Protective effects of tartary buckwheat flavonoids on high TMAO diet-induced vascular dysfunction and liver injury in mice

From gut to liver: Exploring the crosstalk between gut-liver axis and oxidative stress in metabolic dysfunction-associated steatotic liver disease

Non-alcoholic fatty liver disease (NAFLD), now recognized as metabolic dysfunction-associated steatotic liver disease (MASLD), represents a significant and escalating global health challenge. Its prevalence is intricately linked to obesity, insulin resistance, and other components of the metabolic syndrome. As our comprehension of MASLD deepens, it has become evident that this condition extends beyond the liver, embodying a complex, multi-systemic disease with hepatic manifestations that mirror the broader metabolic landscape. This comprehensive review delves into the critical interplay between the gut-liver axis and oxidative stress, elucidating their pivotal roles in the etiology and progression of MASLD. Our analysis reveals several key findings: (1) Bile acid dysregulation can trigger oxidative stress through enhanced ROS production in hepatocytes and Kupffer cells, leading to mitochondrial dysfunction and lipid peroxidation; (2) Gut microbiota dysbiosis disrupts intestinal barrier function, allowing increased translocation of endotoxins like LPS, which activate inflammatory pathways through TLR4 signaling and promote oxidative stress via NADPH oxidase activation; (3) The redox-sensitive transcription factors NF-κB and Nrf2 serve as crucial mediators in the gut-liver axis, with NF-κB regulating inflammatory responses and Nrf2 orchestrating antioxidant defenses; (4) Oxidative stress-induced damage to intestinal barrier function creates a destructive feedback loop, further exacerbating liver inflammation and disease progression. These findings highlight the complex interrelationship between gut-liver axis dysfunction and oxidative stress in MASLD pathogenesis, suggesting potential therapeutic targets for disease management.

Trimethylamine N-oxide induces non-alcoholic fatty liver disease by activating the PERK

Nonalcoholic fatty liver disease (NAFLD) is a liver disease causing different progressive pathological changes. Trimethylamine N-oxide (TMAO), a product of gut microbiota metabolism, is a specific agonist of the protein kinase R-like endoplasmic reticulum kinase (PERK) pathway, one of the endoplasmic reticulum stress (ERS) pathways. TMAO has been associated with the occurrence and development of NAFLD based on the results of previous studies, but whether the simple consumption of TMAO can directly induce NAFLD and its underlying mechanism remain unclear. To investigate this question, we constructed an animal model in which adult male zebrafish were fed a controlled diet containing 1 % or 3 % TMAO for 20 weeks. Eventually, we observed that TMAO caused lipid accumulation, inflammatory infiltration, liver injury and liver fibrosis in zebrafish livers; meanwhile, the PERK signaling pathway was activated in the zebrafish livers. This finding was further confirmed in HepG2 cells and hepatic stellate cells models. In conclusion, this study found that TMAO directly induced different pathological states of NAFLD in zebrafish liver, and the activation of PERK pathway is an important mechanism, which may provide crucial strategies for the diagnosis and treatment of NAFLD.

Trimethylamine N-Oxide in Aquatic Foods

Trimethylamine N-oxide (TMAO), a characteristic nonprotein nitrogen compound, is widely present in seafood, which exhibits osmoregulatory effects for marine organisms in vivo and plays an important role in aquaculture and aquatic product preservation. However, much attention has been focused on the negative effect of TMAO since it has recently emerged as a putative promoter of chronic diseases. To get full knowledge and maximize our ability to balance the positive and negative aspects of TMAO, in this review, we comprehensively discuss the TMAO in aquatic products from the aspects of physiological functions for marine organisms, flavor, quality, the conversion of precursors, the influences on human health, and the seafood ingredients interaction consideration. Though the circulating TMAO level is inevitably enhanced after seafood consumption, dietary seafood still exhibits beneficial health effects and may provide nutraceuticals to balance the possible adverse effects of TMAO.

Gut microbial metabolites in MASLD: Implications of mitochondrial dysfunction in the pathogenesis and treatment

With an increasing prevalence, metabolic dysfunction-associated steatotic liver disease (MASLD) has become a major global health problem. MASLD is well-known as a multifactorial disease. Mitochondrial dysfunction and alterations in the gut bacteria are 2 vital events in MASLD. Recent studies have highlighted the cross-talk between microbiota and mitochondria, and mitochondria are recognized as pivotal targets of the gut microbiota to modulate the host's physiological state. Mitochondrial dysfunction plays a vital role in MASLD and is associated with multiple pathological changes, including hepatocyte steatosis, oxidative stress, inflammation, and fibrosis. Metabolites are crucial mediators of the gut microbiota that influence extraintestinal organs. Additionally, regulation of the composition of gut bacteria may serve as a promising therapeutic strategy for MASLD. This study reviewed the potential roles of several common metabolites in MASLD, emphasizing their impact on mitochondrial function. Finally, we discuss the current treatments for MASLD, including probiotics, prebiotics, antibiotics, and fecal microbiota transplantation. These methods concentrate on restoring the gut microbiota to promote host health.

Thioredoxin/Glutaredoxin Systems and Gut Microbiota in NAFLD: Interplay, Mechanism, and Therapeutical Potential

Non-alcoholic fatty liver disease (NAFLD) is a common clinical disease, and its pathogenesis is closely linked to oxidative stress and gut microbiota dysbiosis. Recently accumulating evidence indicates that the thioredoxin and glutaredoxin systems, the two thiol-redox dependent antioxidant systems, are the key players in the NAFLD's development and progression. However, the effects of gut microbiota dysbiosis on the liver thiol-redox systems are not well clarified. This review explores the role and mechanisms of oxidative stress induced by bacteria in NAFLD while emphasizing the crucial interplay between gut microbiota dysbiosis and Trx mediated-redox regulation. The paper explores how dysbiosis affects the production of specific gut microbiota metabolites, such as trimethylamine N-oxide (TMAO), lipopolysaccharides (LPS), short-chain fatty acids (SCFAs), amino acids, bile acid, and alcohol. These metabolites, in turn, significantly impact liver inflammation, lipid metabolism, insulin resistance, and cellular damage through thiol-dependent redox signaling. It suggests that comprehensive approaches targeting both gut microbiota dysbiosis and the thiol-redox antioxidant system are essential for effectively preventing and treating NAFLD. Overall, comprehending the intricate relationship between gut microbiota dysbiosis and thiol-redox systems in NAFLD holds significant promise in enhancing patient outcomes and fostering the development of innovative therapeutic interventions.

A review: The nutrition components, active substances and flavonoid accumulation of Tartary buckwheat sprouts and innovative physical technology for seeds germinating

Compared with the common grain, Tartary buckwheat enjoys higher nutritional value. Some distinctive nutrition associated with physiological activity of Tartary buckwheat is valuable in medicine. In addition, it's a good feed crop. In the paper, the main components (starch, protein, amino acid, fatty acid and mineral) and polyphenol bioactive components in Tartary buckwheat and its sprouts were reviewed, and the accumulation of flavonoids in sprouts during germination, especially the methods, synthetic pathways and mechanisms of flavonoid accumulation was summarized. The research on bioactive components and health benefits of Tartary buckwheat also were reviewed. Besides, the applications of innovative physical technology including microwave, magnetic, electromagnetic, ultrasonic, and light were also mentioned and highlighted, which could promote the enrichment of some active substances during seeds germination and growth of Tartary buckwheat sprouts. It would give a good support and benefit for the research and processing of Tartary buckwheat and its sprouts in next day.

