Interactions of Dihydromyricetin, a Flavonoid from Vine Tea (Ampelopsis grossedentata) with Gut Microbiota

Tongbian decoction restores intestinal microbiota and activates 5-hydroxytryptamine signaling: implication in slow transit constipation

Introduction

Slow transit constipation (STC) is a type of functional constipation. The detailed mechanism of STC, for which there is currently no effective treatment, is unknown as of yet. Tongbian decoction (TBD), a traditional Chinese medicinal formula, is commonly used to treat STC in clinical settings. However, the potential impact of TBD on the management of STC via modulation of the gut microbiota remains unclear.

Methods

Pseudo-germ-free rats were constructed after 6 days of treatment with bacitracin, neomycin, and streptomycin (abbreviated as ABX forthwith). Based on the successful construction of pseudo-germ-free rats, the STC model (ABX + STC) was induced using loperamide hydrochloride. After successful modeling, based on the different sources of donor rat microbiota, the ABX + STC rats were randomly divided into three groups: Control → ABX + STC, STC → ABX + STC, and STC + TBD → ABX + STC for fecal microbiota transplant (FMT). Body weight, fecal water content, and charcoal power propelling rate of the rats were recorded. Intestinal microbiota was detected by 16S rRNA sequencing, and the 5-hydroxytryptamine (5-HT) signaling pathway was examined by western blots, immunofluorescence, and immunohistochemical analysis.

Results

After treatment with fecal bacterial solutions derived from rats treated with Tongbian decoction (TBD), there was an increase in body weight, fecal water content, and the rate of charcoal propulsion in the rats. Additionally, activation of the 5-hydroxytryptamine (5-HT) signaling pathway was observed. The 16S rRNA sequencing results showed that the fecal bacterial solution from TBD-treated rats affected the intestinal microbiota of STC rats by increasing the proliferation of beneficial bacteria and suppressing the expansion of harmful bacteria.

Conclusion

Our study showed that TBD alleviated constipation in STC rats by modulating the structure of the intestinal microbiota.

Effects of dietary dihydromyricetin on growth performance, antioxidant capacity, immune response and intestinal microbiota of shrimp (Litopenaeus vannamei)

A 56-day culture trial was conducted to evaluate the effects of dietary dihydromyricetin (DMY) on growth performance, antioxidant capacity, immune response and intestinal microbiota of shrimp (Litopenaeus vannamei). 840 healthy shrimp (1.60 ± 0.21 g) in total were fed with four different levels of DMY diets at 0 (Control), 100 (D1), 200 (D2), and 300 (D3) mg/kg, respectively. Samples were collected after the culture trial, and then, a 7-day challenge experiment against Vibrio parahaemolyticus was conducted. The results demonstrated that DMY significantly enhanced the activity of protease, amylase and lipase as well as the expression of lipid and protein transport-related genes (P < 0.05). The results of plasma lipid parameters indicated that DMY reduced lipid deposition, manifested by significantly (P < 0.05) decreased plasma total cholesterol (T-CHO), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C). The expression of genes involved in fatty acid β-oxidation and triglyceride catabolism was significantly up-regulated (P < 0.05), and genes involved in triglyceride synthesis were significantly down-regulated in DMY groups when compared to control group (P < 0.05). Moreover, dietary DMY also significantly (P < 0.05) increased the total antioxidant capacity (T-AOC), antioxidant enzymes activity and glutathione (GSH) content of shrimp, and a significant increase of total hemocytes count (THC), phagocytic rate (PR), antibacterial activity (AA) and bacteriolytic activity (BA) was observed in DMY groups (P < 0.05). The addition of DMY to the diet significantly augmented immune response by up-regulating the expression of genes related to toll-like receptors (Toll) signaling pathway, immune deficiency (IMD) signaling pathway and intestinal mucin. Furthermore, dietary DMY could modulate the composition and abundance of intestinal microbiota. In conclusion, DMY showed promising potential as a functional feed additive for shrimp to improve the growth performance and physiological health.

Research progress of dihydromyricetin in the treatment of diabetes mellitus

Diabetic Mellitus (DM), a chronic metabolic disorder disease characterized by hyperglycemia, is mainly caused by the absolute or relative deficiency of insulin secretion or decreased insulin sensitivity in target tissue cells. Dihydromyricetin (DMY) is a flavonoid compound of dihydroflavonol that widely exists in Ampelopsis grossedentata. This review aims to summarize the research progress of DMY in the treatment of DM. A detailed summary of related signaling induced by DMY are discussed. Increasing evidence implicates that DMY display hypoglycemic effects in DM via improving glucose and lipid metabolism, attenuating inflammatory responses, and reducing oxidative stress, with the signal transduction pathways underlying the regulation of AMPK or mTOR/autophagy, and relevant downstream cascades, including PGC-1α/SIRT3, MEK/ERK, and PI3K/Akt signal pathways. Hence, the mechanisms underlying the therapeutic implications of DMY in DM are still obscure. In this review, following with a brief introduction of the absorption, metabolism, distribution, and excretion characteristics of DMY, we summarized the current pharmacological developments of DMY as well as possible molecular mechanisms in the treatment of DM, aiming to push the understanding about the protective role of DMY as well as its preclinical assessment of novel application.

Dihydromyricetin ameliorated nonalcoholic steatohepatitis in mice by regulating the composition of serous lipids, bile acids and ileal microflora

BACKGROUND

Dihydromyricetin (DMY) is a natural flavonoid with anti-nonalcoholic steatohepatitis (NASH) activity. However, the effects of DMY on the composition of lipids and bile acids (BAs) in serum, and gut microbiota (GM) in ileum of mice with NASH are not clear.

METHODS

After male C57BL/6 mice was fed with methionine and choline deficiency (MCD) diet and simultaneously administered with DMY (300 mg/kg/day) by gavage for 8 weeks, the pathological changes of liver tissue were observed by Oil Red O, hematoxylin eosin and Masson staining, the levels of serum alaninea minotransferase, aspartate aminotransferase and liver triglyceride, malonic dialdehyde were detected by the detection kits, the composition and contents of serum lipids and BAs were detected by Liquid Chromatograph-Mass Spectrometry, the mRNA levels of hepatic BAs homeostasis-related genes were detected by RT-qPCR, and microbiological diversity in ileum was analyzed by 16S rDNA sequencing.

RESULTS

The results showed that the significant changes including 29 lipids, 4 BAs (23-nor-deoxycholic acid, ursodeoxycholic acid, 7-ketodeoxycholic acid and cholic acid), 2 BA transporters (Mrp2 and Oatp1b2) and 8 GMs between MCD and DMY groups. Among them, DMY treatment significantly down-regulated 21 lipids, 4 BAs mentioned above, the ratio of Firmicutes/Bacteroidota and the abundance of Erysipelotrichaceae, Faecalibacuium, significantly up-regulated 8 lipids and 5 GMs (Verrucomicrobiota, Bacteroidota, Actinobacteria, Akkermansiaceae and Akkermansia).

