Targeting gut microbiota in type 2 diabetes mellitus: Potential roles of dietary flavonoids

Hesperetin-Enhanced Metformin to Alleviate Cognitive Impairment via Gut-Brain Axis in Type 2 Diabetes Rats

Diabetes constitutes a risk factor for cognitive impairment, whereas insulin resistance serves as the shared pathogenesis underlying both diabetes and cognitive decline. The use of metformin for treating cognitive impairment remains controversial. The present study found that hesperetin, a flavanone derived from citrus peel, enhanced metformin's efficacy in reducing blood sugar levels, improving insulin sensitivity, and ameliorating cognitive impairment in diabetic rats. Additionally, it reduced the required dosage of metformin to one-third of its conventional dose. Transcriptome analysis and 16S rRNA sequencing revealed that the activation of insulin and cyclic-adenosine monophosphate response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) pathways benefited from the regulation of gut microbiota and the promotion of short-chain fatty acid (SCFA) producers such as Romboutsia. Furthermore, this study demonstrated that hesperetin supplementation counteracted the upregulation of β-site amyloid precursor protein cleaving enzyme 1 (BACE1), a pathological factor of Alzheimer's disease (AD) that was induced by metformin. Our findings reveal that hesperetin can be used in supplementary treatment for cognitive impairment associated with diabetes.

Role of Flavonoids in Mitigating the Pathological Complexities and Treatment Hurdles in Alzheimer's Disease

With the passage of time, people step toward old age and become more prone to several diseases associated with the age. One such is Alzheimer's disease (AD) which results into neuronal damage and dementia with the progression of age. The existing therapeutics has been hindered by various enkindles like less eminent between remote populations, affordability issues and toxicity profiles. Moreover, lack of suitable therapeutic option further worsens the quality of life in older population. Developing an efficient therapeutic intervention to cure AD is still a challenge for medical fraternity. Recently, alternative approaches attain the attention of researchers to focus on plant-based therapy in mitigating AD. In this context, flavonoids gained centrality as a feasible treatment in modifying various neurological deficits. This review mainly focuses on the pathological facets and economic burden of AD. Furthermore, we have explored the possible mechanism of flavonoids with the preclinical and clinical aspects for curing AD. Flavonoids being potential therapeutic, target the pathogenic factors of AD such as oxidative stress, inflammation, metal toxicity, Aβ accumulation, modulate neurotransmission and insulin signaling. In this review, we emphasized on potential neuroprotective effects of flavonoids in AD pathology, with focus on both experimental and clinical findings. While preclinical studies suggest promising therapeutic benefits, clinical data remains limited and inconclusive. Thus, further high-quality clinical trials are necessary to validate the efficacy of flavonoids in AD. The study aim is to promote the plant-based therapies and encourage people to add flavonoids to regular diet to avail the beneficial effects in preventive therapy for AD.

Global bibliometric analysis of traditional Chinese medicine regulating gut microbiota in the treatment of diabetes from 2004 to 2024

Objectives

The therapeutic efficacy of Traditional Chinese Medicine (TCM) in modulating gut microbiota for diabetes treatment has garnered increasing scholarly attention. This study aims to meticulously examine current research trajectories and focal areas from 2004 to 2024, providing a foundational framework for future inquiries.

Methods

A comprehensive search of documents published between 2004 and 2024 was conducted using the Web of Science database. The resulting data were analyzed and visualized using R software, VOSviewer, and CiteSpace.

Results

The study included a total of 751 documents. From 2004 to 2022, the number of annual publications showed a continuous upward trend (2004: n = 1 to 2022: n = 159), and the number of publications in 2023 (n = 141) decreased slightly from the previous year. China emerged as the leading country in terms of article publications (n = 430). Additionally, the United States played a prominent role in international research collaborations. Frontiers in Pharmacology (n = 31) was the most frequently published journal, while Nature (n = 1,147) achieved the highest citation count. Key identified keywords included obesity, insulin resistance, inflammation, and oxidative stress.

Conclusion

Three key research focuses in this domain include: the therapeutic effects of active constituents in TCM on diabetes via gut microbiota modulation, the underlying mechanisms through which TCM influences gut microbiota in diabetes management, and the targeted regulation of specific gut bacterial populations by TCM in the treatment of diabetes.

