased and a 30 % reduction in blood glucose levels was demonstrated 30 min after glucose loading. Insulin tolerance tests also showed Sudachitin to increase systemic insulin sensitivity. Additionally, we observed that Sudachitin raised intracellular cAMP levels in pancreatic islets. Phosphodiesterase (PDE) activity assays revealed Sudachitin to inhibit PDE activity and computer simulations predicted a high binding affinity between PDEs and Sudachitin. These findings suggest that Sudachitin enhances both insulin secretion and insulin sensitivity via an increase in intracellular cAMP resulting from PDE inhibition. These insights may facilitate understanding the mechanisms underlying the regulation of glucose metabolism by Sudachitin and other isoflavones.

Antioxidant, Anti-Inflammatory, Anti-Diabetic, and Pro-Osteogenic Activities of Polyphenols for the Treatment of Two Different Chronic Diseases: Type 2 Diabetes Mellitus and Osteoporosis

Polyphenols are natural bioactives occurring in medicinal and aromatic plants and food and beverages of plant origin. Compared with conventional therapies, plant-derived phytochemicals are more affordable and accessible and have no toxic side effects. Thus, pharmaceutical research is increasingly inclined to discover and study new and innovative natural molecules for the treatment of several chronic human diseases, like type 2 diabetes mellitus (T2DM) and osteoporosis. These pathological conditions are characterized by a chronic inflammatory state and persistent oxidative stress, which are interconnected and lead to the development and worsening of these two health disorders. Oral nano delivery strategies have been used to improve the bioavailability of polyphenols and to allow these natural molecules to exert their antioxidant, anti-inflammatory, anti-diabetic, and pro-osteogenic biological activities in in vivo experimental models and in patients. Polyphenols are commonly used in the formulations of nutraceuticals, which can counteract the detrimental effects of T2DM and osteoporosis pathologies. This review describes the polyphenols that can exert protective effects against T2DM and osteoporosis through the modulation of specific molecular markers and pathways. These bioactives could be used as adjuvants, in combination with synthetic drugs, in the future to develop innovative therapeutic strategies for the treatment of T2DM and osteoporosis.

The association of dietary total flavonoids and their subclasses with the risk of type 2 diabetes: a prospective cohort study

BACKGROUND

Data from mechanistic studies suggest flavonoids may benefit glucose metabolism, but their associations with type 2 diabetes (T2D) remain unclear. This study examined the prospective associations of dietary intake of total, classes, and individual flavonoids, as well as their source foods, with T2D in the CArdioVascular disease Association Study (CAVAS).

METHODS

A total of 16,666 Korean men and women were enrolled at baseline, and 953 were newly diagnosed with T2D over a median follow-up of 5.96 years. Intake of flavonoids was cumulatively averaged using all food frequency questionnaires before the censoring events. A Poisson regression model was used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs).

RESULTS

Women with higher total flavonoid, flavonol, isoflavone, and proanthocyanidin intake had a lower risk of T2D (fourth vs. first quartile, IRR 0.62; 95% CI 0.44-0.89; P for linearity and non-linearity < 0.05 for total flavonoids), while in men, flavanones, anthocyanins, and proanthocyanidins, but not total flavonoids, were inversely associated with T2D risk (all P interaction for sex > 0.05). The key source foods contributing to flavonoid intake were also different between men and women, except for apples: tangerines and strawberries in men and green leafy vegetables and soy products in women.

CONCLUSIONS

A higher intake of total flavonoids, particularly from vegetables, soybeans, and apples, may be associated with lower risk of T2D in women. However, flavonoids from fruits, rather than total flavonoids, may be inversely associated in men. The association between flavonoid intake and the risk of T2D may be contingent upon the dietary sources of flavonoids consumed.