Trimethylamine N-Oxide Exacerbates Neuroinflammation and Motor Dysfunction in an Acute MPTP Mice Model of Parkinson's Disease

Observational studies have shown abnormal changes in trimethylamine N-oxide (TMAO) levels in the peripheral circulatory system of Parkinson's disease (PD) patients. TMAO is a gut microbiota metabolite that can cross the blood-brain barrier and is strongly related to neuroinflammation. Neuroinflammation is one of the pathological drivers of PD. Herein, we investigated the effect of TMAO on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. TMAO pretreatment was given by adding 1.5% (w/v) TMAO to the drinking water of the mice for 21 days; then, the mice were administered MPTP (20 mg/kg, i.p.) four times a day to construct an acute PD model. Their serum TMAO concentrations, motor function, dopaminergic network integrity, and neuroinflammation were then assayed. The results showed that TMAO partly aggravated the motor dysfunction of the PD mice. Although TMAO had no effect on the dopaminergic neurons, TH protein content, and striatal DA level in the PD mice, it significantly reduced the striatal 5-HT levels and aggravated the metabolism of DA and 5-HT. Meanwhile, TMAO significantly activated glial cells in the striatum and the hippocampi of the PD mice and promoted the release of inflammatory cytokines in the hippocampus. In summary, higher-circulating TMAO had adverse effects on the motor capacity, striatum neurotransmitters, and striatal and hippocampal neuroinflammation in PD mice.

Tartary buckwheat flavonoids alleviates high-fat diet induced kidney fibrosis in mice by inhibiting MAPK and TGF-β1/Smad signaling pathway

Tartary buckwheat flavonoids (TBF) are active components extracted from Tartary buckwheat, which have abundant biological effects. According to this study, we investigated the effect of TBF on high-fat diet (HFD)-induced kidney fibrosis and its related mechanisms. In vivo, we established an HFD-induced kidney fibrosis model in mice and administered TBF. The results showed that TBF was able to alleviate kidney injury and inflammatory response. Subsequently, the mRNA levels between the HFD group and the TBF + HFD group were detected using RNA-seq assay. According to the gene set enrichment analysis (GSEA) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results, the differential genes were enriched in lipid metabolism and mitogen-activated protein kinases(MAPK) signaling pathways. We examined the protein expression of lipid metabolism-related pathways and the level of lipid metabolism. The results showed that TBF significantly activated the adenosine monophosphate activated protein kinase/acetyl-CoA carboxylase (AMPK/ACC) pathway and effectively reduced kidney total cholesterol (TC), triglyceride (TG) and low-density lipoproteinc cholesterol (LDL-C) levels and increased high-density lipoprotein cholesterol (HDL-C) levels in mice. TBF also inhibited transforming growth factor-β1/Smad (TGF-β1/Smad) and MAPK signaling pathways, thus slowing down the kidney fibrosis process. In vitro, using palmitic acid (PA) to stimulate TCMK-1 cells, the in vivo results similarly demonstrated that TBF could alleviate kidney fibrosis in HFD mice by inhibiting TGF1/Smad signaling pathway and MAPK signaling pathway.

Integrated transcriptome and metabolome provide insight into flavonoid variation in goji berries (Lycium barbarum L.) from different areas in China

Goji berries (Lycium barbarum L.) were rich in flavonoids, showing high nutritional and medicinal value. However, a thorough evaluation and comparison of the flavonoids in goji berries from various regions and the possible biological regulation pathways with differences are scanty. Here, we investigated the flavonoid metabolites and gene expression levels of goji berries from three major production areas in China using transcriptomics sequencing and metabolomics. The total flavonoid content and total polyphenol content of goji berry in Ningxia (57.87 μg/g and 183.41 μg/g, respectively) were higher than in Qinghai (50.77 μg/g and 156.81 μg/g) and Gansu (47.86 μg/g and 111.17 μg/g). We identified the 105 differentially accumulated flavonoids (DAFs) and 1858 differentially expressed genes (DEGs) from the goji berries in three habitats. Interestingly, gossypetin-3-O-rutinoside and isorhamnetin were significantly expressed between Ningxia and Qinghai berries. The chalcone isomerase (CHI), chalcone synthase (CHS), and flavonol synthase (FLS) genes also played key roles in the regulation of flavonoid synthesis. In addition, MYB1 positively regulated the expression of quercetin-3-O-glucoside, quercetin-7-O-glucoside and isohyperoside. As a result, we speculated that CHI, CHS, FLS genes, and related transcription factors jointly controlled the variation of flavone accumulation in goji berries. These findings may provide a new perspective for understanding the accumulation and molecular mechanisms of goji flavonoids.

Potential Role of Quercetin Glycosides as Anti-Atherosclerotic Food-Derived Factors for Human Health

Quercetin is a monomeric polyphenol of plant origin that belongs to the flavonol-type flavonoid subclass. Extensive studies using cultured cells and experimental model animals have demonstrated the anti-atherosclerotic effects of dietary quercetin in relation to the prevention of cardiovascular disease (CVD). As quercetin is exclusively present in plant-based foods in the form of glycosides, this review focuses on the bioavailability and bioefficacy of quercetin glycosides in relation to vascular health effects. Some glucose-bound glycosides are absorbed from the small intestine after glucuronide/sulfate conjugation. Both conjugated metabolites and deconjugated quercetin aglycones formed by plasma β-glucuronidase activity act as food-derived anti-atherogenic factors by exerting antioxidant, anti-inflammatory, and plasma low-density lipoprotein cholesterol-lowering effects. However, most quercetin glycosides reach the large intestine, where they are subject to gut microbiota-dependent catabolism resulting in deglycosylated aglycone and chain-scission products. These catabolites also affect vascular health after transfer into the circulation. Furthermore, quercetin glycosides may improve gut microbiota profiles. A variety of human cohort studies and intervention studies support the idea that the intake of quercetin glycoside-rich plant foods such as onion helps to prevent CVD. Thus, quercetin glycoside-rich foods offer potential benefits in terms of cardiovascular health and possible clinical applications.

Quercetin inhibits hepatotoxic effects by reducing trimethylamine-N-oxide formation in C57BL/6J mice fed with a high L-carnitine diet

L-Carnitine can be metabolized to trimethylamine (TMA) by gut microbiota and further converted into trimethylamine N-oxide (TMAO) in the liver, leading to liver damage. This study aimed to investigate the protective effect of quercetin against high L-carnitine-induced liver toxicity in mice. 3% L-carnitine drinking water was used to feed mice in this study. The formation of TMAO in the blood circulation of the tested mice was down-regulated following quercetin treatment. Administration of quercetin could also effectively antagonize the liver injury caused by high L-carnitine intake, which was proved by the decreased serum AST and ALT activities and the reduced levels of inflammatory liver cytokines (IL-1, IL-6, TNF-α, and TNF-β). Moreover, quercetin exhibited a rebalancing effect on dyslipidemia (TC, TG, HDL, and LDL) and antioxidant abilities (SOD, GSH-Px, MDA, and RAHFR) in L-carnitine-treated mice. The results of hepatic H&E and Oil Red O staining further verified the liver injury of high L-carnitine-treated mice and the protective effects of quercetin. These findings suggested that quercetin could attenuate the hepatotoxic effects of the mice fed with a high L-carnitine diet via inhibiting the circulating TMAO formation.