CONCLUSIONS

The results suggested that DMY may alleviate MCD diet-induced NASH through decreasing the serum levels of toxic BAs which regulated by liver Oatp1b2 and Mrp2, regulating the metabolism of related lipids, and up-regulating intestinal probiotics (Actinobacteria and Verrucomicrobiota at the phylum level; Akkermansiaceae at the family level; Akkermansiaat at the genus level) and inhibiting intestinal harmful bacteria (Firmicutes at the phylum level; Erysipelotrichaceae at the family level; Faecalibaculum at the genus level).

Exploring the Impact of Ampelopsis Grossedentata Flavonoids on Growth Performance, Ruminal Microbiota, and Plasma Physiology and Biochemistry of Kids

This study was conducted to evaluate the influences of supplementing Ampelopsis grossedentata flavonoids (AGF) on the rumen bacterial microbiome, plasma physiology and biochemistry, and growth performance of goats. Twenty-four Nubian kids were randomly allocated to three dietary treatments: the control (CON, basal diet), the 1.0 g/kg AGF treatment (AGF), and the 12.5 mg/kg monensin treatment (MN). This trial consisted of 10 days for adaptation and 90 days for data and sample collection. The results reveal that Bacteroidetes, Firmicutes, and Proteobacteria are the dominant phyla in kids' rumen. Compared with the CON group, the alpha diversity in the MN and AGF groups significantly increased (p < 0.01). Beta-diversity shows that rumen microbial composition is more similar in the MN and AGF groups. LEfSe analysis shows that Prevotella_1 in the AGF group were significantly higher than those in the MN and CON group. The high-density lipoprotein cholesterol and glucose levels in the AGF group were significantly higher than those in the CON group (p < 0.05), whereas the low-density lipoprotein cholesterol, glutamic-pyruvic transaminase, and alkaline phosphatase levels exhibited the opposite trend. The average daily gains in the AGF and MN groups significantly increased, while the feed-to-gain ratios were significantly decreased (p < 0.05). The results suggest that adding AGF to the diet improves microbial composition and has important implications for studying juvenile livestock growth and improving economic benefits.

Dihydromyricetin promotes GLP-1 release and glucose uptake by STC-1 cells and enhances the effects of metformin upon STC-1 cells and diabetic mouse model

BACKGROUND

Glucagon-like peptide-1 (GLP-1) is an intestinally produced hormone released by the L-cells to stimulate glucose-dependent insulin release. Vine tea, a traditional Chinese medicine made from the delicate stem and leaves of Ampelopsis grossedentata, has been reported to exert antidiabetic effects; however, the role and mechanism of dihydromyricetin, the main active ingredient of vine tea, remain unclear.

METHODS AND RESULTS

MTT assay was applied to detect cell viability. GLP-1 levels in the culture medium using a mouse GLP-1 ELISA kit. The level of GLP-1 in cells was examined using IF staining. NBDG assay was performed to evaluate the glucose uptake by STC-1 cells. The in vivo roles of dihydromyricetin in the diabetes mellitus mouse model were investigated. In this study, 25 μM dihydromyricetin, was found to cause no significant suppression of STC-1 cell viability. Dihydromyricetin markedly elevated GLP-1 secretion and glucose uptake by STC-1 cells. Although metformin increased GLP-1 release and glucose uptake by STC-1 cells more, dihydromyricetin further enhanced the effects of metformin. Moreover, dihydromyricetin or metformin alone significantly promoted the phosphorylation of AMPK, increased GLUT4 levels, inhibited ERK1/2 and IRS-1 phosphorylation, and decreased NF-κB levels, and dihydromyricetin also enhanced the effects of metformin on these factors. The in vivo results further confirmed the antidiabetic function of dihydromyricetin.

CONCLUSION

Dihydromyricetin promotes GLP-1 release and glucose uptake by STC-1 cells and enhances the effects of metformin upon STC-1 cells and diabetic mice, which might ameliorate diabetes through improving L cell functions. The Erk1/2 and AMPK signaling pathways might be involved.

Dihydromyricetin Protects Against Salsolinol-Induced Toxicity in Dopaminergic Cell Line: Implication for Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease associated with loss of dopaminergic neurons in the substantia nigra pars compacta. Although aging is the primary cause, environmental and genetic factors have also been implicated in its etiology. In fact, the sporadic nature of PD (i.e., unknown etiology) renders the uncovering of the exact pathogenic mechanism(s) or development of effective pharmacotherapies challenging. In search of novel neuroprotectants, we showed that butyrate (BUT), a short-chain fatty acid, protects against salsolinol (SALS)-induced toxicity in human neuroblastoma-derived SH-SY5Y cells, which are considered an in-vitro model of PD. Dihydromyricetin (DHM), a flavonoid derived from Asian medicinal plant, has also shown effectiveness against oxidative damage and neuroinflammation, hallmarks of neurodegenerative diseases. Here we show that pretreatment of SH-SY5Y cells with DHM concentration-dependently prevented SALS-induced toxicity and that a combination of DHM and BUT resulted in a synergistic protection. The effects of both DHM and BUT in turn could be completely blocked by flumazenil (FLU), a GABA_A antagonist acting at benzodiazepine receptor site, and by bicuculline (BIC), a GABA_A antagonist acting at orthosteric site. Beta-hydroxybutyrate (BHB), a free fatty acid 3 (FA3) receptor antagonist, also fully blocked the protective effect of DHM. BHB was shown previously to only partially block the protective effect of BUT. Thus, there are some overlaps and some distinct differences in protective mechanisms of DHM and BUT against SALS-induced toxicity. It is suggested that a combination of DHM and BUT may have therapeutic potential in PD. However, further in-vivo verifications are necessary.

Dietary flavonoids: a novel strategy for the amelioration of cognitive impairment through intestinal microbiota

The chances of people suffering from cognitive impairments increase gradually with age. Diet and lifestyle are closely related to the occurrence and development of cognitive function. Dietary flavonoid supplementation has been shown to be one of the protective factors against cognitive decline. Flavonoids belong to a class of polyphenols that have been proposed for the treatment of cognitive decline. Recent evidence has shown that intestinal flora in the human body can interact with flavonoids. Intestinal microbiota can modify the chemical structure of flavonoids, producing new metabolites, the pharmacological activities of which may be different from those of the parent; meanwhile, flavonoids and their metabolites can, in turn, regulate the composition and structure of intestinal flora. Notably, intestinal flora affect host nervous system activity through the gut-brain axis, ultimately causing changes in cognitive function. This review therefore summarizes the interaction of dietary flavonoids and intestinal flora, and their protective effect against cognitive decline through the gut-brain axis, indicating that dietary flavonoids may ameliorate cognitive impairment through their interaction with intestinal microbiota. © 2022 Society of Chemical Industry.

