Palmatine regulates bile acid cycle metabolism and maintains intestinal flora balance to maintain stable intestinal barrier

Theabrownin remodels the circadian rhythm disorder of intestinal microbiota induced by a high-fat diet to alleviate obesity in mice

The intestinal microbiota undergoes diurnal compositional and functional oscillations within a day, which affect the metabolic homeostasis of the host and exacerbate the occurrence of obesity. TB has the effect of reducing body weight and lipid accumulation, but the mechanism of improving obesity caused by a high-fat diet based on the circadian rhythm of intestinal microorganisms has not been clarified. In this study, we used multi-omics and imaging approaches to investigate the mechanism of TB in alleviating obesity in mice based on the circadian rhythm of gut microbiota. The results showed that TB could significantly regulate the levels and rhythmic expression of serum lipid indicators (TG, TC, LDL) and serum hormones (MT, FT3, LEP, CORT). The number of intestinal microbiota colonizing the colonic epithelium underwent daily fluctuations. TB remodeled the rhythmic oscillation of gut microbes (i.e., Lachnospiraceae_NK4A136_group, Alistipes, etc.), including the number, composition, abundance and rhythmic expression of the biogeographic localization of microbes. TB notably reduced the levels of 16 bile acids (TCA, THDCA, TCDA, GHDCA, T-α-MCA, etc.) and restored the balance of bile acid metabolism. It was found that TB may mitigate high-fat diet-induced obesity in mice by reshaping the circadian rhythm of the gut microbiome and regulating bile acid metabolism.

The Chemical Constituents and Anti-Hyperlipidemia Effect of Salt-Processed Fenugreek Seed

The seed of fenugreek (FS) was traditionally used in diets and as a spice in India, as well as medicine in China. It had anti-diabetic and anti-hypolipidemic effects. According to the theory of traditional Chinese medicine, the effects of FS were enhanced after salt processing. But the enhanced effect of salt-processed fenugreek seed (SFS) on anti-hyperlipidemia was not yet fully understood. By UPLC-QTOF-MS analysis, five flavonoids and six saponins were tentatively identified in SFS. Salt processing increased the dissolution of polysaccharides and trigonelline. FS and SFS significantly improved the serum biochemical indexes, including total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-C) of hyperlipidemic rats, promoted the excretion of TC and total bile acid (TBA), and downregulated aspartate aminotransferase (AST). According to the results of factor analysis, FS and SFS restored the severity of hyperlipidemia to a similar extent, and SFS enhanced the excretion of cholesterol more significantly. FS and SFS reduced the ratio of Firmicutes/Bacteroidetes (F/B), which was upregulated in HFD group. Additionally, SFS significantly increased the abundance of Ruminococcus_1, which was negatively correlated with blood lipid levels. Thus, to regulate gut microbiota and promote the excretion of cholesterol were the mechanisms of the effects of SFS on hyperlipidemia. The higher amounts of total polysaccharides and trigonelline in SFS than in FS led to their different effects.

A Hepatic Oxidative Metabolite of Palmatine Ameliorates DSS-Induced Ulcerative Colitis by Regulating Macrophage Polarization Through AMPK/NF-κB Pathway

Palmatine (PAL) and berberine are both classified as protoberberine alkaloids, derived from several traditional Chinese herbs such as Coptis chinensis Franch. and Phellodendron chinense Schneid. These compounds are extensively used in treating dysentery and colitis. PAL is one of the crucial quality markers for these plants in the Chinese Pharmacopoeia. A key metabolite of PAL, 8-Oxypalmatine (OPAL), shows favorable anti-inflammatory activity and better safety compared to PAL, though its mechanisms in ulcerative colitis (UC) are not fully understood. This study used a dextran sodium sulfate-induced colitis mouse model to explore OPAL's effects. The results indicated that OPAL provided superior therapeutic effects to those of PAL, alleviating colitis symptoms and reducing colon inflammation by modulating pro-inflammatory (tumor necrosis factor-α, interleukin-1β, and interleukin-6) and anti-inflammatory (transforming growth factor-β and interleukin-10) cytokines. Additionally, OPAL helped rebuild the mucus barrier and upregulated tight junction proteins, thereby restoring intestinal integrity. Notably, OPAL inhibited the M1 macrophages infiltration while promoting M2 macrophage distribution in the colon. Its role in fostering M2 polarization and modulating the inflammatory cytokine profile was further confirmed in vitro. Importantly, the anti-inflammatory effects were primarily linked to AMP-activated protein kinase activation, which subsequently inhibited the nuclear factor-kappa B pathway. These findings highlight OPAL as a crucial active metabolite responsible for the therapeutic effects of PAL against UC, emphasizing its potential as a novel treatment for this condition.

