Involvement of the PI3K/Akt signal pathway in the hypoglycemic effects of tea polysaccharides on diabetic mice

Evidence of traditional Chinese medicine for treating type 2 diabetes mellitus: from molecular mechanisms to clinical efficacy

CONTEXT

The global prevalence of type 2 diabetes mellitus (T2DM) has increased significantly in recent decades. Despite numerous studies and systematic reviews, there is a gap in comprehensive and up-to-date evaluations in this rapidly evolving field.

OBJECTIVE

This review provides a comprehensive and current overview of the efficacy of Traditional Chinese Medicine (TCM) in treating T2DM.

METHODS

A systematic review was conducted using PubMed, Web of Science, Wanfang Data, CNKI, and Medline databases, with a search timeframe extending up to November 2023. The search strategy involved a combination of subject terms and free words in English, including 'Diabetes,' 'Traditional Chinese Medicine,' 'TCM,' 'Hypoglycemic Effect,' 'Clinical Trial,' and 'Randomized Controlled Trial.' The studies were rigorously screened by two investigators, with a third investigator reviewing and approving the final selection based on inclusion and exclusion criteria.

RESULTS

A total of 108 relevant papers were systematically reviewed. The findings suggest that TCMs not only demonstrate clinical efficacy comparable to existing Western medications in managing hypoglycemia but also offer fewer adverse effects and a multitarget therapeutic approach. Five main biological mechanisms through which TCM treats diabetes were identified: improving glucose transport and utilization, improving glycogen metabolism, promoting GLP-1 release, protecting pancreatic islets from damage, and improving intestinal flora.

CONCLUSIONS

TCM has demonstrated significant protective effects against diabetes and presents a viable option for the prevention and treatment of T2DM. These findings support the further exploration and integration of TCM into broader diabetes management strategies.

Extraction methods, chemical compositions, molecular structure, health functions, and potential applications of tea polysaccharides as a promising biomaterial: a review

Tea polysaccharides (TPS) have attracted much attention due to their multiple biological activities, excellent biocompatibility and good biodegradability, creating a wide range of potential applications in the food and pharmaceutical industries. However, the high molecular weight and complexity of TPS components have restricted its purification and bioactivity, limiting its potential applications. In this review, the effects of various extraction methods, tea processing, and degree of fermentation on the composition and structure of TPS were thoroughly investigated to overcome this dilemma. Through a comprehensive analysis of in vivo and in vitro studies, the health benefits of TPS are discussed in detail, including antioxidant, anti-obesity, modulation of gut microbial communities, and anticancer bioactivities. Typical structural characterization techniques of TPS are also summarized, and interactions with common food components are discussed in depth, providing a deeper perspective on the overall knowledge of TPS. Finally, this review offers an extensive overview of the wide range of applications of TPS, including its strong emulsifying properties and bio-accessibility, in various fields such as food nutrition, drug delivery, encapsulation films, and emulsifiers. This review aims to provide a theoretical basis for the profound development of TPS for productive utilization.

Effect of Black Tea Polysaccharides on Alleviating Type 2 Diabetes Mellitus by Regulating PI3K/Akt/GLUT2 Pathway

The bioactivity of tea polysaccharides (TPs) has been widely reported, but studies to date have focused on green tea. Some human health investigations have implied that black tea may possess potential antidiabetic effects, but less is known about their potential role and related antidiabetic mechanism. The present study was, therefore, conducted to investigate the chemical properties and antidiabetic activity of TPs from black tea. Monosaccharide composition revealed that Alduronic acid (77.8 mol%) considerably predominated in the fraction. TP conformation analysis indicated that three components in TPs were all typical of high-branching structures. Oral administration of TPs could effectively alleviate fasting blood glucose in type 2 diabetes mellitus (T2D) mice, with the values 23.6 ± 1.42, 19.6 ± 2.25, and 16.4 ± 2.07 mmol/L in the 200, 400, and 800 mg/kg·BW groups, respectively. Among these TPs groups, the 800 mg/kg·BW groups significantly decreased by 37.88% when compared with the T2D+water group (p < 0.05). Further studies demonstrated that TP treatment upregulated the expression of p-Akt/p-PI3K (p < 0.001). Additionally, TP treatment significantly promoted glucose transporter protein 2 (GLUT2) translocation in the liver (p < 0.001). These findings suggest that TPs from black tea protect against T2D by activating PI3K/Akt/GLUT2 signaling and might serve as a novel therapeutic candidate for T2D.

Antidiabetic Potential of Tea and Its Active Compounds: From Molecular Mechanism to Clinical Evidence

Diabetes mellitus (DM) is a chronic endocrine disorder that poses a long-term risk to human health accompanied by serious complications. Common antidiabetic drugs are usually accompanied by side effects such as hepatotoxicity and nephrotoxicity. There is an urgent need for natural dietary alternatives for diabetic treatment. Tea (Camellia sinensis) consumption has been widely investigated to lower the risk of diabetes and its complications through restoring glucose metabolism homeostasis, safeguarding pancreatic β-cells, ameliorating insulin resistance, ameliorating oxidative stresses, inhibiting inflammatory response, and regulating intestinal microbiota. It is indispensable to develop effective strategies to improve the absorption of tea active compounds and exert combinational effects with other natural compounds to broaden its hypoglycemic potential. The advances in clinical trials and population-based investigations are also discussed. This review primarily delves into the antidiabetic potential and underlying mechanisms of tea active compounds, providing a theoretical basis for the practical application of tea and its active compounds against diabetes.

Enhanced hypoglycemic effects of konjac glucomannan combined with Polygonatum cyrtonema Hua polysaccharide in complete nutritional liquid diet fed type 2 diabetes mice

In our aging society, dysphagia and malnutrition are growing concerns, necessitating intervention. Liquid nutrition support offers a practical solution for traditional dietary issues, but it raises a key issue: the potential for post-meal glucose spikes impacting efficacy. This study examined the effects of supplementation of Polygonatum cyrtonema Hua polysaccharide (PCP), konjac glucomannan (KGM) and their combination on acute phase postprandial glycemic response and long-term glucose metabolism in T2DM mice on a complete nutritional liquid diet. KGM was more effective in reducing postprandial glucose response, while PCP was more prominent in ameliorating long-term glucose metabolism. The KGM-PCP combination demonstrated superior outcomes in fasting blood glucose, insulin, and glucose homeostasis. PCP and KGM also influenced the composition and abundance of the gut microbiome, with the H-PCP group showing optimal performance. Moreover, the KGM-PCP combination improved body weight, lipid homeostasis, and liver health the most. PCP potentially regulates glycemia through metabolic pathways, while KGM improves glycemic metabolism by reducing postprandial glucose levels in response to viscous intestinal contents. This research identifies the structure, viscosity properties, and hypoglycemic effects of KGM and PCP in complete nutritional liquid diet fed T2DM mice, enabling their strategic utilization as hypoglycemic components in nutritional administration and glycemic regulation.