The Interaction between Flavonoids and Intestinal Microbes: A Review

In recent years, research on the interaction between flavonoids and intestinal microbes have prompted a rash of food science, nutriology and biomedicine, complying with future research trends. The gut microbiota plays an essential role in the maintenance of intestinal homeostasis and human health, but once the intestinal flora dysregulation occurs, it may contribute to various diseases. Flavonoids have shown a variety of physiological activities, and are metabolized or biotransformed by gut microbiota, thereby producing new metabolites that promote human health by modulating the composition and structure of intestinal flora. Herein, this review demonstrates the key notion of flavonoids as well as intestinal microbiota and dysbiosis, aiming to provide a comprehensive understanding about how flavonoids regulate the diseases by gut microbiota. Emphasis is placed on the microbiota-flavonoid bidirectional interaction that affects the metabolic fate of flavonoids and their metabolites, thereby influencing their metabolic mechanism, biotransformation, bioavailability and bioactivity. Potentially by focusing on the abundance and diversity of gut microbiota as well as their metabolites such as bile acids, we discuss the influence mechanism of flavonoids on intestinal microbiota by protecting the intestinal barrier function and immune system. Additionally, the microbiota-flavonoid bidirectional interaction plays a crucial role in regulating various diseases. We explain the underlying regulation mechanism of several typical diseases including gastrointestinal diseases, obesity, diabetes and cancer, aiming to provide a theoretical basis and guideline for the promotion of gastrointestinal health as well as the treatment of diseases.

Dihydromyricetin Enhances Exercise-Induced GLP-1 Elevation through Stimulating cAMP and Inhibiting DPP-4

The purpose of this study was to examine whether endogenous GLP-1 (glucagon-like peptide-1) could respond to exercise training in mice, as well as whether dihydromyricetin (DHM) supplementation could enhance GLP-1 levels in response to exercise training. After 2 weeks of exercise intervention, we found that GLP-1 levels were significantly elevated. A reshaped gut microbiota was identified following exercise, as evidenced by the increased abundance of Bifidobacterium, Lactococcus, and Alistipes genus, which are involved in the production of short-chain fatty acids (SCFAs). Antibiotic treatment negated exercise-induced GLP-1 secretion, which could be reversed with gut microbiota transplantation. Additionally, the combined intervention (DHM and exercise) was modeled in mice. Surprisingly, the combined intervention resulted in higher GLP-1 levels than the exercise intervention alone. In exercised mice supplemented with DHM, the gut microbiota composition changed as well, while the amount of SCFAs was unchanged in the stools. Additionally, DHM treatment induced intracellular cAMP in vitro and down-regulated the gene and protein expression of dipeptidyl peptidase-4 (DPP-4) both in vivo and in vitro. Collectively, the auxo-action of exercise on GLP-1 secretion is associated with the gut-microbiota-SCFAs axis. Moreover, our findings suggest that DHM interacts synergistically with exercise to enhance GLP-1 levels by stimulating cAMP and inhibiting DPP-4.

Intervention Effects of Okra Extract on Brain-Gut Peptides and Intestinal Microorganisms in Sleep Deprivation Rats

Objective

Okra, possessing various bioactive components, is used to treat different diseases. This study sought to estimate the intervention effects of okra extract (OE) on brain-gut peptides (BGPs) and intestinal microorganisms in sleep deprivation (SD) rats.

Methods

SD rat models were established using the modified multiple platform method and then treated with normal saline, diazepam tablets, or different doses of OE. Body weight and average daily water consumption of rats were recorded. Depressive behaviors of rats were assessed by the open field test and sucrose preference test. Serum levels of noradrenaline, melatonin, inflammatory factors (IL-1β/IL-6/TNF-α/IL-4/IL-10), and BGP indexes, including gastrin (GAS), motilin (MTL), 5-hydroxytryptamine (5-HT), cholecystokinin (CCK), and vasoactive intestinal peptide (VIP) were measured by ELISA. Additionally, the DNA relative contents of representative intestinal microorganisms in the collected rat feces were determined using RT-qPCR.

Results

SD decreased body weight and average daily water consumption and induced depressive behaviors as well as stress and inflammatory responses in rats. SD rats exhibited lowered GAS, MTL, 5-HT, and VIP but elevated CCK and showed diminished DNA relative contents of Bacteroidetes and probiotics (Bifidobacteria and Lactobacilli) but increased Clostridium perfringens. OE at different doses ameliorated the depressive behaviors and mitigated the stress and inflammatory responses in SD rats, raised the serum contents of GAS, MTL, 5-HT, and VIP, reduced CCK level, elevated the DNA relative contents of Bacteroidetes and probiotics, but diminished Clostridium perfringens. OE exhibited similar intervention effects to diazepam tablets (positive control).

Conclusion

OE exerts intervention effects on BGPs and intestinal microorganisms in SD rats.

Flavonoids as Potential Antiviral Agents for Porcine Viruses

Flavonoids are types of natural substances with phenolic structures isolated from a variety of plants. Flavonoids have antioxidant, anti-inflammatory, anticancer, and antiviral activities. Although most of the research or applications of flavonoids are focused on human diseases, flavonoids also show potential applicability against porcine virus infection. This review focuses on the recent progress in antiviral mechanisms of potential flavonoids against the most common porcine viruses. The mechanism discussed in this paper may provide a theoretical basis for drug screening and application of natural flavonoid compounds and flavonoid-containing herbs to control porcine virus infection and guide the research and development of pig feed additives.

Responses of two marine fish to organically complexed Zn: Insights from microbial community and liver transcriptomics

The diversity and adjustability of metal-organic complex enhance the function of metals and promote the burgeoning fields of chemical biology. In the present study, we chose two marine fish to explore the effects of a dihydromyricetin (DMY)-Zn(II) complex on the intestinal microbiome composition and liver biological function using high-throughput sequencing technology. Two economic fish species commonly found in Southern China (golden pompano Trachinotus ovatus and pearl gentian grouper ♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatus) were exposed to dietary DMY-Zn complex for 4-week. Our study found that DMY-Zn performed a vital function on the improved anti-oxidative ability of both fish species. The Zn complex improved the stability of microbial community structure of the golden pompano by enhancing the α-diversity, but its impacts on the composition and diversity of intestine microorganisms of grouper were insignificant. BugBase results showed that the intestine microbiota following DMY-Zn exposure contained a lower abundance of potentially pathogenic bacteria and higher abundance of aerobic bacteria. Intestine health and utilization of carbohydrates were improved in the golden pompano, and unclassified bacteria were significantly enriched in the grouper. Liver transcriptome indicated that DMY-Zn affected the oxidative phosphorylation process (OXPHOS). Specifically, the OXPHOS process (map00190) was activated by promoting the glucose uptake (map04251, map04010) in golden pompano and lipid metabolism (map00071, map00140, map00062 and map00564) in grouper. Such difference in the responses of intestine microbiome and liver metabolism may be possibly explained by their different Zn basal requirements. Our study demonstrated that different fish species may have different responses to dietary DMY-Zn complex. The results provided a reference for the application of new additives in aquatic animal feed, and new insights into the roles of metal-organic complex in their biological impacts on fish.