Metabolite Profiling of Tartary Buckwheat Extracts in Rats Following Co-Administration of Ethanol Using UFLC-Q-Orbitrap High-Resolution Mass Spectrometry

Tartary buckwheat, a gluten-free pseudocereal, has received considerable attention owing to its unique nutritional ingredients and beneficial health effects such as anti-tumor, anti-oxidation, anti-inflammation and hepatoprotective activities. Pharmacokinetic and metabolite profiling have been preliminarily assessed for Tartary buckwheat extracts. However, its metabolites have not yet been characterized in vivo after co-administration with ethanol when Tartary buckwheat extracts are used for the treatment of alcoholic liver disease. In this paper, a Q-Exactive orbitrap high-resolution mass spectrometer was employed to identify the metabolites of Tartary buckwheat extracts in rat biological samples. Compared with previous metabolite profiling results, a total of 26 novel metabolites were found in rat biological samples, including 11, 10, 2 and 5 novel metabolites in rat plasma, bile, urine and feces, respectively, after oral co-administration of 240 mg/kg Tartary buckwheat extracts with ethanol (42%, v/v). The major metabolic pathways of the constituents in Tartary buckwheat extracts involved hydroxylation, methylation, glucuronidation, acetylation and sulfation. Quercetin and its metabolites may be the pharmacological material basis of Tartary buckwheat for the protective effect against alcoholic liver injury. The research enriched in vivo metabolite profiling of Tartary buckwheat extracts, which provided experimental data for a comprehensive understanding and rational use of Tartary buckwheat against alcoholic liver disease.

Trimethylamine-N-Oxide Promotes Osteoclast Differentiation and Bone Loss via Activating ROS-Dependent NF-κB Signaling Pathway

Trimethylamine-N-oxide (TMAO), an important gut microbiota (GM)-derived metabolite, has been shown to be abnormally increased in osteoporosis. However, the role and underlying mechanism of TMAO in regulating bone loss during osteoporosis have not been fully investigated. In the current study, we found that 100–400 μM TMAO dose-dependently enhanced TRAP-positive osteoclasts, F-actin ring formation, and resorption area on bovine bone slices and up-regulated osteoclast-related gene expression (Calcr, Traf6, Dcstamp, Acp5, C-Fos, and NFATc1). Western blotting validated that TMAO not only activated NF-κB signaling pathway but also stimulated c-Fos and NFATc1 protein expression in a dose-dependent manner. Furthermore, BAY 11-7082, an NF-κB inhibitor, pretreatment markedly suppressed TRAP-positive osteoclast formation and osteoclast-related genes under TMAO treatment. BAY 11-7082 also inhibited p-p65/p65, c-Fos, and NFATc1 protein expression promoted by TMAO. Moreover, TMAO significantly increased ROS production, which was inhibited by N-acetylcysteine (NAC), an ROS antagonist. In addition, we proved that NAC pretreatment could inhibit TMAO-promoted NF-κB activation. NAC also suppressed TRAP-positive osteoclast formation, osteoclast-related gene expression, and protein expression of c-Fos and NFATc1 under TMAO treatment. In vivo studies showed significantly decreased bone mass and increased TRAP-positive osteoclasts in TMAO-treated C57BL/6 mice. Moreover, western-blotting and immunohistochemical staining showed that TMAO administration markedly stimulated NF-κB p65 expression. Additionally, TMAO administration significantly promoted the gene and protein expression of C-Fos and NFATc1. In conclusion, TMAO could promote osteoclast differentiation and induce bone loss in mice by activating the ROS-dependent NF-κB signaling pathway.

Black raspberry extract can lower serum LDL cholesterol via modulation of gut microbial composition and serum bile acid profile in rats fed trimethylamine-N-oxide with a high-fat diet

Blood trimethylamine-N-oxide (TMAO) has been associated with cardiovascular disease. Black raspberry (Rubus occidentalis, BR) has been regarded to be beneficial for cardiovascular health. This study aimed to investigate how BR extract affects serum lipid profile, gut microbial composition, metabolites in rats fed TMAO with a high-fat diet. Dietary TMAO increased serum LDL cholesterol, while BR extract decreased its level. α-Diversity of gut microbiota was not changed; however, in the rats fed TMAO, Macellibacteroides and Mucispirillum were enriched, while Ruminococcaceae was reduced. The BR supplementation could restore Macellibacteroides, Clostridium, and Ruminococcaceae. The BR supplementation increased cecal hippuric acid and serum farnesoid X receptor-antagonistic bile acids, including ursodeoxycholic acid (UDCA), tauro-α-muricholic acid, and tauro-UDCA. The BR supplementation tended to upregulate Cyp7a1 and Abcg5 expressions while downregulating Srebf2 and Hmgcr expressions. BR extract affects the gut bacterial community and microbial metabolites, lowering serum LDL cholesterol in rats with elevated serum TMAO.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01079-y.

Hepatoprotective Effect of Cereal Vinegar Sediment in Acute Liver Injury Mice and Its Influence on Gut Microbiota

Cereal vinegar sediment (CVS) is a natural precipitate formed during the aging process of traditional grain vinegar. It has been used as Chinese traditional medicine, while its composition and function are reported minimally. In this study, we measured CVS in terms of saccharide, protein, fat and water content, and polyphenol and flavonoid content. Furthermore, we determined the amino acids, organic acids, and other soluble metabolites in CVS using reverse-phase high-performance liquid chromatography (RP-HPLC), HPLC, and liquid chromatography with tandem mass spectrometry (LC-MS/MS) platforms. The hepatoprotective effect of CVS was evaluated in acute CCl₄-induced liver injury mice. Administration of CVS for 7 days prior to the CCl₄ treatment can significantly decrease liver alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels and reactive oxygen species (ROS) levels, compared with those in the hepatic injury model group. The gut microbiota was changed by CCl₄ administration and was partly shifted by the pretreatment of CVS, particularly the Muribaculaceae family, which was increased in CVS-treated groups compared with that in the CCl₄ administration group. Moreover, the abundances of Alistipes genus and Muribaculaceae family were correlated with the liver ALT, AST, and malondialdehyde (MDA) levels. Our results illustrated the composition of CVS and its hepatoprotective effect in mice, suggested that CVS could be developed as functional food to prevent acute liver injury.

Chemical Profile, Antimicrobial and Antioxidant Activity Assessment of the Crude Extract and Its Main Flavonoids from Tartary Buckwheat Sprouts

The purpose of this study was to investigate the major flavonoids content and bioactivities of Tartary buckwheat sprouts. The crude methanol extract (ME) of Tartary buckwheat sprouts was abundant in flavonoids, and six major flavonoids, including isoorientin, vitexin, isovitexin, rutin, quercetin, and kaemferol were successfully determined from the sprouts by the high-performance liquid chromatography (HPLC) method. Generally, the flavonoid content of buckwheat sprouts was in the order of rutin > quercetin > isovitexin > vitexin> isoorientin > kaemferol. The highest rutin content of the ME and sprout cultures was 89.81 mg/g and 31.50 mg/g, respectively. Antibacterial activity results indicated the ME displayed notable inhibitory activity against the five tested bacteria, and its minimum inhibitory concentration (MIC) values ranged from 0.8 mg/mL to 3.2 mg/mL. Among the six flavonoids, quercetin was the most active compound, which exhibited strong activity against all tested bacteria except for E. coli and S. epidermidis, with its MIC values ranging from 0.2 mg/mL to 0.4 mg/mL. For the antifungal activity assay, the ME of Tartary buckwheat sprouts and four flavonoids could significantly inhibit the spore germination of two pathogenic fungi, and their inhibitory efficiency was concentration dependent. Quercetin was the most active one, which significantly inhibited the spore germination of F. oxysporum f. sp. vasinfectum and F. oxysporum f. sp. cucumerinum, and its median effective inhibitory concentration (IC50) value was 42.36 and 32.85 µg/mL, respectively. The antioxidant activity results showed that quercetin, kaemferol, and rutin displayed excellent antioxidant activity in the DPPH radical scavenging test, and their IC50 value was calculated as 5.60, 16.23, and 27.95 µg/mL, respectively. This is the first report on the antimicrobial activity of the crude extract of Tartary buckwheat sprouts. These results indicated that the methanol extract of Tartary buckwheat sprouts could be used as a potential antimicrobial or antioxidant agent in the future.