In Silico and In Vitro Analyses to Repurpose Quercetin as a Human Pancreatic α-Amylase Inhibitor

Human pancreatic α-amylase (HPA), situated at the apex of the starch digestion hierarchy, is an attractive therapeutic approach to precisely regulate blood glucose levels, thereby efficiently managing diabetes. Polyphenols offer a natural and multifaceted approach to moderate postprandial sugar spikes, with their slight modulation in carbohydrate digestion and potential secondary benefits, such as antioxidant and anti-inflammatory effects. Taking into consideration the unfavorable side effects of currently available commercial medications, we aimed to study a library of polyphenols attributed to their remarkable antidiabetic properties and screened the most potent HPA inhibitor via a comprehensive in silico study encompassing molecular docking, molecular mechanics with generalized Born and surface area solvation (MM/GBSA) calculation, molecular dynamics (MD) simulation, density functional theory (DFT) study, and pharmacokinetic properties followed by an in vitro assay. Significant hydrogen bonding with the catalytic triad residues of HPA, prominent MM/GBSA binding energy of -27.03 kcal/mol, and the stable nature of the protein-ligand complex with regard to 100 ns MD simulation screened quercetin as the best HPA inhibitor. Additionally, quercetin showed strong reactivity in the substrate-binding pocket of HPA and exhibited favorable pharmacokinetic properties with a considerable inhibitory concentration (IC50) of 57.37 ± 0.9 μg/mL against α-amylase. This study holds prospects for HPA inhibition and suggests quercetin as an approach to therapy for diabetes; however, it is imperative to conduct further research.

The associations between dietary flavonoid intake and the prevalence of diabetes mellitus: Data from the National Health and Nutrition Examination Survey 2007-2010 and 2017-2018

Background

Diabetes mellitus (DM) is a prominent health concern worldwide, leading to the high incidence of disability and mortality and bringing in heavy healthcare and social burden. Plant-based diets are reported associated with a reduction of DM risk. Plant-based diets are rich in flavonoids, which possess properties such as scavenging free radicals and exerting both anti-inflammatory and antioxidant effects.

Purpose

However, whether dietary flavonoids are associated with the prevalence of DM remains controversial. The potential reasons for contradictory epidemiological outcomes on the association between dietary flavonoids and DM prevalence have not been determined.

Methods

To address these limitations, we employed data from 22,481 participants in the National Health and Nutrition Examination Survey to explore the association between the intake of flavonoids and DM prevalence by weighted Logistic regression and weighted restricted cubic splines.

Results

We found that the prevalence of DM was inversely associated with the intake of total flavonoids in the second quartile [Odds Ratio (OR) 0.78 95% confidence interval (CI) (0.63, 0.97), p = 0.028], in the third quartile [0.76 (0.60, 0.97), p = 0.031], and in the fourth quartile [0.80 (0.65, 0.97), p = 0.027]. However, the p for trend was not significant [0.94 (0.88, 1.01), p = 0.096]. Moreover, the association between DM prevalence and the intake of total flavonoids was significantly influenced by race (p for interaction = 0.006). In Mexican Americans, there was a significant positive association between DM prevalence and total flavonoid intake within the third quartile [1.04 (1.02, 1.07), p = 0.003]. Total flavan-3-ol and subtotal catechin intake exhibited a non-linear U-shaped association with DM prevalence (p for non-linearity < 0.0001 and p for non-linearity < 0.0001, respectively). Compared to the first quartile of corresponding intakes, consumption within the third quartile of subtotal catechins [0.70 (0.55, 0.89), p = 0.005] and total flavan-3-ols [0.65 (0.50, 0.84), p = 0.002] was associated with a lower prevalence of DM.

Conclusion

Taken together, our study may provide preliminary research evidence for personalized improvement of dietary habits to reduce the prevalence of diabetes.