Hypoglycemic Effects of Gynura divaricata (L.) DC Polysaccharide and Action Mechanisms via Modulation of Gut Microbiota in Diabetic Mice

Aiming to provide a basis for the application of Gynura divaricata (L.) DC polysaccharide (GDP) in functional foods, the hypoglycemic effects of GDP, and action mechanisms, were investigated. Results showed that GDP effectively inhibited α-glucosidase and remarkably increased the glucose absorption, glycogen content, and pyruvate kinase and hexokinase activities of insulin-resistant HepG2 cells, indicating its potent in vitro hypoglycemic effect. In streptozotocin-induced type 2 diabetes mice, GDP significantly improved various glycolipid metabolism-related indices in serum and liver, e.g., fasting blood glucose, oral glucose tolerance, glycosylated serum protein content, serum insulin level, antioxidant enzyme activities, TG, TC, LDL-C, and HDL-C levels, and hepatic glycogen content, and recovered the structure of gut microbiota to the normal level. It was also found that GDP significantly affected the expression of related genes in the PI3K/Akt, AMPK, and GS/GSK-3β signaling pathways. Therefore, GDP regulates blood glucose possibly by directly inhibiting α-glucosidase, exerting antioxidant activity, and regulating intestinal microbiota.

Genus Physalis L.: A review of resources and cultivation, chemical composition, pharmacological effects and applications

ETHNOPHARMACOLOGICAL RELEVANCE

The genus Physalis L. (Solanaceae) is commonly used in the treatment of dermatitis, leprosy, bronchitis, pneumonia, hepatitis and rheumatism in China and other Asian countries.

AIM OF THE REVIEW

This article reviews the resources, cultivation, phytochemistry, pharmacological properties, and applications of Physalis L., and proposes further research strategies to enhance its therapeutic potential in treating various human diseases.

MATERIALS AND METHODS

We conducted a systematic search of electronic databases, including CNKI, SciFinder and PubMed, using the term "Physalis L." to collect information on the resources, phytochemistry, pharmacological activities, and applications of Physalis L. in China during the past ten years (2013.1-2023.1).

RESULTS

So far, a variety of chemical constituents have been isolated and identified from Physalis L. mainly including steroids, flavonoids, and so on. Various pharmacological activities were evaluated by studying different extracts of Physalis L., these activities include anti-inflammatory, antibacterial, antioxidant, antiviral, antineoplastic, and other aspects.

CONCLUSION

Physalis L. occupies an important position in the traditional medical system. It is cost-effective and is a significant plant with therapeutic applications in modern medicine. However, further in-depth studies are needed to determine the medical use of this plant resources and cultivation, chemical composition, pharmacological effects and applications.

Recent insights into the physicochemical properties, bioactivities and their relationship of tea polysaccharides

Tea polysaccharides (TPS) is receiving global concern in past years due to their therapeutic effects in many diseases such as obesity and diabetes. Many publications imply that the unique physicochemical properties and bioactivities of TPS are prerequisites for its use as a biofilm, drug carrier and emulsifier. Despite numerous healthy benefits, studies on the in-deep structure-activity relationship of TPS still not well explored and explained yet. The main reasons for the research limitation are attributed mainly to the unbreakable advanced structural research technology and the formation of TPS conjugates. The present review also summarizes some similar parameters in primary structure of TPS with better bioactivities, discusses the relationships between their physicochemical properties and bioactivities, and suggests that function-specific TPS would be obtained in the future if the links between preparation methods, physicochemical properties and bioactivities of TPS could be well understood and established.

Purification, structural characteristics and anti-atherosclerosis activity of a novel green tea polysaccharide

A new homogeneous polysaccharide (TPS3A) was isolated and purified from Tianzhu Xianyue fried green tea by DEAE-52 cellulose and Sephacryl S-500 column chromatography. Structural characterization indicated that TPS3A mainly consisted of arabinose, galactose, galacturonic acid and rhamnose in a molar ratio of 5.84: 4.15: 2.06: 1, with an average molecular weight of 1.596 × 104 kDa. The structure of TPS3A was characterized as a repeating unit consisting of 1,3-Galp, 1,4-Galp, 1,3,6-Galp, 1,3-Araf, 1,5-Araf, 1,2,4-Rhap and 1-GalpA, with two branches on the C6 of 1,3,6-Galp and C2 of 1,2,4-Rhap, respectively. To investigate the preventive effects of TPS3A on atherosclerosis, TPS3A was administered orally to ApoE-deficient (ApoE-/-) mice. Results revealed that TPS3A intervention could effectively delay the atherosclerotic plaque progression, modulate dyslipidemia, and reduce the transformation of vascular smooth muscle cells (VSMCs) from contractile phenotype to synthetic phenotype by activating the expression of contractile marker alpha-smooth muscle actin (α-SMA) and inhibiting the expression of synthetic marker osteopontin (OPN) in high-fat diet-induced ApoE-/- mice. Our findings suggested that TPS3A markedly alleviated atherosclerosis by regulating dyslipidemia and phenotypic transition of VSMCs, and might be used as a novel functional ingredient to promote cardiovascular health.

A review on the hypoglycemic effect, mechanism and application development of natural dietary polysaccharides

Diabetes mellitus (DM) as one chronic metabolic disease was greatly increased over recent decades. The major agents treating diabetes have noticeable side effects as well as the tolerability problems. The bioactive dietary polysaccharides from abundant natural resources exhibit good hypoglycemic effect with rare adverse effects, which might serve as a candidate to prevent and treat diabetes. However, the correlations between the hypoglycemic mechanism of polysaccharides and their structure were not mentioned in several studies, what's more, most of the current hypoglycemic studies on polysaccharides were based on in vitro and in vivo experiments, and there was a lack of knowledge about the effects in human clinical trials. The aim of this review is to discuss recent literature about the variety of dietary polysaccharides with hypoglycemic activity, as well the mechanism of action and the structure-function relationship are highlighted. Meanwhile, the application of dietary polysaccharides in functional foods and clinical medicine are realized with an in-depth understanding. So as to promote the exploration of dietary polysaccharides in low glycemic healthy foods or clinical medicine to prevent and treat diabetes.

Study of the Mechanism of Astragali Radix in Treating Type 2 Diabetes Mellitus and Its Renal Protection Based on Enzyme Activity, Network Pharmacology, and Experimental Verification

Astragali Radix (AR) is a common Chinese medicine and food. This article aims to reveal the active role of AR in treating Type 2 diabetes mellitus (T2DM) and its renal protective mechanism. The hypoglycemic active fraction was screened by α-glucosidase and identified by UPLC-QE-Orbitrap-MS spectrometry. The targets and KEGG pathway were determined through the application of network pharmacology methodology. Molecular docking and molecular dynamics simulation technology were used for virtual verification. Subsequently, a mouse model of T2DM was established, and the blood glucose and renal function indexes of the mice after administration were analyzed to further prove the pharmacodynamic effect and mechanism of AR in the treatment of T2DM. HA was determined as the best hypoglycemic active fraction by the α-glucosidase method, with a total of 23 compounds identified. The main active components, such as calycoside-7-O-β-D-glucoside, methylnisoline, and formononetin, were revealed by network pharmacology. In addition, the core targets and the pathway have also been determined. Molecular docking and molecular dynamics simulation techniques have verified that components and targets can be well combined. In vivo studies have shown that AR can reduce blood sugar levels in model mice, enhance the anti-inflammatory and antioxidant activities of kidney tissue, and alleviate kidney damage in mice. And it also has regulatory effects on proteins such as RAGE, PI3K, and AKT. AR has a good therapeutic effect on T2DM and can repair disease-induced renal injury by regulating the RAGE/PI3K/Akt signaling pathway. This study provides ideas for the development of new drugs or dietary interventions for the treatment of T2DM.