Higher circulating Trimethylamine N-oxide levels are associated with worse severity and prognosis in pulmonary hypertension: a cohort study

BACKGROUND

Trimethylamine N-oxide (TMAO), the gut microbiota-dependent metabolite, is a potential biomarker in several cardiovascular diseases. However, no study has investigated its value in pulmonary hypertension (PH). Therefore, this study aimed to explore the association between plasma TMAO levels and prognosis in patients with PH.

METHODS

Inpatients with idiopathic/heritable pulmonary arterial hypertension (IPAH/HPAH), PAH associated with congenital heart disease (CHD-PAH), and chronic thromboembolic pulmonary hypertension (CTEPH) at Fuwai Hospital were enrolled after excluding those with relative comorbidities. The endpoint was defined as a composite outcome including death, rehospitalisation due to heart failure, and at least 15% decreased 6-min walk distance from the baseline. Fasting blood samples were collected to measure plasma levels of TMAO and other clinical indicators. The associations between TMAO levels with disease severity and patients' prognosis were investigated.

RESULTS

In total, 163 patients with PH were included, with a mean follow-up duration of 1.3 years. After adjusting for confounding factors, elevated TMAO levels were still associated with severe disease conditions. TMAO levels dynamically decreased in stable and improved patients after treatment [ΔTMAO = - 0.2 (- 1.6, 0.7) μmol/L, P = 0.006]. Moreover, high plasma TMAO levels predicted a poor prognosis in the PH cohort (P < 0.001), and the association remained significant after adjusting the confounders, including treatment, risk stratification, and PH subtypes.

CONCLUSION

Elevated plasma TMAO levels were associated with severe disease conditions and poor prognosis in patients with PH, indicating its potential biomarker role in PH.

Gut Metabolite Trimethylamine-N-Oxide in Atherosclerosis: From Mechanism to Therapy

Atherosclerosis is associated with various pathological manifestations, such as ischemic heart disease, ischemic stroke, and peripheral arterial disease, and remains a leading cause of public health concern. Atherosclerosis is an inflammatory disease characterized by endothelial dysfunction; vascular inflammation; and the deposition of lipids, cholesterol, calcium, and cellular debris within the vessel wall intima. In-depth studies of gut flora in recent years have shown that bacterial translocation and the existence of bacterial active products in blood circulation can affect the inflammatory state of the whole blood vessel. The gut flora is considered to be a large “secretory organ,” which produces trimethylamine-N-oxide (TMAO), short-chain fatty acids and secondary bile acids by breaking down the ingested food. Studies have shown that TMAO is an independent risk factor for the occurrence of malignant adverse cardiovascular events, but whether it is harmful or beneficial to patients with cardiovascular diseases with mild or no clinical manifestations remains controversial. We review the relationship between TMAO and its precursor (L-carnitine) and coronary atherosclerosis and summarize the potential molecular mechanism and therapeutic measures of TMAO on coronary atherosclerosis.

Transcriptome sequencing and metabolomics analyses provide insights into the flavonoid biosynthesis in Torreya grandis kernels

The kernel of Torreya grandis (T. grandis) is a rare nut with a variety of bioactive compounds. Flavonoids are a very important class of bioactive compounds with high antioxidant activity in T. grandis kernels. However, the flavonoid compositions which mainly contribute to antioxidant capacity and the molecular basis of flavonoid biosynthesis in T. grandis remain unclear. Here, transcriptome sequencing and metabolomics analysis for kernels were performed. In total, 124 flavonoids were identified. Among them, 9 flavonoids were highly correlated with antioxidant activity. Furthermore, unigenes encoding CHS, DFR and ANS showed significant correlation with the 9 flavonoids. Transient overexpression of TgDFR1 in tobacco leaves resulted in increased antioxidant activity. Moreover, several transcription factors from MYB, bHLH and bZIP families were identified by co-expression assay, suggesting that they may regulate flavonoid biosynthesis. Our findings provide a molecular basis and new insights into the flavonoid biosynthesis in T. grandis kernels.

Bioactive compounds, health benefits, and industrial applications of Tartary buckwheat (Fagopyrum tataricum)

Tartary buckwheat belongs to the family Polygonaceae, which is a traditionally edible and medicinal plant. Due to its various bioactive compounds, the consumption of Tartary buckwheat is correlated to a wide range of health benefits, and increasing attention has been paid to its potential as a functional food. This review summarizes the main bioactive compounds and important bioactivities and health benefits of Tartary buckwheat, emphasizing its protective effects on metabolic diseases and relevant molecular mechanisms. Tartary buckwheat contains a wide range of bioactive compounds, such as flavonoids, phenolic acids, triterpenoids, phenylpropanoid glycosides, bioactive polysaccharides, and bioactive proteins and peptides, as well as D-chiro-inositol and its derivatives. Consumption of Tartary buckwheat and Tartary buckwheat-enriched products is linked to multiple health benefits, e.g., antioxidant, anti-inflammatory, antihyperlipidemic, anticancer, antidiabetic, antiobesity, antihypertensive, and hepatoprotective activities. Especially, clinical studies indicate that Tartary buckwheat exhibits remarkable antidiabetic activities. Various tartary buckwheat -based foods presenting major health benefits as fat and blood glucose-lowering agents have been commercialized. Additionally, to address the safety concerns, i.e., allergic reactions, heavy metal and mycotoxin contaminations, the quality control standards for Tartary buckwheat and its products should be drafted and completed in the future.

Intravenous trimethylamine N-oxide infusion does not modify circulating markers of liver health, glucose tolerance, and milk production in early-lactation cows

In rodents and humans, the gut bacteria-derived metabolite trimethylamine N-oxide (TMAO) has been implicated in the progression of cardiovascular disease, chronic kidney disease, fatty liver, and insulin resistance; however, the effects of TMAO on dairy cattle health and milk production have not been defined. We aimed to determine whether intravenous TMAO infusion modifies measures of liver health, glucose tolerance, and milk production in early-lactation cows. Eight early-lactation Holstein cows (30.4 ± 6.41 d in milk; 2.88 ± 0.83 lactations) were enrolled in a study with a replicated 4 × 4 Latin square design. Cows were intravenously infused TMAO at 0 (control), 20, 40, or 60 g/d for 6 d. Washout periods lasted 9 d. Intravenous glucose tolerance tests (GTT) occurred on d 5. Blood was collected daily. Milk was collected on d -1, 0, 5, and 6. Urine was collected on d -1 and 6. Circulating metabolites, milk components, and TMAO concentrations in milk, urine, and plasma were quantified. Data were analyzed using a mixed model that included the fixed effects of treatment. Concentrations of TMAO in plasma, milk, and urine increased linearly with increasing dose. Dry matter intake and milk production were not modified by treatment. Daily plasma triacylglycerol, fatty acid (FA), and glucose concentrations were not modified. Serum albumin, total protein, globulin, total bilirubin, direct bilirubin, aspartate aminotransferase, γ-glutamyl transferase, and glutamate dehydrogenase concentrations were also not modified by treatment. Serum GTT glucose, FA, and insulin concentrations were not modified by treatment. Plasma total, reduced, and oxidized glutathione concentrations were also not modified by treatment. We conclude that a 6-d intravenous infusion of TMAO does not influence measures of liver health, glucose tolerance, or milk production in early-lactation dairy cows.