Elnosary M, L. Ashour M, M. Abd El-Moneam N, A. Shreadah M. Flavonoids Biosynthesis in Plants as a Defense Mechanism: Role and Function Concerning Pharmacodynamics and Pharmacokinetic Properties

Flavonoids are a major class of secondary metabolites that comprises more than 6000 compounds that have been identified. They are biosynthesized via the phenylpropanoid metabolic pathway that involves groups of enzymes such as isomerases, hydroxylases, and reductases that greatly affect the determination of the flavonoid skeleton. For example, transferase enzymes responsible for the modification of sugar result in changes in the physiological activity of the flavonoids and changes in their physical properties, such as solubility, reactivity, and interaction with cellular target molecules, which affect their pharmacodynamics and pharmacokinetic properties. In addition, flavonoids have diverse biological activities such as antioxidants, anticancer, and antiviral in managing Alzheimer’s disease. However, most marine flavonoids are still incompletely discovered because marine flavonoid biosynthesis is produced and possesses unique substitutions that are not commonly found in terrestrial bioactive compounds. The current chapter will illustrate the importance of flavonoids’ role in metabolism and the main difference between marine and terrestrial flavonoids.

Anthocyanin actions at the gastrointestinal tract: Relevance to their health benefits

Anthocyanins (AC) are flavonoids abundant in the human diet, which consumption has been associated to several health benefits, including the mitigation of cardiovascular disease, type 2 diabetes, non-alcoholic fatty liver disease, and neurological disorders. It is widely recognized that the gastrointestinal (GI) tract is not only central for food digestion but actively participates in the regulation of whole body physiology. Given that AC, and their metabolites reach high concentrations in the intestinal lumen after food consumption, their biological actions at the GI tract can in part explain their proposed local and systemic health benefits. In terms of mechanisms of action, AC have been found to: i) inhibit GI luminal enzymes that participate in the absorption of lipids and carbohydrates; ii) preserve intestinal barrier integrity and prevent endotoxemia, inflammation and oxidative stress; iii) sustain goblet cell number, immunological functions, and mucus production; iv) promote a healthy microbiota; v) be metabolized by the microbiota to AC metabolites which will be absorbed and have systemic effects; and vi) modulate the metabolism of GI-generated hormones. This review will summarize and discuss the latest information on AC actions at the GI tract and their relationship to overall health benefits.

Polyphenol-Rich Beverage Consumption Affecting Parameters of the Lipid Metabolism in Healthy Subjects

Polyphenols are a diverse and widely distributed class of secondary metabolites, which possess numerous beneficial properties including a modulation of glucose and lipid metabolism. This placebo-controlled human intervention study was performed to explore effects of polyphenol-rich beverage (PRB) uptake on lipid metabolism, as well as DNA integrity. In this case, 36 healthy men were randomly divided to consume either 750 mL of a PRB (containing 51% chokeberry, cranberry, and pomegranate) or a placebo drink daily for eight weeks. Only PRB consumption was found to decrease fat and protein intakes significantly compared to the preceding one-week washout period. During the intervention with PRB an increased fat-free mass was shown after four weeks, whereas a significant elevation in body weight and leptin was observed in placebo group. Blood lipids were not significantly altered after PRB consumption, while triglyceride levels increased after placebo drink intake. In platelets, a significant inhibition of phosphodiesterase (PDE) activity was observed, more pronounced in test group. Consuming the PRB decreased total DNA strand breaks in whole blood as well as H₂O₂-induced breaks in isolated lymphocytes. Overall, our study suggested beneficial effects on lipid metabolism by reduced energy intake, modulation of biomarkers such as PDE activity and improved DNA integrity associated with PRB consumption.