Biological Potential and Mechanisms of Tea's Bioactive Compounds in Tea: An Updated Review

BACKGROUND

Tea (Camellia sinensis) has a rich history and is widely consumed across many countries, and is categorized into green tea, white tea, oolong tea, yellow tea, black tea, and dark tea based on the level of fermentation. Based on a review of previous literature, the commonly recognized bioactive substances in tea include tea polyphenols, amino acids, polysaccharides, alkaloids, terpenoids, macro minerals, trace elements, and vitamins, which have been known to have various potential health benefits, such as anticancer, antioxidant, anti-inflammatory, anti-diabetes, and anti-obesity properties, cardiovascular protection, immune regulation, and control of the intestinal microbiota. Most studies have only pointed out the characteristics of tea's bioactivities, so a comprehensive summary of the pharmacological characteristics and mechanisms of tea's bioactivities and their use risks are vital.

AIM

of Review The aim of this paper is to summarize the bioactive substances of tea and their pharmacological characteristics and mechanisms, providing a scientific basis for the application of bioactive substances in tea and outlining future research directions for the study of bioactive substances in tea. Key Scientific Concepts of Review This review summarizes the main biologically active substances, pharmacological effects, and mechanisms and discusses the potential risks. It may help researchers to grasp more comprehensive progress in the study of tea bioactive substances to further promote the application of tea as a natural bioactive substance in the medical field.

Research progress on the hypoglycemic activity and mechanisms of natural polysaccharides

The incidence of diabetes, as a metabolic disease characterized by high blood sugar levels, is increasing every year. The predominantly western medicine treatment is associated with certain side effects, which has prompted people to turn their attention to natural active substances. Natural polysaccharide is a safe and low-toxic natural substance with various biological activities. Hypoglycemic activity is one of the important biological activities of natural polysaccharides, which has great potential for development. A systematic review of the latest research progress and possible molecular mechanisms of hypoglycemic activity of natural polysaccharides is of great significance for better understanding them. In this review, we systematically reviewed the relationship between the hypoglycemic activity of polysaccharides and their structure in terms of molecular weight, monosaccharide composition, and glycosidic bonds, and summarized underlying molecular mechanisms the hypoglycemic activity of natural polysaccharides. In addition, the potential mechanisms of natural polysaccharides improving the complications of diabetes were analyzed and discussed. This paper provides some valuable insights and important guidance for further research on the hypoglycemic mechanisms of natural polysaccharides.

Protective Effects of Different Selenium Green Tea Polysaccharides on the Development of Type 2 Diabetes in Mice

Selenium polysaccharides have attracted significant interest due to their superior function to that of individual polysaccharides. However, limited research has compared the protective effects of different selenium polysaccharides from different selenization methods on diabetes. This work aims to compare the preventive effects of natural selenium-enriched green tea polysaccharides (NSe-TPS), synthetic selenized green tea polysaccharides (PCSe-TPS), and a mixture of sodium selenite and green tea polysaccharides (ordinary tea polysaccharides (Ord-TPS)+Se) on the development of diabetes. While establishing a diabetes model induced by a high-sugar, high-fat diet combined with streptozotocin, different selenium polysaccharides were administered daily by gavage for nine weeks. Our findings indicate that PCSe-TPS exhibited superior preventive effects on developing type 2 diabetes compared to NSe-TPS and Ord-TPS+Se. PCSe-TPS effectively regulated glucose metabolism and insulin resistance by activating the PI3K/Akt pathway, thereby preventing elevated blood glucose levels. Additionally, PCSe-TPS mitigated oxidative damage and inflammatory responses in liver tissues. Notably, PCSe-TPS intervention reversed the decline in bacterial species richness and the abundance of unclassified_Oscillospiraceae during the development of diabetes in mice. These results provide valuable insights into the protective effects of PCSe-TPS against diabetes development, highlighting its advantages over NSe-TPS and Ord-TPS+Se.

Selenium-Enriched and Ordinary Black Teas Regulate the Metabolism of Glucose and Lipid and Intestinal Flora of Hyperglycemic Mice

Black tea is one of the six major tea categories and has a variety of bioactivities. However, little is known about its comprehensive evaluation of hypoglycemic effects and potential mechanisms. In this study, we investigated the in vivo hypoglycemic activity and potential mechanism for aqueous extracts of ordinary black tea (BT) and selenium-enriched black tea (Se-BT) by using an established high-fat diet together with streptozotocin (STZ)-induced hyperglycemic mouse model. Additionally, we also explored their α-glucosidase inhibition activity. The results show that both BT and Se-BT had a favorable glycosidase inhibitory activity. Moreover, the intervention of BT and Se-BT could regulate the mRNA expression and the level of serum parameters related to glucose and lipid metabolisms. Accordingly, they could activate the phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) signaling pathway and alleviate insulin resistance (IR) and hyperglycemia. Moreover, supplementation of BT and Se-BT increased the richness and diversity of intestinal flora and altered the abundance of beneficial and harmful bacteria. Both BT and Se-BT could regulate glucose metabolism, alleviate tissue damage, and restore intestinal flora dysbiosis, suggesting that they could be used as a natural functional food for preventing hyperglycemia.

Special tea products featuring functional components: Health benefits and processing strategies

The functional components in tea confer various potential health benefits to humans. To date, several special tea products featuring functional components (STPFCs) have been successfully developed, such as O-methylated catechin-rich tea, γ-aminobutyric acid-rich tea, low-caffeine tea, and selenium-rich tea products. STPFCs have some unique and enhanced health benefits when compared with conventional tea products, which can meet the specific needs and preferences of different groups and have huge market potential. The processing strategies to improve the health benefits of tea products by regulating the functional component content have been an active area of research in food science. The fresh leaves of some specific tea varieties rich in functional components are used as raw materials, and special processing technologies are employed to prepare STPFCs. Huge progress has been achieved in the research and development of these STPFCs. However, the current status of these STPFCs has not yet been systematically reviewed. Here, studies on STPFCs have been comprehensively reviewed with a focus on their potential health benefits and processing strategies. Additionally, other chemical components with the potential to be developed into special teas and the application of tea functional components in the food industry have been discussed. Finally, suggestions on the promises and challenges for the future study of these STPFCs have been provided. This paper might shed light on the current status of the research and development of these STPFCs. Future studies on STPFCs should focus on screening specific tea varieties, identifying new functional components, evaluating health-promoting effects, improving flavor quality, and elucidating the interactions between functional components.