1H NMR metabolomic and transcriptomic analyses reveal urinary metabolites as biomarker candidates in response to protein undernutrition in adult rats

Protein undernutrition contributes to the development of various diseases in broad generations. Urinary metabolites may serve as non-invasive biomarkers of protein undernutrition; however, this requires further investigation. We aimed to identify novel urinary metabolites as biomarker candidates responsive to protein undernutrition. Adult rats were fed control (CT; 14 % casein) or isoenergetic low-protein (LP; 5 % casein) diets for 4 weeks. 1H NMR metabolomics was applied to urine, plasma and liver samples to identify metabolites responsive to protein undernutrition. Liver samples were subjected to mRNA microarray and quantitative PCR analyses to elucidate the mechanisms causing fluctuations in identified metabolites. Urinary taurine levels were significantly lower in the LP group than in the CT group at week 1 and remained constant until week 4. Hepatic taurine level and gene expression level of cysteine dioxygenase type 1 were also significantly lower in the LP group than in the CT group. Urinary trimethylamine N-oxide (TMAO) levels were significantly higher in the LP group than in the CT group at week 2 and remained constant until week 4. Hepatic TMAO level and gene expression levels of flavin-containing mono-oxygenase 1 and 5 were also significantly higher in the LP group than in the CT group. In conclusion, urinary taurine and TMAO levels substantially responded to protein undernutrition. Furthermore, changes in hepatic levels of these metabolites and gene expressions associated with their metabolic pathways were also reflected in their fluctuating urinary levels. Thus, taurine and TMAO could act as non-invasive urinary biomarker candidates to detect protein undernutrition.

Use of dietary phytochemicals for inhibition of trimethylamine N-oxide formation

Trimethylamine-N-oxide (TMAO) has been reported as a risk factor for atherosclerosis development, as well as for other cardiovascular disease (CVD) pathologies. The objective of this review is to provide a useful summary on the use of phytochemicals as TMAO-reducing agents. This review discusses the main mechanisms by which TMAO promotes CVD, including the modulation of lipid and bile acid metabolism, and the promotion of endothelial dysfunction and oxidative stress. Current knowledge on the available strategies to reduce TMAO formation are discussed, highlighting the effect and potential of phytochemicals. Overall, phytochemicals (i.e., phenolic compounds or glucosinolates) reduce TMAO formation by modulating gut microbiota composition and/or function, inhibiting host's capacity to metabolize TMA to TMAO, or a combination of both. Perspectives for design of future studies involving phytochemicals as TMAO-reducing agents are discussed. Overall, the information provided by this review outlines the current state of the art of the role of phytochemicals as TMAO reducing agents, providing valuable insight to further advance in this field of study.

Hawthorn fruit extract reduced trimethylamine-N-oxide (TMAO)-exacerbated atherogenesis in mice via anti-inflammation and anti-oxidation

Background

Trimethylamine-N-oxide (TMAO) is an independent risk factor for atherosclerosis. Consumption of hawthorn fruit is believed to be cardio-protective, yet whether it is able to suppress the TMAO-induced atherosclerosis remains unexplored. The present study was to investigate the effects of hawthorn fruit extract (HFE) on TMAO-exacerbated atherogenesis.

Methods

Five groups of male Apolipoprotein E knock-out (ApoE^−/−) mice were fed a low-fat diet (LFD), a Western high-fat diet (WD), or one of the three WDs containing 0.2% TMAO (WD + TMAO), 0.2% TMAO plus 1% HFE (WD + TMAO + L-HFE), or 0.2% TMAO plus 2% HFE (WD + TMAO + H-HFE), respectively. After 12-weeks of intervention, plasma levels of TMAO, lipid profile, inflammatory biomarkers, and antioxidant enzyme activities were measured. Atherosclerotic lesions in the thoracic aorta and aortic sinus were evaluated. The sterols and fatty acids in the liver and feces were extracted and measured. Hepatic expressions of inflammatory biomarkers and antioxidant enzymes were analyzed.

Results

Dietary TMAO accelerated atherogenesis, exacerbated inflammation, and reduced antioxidant capacities in the plasma and the liver. TMAO promoted hepatic cholesterol accumulation by inhibiting fecal excretion of acidic sterols. HFE could dose-dependently reduce the TMAO-aggravated atherosclerosis and inflammation. HFE was also able to reverse the TMAO-induced reduction in antioxidant capacity by up-regulating the expression of antioxidant enzymes including superoxide dismutase 1 (SOD1), SOD2, glutathione peroxidase 3 (GSH-Px3), and catalase (CAT) in the liver. Moreover, the hepatic cholesterol content was lowered by HFE via enhanced fecal excretion of neutral and acidic sterols.

Conclusions

The present results indicated that HFE was able to reduce the TMAO-exacerbated atherogenesis by attenuating inflammation and improving antioxidant capacity at least in mice.

Graphic abstract

Comparative cellular, physiological and transcriptome analyses reveal the potential easy dehulling mechanism of rice-tartary buckwheat (Fagopyrum Tararicum)

BACKGROUND

Tartary buckwheat has gained popularity in the food marketplace due to its abundant nutrients and high bioactive flavonoid content. However, its difficult dehulling process has severely restricted its food processing industry development. Rice-tartary buckwheat, a rare local variety, is very easily dehulled, but the cellular, physiological and molecular mechanisms responsible for this easy dehulling remains largely unclear.

RESULTS

In this study, we integrated analyses of the comparative cellular, physiological, transcriptome, and gene coexpression network to insight into the reason that rice-tartary buckwheat is easy to dehull. Compared to normal tartary buckwheat, rice-tartary buckwheat has significantly brittler and thinner hull, and thinner cell wall in hull sclerenchyma cells. Furthermore, the cellulose, hemicellulose, and lignin contents of rice-tartary buckwheat hull were significantly lower than those in all or part of the tested normal tartary buckwheat cultivars, respectively, and the significant difference in cellulose and hemicellulose contents between rice-tartary buckwheat and normal tartary buckwheat began at 10 days after pollination (DAP). Comparative transcriptome analysis identified a total of 9250 differentially expressed genes (DEGs) between the rice- and normal-tartary buckwheat hulls at four different development stages. Weighted gene coexpression network analysis (WGCNA) of all DEGs identified a key module associated with the formation of the hull difference between rice- and normal-tartary buckwheat. In this specific module, many secondary cell wall (SCW) biosynthesis regulatory and structural genes, which involved in cellulose and hemicellulose biosynthesis, were identified as hub genes and displayed coexpression. These identified hub genes of SCW biosynthesis were significantly lower expression in rice-tartary buckwheat hull than in normal tartary buckwheat at the early hull development stages. Among them, the expression of 17 SCW biosynthesis relative-hub genes were further verified by quantitative real-time polymerase chain reaction (qRT-PCR).

CONCLUSIONS

Our results showed that the lower expression of SCW biosynthesis regulatory and structural genes in rice-tartary buckwheat hull in the early development stages contributes to its easy dehulling by reducing the content of cell wall chemical components, which further effects the cell wall thickness of hull sclerenchyma cells, and hull thickness and mechanical strength.