Gut microbiota and host Cyp450s co-contribute to pharmacokinetic variability in mice with non-alcoholic steatohepatitis: Effects vary from drug to drug

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Drugs’ pharmacokinetics were changed in NASH disease.

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A systematical research on cocktail drugs in NASH.

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Gut microbiota can bio-transform some drugs in vitro, and the metabolic rate was different in NASH.

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The gut microbiota and the host co-contributed the pharmacokinetic variability of drugs in NASH.

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The degree of influence on pharmacokinetic variability varies from drug to drug.

Introduction

Pharmacokinetic variability in disease state is common in clinical practice, but its underlying mechanism remains unclear. Recently, gut microbiota has been considered to be pharmacokinetically equivalent to the host liver. Although some studies have explored the roles of gut microbiota and host Cyp450s in drug pharmacokinetics, few have explored their effects on pharmacokinetic variability, especially in disease states.

Objectives

In this study, we aim to investigate the effects of gut microbiota and host Cyp450s on pharmacokinetic variability in mice with non-alcoholic steatohepatitis (NASH), and to elucidate the contribution of gut microbiota and host Cyp450s to pharmacokinetic variability in this setting.

Methods

The pharmacokinetic variability of mice with NASH was explored under intragastric and intravenous administrations of a cocktail mixture of omeprazole, phenacetin, midazolam, tolbutamide, chlorzoxazone, and metoprolol, after which the results were compared with those obtained from the control group. Thereafter, the pharmacokinetic variabilities of all drugs and their relations to the changes in gut microbiota and host Cyp450s were compared and analyzed.

Results

The exposures of all drugs, except metoprolol, significantly increased in the NASH group under intragastric administration. However, no significant increase in the exposure of all drugs, except tolbutamide, was observed in the NASH group under intravenous administration. The pharmacokinetic variabilities of phenacetin, midazolam, omeprazole, and chlorzoxazone were mainly associated with decreased elimination activity in the gut microbiota. By contrast, the pharmacokinetic variability of tolbutamide was mainly related to the change in the host Cyp2c65. Notably, gut microbiota and host Cyp450s exerted minimal effects on the pharmacokinetic variability of metoprolol.

Conclusion

Gut microbiota and host Cyp450s co-contribute to the pharmacokinetic variability in mice with NASH, and the degree of contribution varies from drug to drug. The present findings provide new insights into the explanation of pharmacokinetic variability in disease states.

Dihydromyricetin improves meat quality and promotes skeletal muscle fiber type transformations via AMPK signaling in growing-finishing pigs

As the demand of consumers for good meat quality is increasing, there is more interest in improving pork quality by nutritional regulation. Dihydromyricetin (DHM), a group of bioactive flavonoids, exhibits excellent biological functions and pharmacological activities. This study aimed to investigate whether dietary DHM supplementation in growing-finishing pigs could provide high-quality pork. A total of 24 healthy castrated Duroc × Landrace × Yorkshire (DLY) pigs with an average body weight of 26.95 ± 0.26 kg were randomly divided into four groups (basal diet and a basal diet supplemented with 100, 300 and 500 mg kg^-1 DHM) with 6 duplicates and one pig per replicate. The growth performance, carcass traits and pork quality of growing-finishing pigs were detected. Then, tandem mass tag (TMT) based quantitative proteomics, western blotting and real-time quantitative polymerase chain reaction (RT-qPCR) were used to explore the regulatory mechanism of DHM on pork quality. The results showed that DHM decreased the feed to gain ratio (F/G) and improved the sensory quality (shear force and meat color) and nutritional value (crude protein content and amino acid composition) of pork in growing-finishing pigs. Totally 22 differentially expressed proteins were identified, among which the down-regulated heat shock protein-β1 (HSPB1) and up-regulated Troponin C-slow (TNNC1) contributed towards explaining the positive effect of DHM on the tenderness and meat color of pork. GO enrichment analysis revealed that better meat color was also linked to higher levels of oxidative metabolism and hemoglobin complexes in pork. Western blotting and RT-qPCR analysis showed that DHM induced a muscle fiber type transformation from fast-switch to slow-switch by activating the AMP-activated protein kinase (AMPK) signal, thereby improving the pork quality. Taken together, our findings provide effective evidence for the application of DHM in high-quality pork production.

Discovery and Characterization of the Naturally Occurring Inhibitors Against Human Pancreatic Lipase in Ampelopsis grossedentata

Pancreatic lipase (PL) inhibitor therapy has been validated as an efficacious way for preventing and treating obesity and overweight. In the past few decades, porcine PL (pPL) is widely used as the enzyme source for screening the PL inhibitors, which generates a wide range of pPL inhibitors. By contrast, the efficacious inhibitors against human PL (hPL) are rarely reported. This study aims to discover the naturally occurring hPL inhibitors from edible herbal medicines (HMs) and to characterize the inhibitory mechanisms of the newly identified hPL inhibitors. Following the screening of the inhibition potentials of more than 100 HMs against hPL, Ampelopsis grossedentata extract (AGE) displayed the most potent hPL inhibition activity. After that, the major constituents in AGE were identified and purified, while their anti-hPL effects were assayed in vitro. The results clearly showed that two abundant constituents in AGE (dihydromyricetin and iso-dihydromyricetin) were moderate hPL inhibitors, while myricetin and quercetin were strong hPL inhibitors [half-maximal inhibitory concentration (IC50) values were around 1.5 μM]. Inhibition kinetic analyses demonstrated that myricetin and quercetin potently inhibited hPL-catalyzed near-infrared fluorogenic substrate of human pancreatic lipase (DDAO-ol) hydrolysis in a non-competitive inhibition manner, with Ki values of 2.04 and 2.33 μM, respectively. Molecular dynamics simulations indicated that myricetin and quercetin could stably bind on an allosteric site of hPL. Collectively, this study reveals the key anti-obesity constituents in AGE and elucidates their inhibitory mechanisms against hPL, which offers convincing evidence to support the anti-obesity and lipid-lowering effects of this edible herb.

Amaranth Seed Polyphenol, Fatty Acid and Amino Acid Profile

In this paper, the extraction of polyphenols from amaranth seed using a Box–Benhken design using four factors—ultra-turrax speed, solid-to-liquid ratio (RSL), methanol concentration and extraction time—were studied. There were two responses studied for the model: total phenolic content (TPC) and total flavonoid content (TFC). The factors which influenced the most the extraction of the TPC and TFC were the RSL, methanol concentration and ultra-turrax speed. Twelve phenolic acids (rosmarinic acid, p-coumaric acid, chlorogenic acid, vanillic acid, caffeic acid, p-hydroxybenzoic acid, protocatechuic acid and gallic acid) and flavonoids (kaempferol, quercetin, luteolin and myricetin) were studied, and the most abundant one was kaempferol followed by myricetin. The amaranth seed is a valuable source of fatty acids, and 16.54% of the total fatty acids determined were saturated fatty acids, while 83.45% of the fatty acids were unsaturated ones. Amaranth seed is a valuable source of amino acids, with 9 essential amino acids being reported: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.