Walnut-Derived Peptides Promote Autophagy via the Activation of AMPK/mTOR/ULK1 Pathway to Ameliorate Hyperglycemia in Type 2 Diabetic Mice

Autophagy flux plays a significant protective role in type 2 diabetes mellitus (T2DM). However, the mechanisms by which autophagy mediates insulin resistance (IR) to ameliorate T2DM remain unclear. This study explored the hypoglycemic effects and mechanisms of walnut-derived peptides (fraction 3-10 kDa and LP5) in streptozotocin and high-fat-diet-induced T2DM mice. Findings revealed that walnut-derived peptides reduced the levels of blood glucose and FINS and ameliorated IR and dyslipidemia. They also increased SOD and GSH-P_X activities and inhibited the secretion of TNF-α, IL-6, and IL-1β. Additionally, they increased the levels of ATP, COX, SDH, and MMP of liver mitochondria. Western blotting indicated that walnut-derived peptides up-regulated LC3-II/LC3-I and Beclin-1 expression, while they down-regulated p62 expression, which may be associated with the activation of the AMPK/mTOR/ULK1 pathway. Finally, the AMPK activator (AICAR) and inhibitor (Compound C) were used to verify that LP5 could activate autophagy through the AMPK/mTOR/ULK1 pathway in IR HepG2 cells.

Insulin resistance, autophagy and apoptosis in patients with polycystic ovary syndrome: Association with PI3K signaling pathway

Polycystic ovary syndrome (PCOS) is a disease in which endocrine metabolic abnormalities coexist with reproductive system abnormalities, with the main clinical manifestations including abnormal menstruation, hirsutism, acne, infertility, and obesity, and it is also a high risk for the development of many pregnancy complications, gynecological malignancies and other diseases. Therefore, timely intervention to prevent the progression of PCOS is of great significance for improving the quality of life of most female patients. Insulin resistance (IR) is one of the most common endocrine disorders in PCOS patients, with approximately 75% of PCOS patients experiencing varying degrees of IR. It is now believed that it is mainly related to the PI3K signaling pathway. The role of autophagy and apoptosis of ovarian granulosa cells (GCs) in the pathogenesis of PCOS has also been gradually verified in recent years. Coincidentally, it also seems to be associated with the PI3K signaling pathway. Our aim is to review these relevant studies, to explore the association between the IR, cellular autophagy and apoptosis in PCOS patients and the PI3K pathway. We summarize some of the drug studies that have improved PCOS as well. We have also found that proteomics holds great promise in exploring the pathogenesis of PCOS, and we have published our views on this.

Polygonatum sibiricum saponin Exerts Beneficial Hypoglycemic Effects in Type 2 Diabetes Mice by Improving Hepatic Insulin Resistance and Glycogen Synthesis-Related Proteins

Type 2 diabetes mellitus (T2DM) is a systemic metabolic disorder characterized by insulin deficiency and insulin resistance. Recently, it has become a significant threat to public health. Polygonatum sibiricum saponin (PSS) has potential hypoglycemic effects, but its specific mechanism needs further study. In this study, PSS significantly decreased the level of blood glucose, water intake, and the organ index in diabetic mice. Meanwhile, PSS effectively reduced the content of total triglyceride (TG), total cholesterol (TCHO), low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) in the blood, and increased the content of high-density lipoprotein cholesterol (HDL-C). This suggests that PSS could reduce the content of blood lipids and initially improve the damage of hepatocytes. We found that PSS alleviated hepatic insulin resistance, repaired islet beta cells, and enabled insulin to play its biological role normally. It also improved oral glucose tolerance and abated serum lipopolysaccharide (LPS) and glycosylated hemoglobin (HbA1c) levels in T2DM mice. Furthermore, studies have found that PSS increased the content of phosphorylated protein kinase B (AKT), thereby promoting the effect of glucose transporter 4 (GLUT-4), and activating glycogen synthase kinase 3beta (GSK-3β) and glycogen synthase (GS) proteins to promote hepatic glycogen synthesis. Finally, we found that PSS could promote the growth of beneficial bacteria such as Bifidobacterium and Lactobacillus, reduce the growth of harmful bacteria such as Enterococcus and Enterobacter, and preliminarily improve the composition of important bacteria in the intestine. These studies indicate that PSS has an excellent hypoglycemic effect, which provides a potential new treatment for T2DM and guidance for more in-depth research.

Feeding tea polysaccharides affects lipid metabolism, antioxidant capacity and immunity of common carp (Cyprinus carpio L.)

Tea polysaccharides plays a role in lipid metabolism, antioxidant capacity and immunity of mammals. To investigate the functions of tea polysaccharides on fish, the common carp (Cyprinus carpio L.) was selected as the animal model in this study. In our study, the common carp (45±0.71g) were randomly divided into four groups and were fed fodder with 50% carbohydrate. The common carp were orally administrated with 0 mg/kg BW (control group), 200 mg/kg BW (low-dose group), 400 mg/kg BW (medium-dose group) and 800 mg/kg BW (high-dose group) tea polysaccharide for two week. At the end of experiment, the serum glucose, TG, MDA contents and antioxidase activities were measured by commercial kits. The serum immune factors levels were tested by ELISA. The genes expression levels related to antioxidant capacity, metabolism and immunity were measured by real-time PCR. The results showed that the glucose, TG and MDA contents in serum were significantly decreased by tea polysaccharides treatment. The serum activities of SOD were significantly increased by low-dose tea polysaccharides treatment. The serum activities of GPX were significantly increased by medium-dose tea polysaccharides treatment. The serum levels of IL-1β and TNFα were significantly decreased in the tea polysaccharides treatment group. In the high-dose treatment group, the serum level of TGFβ was significantly increased, and the serum level of IL-12 was markedly decreased. In the hepatopancreas, the expression of acc1, fas, srebp1c, lpl, gys and pparγ were significantly reduced, and the expression of pygl, cat, mnsod, ho-1 and gr were significantly up-regulated in the tea polysaccharides group. In the intestine, the expression of zo-1, occ and gip was significantly up-regulated in the high-dose treatment group. Moreover, the expression of glut2 and sglt1 were significantly down regulated. In the spleen, the expression of il-12, tnfα and il-6 were significantly decreased, and the expression of il-10 and tgfβ was significantly increased by the tea polysaccharides. In the spleen cells, the tea polysaccharides could relieve the LPS-induced immune damage. In conclusion, tea polysaccharides can improve antioxidant capacity, lipid metabolism and immunity of common carp.