Progress in Research on Colorectal Cancer-Related Microorganisms and Metabolites

Intestinal flora is an important component in the human body, which have been reported to be involved in the occurrence and development of colorectal cancer (CRC). Indeed, changes in the intestinal flora in CRC patients compared to those in control subjects have been reported. Several bacterial species have been shown to exhibit the pro-inflammatory and pro-carcinogenic properties, which could consequently have an impact on colorectal carcinogenesis. In this review, we summarize the current knowledge on the potential links between the intestinal microbiota and CRC. We illustrated the mechanisms by which intestinal flora imbalance affects CRC, mainly focusing on inflammation, microbial metabolites, and specific bacteria species. In addition, we discuss how a diet exhibits a strong impact on microbial composition and provides risks for developing CRC. Finally, we describe the potential future directions that are based on intestinal microbiota manipulation for CRC diagnosis and treatment.

Can Meat and Meat-Products Induce Oxidative Stress?

High meat and meat-products consumption has been related to degenerative diseases. In addition to their saturated fatty acids and cholesterol contents, oxidation products generated during their production, storage, digestion, and metabolization have been largely implicated. This review begins by summarizing the concept of meat and meat-products by the main international regulatory agencies while highlighting the nutritional importance of their consumption. The review also dials in the controversy of white/red meat classification and insists in the need of more accurate classification based on adequate scores. Since one of the negative arguments that meat receives comes from the association of its consumption with the increase in oxidative stress, main oxidation compounds (malondialdehyde, thermaloxidized compounds, 4-hydroxy-nonenal, oxysterols, or protein carbonyls) generated during its production, storage, and metabolization, are included as a central aspect of the work. The review includes future remarks addressed to study the effects meat consumption in the frame of diet-gene interactions, stressing the importance of knowing the genetic variables that make individuals more susceptible to a possible oxidative stress imbalance or antioxidant protection. The importance of consumed meat/meat-products in the frame of a personalized nutrition reach in plant-food is finally highlighted considering the importance of iron and plant biophenols on the microbiota abundance and plurality, which in turn affect several aspects of our physiology and metabolism.

Dietary bioactive ingredients to modulate the gut microbiota-derived metabolite TMAO. New opportunities for functional food development

There is a growing body of clinical evidence that supports a strong association between elevated circulating trimethylamine N-oxide (TMAO) levels with increased risk of developing adverse cardiovascular outcomes such as atherosclerosis and thrombosis. TMAO is synthesized through a meta-organismal stepwise process that involves (i) the microbial production of TMA in the gut from dietary precursors and (ii) its subsequent oxidation to TMAO by flavin-containing monooxygenases in the liver. Choline, l-carnitine, betaine, and other TMA-containing compounds are the major dietary precursors of TMA. TMAO can also be absorbed directly from the gastrointestinal tract after the intake of TMAO-rich foods such as fish and shellfish. Thus, diet is an important factor as it provides the nutritional precursors to eventually produce TMAO. A number of studies have attempted to associate circulating TMAO levels with the consumption of diets rich in these foods. On the other hand, there is growing interest for the development of novel food ingredients that reduce either the TMAO-induced damage or the endogenous TMAO levels through the interference with microbiota and host metabolic processes involved in TMAO pathway. Such novel functional food ingredients would offer great opportunities to control circulating TMAO levels or its effects, and potentially contribute to decrease cardiovascular risk. In this review we summarize and discuss current data regarding the effects of TMA precursors-enriched foods or diets on circulating TMAO levels, and recent findings regarding the circulating TMAO-lowering effects of specific foods, food constituents and phytochemicals found in herbs, individually or in extracts, and their potential beneficial effect for cardiovascular health.

Metabolite Profiling and Transcriptome Analyses Provide Insights into the Flavonoid Biosynthesis in the Developing Seed of Tartary Buckwheat (Fagopyrum tataricum)

Tartary buckwheat (Fagopyrum tataricum) seeds are rich in flavonoids. However, the detailed flavonoid compositions and the molecular basis of flavonoid biosynthesis in tartary buckwheat seeds remain largely unclear. Here, we performed a combined metabolite profiling and transcriptome analysis to identify flavonoid compositions and characterize genes involved in flavonoid biosynthesis in the developing tartary buckwheat seeds. In total, 234 flavonoids, including 10 isoflavones, were identified. Of these, 80 flavonoids were significantly differential accumulation during seed development. Transcriptome analysis indicated that most structural genes and some potential regulatory genes of flavonoid biosynthesis were significantly differentially expressed in the course of seed development. Correlation analysis between transcriptome and metabolite profiling shown that the expression patterns of some differentially expressed structural genes and regulatory genes were more consistent with the changes in flavonoids profiles during seed development and promoted one SG7 subgroup R2R3-MYB transcription factors (FtPinG0009153900.01) was identified as the key regulatory gene of flavonoid biosynthesis. These findings provide valuable information for understanding the mechanism of flavonoid biosynthesis in tartary buckwheat seeds and the further development of tartary buckwheat health products.

Increased Trimethylamine N-Oxide Is Not Associated with Oxidative Stress Markers in Healthy Aged Women

Increased plasma trimethylamine N-oxide (TMAO) levels have been associated with cardiovascular diseases (CVD). L-carnitine induces TMAO elevation in human blood, and thus, it has been suggested as developing atherosclerosis. The aim of this study was to determine the relation between selected markers of oxidative stress and plasma TMAO concentration induced by L-carnitine supplementation for 24 weeks in healthy aged women. Twenty aged women were supplemented during 24 weeks with either 1500 mg L-carnitine-L-tartrate (n = 11) or isonitrogenous placebo (n = 9) per day. Fasting blood samples were taken from antecubital vein. L-carnitine supplementation induced an increase in TMAO, but not in γ-butyrobetaine (GBB). Moreover, there were no significant changes in serum ox-LDL, myeloperoxidase, protein carbonyls, homocysteine, and uric acid concentrations due to supplementation. Significant reduction in white blood cell counts has been observed following 24-week supplementation, but not attributable to L-carnitine. Our results in healthy aged women indicated no relation between TMAO and any determined marker of oxidative stress over the period of 24 weeks. At the same time, plasma GBB levels were not affected by L-carnitine supplementation. Further clinical studies of plasma GBB level as a prognostic marker are needed.

Oolong Tea Extract and Citrus Peel Polymethoxyflavones Reduce Transformation of l-Carnitine to Trimethylamine-N-Oxide and Decrease Vascular Inflammation in l-Carnitine Feeding Mice

Carnitine, a dietary quaternary amine mainly from red meat, is metabolized to trimethylamine (TMA) by gut microbiota and subsequently oxidized to trimethylamine-N-oxide (TMAO) by host hepatic enzymes, flavin monooxygenases (FMOs). The objective of this study aims to investigate the effects of flavonoids from oolong tea and citrus peels on reducing TMAO formation and protecting vascular inflammation in carnitine-feeding mice. The results showed that mice treated with 1.3% carnitine in drinking water significantly (p < 0.05) increased the plasma levels of TMAO compared to control group, whereas the plasma TMAO was remarkedly reduced by flavonoids used. Meanwhile, these dietary phenolic compounds significantly (p < 0.05) decreased hepatic FMO3 mRNA levels compared to carnitine only group. Additionally, oolong tea extract decreased mRNA levels of vascular inflammatory markers such as tissue necrosis factor-alpha (TNF-α), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin. Polymethoxyflavones significantly lowered the expression of VCAM-1 and showed a decreasing trend in TNF-α and E-selectin mRNA expression compared to the carnitine group. Genus-level analysis of the gut microbiota in the cecum showed that these dietary phenolic compounds induced an increase in the relative abundances of Bacteroides. Oolong tea extract-treated group up-regulated Lactobacillus genus, compared to the carnitine only group. Administration of polymethoxyflavones increased Akkermansia in mice.