Molecular Mechanism Underlying the Regulatory Effect of Vine Tea on Metabolic Syndrome by Targeting Redox Balance and Gut Microbiota

Metabolic syndrome (MS) is a metabolic disorder that arises from the increasing prevalence of obesity. The pathophysiology seems to be largely attributable to the imbalance of lipid and glucose metabolism, redox signaling pathways, and gut microbiota. The increased syndromes, such as type 2 diabetes and cardiovascular disease demands natural therapeutic attention for those at high risk. Vine tea, as a traditional medicinal and edible resource rich in flavonoids, especially for dihydromyricetin (DHM), exhibits promising health benefits on the intervention of MS, but the specific molecular mechanism has not been systematically elucidated. The present article aims to summarize the regulatory effects and biological targets of vine tea or DHM on MS, and analyze the underlying potential molecular mechanisms in cells, animals, and humans, mainly by regulating the redox associated signaling pathways, such as Nrf2, NF-κB, PI3K/IRS2/AKT, AMPK-PGC1α-SIRT1, SIRT3 pathways, and the crosstalk among them, and by targeting several key biomarkers. Moreover, vine tea extract or DHM has a positive impact on the modulation of intestinal microecology by upregulating the ratio of Firmicutes/Bacteroidetes (F/B) and increasing the relative abundance of Akkermansia muciniphila. Therefore, this review updated the latest important theoretical basis and molecular evidence for the development and application of vine tea in dietary functional products or drugs against MS and also imputed the future perspectives to clarify the deep mechanism among vine tea or DHM, redox associated signaling pathways, and gut microbiota.

Mechanism of Dihydromyricetin on Inflammatory Diseases

Inflammation plays a crucial role in a variety of diseases, including diabetes, arthritis, asthma, Alzheimer’s disease (AD), acute cerebral stroke, cancer, hypertension, and myocardial ischemia. Therefore, we need to solve the problem urgently for the study of inflammation-related diseases. Dihydromyricetin (DHM) is a flavonoid mainly derived from Nekemias grossedentata (Hand.-Mazz.) J.Wen and Z.L.Nie (N.grossedentata). DHM possesses many pharmacological effects, including anti-inflammatory (NLRP-3, NF-κB, cytokines, and neuroinflammation), antioxidant, improving mitochondrial dysfunction, and regulating autophagy and so on. In this review, we consulted the studies in the recent 20 years and summarized the mechanism of DHM in inflammation-related diseases. In addition, we also introduced the source, chemical structure, chemical properties, and toxicity of DHM in this review. We aim to deepen our understanding of DHM on inflammation-related diseases, clarify the relevant molecular mechanisms, and find out the problems and solutions that need to be solved urgently. Providing new ideas for DHM drug research and development, as well as broaden the horizons of clinical treatment of inflammation-related diseases in this review. Moreover, the failure of clinical transformation of DHM poses a great challenge for DHM as an inflammation related disease.

A multifaceted review on dihydromyricetin resources, extraction, bioavailability, biotransformation, bioactivities, and food applications with future perspectives to maximize its value

Natural bioactive compounds present a better alternative to prevent and treat chronic diseases owing to their lower toxicity and abundant resources. (+)-Dihydromyricetin (DMY) is a flavanonol, possessing numerous interesting bioactivities with abundant resources. This review provides a comprehensive overview of the recent advances in DMY natural resources, stereoisomerism, physicochemical properties, extraction, biosynthesis, pharmacokinetics, and biotransformation. Stereoisomerism of DMY should be considered for better indication of its efficacy. Biotechnological approach presents a potential tool for the production of DMY using microbial cell factories. DMY high instability is related to its powerful antioxidant capacity due to pyrogallol moiety in ring B, and whether preparation of other analogues could demonstrate improved properties. DMY demonstrates poor bioavailability based on its low solubility and permeability with several attempts to improve its pharmacokinetics and efficacy. DMY possesses various pharmacological effects, which have been proven by many in vitro and in vivo experiments, while clinical trials are rather scarce, with underlying action mechanisms remaining unclear. Consequently, to maximize the usefulness of DMY in nutraceuticals, improvement in bioavailability, and better understanding of its actions mechanisms and drug interactions ought to be examined in the future along with more clinical evidence.

Effect of dietary dihydromyricetin supplementation on lipid metabolism, antioxidant capacity and skeletal muscle fiber type transformation in mice

This study aimed to investigate the effect of dietary dihydromyricetin (DHM) supplementation on lipid metabolism, antioxidant capacity and muscle fiber type transformation. Twenty-four male Kunming mice were randomly allotted to either control (basal diet) or DHM diets (supplemented with 300 mg/kg DHM). Our data showed that DHM administration decreased the triglycerides (TG) and low-density lipoprotein cholesterol (LDL-C) contents, and increased the catalase (CAT), total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities in serum. In the liver, DHM decreased the TG and malondialdehyde (MDA) levels and increased the T-SOD and GSH-Px activities. For the tibialis anterior (TA) muscle, DHM increased the total antioxidant capacity (T-AOC) level and T-SOD activities. Western blotting and real-time quantitative PCR analysis showed that DHM increased the protein and mRNA levels of MyHC I and MyHC IIa and decreased the protein and mRNA levels of MyHC IIb in TA muscle, which may be achieved by activating the AMP-activated protein kinase (AMPK) signal. The mRNA levels of several regulatory factors related to mitochondrial function were up-regulated by DHM. In conclusion, dietary 300 mg/kg DHM supplementation improved lipid metabolism and antioxidant capacity and promoted the transformation of muscle fiber type from glycolysis to oxidation in mice.

Investigation of the metabolites of five major constituents from Berberis amurensis in normal and pseudo germ-free rats

Berberis amurensis (Berberidaceae) is a traditional Chinese medicine, which is often used to treat hypertension, inflammation, dysentery and enteritis. It contains alkaloids, mainly including berberine, berbamine, magnoflorine, jatrorrhizine and palmatine. Berberis amurensis extracts (BAEs) is often orally taken. Oral herbs might be metabolized by intestinal bacteria in the small intestine. However, the interaction between the herb and the gut microbiota is still unknown. In the current study, UPLC/Q-TOF-MS/MS combined with Metabolitepilot and Peakview software was used to identify the metabolites of BAEs in anti-biotic cocktail induced pseudo germ-free rats and normal rats. As a result, a total of 46 metabolites in normal rats were detected and its main metabolic pathways include demethylation, dehydrogenation, methylation, hydroxylation, sulfation and glucuronidation. Only 29 metabolites existed in pseudo germ-free rats. Dehydrogenated metabolites (M29, M30, M34 and M36), methylated metabolites (M33, M41 and M46) and other metabolites were not detected in pseudo germ-free rats. The result implied that the intestinal bacteria have an influence on the metabolism of BAEs. Furthermore, this investigation might contribute to the understanding of the metabolism of BAEs, and further promote its clinical application.