Flavonoids and the gut microbiome: a powerful duo for brain health

Flavonoids, a class of polyphenolic compounds, are widely distributed in plant-based foods and have been recognized for their potential to promote overall health and well-being. Flavonoids in fruits and vegetables offer various beneficial effects such as anti-aging, anticancer, and anti-inflammatory properties. Flavonoids have been extensively studied for their neuroprotective properties, which are attributed to their ability to cross the blood-brain barrier and interact with neural cells. Factors like gut microbiota composition, age, genetics, and diet can impact how well flavonoids are absorbed in the gut. The gut microbiota can enhance the absorption of flavonoids through enzymatic processes, making microbiota composition a key factor influenced by age, genetics, and diet. Flavonoids can modulate the gut microbiota through prebiotic and antimicrobial effects, affecting the production of beneficial microbial metabolites like short-chain fatty acids (SCFAs) such as butyrate, which play a role in brain function and health. The gut microbiome also modulates the immune system, which is critical for preventing neuroinflammation. Additionally, flavonoids can benefit mental and psychological health by influencing anti-inflammatory signaling pathways in brain cells and increasing the absorption of tyrosine and tryptophan, precursors to neurotransmitters like serotonin, dopamine, norepinephrine, adrenaline, and gamma-aminobutyric acid (GABA). The flavonoid-gut microbiome axis is a complex and multifaceted relationship that has significant implications for neurological health. This review will explore how genetic and environmental factors can impact flavonoid absorption and the positive effects of flavonoids on brain health and the gut microbiota network.

Hydrogen Sulfide and Gut Microbiota: Their Synergistic Role in Modulating Sirtuin Activity and Potential Therapeutic Implications for Neurodegenerative Diseases

The intricate relationship between hydrogen sulfide (H2S), gut microbiota, and sirtuins (SIRTs) can be seen as a paradigm axis in maintaining cellular homeostasis, modulating oxidative stress, and promoting mitochondrial health, which together play a pivotal role in aging and neurodegenerative diseases. H2S, a gasotransmitter synthesized endogenously and by specific gut microbiota, acts as a potent modulator of mitochondrial function and oxidative stress, protecting against cellular damage. Through sulfate-reducing bacteria, gut microbiota influences systemic H2S levels, creating a link between gut health and metabolic processes. Dysbiosis, or an imbalance in microbial populations, can alter H2S production, impair mitochondrial function, increase oxidative stress, and heighten inflammation, all contributing factors in neurodegenerative diseases such as Alzheimer's and Parkinson's. Sirtuins, particularly SIRT1 and SIRT3, are NAD+-dependent deacetylases that regulate mitochondrial biogenesis, antioxidant defense, and inflammation. H2S enhances sirtuin activity through post-translational modifications, such as sulfhydration, which activate sirtuin pathways essential for mitigating oxidative damage, reducing inflammation, and promoting cellular longevity. SIRT1, for example, deacetylates NF-κB, reducing pro-inflammatory cytokine expression, while SIRT3 modulates key mitochondrial enzymes to improve energy metabolism and detoxify reactive oxygen species (ROS). This synergy between H2S and sirtuins is profoundly influenced by the gut microbiota, which modulates systemic H2S levels and, in turn, impacts sirtuin activation. The gut microbiota-H2S-sirtuin axis is also essential in regulating neuroinflammation, which plays a central role in the pathogenesis of neurodegenerative diseases. Pharmacological interventions, including H2S donors and sirtuin-activating compounds (STACs), promise to improve these pathways synergistically, providing a novel therapeutic approach for neurodegenerative conditions. This suggests that maintaining gut microbiota diversity and promoting optimal H2S levels can have far-reaching effects on brain health.