Protocatechuic Acid-Ameliorated Endothelial Oxidative Stress through Regulating Acetylation Level via CD36/AMPK Pathway

As one of the main metabolites of anthocyanin, protocatechuic acid (PCA) possesses strong antioxidant activity. In the present study, we explored the capacity of PCA on the alleviation of endothelial oxidative stress and investigated the underlying mechanisms using RNA sequencing (RNA-Seq). In comparison with palmitic acid (PA)-treated cells, PCA (100 μM) significantly decreased the generations of 3-nitrotyrosine (3-NT) and 8-hydroxydeoxyguanosine (8-OHdG) (0.82 ± 0.01 vs 1.16 ± 0.05 and 0.80 ± 0.01 vs 1.48 ± 0.15, respectively, p < 0.01), two biomarkers of oxidative damage, and restored the levels of nitric oxide (NO) (0.97 ± 0.04 vs 0.54 ± 0.02, p < 0.01) and mitochondrial membrane potential (MMP) (0.96 ± 0.03 vs 0.86 ± 0.02, p < 0.01) in human umbilical vein endothelial cells (HUVECs). PCA also obviously reduced the level of reactive oxygen species (ROS) (0.86 ± 0.15 vs 2.67 ± 0.09, p < 0.01) in aorta from high-fat diet (HFD)-fed mice. RNA-Seq and Western blot analysis indicated that PCA markedly reduced the expression of cluster of differentiation 36 (CD36), a membrane fatty acid transporter, and reduced the generations of adenosine triphosphate (ATP) and acetyl coenzyme A (Ac-CoA). These effects of PCA were associated with decreased level of acetylated-lysine and restored the activity of manganese-dependent superoxide dismutase (MnSOD) through reducing the generation of Ac-CoA or activating Sirt1 and Sirt3 via a CD36/AMP-kinase (AMPK) dependent pathway.

Dietary betaine reduces liver lipid accumulationviaimprovement of bile acid and trimethylamine-N-oxide metabolism in blunt-snout bream

Dietary betaine decreased liver lipid accumulation caused by dietary carbohydrate through changes of TMA formation and TMAO and bile acid metabolism.

Buckwheat and CVD Risk Markers: A Systematic Review and Meta-Analysis

The effects of buckwheat intake on cardiovascular diseases (CVDs) have not been systematically investigated. The aim of the present study was to comprehensively summarize studies in humans and animals, evaluating the impact of buckwheat consumption on CVD risk markers and to conduct a meta-analysis of relevant data. Thirteen randomized, controlled human studies, two cross-sectional human studies and twenty-one animal studies were identified. Using random-effects models, the weighted mean difference of post-intervention concentrations of blood glucose, total cholesterol and triglycerides were significantly decreased following buckwheat intervention compared with controls [differences in blood glucose: -0.85 mmol/L (95% CI: -1.31, -0.39), total cholesterol: 0.50 mmol/L (95% CI: -0.80, -0.20) and triglycerides: 0.25 mmol/L (95% CI: -0.49, -0.02)]. Responses of a similar magnitude were seen in two cross-sectional studies. For animal studies, nineteen of twenty-one studies showed a significant reduction in total cholesterol of between 12% and 54%, and fourteen of twenty studies showed a significant reduction in triglycerides of between 2% and 74%. All exhibited high unexplained heterogeneity. There was inconsistency in HDL cholesterol outcomes in both human and animal studies. It remains unclear whether increased buckwheat intake significantly benefits other markers of CVD risk, such as weight, blood pressure, insulin, and LDL-cholesterol, and underlying mechanisms responsible for any effects are unclear.

Balancing Herbal Medicine and Functional Food for Prevention and Treatment of Cardiometabolic Diseases through Modulating Gut Microbiota

It has become apparent that gut microbiota is closely associated with cardiometabolic diseases (CMDs), and alteration in microbiome compositions is also linked to the host environment. Next generation sequencing (NGS) has facilitated in-depth studies on the effects of herbal medicine and functional food on gut microbiota. Both herbal medicine and functional food contain fiber, polyphenols and polysaccharides, exerting prebiotics-like activities in the prevention and treatment of CMDs. The administrations of herbal medicine and functional food lead to increased the abundance of phylum Bacteroidetes, and genus Akkermansia, Bifidobacteria, Lactobacillus, Bacteroides and Prevotella, while reducing phylum Firmicutes and Firmicutes/Bacteroidetes ratio in gut. Both herbal medicine and functional food interact with gut microbiome and alter the microbial metabolites including short-chain fatty acids (SCFAs), bile acids (BAs) and lipopolysaccharides (LPS), which are now correlated with metabolic diseases such as type 2 diabetes (T2D), obesity and non-alcoholic fatty liver disease (NAFLD). In addition, trimethylamine (TMA)-N-oxide (TMAO) is recently linked to atherosclerosis (AS) and cardiovascular disease (CVD) risks. Moreover, gut-organs axes may serve as the potential strategy for treating CMDs with the intervention of herbal medicine and functional food. In summary, a balance between herbal medicine and functional food rich in fiber, polyphenols and polysaccharides plays a vital role in modulating gut microbiota (phylum Bacteroidetes, Firmicutes and Firmicutes/Bacteroidetes ratio, and genus Akkermansia, Bifidobacteria, Lactobacillus, Bacteroides and Prevotella) through SCFAs, BAs, LPS and TMAO signaling regarding CMDs. Targeting gut-organs axes may serve as a new therapeutic strategy for CMDs by herbal medicine and functional food in the future. This review aims to summarize the balance between herbal medicine and functional food utilized for the prevention and treatment of CMDs through modulating gut microbiota.

Global transcriptome analysis and identification of genes involved in nutrients accumulation during seed development of rice tartary buckwheat (Fagopyrum Tararicum)

Tartary buckwheat seeds are rich in various nutrients, such as storage proteins, starch, and flavonoids. To get a good knowledge of the transcriptome dynamics and gene regulatory mechanism during the process of seed development and nutrients accumulation, we performed a comprehensive global transcriptome analysis using rice tartary buckwheat seeds at different development stages, namely pre-filling stage, filling stage, and mature stage. 24 819 expressed genes, including 108 specifically expressed genes, and 11 676 differentially expressed genes (DEGs) were identified. qRT-PCR analysis was performed on 34 DEGs to validate the transcriptome data, and a good consistence was obtained. Based on their expression patterns, the identified DEGs were classified to eight clusters, and the enriched GO items in each cluster were analyzed. In addition, 633 DEGs related to plant hormones were identified. Furthermore, genes in the biosynthesis pathway of nutrients accumulation were analyzed, including 10, 20, and 23 DEGs corresponding to the biosynthesis of seed storage proteins, flavonoids, and starch, respectively. This is the first transcriptome analysis during seed development of tartary buckwheat. It would provide us a comprehensive understanding of the complex transcriptome dynamics during seed development and gene regulatory mechanism of nutrients accumulation.