Extensive metabolism of flavonoids relevant to their potential efficacy on Alzheimer's disease

Alzheimer's disease (AD) is an age-related neurodegenerative disorder, the incidence of which is climbing with ever-growing aged population, but no cure is hitherto available. The epidemiological studies unveiled that chronic intake of flavonoids was negatively associated with AD risk. Flavonoids, a family of natural polyphenols widely distributed in human daily diets, were readily conjugated by phase II drug metabolizing enzymes after absorption in vivo, and glucuronidation could occur in 1 min following intravenous administration. Recently, as many as 191 metabolites were obtained after intragastric administration of a single flavonoid, indicating that other bioactive metabolites, besides conjugates, might be formed and account for the contradiction between efficacy of flavonoids in human or animal models and low systematic exposure of flavonoid glycosides or aglycones. In this review, metabolism of complete 68 flavonoid monomers potential for AD treatment, grouped in flavonoid O-glycosides, flavonoid aglycones, flavonoid C-glycosides, flavonoid dimers, flavonolignans and prenylated flavonoids according to their common structural elements, respectively, has been systematically retrospected, summarized and discussed, including their unequivocally identified metabolites, metabolic interconversions, metabolic locations, metabolic sites (regio- or stereo-selectivity), primarily involved metabolic enzymes or intestinal bacteria, and interspecies correlations or differences in metabolism, and their bioactive metabolites and the underlying mechanism to reverse AD pathology were also reviewed, providing whole perspective about advances on extensive metabolism of diverse potent flavonoids in vivo and in vitro up to date and aiming at elucidation of mechanism of actions of flavonoids on AD or other central nervous system (CNS) disorders.

Dihydromyricetin improves DSS-induced colitis in mice via modulation of fecal-bacteria-related bile acid metabolism

Recent studies show that the nutraceutical supplement dihydromyricetin (DHM) can alleviate IBD in murine models by downregulating the inflammatory pathways. However, the molecular mechanistic link between the therapeutic efficiency of DHM, gut microbiota, and the metabolism of microbial BAs remains elusive. In this study, we explored the improvement of DHM on the dysregulated gut microbiota of mice with dextran sulfate sodium (DSS)-induced colitis. We found that DHM could markedly improve colitis symptoms, gut barrier disruption, and colonic inflammation in DSS-treated mice. In addition, bacterial 16S rDNA sequencing assay demonstrated that DHM could alleviate gut dysbiosis in mice with colitis. Furthermore, antibiotic-mediated depletion of the gut microflora and fecal microbiome transplantation (FMT) demonstrated that the therapeutic efficiency of DHM was closely associated with gut microbiota. BA-targeted metabolomics analysis revealed that DHM restored the metabolism of microbial BAs in the gastrointestinal tract during the development of colitis. DHM significantly enriched the proportion of the beneficial Lactobacillus and Akkermansia genera, which were correlated with increased gastrointestinal levels of unconjugated BAs involving chenodeoxycholic acid and lithocholic acid, enabling the BAs to activate specific receptors, such as FXR and TGR5, and maintaining intestinal integrity. Taken together, DHM could alleviate DSS-induced colitis in mice by restoring the dysregulated gut microbiota and BA metabolism, leading to improvements in intestinal barrier function and colonic inflammation. Increased microbiota-BAs-FXR/TGR5 signaling may be the potential targets of DHM in colitis. Therefore, our findings provide novel insights into the development of novel DHM-derived drugs for the management of IBD.

Myricetin supplementation decreases hepatic lipid synthesis and inflammation by modulating gut microbiota

The relationship between poor in vivo bioavailability and effective pharmacological activity are not yet fully clarified for many flavonoids. The analysis of flavonoids-induced alterations in the gut microbiota represents a promising approach to provide useful clues to elucidate the mechanism of action. Here, we investigate the effect of myricetin supplementation on high-fat-diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) in rats and explore the associations with the gut microbiota through high-throughput analyses. The 12-week myricetin supplementation and fecal microbiota transplantation outcomes suggest that myricetin significantly slows the development of NAFLD. Meanwhile, the anti-NAFLD effects of myricetin are associated with the modulation of the gut microbiota composition. Myricetin reduces hepatic lipid synthesis and inflammation through modulations in fecal butyric-acid-related gut microbiota and protection of the gut barrier function. This study may facilitate the elucidation of the action mechanism of flavonoids with low bioavailability.

Molecular mechanisms and therapeutic implications of dihydromyricetin in liver disease

Recent studies demonstrated that dihydromyricetin (DHM) has prominent therapeutic effects on liver injury and liver cancer. By summarizing the current preclinical in vitro and in vivo studies, the present review examines the preventive and therapeutic effects of DHM on liver disorders as well as its potential mechanisms. Briefly, in both chemical- and alcohol-induced liver injury models, DHM ameliorates hepatocyte necrosis and steatosis while promoting liver regeneration. In addition, DHM can alleviate nonalcoholic fatty liver disease (NAFLD) via regulating lipid/glucose metabolism, probably due to its anti-inflammatory or sirtuins-dependent mechanisms. Furthermore, DHM treatment inhibits cell proliferation, induces apoptosis and autophagy and regulates redox balance in liver cancer cells, thus exhibiting remarkable anti-cancer effects. The pharmacological mechanisms of DHM may be associated with its anti-inflammatory, anti-oxidative and apoptosis-regulatory benefits. With the accumulating interests in utilizing natural products to target common diseases, our work aims to improve the understanding of DHM acting as a novel drug candidate for liver diseases and to accelerate its translation from bench to bedside.

Discovery and characterization of flavonoids in vine tea as catechol-O-methyltransferase inhibitors

Vine tea has been used as a traditionally functional herbal tea in China for centuries, which exhibits paramount potential for chronic metabolic diseases. Herein, the inhibitory potential of vine tea toward human catechol-O-methyltransferase (hCOMT) was investigated. A practical bioactivity-guided fractionation combined with chemical profiling strategy was developed to identify the naturally occurring hCOMT inhibitors. Five flavonoids in vine tea displayed moderate to strong inhibition on hCOMT with IC₅₀ values ranging from 0.96 μM to 42.47 μM, in which myricetin was the critically potent constituent against hCOMT. Inhibition kinetics assays and molecular docking simulations showed that myricetin could bind to the active site of COMT and inhibited COMT-catalyzed 3-BTD methylation in a mixed manner. Collectively, our findings not only suggested that the strong hCOMT inhibition of vine tea has guiding significance in the drug exposure of catechol drugs, but also identified a promising lead compound for developing more efficacious hCOMT inhibitors.