Fucoxanthin Mitigates High-Fat-Induced Lipid Deposition and Insulin Resistance in Skeletal Muscle through Inhibiting PKM1 Activity

Glucose and lipid metabolism dysregulation in skeletal muscle contributes to the development of metabolic disorders. The efficacy of fucoxanthin in alleviating lipid metabolic disorders in skeletal muscle remains poorly understood. In this study, we systematically investigated the impact of fucoxanthin on mitigating lipid deposition and insulin resistance in skeletal muscle employing palmitic acid-induced lipid deposition in C2C12 cells and ob/ob mice. Fucoxanthin significantly alleviated PA-induced skeletal muscle lipid deposition and insulin resistance. In addition, fucoxanthin prominently upregulated the expression of lipid metabolism-related genes (Pparα and Cpt-1), promoting fatty acid β-oxidation metabolism. Additionally, fucoxanthin significantly increased the expression of Pgc-1α and Tfam, elevated the mtDNA/nDNA ratio, and reduced ROS levels. Further, we identified pyruvate kinase muscle isozyme 1 (PKM1) as a high-affinity protein for fucoxanthin by drug affinity-responsive target stability and LC-MS and confirmed their robust interaction by CETSA, microscale thermophoresis, and circular dichroism. Supplementation with pyruvate, the product of PKM1, significantly attenuated the beneficial effects of fucoxanthin on lipid deposition and insulin resistance. Mechanistically, fucoxanthin reduced glucose glycolysis rate and enhanced mitochondrial biosynthesis and fatty acid β-oxidation through inhibiting PKM1 activity, thereby alleviating lipid metabolic stress. These findings present a novel clinical strategy for treating metabolic diseases using fucoxanthin.

Mulberry polyphenols restored both small and large intestinal microflora in db/db mice, potentially alleviating type 2 diabetes

Polyphenols in mulberry fruit have potential anti-diabetic effects by targeting the gut microbiota. This study investigated how mulberry polyphenols (MPs) influence the microbiota of the small and large intestines and their effects on type 2 diabetes symptoms. The results showed lower microbiota densities in the small intestine. MP treatments improved microbiota richness and diversity in both intestines, similar to metformin. In particular, at a 400 mg kg-1 dose, mulberry polyphenols decreased Firmicutes, Lactobacillus, and Bacilli, while increasing Bacteroidetes, leading to elevated propionate and butyrate levels. Less abundant small intestinal microbiota, like Enterobacterales, Mycoplasmatales, Enterobacteriaceae, and Ureaplasma, were involved in regulating blood glucose and insulin levels. Functional analysis suggested that mulberry polyphenols reshaped the small intestinal microbiota to influence blood glucose balance via unknown pathways, while in the large intestine, they primarily affected blood glucose through carbohydrate transport and metabolism. Based on their ability to regulate the composition of intestinal flora, MPs likely improved glucose homeostasis by enhancing glucose utilization, supporting pancreatic tissue health, and increasing serum antioxidant capacity. However, the specific mechanisms underlying this potential are yet to be fully explored. This study provides new insights into the influence of MPs on remodeling the microbiota residing in both the small and large intestines, which thereby may contribute to the improvement of the pathophysiology of type 2 diabetes.

Analysis of the antioxidant activity of toons sinensis extract and their biological effects on broilers

Plant extracts are rich in a variety of nutrients and contain a large number of bioactive compounds, and compared with traditional feed additives, they have advantages such as wide sources, natural safety and rich nutrition. This study employed in vitro antioxidant and animal experiments to comprehensively evaluate the use of Toona sinensis extract (TSE) in broiler production. 508 1-day-old Cobb 500 broilers were randomly assigned to the 7 experimental groups with 6 replications and 12 birds/replicate. Two groups received Vitamin C (VC) 300 g/t and Vitamin E 500 g/t, and five dose groups of TSE received 0, 300, 600, 900, and 1,200 g/t of TSE in their feed. The study spanned 42 days, with a starter phase (1-21 days) and a finisher phase (22-42 days). The results showed that compared to ascorbic acid, TSE had the scavenging ability of 2,2-Diphenyl-1-picrylhydrazyl and hydroxyl radical, with IC50 values of 0.6658 mg/mL and 33.1298 mg/mL, respectively. Compared to TSE 0 group, broilers fed with 1,200 g/t TSE showed significant weight gain during the starter phase and increased the feed-to-weight gain ratio during both the starter and finisher phases. Additionally, broilers receiving 1,200 g/t TSE had enhanced dry matter and organic matter utilization. Concerning meat quality, broilers in the 1,200 g/t TSE group demonstrated increased cooked meat yield, and pH value, as well as higher antioxidant capacity (T-AOC), dismutase (SOD), and glutathione peroxidase (GSH-PX) in serum. In addition, there was no significant difference in ileal microflora due to TSE supplementation. In summary, this study confirms the positive impact of a dietary inclusion of 1,200 g/t TSE on broiler growth, meat quality, and serum antioxidants.