Hypoglycemic activity in vitro and vivo of a water-soluble polysaccharide from Astragalus membranaceus

The polysaccharide AMP as one main bioactive component of Astragalus membranaceus (Fisch.) Bunge was separated and characterized. The results showed that AMP was a typical acidic heteropolysaccharide dominated by glucose, galacturonic acid and arabinose with typical shear-thinning and fluid-like behavior. Scanning electron microscopy images showed that AMP existed in the state of lamellar aggregates with a smooth compact surface. In addition, AMP exhibited strong antioxidant activity with an oxygen radical absorption capacity value of 278.68 ± 9.31 μM TE per g, and excellent α-glucosidase inhibitory activity and cholate binding ability. Furthermore, in vivo, AMP treatment significantly decreased blood glucose and serum insulin levels, improved glucose intolerance and insulin resistance, regulated the blood lipid profile, alleviated oxidative stress, and relieved liver damage in type 2 diabetes mellitus (T2DM) mice. Pearson correlation analysis suggested that the mitigation of oxidative stress contributed to the hypoglycemic effect of AMP, indicating that it is a beneficial functional food ingredient for T2DM.

Isolation, Structural Characterization, and Hypoglycemic Activities In Vitro of Polysaccharides from Pleurotus eryngii

Pleurotus eryngii (PE) is an edible mushroom with high nutritional value. Pleurotus eryngii polysaccharides (PEPs) are one of the main active ingredients and manifest a great variety of biological activities. This study mainly focused on the chemical characterization and biological activities of PEPs, which were separated into two fractions (named WPS and P-1). WPS is mainly dominated by β-glycosidic bonds and contains α-glycosidic bonds, and P-1 only contains α-glycosidic bonds. The molecular weights of WPS and P-1 were 4.5 × 10⁵ Da and 2.2 × 10⁴ Da. The result of GC indicated that two the fractions were composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose, with a ratio of 0.35:0.24:0.45:0.24:28.78:1.10 for WPS and 0.95:0.64:0.66:1.84:60.69:0.67 for P-1. The advanced structure studies indicated that the two fractions had no triple-helical structure, where WPS had a dense structure and P-1 had a loose structure. In addition, the antioxidant activity of WPS surpassed P-1, and the two fractions also exhibited a high hypoglycemic activity via inhibiting α-glycosidase activities and promoting the expression of PI3K-AKT signaling pathway based on in vitro assay and cell experiments.

Superoxide-producing thermostable associate from the small intestines of control and alloxan-induced diabetic rats: quantitative and qualitative changes

BACKGROUND

NADPH oxidase 1 (Nox1), which is highly expressed in the colon, is thought to play a potential role in host defense as a physical and innate immune barrier against commensal or pathogenic microbes in the gastrointestinal epithelium. Diabetes can be caused by several biological factors, including insulin resistance is one of them. Alloxan is widely used to induce insulin-dependent diabetes in experimental animals. Alloxan increases the generation of reactive oxygen species as a result of metabolic reactions in the body, along with a massive increase in cytosolic calcium concentration.

METHODS

Using a universal method, a superoxide radical (О₂^-)-thermostable associate between NADPH-containing lipoprotein (NLP) and NADPH oxidase (Nox)- NLP-Nox was isolated and purified from the small intestine (SI) of control (C) and alloxan-induced diabetic (AD) albino rats.

RESULTS

In comparison to the C indices, in AD in the SI, an increase in the specific content of NLP-Nox associate and a decrease in the stationary concentration of produced О₂^- in liquid phase (in solution) and gas phase (during blowing by oxygen of the NLP-Nox solution) were observed. The NLP-Nox of SI associate in C and AD rats produced О₂^- by an immediate mechanism, using NLP as a substrate. The phenomenon of the hiding of the optical absorption maxima of the Nox in oxidized states at pH10,5 was observed in the composition of these SI associates of the C and AD rat groups. The characteristic absorption maxima of the «hidden» Nox were observed under these conditions after reduction by potassium dithionite.

CONCLUSION

Thus, at AD, the decrease in the stationary concentration of produced О₂^- in the solution and gas phase was compensated for by an increase in the specific amount of associate. In addition,  the decrease in the stationary concentration of produced О₂^- by NLP-Nox associates at AD can be linked to a decrease in the level of NADPH in NLP-Nox composition. This could be used as a new mechanism of AD pathogenesis.

Morchella esculenta mushroom polysaccharide attenuates diabetes and modulates intestinal permeability and gut microbiota in a type 2 diabetic mice model

Type 2 diabetes mellitus (T2DM) is a health issue that causes serious worldwide economic problems. It has previously been reported that natural polysaccharides have been studied with regard to regulating the gut microbiota, which plays an important role in T2DM. Here, we investigate the effects of Morchella esculenta polysaccharide (MEP) on a high-fat diet (HFD) and streptozotocin (STZ)-induced T2DM in BALB/c mice. The administration of MEP effectively regulated hyperglycemia and hyperlipidemia and improved insulin sensitivity. We also determined an improvement in gut microbiota composition by 16sRNA pyrosequencing. Treatment with MEP showed an increase in beneficial bacteria, i.e., Lactobacillus and Firmicutes, while the proportion of the opportunistic bacteria Actinobacteria, Corynebacterium, and Facklamia decreased. Furthermore, the treatment of T2DM mice with MEP resulted in reduced endotoxemia and insulin resistance-related pro-inflammatory cytokines interleukin 1β (IL-1β), tumor necrosis factor-alpha (TNF-α), and interleukin 6 (IL-6). Moreover, MEP treatment improved intestinal permeability by modulating the expression of the colon tight-junction proteins zonula occludens-1 (ZO-1), occludin, claudin-1, and mucin-2 protein (MUC2). Additionally, MEP administration affects the metagenome of microbial communities in T2DM mice by altering the functional metabolic pathways. All these findings suggested that MEP is a beneficial prebiotic associated with ameliorating the gut microbiota and its metabolites in T2DM.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Anti-diabetic and gut microbiota modulation effects of sacha inchi (Plukenetia volubilis L.) leaf extract in streptozotocin-induced type 1 diabetic mice

BACKGROUND

Sacha inchi (Plukenetia volubilis L.) tea has been used as an adjuvant treatment for diabetes in Pu'er, in the Yunnan province of China. The effects of sacha inchi tea on diabetes and the underlying mechanisms remain unknown. This study was conducted to investigate the influence of a water extract of sacha inchi (P. volubilis L.) leaves (PWE) on hypoglycemic activity and gut microbiota composition in mice with streptozotocin (STZ)-induced type 1 diabetes mellitus (T1DM). During the 6 weeks of the study, T1DM mice were administered PWE intragastrically at 400 mg kg^-1 body weight (BW) per day.

RESULTS

Treatment with PWE reduced excessive loss of BW and excessive intake of food. It significantly decreased blood glucose levels and improved oral glucose tolerance. The treatment caused protective histopathological transformations in sections of the pancreas, leading to decreased insulin resistance and improved insulin sensitivity. Treatment with PWE also significantly ameliorated disorders of the gut microbiota structure and increased the richness and diversity of intestinal microbial species in T1DM mice. At the genus level, the populations of several crucial bacteria, such as Akkermansia, Parabacteroides, and Muribaculum increased in the PWE treatment group but the abundance of Ruminiclostridium and Oscillibacter decreased.

CONCLUSIONS

Treatment with PWE can ameliorate hyperglycemic symptoms in STZ-induced T1DM mice, and the anti-diabetic effect of PWE was related to the amelioration of gut microbial structural disorder and the enrichment of functional bacteria. © 2022 Society of Chemical Industry.