Dihydromyricetin Acts as a Potential Redox Balance Mediator in Cancer Chemoprevention

Dihydromyricetin (DHM) is a flavonoid extracted from the leaves and stems of the edible plant Ampelopsis grossedentata that has been used for Chinese Traditional Medicine. It has attracted considerable attention from consumers due to its beneficial properties including anticancer, antioxidative, and anti-inflammatory activities. Continuous oxidative stress caused by intracellular redox imbalance can lead to chronic inflammation, which is intimately associated with the initiation, promotion, and progression of cancer. DHM is considered a potential redox regulator for chronic disease prevention, and its biological activities are abundantly evaluated by using diverse cell and animal models. However, clinical investigations are still scanty. This review summarizes the current potential chemopreventive effects of DHM, including its properties such as anticancer, antioxidative, and anti-inflammatory activities, and further discusses the underlying molecular mechanisms of DHM in cancer chemoprevention by targeting redox balance and influencing the gut microbiota.

Reversal Effect of Dihydromyricetin on Multiple Drug Resistance in SGC7901/5-FU Cells

Background:

One of the most common treatment for gastric cancer is chemotherapy, however, multiple drug resistance (MDR) induce the therapeutic effect which result in the failure of anticancer therapy. Dihydromyricetin (DMY) was reported to have antitumor activities on various human cancer cells in vitro, our previous studies demonstrated that DMY combined with mitomycin has inhibitory effect on proliferation of gastric carcinoma cells. However, the underlying role of DMY reversing the MDR of gastric carcinoma is poor understood. The aim of this study was to evaluate the reversal effect of DMY on MDR and investigate the molecular mechanisms in vitro.

Methods:

Using MTT assay, we identified the toxicity of DMY on SGC7901 and SGC7901/5-FU cells. The effect of DMY on 5-FU induced apoptosis was evaluated by flow cytometry analysis. Using RT-PCR and Western blot, we determined the MDR1 mRNA and protein expression.

Results:

DMY induced growth inhibition in both SGC7901 and SGC7901/5-FU cells, the IC50 value was 13.64±1.15 µg/mL, 20.69±1.82 µg/mL respectively. DMY treatment sensitized SGC7901/5-FU cells to cytotoxicity of 5-FU. The combination of DMY with 5-FU increased the apoptosis rate (9.91%, 16.67%) comparing with 5-FU alone (5.25%). Comparing with the control group, the MDR1 mRNA and protein expression in SGC7901/5-FU cells after treatment of DMY decreased significantly (P< 0.05).

Conclusion:

In brief, our study demonstrated that DMY effectively reversed multi-drug resistance occurring in SGC7901/5-FU cells cultured in vitro, and the potential mechanism was involved in the downregulation of the MDR1 expression.

Effects of Hot-Water Extract from Vine Tea (Ampelopsis grossedentata) on Acrylamide Formation, Quality and Consumer Acceptability of Bread

Acrylamide is a harmful substance that could be inhibited by natural products. Vine tea is an edible herb belonging to the Vitaceae family and has been approved by Chinese authorities as a new food ingredient in 2013. However, the effects of vine tea extract on acrylamide formation and bread quality are rarely investigated. In this study, the polyphenol composition of hot-water extract from vine tea was characterized by ultrahigh-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-ESI-HRMS/MS), and its effects on acrylamide formation, quality, and consumer acceptability of bread were investigated. Vine tea extract and its main polyphenol, dihydromyricetin, significantly inhibited the acrylamide formation in bread, especially the low dose of vine tea extract (1.25 g/kg), which decreased the acrylamide formation by 58.23%. The color and texture of bread were significantly affected by vine tea extract or dihydromyricetin, whereas the moisture content was not changed remarkably. Triangle and paired preference tests indicated that, although the aroma, appearance, and taste of the bread with vine tea extract significantly differ from those of the control bread, vine tea extract did not significantly affect the consumer acceptability. In conclusion, the addition of vine tea extract could be used to develop a new and healthy bread product with low acrylamide content.

Composition of rabbit caecal microbiota and the effects of dietary quercetin supplementation and sex thereupon

The purpose of this study was to add to the current understanding of rabbit caecal microbiota. This involved describing its microbial composition and linking this to live performance parameters, as well as determining the effects of dietary quercetin (Qrc) supplementation (2 g/kg feed) and sex on the microbial population. The weight gain and feed conversion ratio of twelve New Zealand White rabbits was measured from 5 to 12 wk old, blood was sampled at 11 wk old for the determination of serum hormone levels, and the rabbits were slaughtered and caecal samples collected at 13 wk old. Ion 16S^TM metagenome sequencing was used to determine the microbiota profile. The dominance of <em>Firmicutes</em> (72.01±1.14% of mapped reads), <em>Lachnospiraceae</em> (23.94±1.01%) and <em>Ruminococcaceae</em> (19.71±1.07%) concurred with previous reports, but variation both between studies and individual rabbits was apparent beyond this. Significant correlations between microbial families and live performance parameters were found, suggesting that further research into the mechanisms of these associations could be useful. Negative correlations with the caecal flavonoid content were found, but the latter was not affected by diet, and the effects of quercetin supplementation on the microbiota were very limited, possibly due to the absorption of the quercetin-aglycone from the gastrointestinal tract prior to the caecum. Nonetheless, <em>Clostridiales Family XIII. Incertae Sedis</em> was more abundant in the quercetin-supplemented rabbits (Control: 0.003±0.003%; Qrc: 0.020±0.000; <em>P</em>=0.005), as was the genus <em>Anaerofustis</em> (Control: 0.000±0.002; Qrc: 0.010±0.002; <em>P</em>=0.003). Serum cortisol levels were higher in females, and several microbial families differed between the sexes. Most were more abundant in female rabbits, including the most abundant, the family <em>Eubacteriaceae</em> (Male: 2.93±0.40; Female: 4.73±0.40; <em>P</em>=0.01).

Analysis of Flavonoid Metabolites in Citrus Peels (Citrus reticulata "Dahongpao") Using UPLC-ESI-MS/MS

Flavonoids are a kind of essential substance for the human body because of their antioxidant properties and extremely high medicinal value. Citrus reticulata “Dahongpao” (DHP) is a special citrus variety that is rich in flavonoids, however little is known about its systematic flavonoids profile. In the present study, the presence of flavonoids in five important citrus varieties, including DHP, Citrus grandis Tomentosa (HZY), Citrus ichangensis Swingle (YCC), Citrus sinensis (L.) Osbeck (TC), and Citrus reticulata ‘Buzhihuo’ (BZH), was determined using a UPLC-ESI-MS/MS-based, widely targeted metabolome. Results showed that a total of 254 flavonoid metabolites (including 147 flavone, 39 flavonol, 21 flavanone, 24 anthocyanins, 8 isoflavone, and 15 polyphenol) were identified. The total flavonoid content of peels from DHP was the highest. DHP could be clearly separated from other samples through clustering analysis and principal component analysis (PCA). Further, 169 different flavonoid metabolites were observed between DHP peels and the other four citrus peels, and 26 down-regulated differential metabolites displayed important biological activities in DHP. At the same time, a unique flavonoid component, tricin 4′-O-syringyl alcohol, was only found in DHP, which could be used as a marker to distinguish between other varieties. This work might facilitate a better understanding of flavonoid metabolites between DHP peels and the other four citrus peels and provide a reference for its sufficient utilization in the future.