Tartary buckwheat flavonoids ameliorate high fructose-induced insulin resistance and oxidative stress associated with the insulin signaling and Nrf2/HO-1 pathways in mice

The present study was conducted to explore the effects of a purified tartary buckwheat flavonoid fraction (TBF) on insulin resistance and hepatic oxidative stress in mice fed high fructose in drinking water (20%) for 8 weeks. The results indicated that continuous administration of TBF dose-dependently improved the insulin sensitivity and glucose intolerance in high fructose-fed mice. TBF treatment also reversed the reduced level of insulin action on the phosphorylation of insulin receptor substrate-1 (IRS-1), protein kinase B (Akt) and phosphatidylinositol 3-kinase (PI3K), as well as the translocation of glucose transporter type 4 (GLUT4) in the insulin-resistant liver. Furthermore, TBF was found to exert high antioxidant capacity as it acts as a shield against oxidative stress induced by high fructose by restoring the antioxidant status, and modulating nuclear factor E2 related factor 2 (Nrf2) translocation to the nucleus with subsequently up-regulated antioxidative enzyme protein expression. Histopathological examinations revealed that impaired pancreatic/hepatic tissues were effectively restored in high fructose-fed mice following TBF treatment. Our results show that TBF intake is effective in preventing the conversion of high fructose-induced insulin resistance and hepatic oxidative stress in mice by improving the insulin signaling molecules and the Nrf2 signal pathway in the liver.

Beneficial effects of apple peel polyphenols on vascular endothelial dysfunction and liver injury in high choline-fed mice

This study was designed to investigate the preventive effects of Red Fuji apple peel polyphenolic extract (APP) on vascular endothelial dysfunction and liver injury in mice fed a high choline diet. The mice were fed 3% dietary choline in drinking water for 8 weeks and displayed vascular dysfunction and liver damage (p < 0.01). The administration of APP at 600 and 900 mg per kg bw significantly elevated serum NO, HDL and 6-Keto-PGF1a levels and lowered serum TC, TG, LDL, ET-1 and TXB2 levels in the HC-fed mice. Besides, APP also caused the reduction of AST, ALT activities and MDA, CRP, TNF-α levels, and increased the hepatic GSH-Px and SOD activities of the HC-fed mice. Furthermore, the histopathology of the liver by conventional H&E and oil red O staining confirmed the liver steatosis induced by a choline diet and the hepatoprotective effect of APP. The experiment results indicated that the polyphenolic extract from apple peel might be regarded as a preventive and therapeutic product for the amelioration of HC diet-induced vascular dysfunction and hepatic injury.

Association of Endothelial Nitric Oxide Synthase Gene Polymorphism with Susceptibility and Nephritis Development of Henoch-Schönlein Purpura in Chinese Han Children

OBJECTIVE

Henoch-Schönlein purpura (HSP) is the most common form of systemic small-vessel vasculitis in children. Previous studies suggested endothelial nitric oxide synthase (eNOS) plays an important role in the pathogenesis and clinical manifestations of HSP. This study aimed to investigate the potential association between 10 single-nucleotide polymorphisms (SNPs) within the eNOS gene and HSP risk and nephritis development in a Chinese Han population.

MATERIALS AND METHODS

A case-control study was conducted including 459 healthy children and 423 children with HSP. SNPs were genotyped by using the MassARRAY system.

RESULTS

The genotypic frequency of rs11771443 was nominally associated with the risk of HSP (p = 0.010), and the C allele significantly increased the risk of HSP (p = 0.003, odds ratio [OR] = 1.331, confidence interval [95% CI] = 1.104-1.605). There was a significant difference in allelic and genotypic distribution of rs1799983 between children with HSP and healthy controls (p = 0.002 and 0.0001, respectively). Strong linkage disequilibrium was observed in two blocks. Significantly fewer T-A-G haplotypes (p = 0.0001, OR = 0.593, 95% CI = 0.448-0.786) were found in children with HSP. No significant association was identified between the 10 SNPs and the pathogenesis of HSP progression to HSP nephritis (HSPN).

CONCLUSIONS

The polymorphisms of eNOS contribute to genetic susceptibility to HSP, but may have no effect on children with HSP progressing to HSPN.

Elevated Circulating Trimethylamine N-Oxide Levels Contribute to Endothelial Dysfunction in Aged Rats through Vascular Inflammation and Oxidative Stress

Vascular endothelial dysfunction, a characteristic of the aging process, is an important risk factor for cardiovascular disease in aging. Although, vascular inflammation and oxidative stress are major contributors to endothelial dysfunction in aging, the underlying mechanisms during the aging process are not fully understood. Accumulating evidence reveals that gut microbiota-dependent metabolite trimethylamine-N-oxide (TMAO) is implicated in the pathogenesis of many cardiovascular diseases. We tested the hypothesis that aging increases circulating TMAO levels, which induce vascular inflammation and oxidative stress, resulting in age-associated endothelial dysfunction. Old (22-mo-old) and young (4-mo-old) Fischer-344 rats were treated without (control) or with 1.0% 3,3-Dimethyl-1-butanol (DMB, an inhibitor of trimethylamine formation) in drinking water for 8 weeks. Compared with young control group, old control group had markedly higher plasma TMAO levels, which were reduced by DMB treatment. Endothelium-dependent relaxation of aorta in response to acetylcholine was impaired in old control group compared with young control group as indicated by decreased maximal relaxation (E_max) and reduced area under the curve (AUC). E_max and AUC were both normalized in old rats treated with DMB. No difference in endothelial-independent relaxation in response to sodium nitroprusside was observed among groups. Molecular studies revealed that old control group exhibits increased expression of proinflammatory cytokines and superoxide production, and decreased expression of endothelial nitric-oxide synthase (eNOS) in the aorta, all of which were restored by DMB treatment. These results suggest that aging increases circulating TMAO levels, which may impair eNOS-derived NO bioavailability by increasing vascular inflammation and oxidative stress, contributing to aging-associated endothelial dysfunction.

Antihypertensive effects of Tartary buckwheat flavonoids by improvement of vascular insulin sensitivity in spontaneously hypertensive rats

Tartary buckwheat flavonoids alleviate hypertension through attenuating vascular insulin resistance and oxidative stress.

Tartary buckwheat flavonoids protect hepatic cells against high glucose-induced oxidative stress and insulin resistance via MAPK signaling pathways

Oxidative stress plays a crucial role in chronic complication of diabetes. In this study, the protective effect of purified tartary buckwheat flavonoids (TBF) fraction against oxidative stress induced by a high-glucose challenge, which causes insulin resistance, was investigated on hepatic HepG2 cells. Oxidative status, phosphorylated mitogen-activated protein kinases (MAPKs), nuclear factor E2 related factor 2 (Nrf2) and p-(Ser307)-IRS-1 expression, and glucose uptake were evaluated. Results suggest that treatment of HepG2 cells with TBF alone improved glucose uptake and antioxidant enzymes, and activated Nrf2, and attenuated the IRS-1 Ser307 phosphorylation, and enhanced total levels of IRS-1. Furthermore, the high glucose-induced changes in antioxidant defences, Nrf2, p-MAPKs, p-IRS1 Ser307, and IRS-1 levels, and glucose uptake were also significantly inhibited by pre-treatment with TBF. Interestingly, the selective MAPK inhibitors significantly enhanced the TBF-mediated protection by inducing changes in the redox status, glucose uptake, p-(Ser307) and total IRS-1 levels. This report firstly showed that TBF could recover the redox status of insulin-resistant HepG2 cells, suggesting that TBF significantly protected the cells against high glucose-induced oxidative stress, and these beneficial effects of TBF on redox balance and insulin resistance were mediated by targeting MAPKs.