Advances in the Utilization of Tea Polysaccharides: Preparation, Physicochemical Properties, and Health Benefits

Tea polysaccharide (TPS) is the second most abundant ingredient in tea following tea polyphenols. As a complex polysaccharide, TPS has a complex chemical structure and a variety of bioactivities, such as anti-oxidation, hypoglycemia, hypolipidemic, immune regulation, and anti-tumor. Additionally, it shows excellent development and application prospects in food, cosmetics, and medical and health care products. However, numerous studies have shown that the bioactivity of TPS is closely related to its sources, processing methods, and extraction methods. Therefore, the authors of this paper reviewed the relevant recent research and conducted a comprehensive and systematic review of the extraction methods, physicochemical properties, and bioactivities of TPS to strengthen the understanding and exploration of the bioactivities of TPS. This review provides a reference for preparing and developing functional TPS products.

Protective Mechanism of Fagopyrum esculentum Moench. Bee Pollen EtOH Extract Against Type II Diabetes in a High-Fat Diet/Streptozocin-Induced C57BL/6J Mice

Bee pollen is known as a natural nutrient storehouse and plays a key role in many biological processes. Based on the preliminary separation, identification, and characterization of the main active components of Fagopyrum esculentum Moench. bee pollen (FBP), the protective effects of F. esculentum bee pollen extract (FBPE) on high-fat-diet (HFD) and streptozocin (STZ) induced type II diabetes mellitus (T2DM) was evaluated in this study. The results revealed that FBPE contains 10 active compounds mainly including luteolin (9.46 g/kg), resveratrol (5.25 g/kg), kaemferol (3.67 g/kg), etc. The animal experiment results showed that FBPE could improve HFD-STZ induced T2DM mice. Moreover, the underlying mechanism of the above results could be: (i) FBPE could reduce the inflammation related to phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway, and (ii) the gut microbiota remodeling. The results of correlation analysis showed Candidatus Arthromitus and SMB53 indicated positive correlations to tumor necrosis factor-α (TNF-α); Coprococcus, Ruminocossus, and Odoribacteraceae reported negative correlations to transforming growth factor-β (TGF-β). That FBPE has an outstanding ability to improve T2DM and could be used as a kind of potential functional food for the prevention of T2DM.

Polysaccharide from Hemerocallis citrina Borani by subcritical water: Bioactivity, purification, characterization, and anti-diabetic effects in T2DM rats

Hemerocallis citrina Borani (daylily) has various health benefits. However, the structural characterization and hypoglycemic effects of its polysaccharide remain unclear. Here, we first report for the first time, the effects of subcritical water extraction temperature on bioactivity of Hemerocallis citrina Borani polysaccharide (HCBP). HCBP extracted at 160 °C had better scavenging ability of free-radical and pancreatic lipase inhibition. This study aimed to investigate the structural characterization and anti-diabetic effects of aforementioned HCBP. HCBP was separated into three fractions using a DEAE-Sepharose Fast Flow. HCBP-1 was the major component with lower molecular weight, HCBP-2 was the least abundant component, HCBP-3 was the component with higher uronic acid and molecular weight. HCBP treatment significantly decreased the concentrations of fasting blood glucose, insulin, total cholesterol, triglyceride, and low density lipoprotein, as well as improved glucose intolerance and insulin resistance in type 2 diabetes mellitus (T2DM) rats. HCBP also protected the kidneys and pancreatic organs by histopathology and immunohistochemical analyses in T2DM rats. In addition, HCBP significantly increased the antioxidant enzymes activities and decreased the level of malonaldehyde to alleviated the oxidative stress injury. The results indicate HCBP extracted by subcritical water is promising functional food ingredients and could be used in T2DM treatment.

Preparation, Physicochemical and Hypoglycemic Properties of Natural Selenium-Enriched Coarse Tea Glycoproteins

Various functional components in tea have been well developed, but less research has been explored on glycoproteins in tea. In this paper, three types of glycoprotein fractions, namely tea selenium-binding glycoprotein1-1 (TSBGP1-1), TSBGP2-1, and TSBGP3-1, respectively, were extracted and purified from selenium-enriched coarse green tea. Chemical analysis revealed that three fractions were glycoproteins, but their selenium content, molecular weight, and monosaccharide composition were significantly different. Fourier transforms infrared (FT-IR) analysis indicated that three fractions contained characteristic absorption peaks of glycoproteins but differed in secondary structural composition. Thermogravimetric (TG) analysis showed that the thermal stability of the three fractions was dramatically distinct. The in vitro hypoglycemic activity showed that TSBGPs significantly activated the insulin receptor substrate 2 (IRS2)/protein kinase B (Akt) pathway in LO2 cells, then enhanced glucose metabolism and inhibited gluconeogenesis, and finally ameliorated insulin resistance (IR) and glucose metabolism disorders. Furthermore, Pearson correlation analysis reveals that the hypoglycemic activity was significantly correlated with Se, protein, monosaccharide composition (especially glucose), molecular weight, and secondary structure. Our results show that Se-enriched tea glycoprotein is a desirable candidate for developing anti-diabetic food, and TSBGP-2 and TSBGP-3 had a better regulation effect. Our results can provide a research reference for the extraction, physicochemical property, and function of selenium-enriched plant glycoproteins.

Characterization of the structure, stability, and activity of hypoglycemic peptides from Moringa oleifera seed protein hydrolysates

Moringa oleifera seed protein hydrolysates exhibit good hypoglycemic activity, but their specific peptide components have not yet been characterized. Here, we identified the ultrafiltration peptide components (<3 kDa) of M. oleifera seed protein hydrolysates. A highly active α-glucosidase inhibitory peptide with an IC₅₀ value of 109.65 μM (MoHpP-2) with the amino acid sequence KETTTIVR was identified. We characterized its structural properties, stability, and hypoglycemic activity. MoHpP-2 was found to be an amphipathic peptide with a β-turn structure, and the hemolysis of red blood cells was not observed when its concentration was lower than 2 mg mL^-1. MoHpP-2 was stable under weakly acidic conditions, at temperatures lower than 60 °C, and at high ion concentrations. Western blotting revealed that MoHpP-2 affected the PI3K and AMPK pathways of HepG2 cells. Molecular docking revealed that MoHpP-2 interacted with α-glucosidase through hydrogen bonding and hydrophobic forces. Thus, MoHpP-2 from M. oleifera seeds could be used to make hypoglycemic functional foods.