The protective effects of flavonoids and carotenoids against diabetic complications-A review of in vivo evidence

Diabetes mellitus is a chronic metabolic disorder caused either by inadequate insulin secretion, impaired insulin function, or both. Uncontrolled diabetes is characterized by hyperglycemia which over time leads to fatal damage to both macro-and microvascular systems, causing complications such as cardiovascular diseases, retinopathy and nephropathy. Diabetes management is conventionally delivered through modifications of diet and lifestyle and pharmacological treatment, using antidiabetic drugs, and ultimately insulin injections. However, the side effects and financial cost of medications often reduce patient compliance to treatment, negatively affecting their health outcomes. Natural phytochemicals from edible plants such as fruits and vegetables (F&V) and medicinal herbs have drawn a growing interest as potential therapeutic agents for treating diabetes and preventing the onset and progression of diabetic complications. Flavonoids, the most abundant polyphenols in the human diet, have shown antidiabetic effects in numerous in vitro and preclinical studies. The underlying mechanisms have been linked to their antioxidant, anti-inflammatory and immunomodulatory activities. Carotenoids, another major group of dietary phytochemicals, have also shown antidiabetic potential in recent in vitro and in vivo experimental models, possibly through a mechanism of action similar to that of flavonoids. However, scientific evidence on the efficacy of these phytochemicals in treating diabetes or preventing the onset and progression of its complications in clinical settings is scarce, which delays the translation of animal study evidence to human applications and also limits the knowledge on their modes of actions in diabetes management. This review is aimed to highlight the potential roles of flavonoids and carotenoids in preventing or ameliorating diabetes-related complications based on in vivo study evidence, i.e., an array of preclinical animal studies and human intervention trials. The current general consensus of the underlying mechanisms of action exerted by both groups of phytochemicals is that their anti-inflammatory action is key. However, other potential mechanisms of action are considered. In total, 50 in vivo studies were selected for a review after a comprehensive database search via PubMed and ScienceDirect from January 2002 to August 2022. The key words used for analysis are type-2 diabetes (T2DM), diabetic complications, flavonoids, carotenoids, antioxidant, anti-inflammatory, mechanisms of prevention and amelioration, animal studies and human interventions.

Total dietary flavonoid intake and risk of cardiometabolic diseases: A dose-response meta-analysis of prospective cohort studies

Several epidemiological studies have suggested that flavonoid intake is associated with a decreased risk of cardiometabolic disease. However, the results remained inconsistent and there is no dose-response meta-analysis for specific outcomes. We conducted a meta-analysis to synthesize the knowledge about their associations and to explore their dose-response relationships. We comprehensively searched the PubMed, Embase, and Web of Science databases for prospective cohort studies published up to December 1, 2021. Summary relative risks (RR) and 95% confidence intervals (CI) were pooled for the association between flavonoid intake and cardiometabolic disease. Evaluations of linear or nonlinear dose-response were presented by restricted cubic splines. We identified 47 articles, including 1,346 676 participants and 127,507 cases in this meta-analysis. The summary of RR per 500 mg/d increase in flavonoid intake was 0.93 (95% CI 0.88-0.98) for cardiovascular disease, 0.89 (95% CI 0.84-0.94) for diabetes, and 0.97 (95% CI 0.94-0.99) for hypertension, respectively. We also found a linearity dose-response association between total flavonoid intake and cardiovascular disease (p nonlinearity = 0.541), and diabetes (p nonlinearity = 0.077). Our finding based on quantitative data suggested that a higher level of flavonoid intake is beneficial for the prevention of cardiometabolic diseases.

Flavonoids metabolism and physiological response to ultraviolet treatments in Tetrastigma hemsleyanum Diels et Gilg