Dietary flavonoids prevent diabetes through epigenetic regulation: advance and challenge

The pathophysiology of diabetes has been studied extensively in various countries, but effective prevention and treatment methods are still insufficient. In recent years, epigenetics has received increasing attention from researchers in exploring the etiology and treatment of diabetes. DNA methylation, histone modifications, and non-coding RNAs play critical roles in the occurrence, maintenance, and progression of diabetes and its complications. Therefore, preventing or reversing the epigenetic alterations that occur during the development of diabetes may reduce the individual and societal burden of the disease. Dietary flavonoids serve as natural epigenetic modulators for the discovery of biomarkers for diabetes prevention and the development of alternative therapies. However, there is limited knowledge about the potential beneficial effects of flavonoids on the epigenetics of diabetes. In this review, the multidimensional epigenetic effects of different flavonoid subtypes in diabetes were summarized. Furthermore, it was discussed that parental flavonoid diets might reduce diabetes incidence in offspring, which represent a promising opportunity to prevent diabetes in the future. Future work will depend on exploring anti-diabetic effects of different flavonoids with different epigenetic regulation mechanisms and clinical trials.Highlights• "Epigenetic therapy" could reduce the burden of diabetic patients• "Epigenetic diet" ameliorates diabetes• Targeting epigenetic regulations by dietary flavonoids in the diabetes prevention• Dietary flavonoids prevent diabetes via transgenerational epigenetic inheritance.

Dietary sinensetin and polymethoxyflavonoids: Bioavailability and potential metabolic syndrome-related bioactivity

Sinensetin is among the most ubiquitous polyphenols in citrus fruit and recently has been extensively studied for its ability to prevent or treat diseases. The current literature on the bioavailability of sinensetin and its derivatives was reviewed and the potential ameliorative effects of metabolic syndrome in humans were evaluated. Sinensetin and its derivatives mainly aggregated in the large intestine and extensively metabolized through gut microbiota (GM) and the liver. So intestinal microorganisms had a significant influence on the absorption and metabolism of sinensetin. Interestingly, not only GM acted on sinensetin to metabolize them, but sinensetin also regulated the composition of GM. Thus, sinensetin was metabolized as methyl, glucuronide and sulfate metabolites in the blood and urine. Furthermore, sinensetin was reported to have the beneficial effect of ameliorating metabolic syndromes, including disorders of lipid metabolism (obesity, NAFLD, atherosclerosis), glucose metabolism disorder (insulin resistant) and inflammation, in terms of improving the composition of intestinal flora and modulating metabolic pathway factors in relevant tissues. The present work strongly elucidated the potential mechanism of sinensetin in improving metabolic disorders and supported the contribution of sinensetin to health benefits, thus offering a better perspective in understanding the role played by sinensetin in human health.

Role of flavonoids in controlling obesity: molecular targets and mechanisms

Obesity presents a major health challenge that increases the risk of several non-communicable illnesses, such as but not limited to diabetes, hypertension, cardiovascular diseases, musculoskeletal and neurological disorders, sleep disorders, and cancers. Accounting for nearly 8% of global deaths (4.7 million) in 2017, obesity leads to diminishing quality of life and a higher premature mortality rate among affected individuals. Although essentially dubbed as a modifiable and preventable health concern, prevention, and treatment strategies against obesity, such as calorie intake restriction and increasing calorie burning, have gained little long-term success. In this manuscript, we detail the pathophysiology of obesity as a multifactorial, oxidative stress-dependent inflammatory disease. Current anti-obesity treatment strategies, and the effect of flavonoid-based therapeutic interventions on digestion and absorption, macronutrient metabolism, inflammation and oxidative stress and gut microbiota has been evaluated. The use of several naturally occurring flavonoids to prevent and treat obesity with a long-term efficacy, is also described.

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.