Characterization of Acidic Tea Polysaccharides from Yellow Leaves of Wuyi Rock Tea and Their Hypoglycemic Activity via Intestinal Flora Regulation in Rats

A bioactive acidic tea polysaccharide from yellow leaves of Wuyi rock tea was successively prepared via DEAE-52 and Superdex-200 columns. Nuclear magnetic resonance (NMR) analysis showed that the main glycosidic bonds were composed of α-l-Araf-(1→, →5)-α-l-Araf-(1→, →4)-α-d-Glcp-(1→, Arap-(1→, →6)-α-d-Glcp-(1→, →2,4)-α-l-Rhap-(1→, →3,4)-α-d-Glcp-(1→, →4)-α-d-GalAp-(1→, →4)-α-d-GalAp-(1→, α-d-Galp-(1→, →6)-β-d-Galp-(1→ and →4)-β-d-Galp-(1→. The molecular weight was 3.9285 × 104 Da. The hypoglycemic effect of acidic tea polysaccharides on streptozotocin-induced type 2 diabetes mellitus rats was evaluated through histopathology and biochemistry analysis. The acidic tea polysaccharide could improve plasma and liver lipid metabolism. Moreover, 16S rRNA gene sequencing revealed that the composition of the intestinal flora changed drastically after treatment, namely, blooms of Bifidobacterium, Blautia, Dorea, and Oscillospira, and a strong reduction in Desulfovibrio and Lactobacillus. The above results illustrated that tea polysaccharides might serve as an effective ingredient to ameliorate glucose metabolism disorders and intestinal flora in hyperglycemic rats.

Large-leaf yellow tea attenuates high glucose-induced vascular endothelial cells injury by up-regulating autophagy and down-regulating oxidative stress

Vascular endothelial cells injury induced by high glucose (HG) plays an important role in the occurrence and development of diabetic vascular complications. Yellow tea has a protective effect on vascular...

Hypoglycemic and Hypolipidemic Effects of Malonyl Ginsenosides from American Ginseng (Panax quinquefolius L.) on Type 2 Diabetic Mice

American ginseng (Panax quinquefolius L.) is popularly consumed as traditional herbal medicine and health food for the treatment of type 2 diabetes mellitus (T2DM). Malonyl ginsenosides (MGR) are the main natural ginsenosides in American ginseng. However, whether the malonyl ginsenosides in P. quinquefolius (PQ-MGR) possess antidiabetic effects has not been explored yet. In this study, the antidiabetic effects and the underlying mechanism of PQ-MGR in high-fat diet/streptozotocin (HFD/STZ)-induced T2DM mice were investigated. The chemical composition was analyzed by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Our results showed that 14 malonyl ginsenosides were identified in the PQ-MGR. Among them, the content of m-Rb₁ represented about 77.4% of the total malonyl ginsenosides. After a 5-week experiment, the PQ-MGR significantly reduced the fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), nonesterified fatty acid (NEFA), alanine transaminase (ALT), and aspartate transaminase (AST) levels and improved glucose tolerance and insulin resistance. Furthermore, Western blot analysis demonstrated that the protein expressions of p-PI3K, p-AKT, p-AMPK, p-ACC, PPAR_γ, and GLUT4 in the liver and skeletal muscle were significantly upregulated after PQ-MGR treatment. In contrast, the protein expressions of p-IRS1 and p-JNK were significantly downregulated. Our results revealed that PQ-MGR could ameliorate glucose and lipid metabolism and insulin resistance in T2DM via regulation of the insulin receptor substrate-1/phosphoinositide3-kinase/protein-kinase B (IRS1/PI3K/Akt) and AMP-activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC) pathways. These findings suggest that PQ-MGR may be used as an antidiabetic candidate drug for T2DM treatment.

Structure, Antioxidant Activity and In Vitro Hypoglycemic Activity of a Polysaccharide Purified from Tricholoma matsutake

The structure, antioxidant activity and hypoglycemic activity in vitro of a novel homogeneous polysaccharide from Tricholoma matsutake (Tmp) were investigated. Structural features suggested that Tmp was consisted of arabinose (Ara), mannose (Man), glucose (Glc) and galactose (Gal) with a molar ratio of 1.9:13.6:42.7:28.3, respectively, with a molecular weight of 72.14 kDa. The structural chain of Tmp was confirmed to contain →2,5)-α-l-Arabinofuranose (Araf)-(1→, →3,5)-α-l-Araf-(1→, β-d-Glucopyranose (Glcp)-(1→, α-d-Mannopyranose (Manp)-(1→, α-d-Galacopyranose (Galp)-(1→, →4)-β-d-Galp-(1→, →3)-β-d-Glcp-(1→, →3)-α-d-Manp-(1→, →6)-3-O-Methyl (Me)-α-d-Manp-(1→, →6)-α-d-Galp-(1→, →3,6)-β-d-Glcp-(1→, →6)-α-d-Manp-(1→ residues. Furthermore, Tmp possessed strong antioxidant activity and showed the strong inhibitory effect on α-glucosidase and α-amylase activities. Then, a further evaluation found that there was a dramatic improvement in the glucose consumption, glycogen synthesis and the activities of pyruvate kinase and hexokinase when the insulin-resistant-human hepatoma cell line (IR-HepG2) was treated with Tmp. The above results indicated that Tmp had good hypoglycemic activity and also exhibited great potentials in in terms of dealing with type 2 diabetes mellitus.

Structural characteristics of a hypoglycemic polysaccharide from Fructus Corni

PFC-3 is a homogeneous polysaccharide extracted from the dried pulps of Fructus Corni with a molecular weight of 40.3 kDa. The crude polysaccharide was obtained and further purified by DEAE-Sephadex A-25 and Sephadex G-100 columns to investigate its structure and glycemic effect. The monosaccharides in the PFC-3, determined by high-performance liquid chromatography, consisted of glucose (Glc), xylose (Xyl), and galactose (Gal) with a mass molar ratio of 2.35:12.49:1.00. The methylation analysis combined with 1D (1H and 13C), and 2D NMR (1H-1H COSY, HSQC, and HMBC) further demonstrated that PFC-3 was mainly composed of 1,3-α-D-Xylp, 1,6-α-D-Galp, 1,2-α-D-Glcp, and T-α-D-Galp, and contained a backbone fragment of →6)-α-D-Galp-(1 → 2)-α-D-Glcp-(1 → 3)-α-D-Xylp-(1 → . The hypoglycemic effect of PFC-3 in vitro was evaluated by glucose uptake and consumption assays, and the results showed that PFC-3 concentration-dependently enhanced glucose uptake and significantly improved glucose consumption in insulin-resistant HepG2 cells. Furthermore, PFC-3 significantly reduced fasting blood glucose level, glycosylated hemoglobin level, amylase activity, ameliorate lipid metabolism, and hepatic lesions in streptozotocin-induced diabetic rats. Our research provided insights into the hypoglycemic activities of PFC-3.

Influencing Factors on the Physicochemical Characteristics of Tea Polysaccharides

Tea polysaccharides (TPSs) are one of the main bioactive constituents of tea with various biological activities such as hypoglycemic effect, antioxidant, antitumor, and immunomodulatory. The bioactivities of TPSs are directly associated with their structures such as chemical composition, molecular weight, glycosidic linkages, and conformation among others. To study the relationship between the structures of TPSs and their bioactivities, it is essential to elucidate the structure of TPSs, particularly the fine structures. Due to the vast variation nature of monosaccharide units and their connections, the structure of TPSs is extremely complex, which is also affected by several major factors including tea species, processing technologies of tea and isolation methods of TPSs. As a result of the complexity, there are few studies on their fine structures and chain conformation. In the present review, we aim to provide a detailed summary of the multiple factors influencing the characteristics of TPS chemical structures such as variations of tea species, degree of fermentation, and preparation methods among others as well as their applications. The main aspects of understanding the structural difference of TPSs and influencing factors are to assist the study of the structure and bioactivity relationship and ultimately, to control the production of the targeted TPSs with the most desired biological activity.