Tetrastigma hemsleyanum Diels et Gilg is a folk herb in Zhejiang Province with anti-inflammatory, antineoplastic, and anti-oxidation effects. Given its pharmacological activity, T. hemsleyanum is known as New "Zhebawei" and included in the medical insurance system of Zhejiang and other provinces. Flavonoids are the most important components of T. hemsleyanum, and their contents are mainly regulated by ultraviolet (UV) radiation. In this study, the total flavonoid contents, flavonoid monomer contents, and flavonoid synthesis related enzyme activities (phenylalanine ammonia-lyase, chalcone synthase, and chalcone isomerase), anti-oxidant enzyme activities (catalase, peroxidase, and superoxide dismutase), and biochemical indicators (malondialdehyde, free amino acid, soluble protein, and soluble sugar) in the leaves (L) and root tubers (R) of T. hemsleyanum with UV treatments were determined. Three kinds of UV radiation (UV-A, UV-B, and UV-C) and six kinds of radiation durations (15 and 30 min, 1, 2, 3, and 5 h) were used. Appropriate doses of UV-B and UV-C radiation (30 min to 3 h) induced eustress, which contributed to the accumulation of flavonoids and improve protective enzyme system activities and bioactive compound contents. Especially, certain results were observed in several special structures of the flavonoid monomer: quercetin contents in L increased by nearly 20 times, isoquercitrin contents in R increased by nearly 34 times; most of flavonoids with glycoside content, such as quercitrin (19 times), baicalin (16 times), and apigenin-7G (13 times), increased multiple times. Compared with the CK group, the flavonoid synthase activities, anti-oxidant enzyme activities, and biochemical substance contents in L and R all increased with UV treatments. This study provides a theoretical foundation for regulating flavonoids by light factors and improving the quality of T. hemsleyanum in production and medical industries.

Association between non-tea flavonoid intake and risk of type 2 diabetes: the Australian diabetes, obesity and lifestyle study

Studies examining the association between flavonoid intake and measures of insulin resistance and β-cell dysfunction, as markers of type 2 diabetes (T2DM) across the adult lifespan, may provide insights into how flavonoids influence T2DM risk. This study examined the cross-sectional associations between flavonoid intakes, from dietary sources other than tea, and biomarkers of glucose tolerance and insulin sensitivity in adults aged 25 years and older participating in the Australian diabetes, obesity and lifestyle (AusDiab) study. Additionally, longitudinal associations between non-tea flavonoid intakes and incident T2DM over 12 years were explored. Eligible participants (n = 7675) had no previous history of T2DM and had completed a food-frequency questionnaire at baseline (1999-2000) from which flavonoid intakes were calculated using United States Department of Agriculture Databases. Restricted cubic splines in regression models were used to examine cross-sectional associations between intakes of total non-tea flavonoids and selected flavonoid subclasses and measures of glucose tolerance and insulin sensitivity including glycated haemoglobin (HbA1c), homeostasis model assessment of β-cell function (HOMA2-% β) and insulin sensitivity (HOMA2-% S), 2-hour post load plasma glucose (PLG), fasting plasma glucose (FPG) and fasting insulin levels. Associations between flavonoid intakes and T2DM risk were estimated using Cox proportional hazards models. Cross-sectionally, significant beneficial associations were observed for intakes of total flavonoids and the flavan-3-ol-monomer, proanthocyanidin, flavonol and anthocyanidin subclasses with measures of glucose tolerance and insulin sensitivity (P < 0.05 for all), except fasting plasma glucose. During follow-up, 344 incident T2DM cases were recorded. Participants with the highest total flavonoid intake had a 21% lower risk of T2DM over 12 years, although this was not statistically significant in multivariable adjusted models [HR (95% CI): 0.79 (0.57, 1.09)]. This study provides some evidence that consuming flavonoid-rich foods may be protective against T2DM through mechanisms related to glucose tolerance and insulin sensitivity.

Links between Insulin Resistance and Periodontal Bacteria: Insights on Molecular Players and Therapeutic Potential of Polyphenols