Preparation of a nanoscale dihydromyricetin-phospholipid complex to improve the bioavailability: in vitro and in vivo evaluations

Dihydromyricetin (DMY), a flavanonol compound found as the most abundant and bioactive constituent in Ampelopsis grossedentata (Hand-Mazz) W.T. Wang, possesses numerous pharmacological activities, such as antioxidant, anti-inflammation, anticancer, anti-microbial, hypoglycemic and hypolipidemic effects, and so on. Recently, DMY shows a promising potential to develop as an agent for the prevention and treatment of Type 2 diabetes mellitus (T2DM). However, the low oral bioavailability of DMY was one of the special concerns to be resolved for its clinical applications. In this study, DMY phospholipid complex (DMY-HSPC COM) was prepared by the solvent evaporation technique and optimized with DMY combination ratio. Scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and Fourier transform infrared spectrophotometry (FT-IR) were carried to characterize the formation of DMY-HSPC COM. The particle size, zeta potential, drug loading and solubility of DMY-HSPC COM were further investigated. The phospholipid complex technology could significantly improve the solubility of DMY. Pharmacokinetic study results of DMY-HSPC COM in healthy SD rats and T2DM rats demonstrated that the oral bioavailability was significantly increased when compared with pure DMY as well, which could be attributed to the improvement of the aqueous solubility of the complex, absorption promotion and a probable decrease in intestinal and hepatic metabolism. In addition, when compared with healthy SD rats, pharmacokinetic parameters of pure DMY and DMY-HSPC COM showed significant difference in T2DM rats. Thus, phospholipid complex technology holds a promising potential for increasing the oral bioavailability of DMY.

Effects of Gut Microbiota on the Bioavailability of Bioactive Compounds from Ginkgo Leaf Extracts

Ginkgo leaf extract (GLE) is a popular herbal medicine and dietary supplement for the treatment of various diseases, including cardiovascular disease. GLE contains a variety of secondary plant metabolites, such as flavonoids and terpenoids, as active components. Some of these phytochemicals have been known to be metabolized by gut microbial enzymes. The aim of this study was to investigate the effects of the gut microbiota on the pharmacokinetics of the main constituents of GLE using antibacterial-treated mice. The bilobalide, ginkgolide A, ginkgolide B, ginkgolide C, isorhamnetin, kaempferol, and quercetin pharmacokinetic profiles of orally administered GLE (600 mg/kg), with or without ciprofloxacin pretreatment (150 mg/kg/day for 3 days), were determined. In the antibacterial-treated mice, the maximum plasma concentration (C_max) and area under the curve (AUC) of isorhamnetin were significantly (p < 0.05) increased when compared with the control group. The C_max and AUC of kaempferol and quercetin (other flavonol glycosides) were slightly higher than those of the control group, but the difference was not statistically significant, while both parameters for terpenoids of GLE showed no significant difference between the antibacterial-treated and control groups. These results showed that antibacterial consumption may increase the bioavailability of isorhamnetin by suppressing gut microbial metabolic activities.

Interactions of tea polyphenols with intestinal microbiota and their implication for cellular signal conditioning mechanism

Tea polyphenols (TP) is the main functional substances in tea. It has been reported that TP can modulate the composition of gut microbes in the human body, in addition, after the bio-transformation by intestinal flora, the metabolites of TP also have positive effects on the health of the host. Lots of researches have shown that TP have possible therapeutic effect against high fat diet induced obesity, which is closely related to the gut flora of the host. Therefore, this review focused on the interactions of TP with intestinal microbiota and their implication for cellular signal conditioning mechanism that will enable us to better study the two-way effects of TP and intestinal microbiota on host health improvement. PRACTICAL APPLICATIONS: TP have been widely concerned for their health care properties. As the functional food components, TP have strong antioxidant and physiological activities for human body. A better understanding on the interactions of TP with intestinal microbiota and their implication for cellular signal conditioning mechanism will lead us to better evaluate the contribution of the microbial metabolites of TP, as well as the regulation of intestinal bacterial diversity and abundance for host health.

Dihydromyricetin Attenuates Metabolic Syndrome And Improves Insulin Sensitivity By Upregulating Insulin Receptor Substrate-1 (Y612) Tyrosine Phosphorylation In db/db Mice

PURPOSE

Dihydromyricetin (DHM), the main bioactive flavonoid in vine tea, exerts multiple health beneficial effects. This work aimed to identify whether a naturally derived flavonoid product, DHM, can significantly attenuate metabolic syndrome and improve insulin sensitivity.

METHODS

10-week-old db/db mice were randomly assigned to receive the antidiabetic agent metformin (Met, 50 mg/kg BW), DHM (1.0 g and 0.5 g/kg BW) or placebo and were simultaneously fed a high-fat diet for 8 weeks. The general status of the animals was observed and recorded daily, body weight and blood glucose levels were measured weekly, during the experimental period. On day 55, the oral glucose tolerance test (OGTT) was performed. After OGTT, all animals were anesthetized and sacrificed by cervical decapitation. Blood samples were collected in tubes to detect plasma insulin and the biochemical parameters of lipid metabolism. Pancreas histological changes and islet fibrosis were demonstrated by H&E staining and Masson staining, respectively. Moreover, the expression of insulin receptor substrate-1 and phosphorylated insulin receptor substrate-1 in the insulin signaling pathway was detected by Western blot assay.

RESULTS

The oral administration of DHM (1.0 g and 0.5 g/kg BW) reduced the fasting blood glucose, serum insulin, and glycated hemoglobin levels and the insulin resistance (HOMA-IR) index. Furthermore, DHM intervention decreased body weight and the serum lipid profile. In addition, DHM treatment also markedly decreased the relative abdominal fat weight. Western blot analysis indicated that DHM upregulated the IRS-1 (Y612) tyrosine phosphorylation, improving insulin resistance. Treatment with dihydromyricetin attenuated the progression of insulin resistance and pancreatic fibrosis in fatty db/db mice.

CONCLUSION

In summary, we determined the antimetabolic syndrome effect of DHM in db/db obese mice. DHM upregulates the IRS-1 (Y612) tyrosine phosphorylation, improving insulin resistance. Therefore, DHM is a promising therapeutic candidate for the control of metabolic syndrome.