Significantly hypoglycemic effect of a novel functional bread rich in mulberry bark and improving the related functions of liver, pancreas, and kidney, on T2D mice

To develop a novel functional food with lowering blood glucose for diabetics, the mixed bread containing mulberry branch bark powder (MBBP) was used for the oral administration of the type 2 diabetic (T2D) mice induced by streptozocin (STZ), high-fat and high-sugar diet for 7 weeks. 5%, 10%, and 15% MBBP bread diets had a significatively positive influence on the biochemical indicators, histological examination, and immunohistochemistry observations in T2D mice. The 15% MBBP-rich bread diet evidently retarded loss weight of T2D mice, and decreased in FBG by about 55% and in glycosylated hemoglobin (HbA1c) levels by about 30%. Its glucose tolerance and serum insulin levels were very close to normal level. The abnormal lipid metabolism and insulin-related index of T2D mice in both the 10% and 15% MBBP bread diet groups were partly reversed. The Western blotting results showed that the expression levels of key proteins in PI3K/AKT signaling pathway were decreased and expression levels of immunoproteins PPARγ, TNF-α, P65, and IL6 were increased. In general, oral MBBP bread diets effectively restored some functions and repaired damage to the pancreas, liver, and kidney in T2D mice. Therefore, MBBP is potential to develop into a novel functional food additive with significantly hypoglycemic effect.

Research progress on the potential delaying skin aging effect and mechanism of tea for oral and external use

Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.

5-Bromoprotocatechualdehyde Combats against Palmitate Toxicity by Inhibiting Parkin Degradation and Reducing ROS-Induced Mitochondrial Damage in Pancreatic β-Cells

Pancreatic β-cell loss is critical in diabetes pathogenesis. Up to now, no effective treatment has become available for β-cell loss. A polyphenol recently isolated from Polysiphonia japonica, 5-Bromoprotocatechualdehyde (BPCA), is considered as a potential compound for the protection of β-cells. In this study, we examined palmitate (PA)-induced lipotoxicity in Ins-1 cells to test the protective effects of BPCA on insulin-secreting β-cells. Our results demonstrated that BPCA can protect β-cells from PA-induced lipotoxicity by reducing cellular damage, preventing reactive oxygen species (ROS) overproduction, and enhancing glucose-stimulated insulin secretion (GSIS). BPCA also improved mitochondrial morphology by preserving parkin protein expression. Moreover, BPCA exhibited a protective effect against PA-induced β-cell dysfunction in vivo in a zebrafish model. Our results provide strong evidence that BPCA could be a potential therapeutic agent for the management of diabetes.

Short-term Cudrania tricuspidata fruit vinegar administration attenuates obesity in high-fat diet-fed mice by improving fat accumulation and metabolic parameters

Previous studies have suggested that vinegar intake can help to reduce body fat and hyperglycemia. Therefore, this study aimed to evaluate the anti-obesity efficacy of vinegar fermented using Cudrania tricuspidata fruits (CTFV) and its main phenolic constituents and to analyze its molecular mechanism and changes in obesity-related metabolizing enzymatic activities. We found that HFD significantly caused hepatic steatosis; increases in body fats, feed efficiency, liver mass, lipids, insulin, oxidative parameters, cardiovascular-associated risk indices, lipase and α-amylase activities, whereas CTFV efficaciously attenuated HFD-induced oxidant stress, fat accumulation, obesity-related enzymatic activity, and the activation or reduction of obesity-related molecular reactions via improving metabolic parameters including phosphorylated insulin receptor substrate 1, protein tyrosine phosphatase 1B, phosphorylated phosphoinositide 3-kinase/protein kinase B, phosphorylated mitogen-activated protein kinases, sterol regulatory element-binding protein 1c, CCAAT/enhancer-binding protein, and fatty acid synthase; and decreases in adiponectin receptor 1, leptin receptor, adenosine monophosphate-activated protein kinase, acetyl-CoA carboxylase, and peroxisome proliferator-activated receptor, subsequently ameliorating HFD-induced obesity. Therefore, CTFV might provide a functional food resource or nutraceutical product for reducing body fat accumulation.

Hypoglycemic and Hypolipidemic Mechanism of Tea Polysaccharides on Type 2 Diabetic Rats via Gut Microbiota and Metabolism Alteration

Diabetes mellitus is a serious threat to human health. Tea is cultivated around the world, and its polysaccharide components are reported to be an effective approach for managing type 2 diabetes with fewer adverse effects than medication. To examine the therapeutic effect of tea polysaccharides on diabetes, a type 2 diabetic rat model was generated. We showed that tea polysaccharides remarkably decreased fasting blood glucose and the levels of total cholesterol, total triglyceride, low-density lipoprotein cholesterol, and free fatty acid of type 2 diabetic rats. 16S rRNA sequencing and metabolomics were used to investigate the variation of gut microbiota and the metabolites profiles of diabetic rats after intervention of tea polysaccharides. We found that tea polysaccharides maintained the diversity of gut microbiota and restored the relative abundance of some bacterial genera (Lachnospira, Victivallis, Roseburia, and Fluviicola) which was reduced by diabetes. According to metabolomics analysis, we found that amino acid and other related metabolites was influenced by tea polysaccharides intervention. Correlation analysis among metabolites, gut microbiota, and parameters of hypoglycemic indicated that tea polysaccharides had hypoglycemic and hypolipidemic effect on type 2 diabetes via the modulation of gut microbiota and the improvement of host metabolism.

Chain conformation of an acidic polysaccharide from green tea and related mechanism of α-amylase inhibitory activity

An acidic tea polysaccharide (TPSA) isolated from green tea was fractionated using a precipitation-fractionation method into seven fractions with different molecular weights. TPSA was characterized as a hyperbranched polysaccharide with a globular homogeneous conformation by analysis of solution parameters of each fraction using static light scattering and viscosity analyses. Observation by transmission electron microscopy confirmed that TPSA occurred as globular homogeneous particles with size in the range of 20-40 nm. To simulate the branched chain segments of TPSA, four model molecules were designed based on chemical structure of TPSA. Molecular docking analysis indicated that the branched chain segments of TPSA similar to the TPSA-4 model molecule showed preferential binding to α-amylase to form the TPSA/α-amylase complex through hydrogen bonding interactions. Circular dichroism spectroscopy showed that the structure of α-amylase was not significantly affected by TPSA. The mechanism of α-amylase inhibitory activity of TPSA was simulated by molecular docking analysis. The branched chain segments of TPSA similar to the TPSA-4 model molecule likely act as a potential competitor to the starch substrate to inhibit the activity of α-amylase.