Type 2 diabetes is a metabolic disease mainly associated with insulin resistance during obesity and constitutes a major public health problem worldwide. A strong link has been established between type 2 diabetes and periodontitis, an infectious dental disease characterized by chronic inflammation and destruction of the tooth-supporting tissue or periodontium. However, the molecular mechanisms linking periodontal bacteria and insulin resistance remain poorly elucidated. This study aims to summarize the mechanisms possibly involved based on in vivo and in vitro studies and targets them for innovative therapies. Indeed, during periodontitis, inflammatory lesions of the periodontal tissue may allow periodontal bacteria to disseminate into the bloodstream and reach tissues, including adipose tissue and skeletal muscles that store glucose in response to insulin. Locally, periodontal bacteria and their components, such as lipopolysaccharides and gingipains, may deregulate inflammatory pathways, altering the production of pro-inflammatory cytokines/chemokines. Moreover, periodontal bacteria may promote ROS overproduction via downregulation of the enzymatic antioxidant defense system, leading to oxidative stress. Crosstalk between players of inflammation and oxidative stress contributes to disruption of the insulin signaling pathway and promotes insulin resistance. In parallel, periodontal bacteria alter glucose and lipid metabolism in the liver and deregulate insulin production by pancreatic β-cells, contributing to hyperglycemia. Interestingly, therapeutic management of periodontitis reduces systemic inflammation markers and ameliorates insulin sensitivity in type 2 diabetic patients. Of note, plant polyphenols exert anti-inflammatory and antioxidant activities as well as insulin-sensitizing and anti-bacterial actions. Thus, polyphenol-based therapies are of high interest for helping to counteract the deleterious effects of periodontal bacteria and improve insulin resistance.

Flavonoid constituents of Amomum tsao-ko Crevost et Lemarie and their antioxidant and antidiabetic effects in diabetic rats - in vitro and in vivo studies

Amomum tsao-ko Crevost et Lemarie (A. tsao-ko) is a well-known dietary spice and traditional Chinese medicine. This study aimed to identify the flavonoids in A. tsao-ko and evaluate their antioxidant and antidiabetic activities in in vitro and in vivo studies. A. tsao-ko methanol extracts possessed a high flavonoid content (1.21 mg QE per g DW) and a total of 29 flavonoids were identified by employing UPLC-MS/MS. In vitro, A. tsao-ko demonstrated antioxidant activity (ORAC value of 34276.57 μM TE/100 g DW, IC₅₀ of ABTS of 3.49 mg mL^-1 and FRAP value of 207.42 μM Fe²⁺ per g DW) and α-amylase and α-glucosidase inhibitory ability with IC₅₀ values of 14.23 and 1.76 mg mL^-1, respectively. In vivo, type 2 diabetes mellitus (T2DM) models were induced by a combined high-fat diet (HFD) and streptozotocin (STZ) injection in rats. Treatment with the A. tsao-ko extract (100 mg freeze-dried powder per kg bw) for 6 weeks could significantly improve impaired glucose tolerance, decrease the levels of fasting blood glucose (FBG), insulin, and malondialdehyde (MDA), and increase the superoxide dismutase (SOD) level. Histopathology revealed that the A. tsao-ko extract preserved the architecture and function of the pancreas. In conclusion, the flavonoid composition of A. tsao-ko exhibits excellent antioxidant and antidiabetic activity in vitro and in vivo. A. tsao-ko could be a novel natural material and developed as a related functional food and medicine in T2DM management.

( -)-Epicatechin and cardiometabolic risk factors: a focus on potential mechanisms of action

This review summarizes experimental evidence on the beneficial effects of ( -)-epicatechin (EC) attenuating major cardiometabolic risk factors, i.e., dyslipidemias, obesity (adipose tissue dysfunction), hyperglycemia (insulin resistance), and hypertension (endothelial dysfunction). Studies in humans are revised and complemented with experiments in animal models, and cultured cells, aiming to understand the molecular mechanisms involved in EC-mediated effects. Firstly, an assessment of EC metabolism gives relevance to both conjugated-EC metabolites product of host metabolism and microbiota-derived species. Integration and analysis of results stress the maintenance of redox homeostasis and mitigation of inflammation as relevant processes associated with cardiometabolic diseases. In these processes, EC appears having significant effects regulating NADPH oxidase (NOX)-dependent oxidant production, nitric oxide (NO) production, and energy homeostasis (mitochondrial biogenesis and function). The potential participation of cell membranes and membrane-bound receptors is also discussed in terms of direct molecular action of EC and EC metabolites reaching cells and tissues.