Anti-Diabetic Effects of Ethanol Extract from Sanghuangporous vaninii in High-Fat/Sucrose Diet and Streptozotocin-Induced Diabetic Mice by Modulating Gut Microbiota

Type 2 diabetes mellitus (T2DM) may lead to abnormally elevated blood glucose, lipid metabolism disorder, and low-grade inflammation. Besides, the development of T2DM is always accompanied by gut microbiota dysbiosis and metabolic dysfunction. In this study, the T2DM mice model was established by feeding a high-fat/sucrose diet combined with injecting a low dose of streptozotocin. Additionally, the effects of oral administration of ethanol extract from Sanghuangporous vaninii (SVE) on T2DM and its complications (including hypoglycemia, hyperlipidemia, inflammation, and gut microbiota dysbiosis) were investigated. The results showed SVE could improve body weight, glycolipid metabolism, and inflammation-related parameters. Besides, SVE intervention effectively ameliorated the diabetes-induced pancreas and jejunum injury. Furthermore, SVE intervention significantly increased the relative abundances of Akkermansia, Dubosiella, Bacteroides, and Parabacteroides, and decreased the levels of Lactobacillus, Flavonifractor, Odoribacter, and Desulfovibrio compared to the model group (LDA > 3.0, p < 0.05). Metabolic function prediction of the intestinal microbiota by PICRUSt revealed that glycerolipid metabolism, insulin signaling pathway, PI3K-Akt signaling pathway, and fatty acid degradation were enriched in the diabetic mice treated with SVE. Moreover, the integrative analysis indicated that the key intestinal microbial phylotypes in response to SVE intervention were strongly correlated with glucose and lipid metabolism-associated biochemical parameters. These findings demonstrated that SVE has the potential to alleviate T2DM and its complications by modulating the gut microbiota imbalance.

Kombucha Reduces Hyperglycemia in Type 2 Diabetes of Mice by Regulating Gut Microbiota and Its Metabolites

Kombucha, which is rich in tea polyphenols and organic acid, is a kind of acidic tea soup beverage fermented by acetic acid bacteria, yeasts, lactic acid bacteria. Kombucha has been reported to possess anti-diabetic activity, but the underlying mechanism was not well understood. In this study, a high-fat, high-sugar diet combined with streptozotocin (STZ) injection was used to induce T2DM model in mice. After four weeks of kombucha intervention, the physiological and biochemical index were measured to determine the diabetes-related indicators. High-throughput sequencing technology was used to analyze the changes in gut microbiota from the feces. The results showed that four weeks of kombucha intervention increased the abundance of SCFAs-producing bacteria and reduced the abundance of gram-negative bacteria and pathogenic bacteria. The improvement in gut microbiota reduced the damage of intestinal barrier, thereby reducing the displacement of lipopolysaccharide (LPS) and inhibiting the occurrence of inflammation and insulin resistance in vivo. In addition, the increased levels of SCFAs-producing bacteria, and thus increasing the SCFAs, improved islet β cell function by promoting the secretion of gastrointestinal hormones (GLP-1/PYY). This study methodically uncovered the hypoglycemic mechanism of kombucha through gut microbiota intervention, and the result suggested that kombucha may be introduced as a new functional drink for T2DM prevention and treatment.

Review of the correlation between Chinese medicine and intestinal microbiota on the efficacy of diabetes mellitus

Diabetes mellitus is a serious metabolic disorder that can lead to a number of life-threatening complications. Studies have shown that intestinal microbiota is closely related to the development of diabetes, making it a potential target for the treatment of diabetes. In recent years, research on the active ingredients of traditional Chinese medicine (TCM), TCM compounds, and prepared Chinese medicines to regulate intestinal microbiota and improve the symptoms of diabetes mellitus is very extensive. We focus on the research progress of TCM active ingredients, herbal compounds, and prepared Chinese medicines in the treatment of diabetes mellitus in this paper. When diabetes occurs, changes in the abundance and function of the intestinal microbiota disrupt the intestinal environment by disrupting the intestinal barrier and fermentation. TCM and its components can increase the abundance of beneficial bacteria while decreasing the abundance of harmful bacteria, regulate the concentration of microbial metabolites, improve insulin sensitivity, regulate lipid metabolism and blood glucose, and reduce inflammation. TCM can be converted into active substances with pharmacological effects by intestinal microbiota, and these active substances can reverse intestinal microecological disorders and improve diabetes symptoms. This can be used as a reference for diabetes prevention and treatment.