Hypolipidemic activity of phytochemical combinations: A mechanistic review of preclinical and clinical studies

Hyperlipidemia, a condition characterized by elevated levels of lipids in the blood, poses a significant risk factor for various health disorders, notably cardiovascular diseases. Phytochemical compounds are promising alternatives to the current lipid-lowering drugs, which cause many undesirable effects. Based on in vivo and clinical studies, combining phytochemicals with other phytochemicals, prebiotics, and probiotics and their encapsulation in nanoparticles is more safe and effective for managing hyperlipidemia than monotherapy. To this end, the results obtained and the mechanisms of action of these combinations were examined in detail in this review.

Investigation of the therapeutic effect of Hedan tablets on high-fat diet-induced obesity in rats by GC-MS technology and 16S ribosomal RNA gene sequencing

Obesity is a persistent metabolic condition resulting from the excessive accumulation or abnormal distribution of body fat. This study aimed to establish an experimental rat model of obesity. The efficacy of treating obesity with Hedan tablets (HDT) was assessed by monitoring changes in weight, blood lipid levels, analyzing inflammatory factors, evaluating organ indices, and observing liver tissue pathology. Furthermore, we utilized 16S ribosomal RNA gene sequencing technology to explore changes in intestinal flora. In addition, GC-MS was used to measure fecal short-chain fatty acid (SCFA) content. The onset of obesity led to a significant decrease in the relative abundance of beneficial bacteria. Conversely, the administration of HDT demonstrated a substantial ability to increase the relative abundance of beneficial bacteria. Obesity resulted in a noteworthy reduction in total SCFAs, a trend significantly reversed in the HDT group. Through correlation analysis, it was determined that HDT mitigated the inflammatory response and improved blood lipid levels by augmenting the abundance of Lactobacillus, Limosilactobacillus, Ruminococcus, and Enterococcus. These particular intestinal flora were identified as regulators of SCFA metabolism, thereby ameliorating metabolic abnormalities associated with obesity. Moreover, HDT intervention elevated the overall fecal concentration of SCFAs, thereby improving metabolic disorders induced by obesity. The anti-obesity effects of HDT are likely attributable to their capacity to influence the composition of intestinal flora and boost SCFA levels in the intestine.

Natural Products in the Modulation of Farnesoid X Receptor Against Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a global health concern with a high prevalence and increasing economic burden, but official medicine remains unavailable. Farnesoid X receptor (FXR), a nuclear receptor member, is one of the most promising drug targets for NAFLD therapy that plays a crucial role in modulating bile acid, glucose, and lipid homeostasis, as well as inhibits hepatic inflammation and fibrosis. However, the rejection of the FXR agonist, obecholic acid, by the Food and Drug Administration for treating hepatic fibrosis raises a question about the functions of FXR in NAFLD progression and the therapeutic strategy to be used. Natural products, such as FXR modulators, have become the focus of attention for NAFLD therapy with fewer adverse reactions. The anti-NAFLD mechanisms seem to act as FXR agonists and antagonists or are involved in the FXR signaling pathway activation, indicating a promising target of FXR therapeutic prospects using natural products. This review discusses the effective mechanisms of FXR in NAFLD alleviation, and summarizes currently available natural products such as silymarin, glycyrrhizin, cycloastragenol, berberine, and gypenosides, for targeting FXR, which can facilitate development of naturally targeted drug by medicinal specialists for effective treatment of NAFLD.

Inhibition of PCSK9 prevents and alleviates cholesterol gallstones through PPARα-mediated CYP7A1 activation

BACKGROUND & AIMS

Dysregulated cholesterol metabolism is the major factor responsible for cholesterol gallstones (CGS). Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role in cholesterol homeostasis and its inhibitors secure approval for treating various cholesterol metabolic disorders such as hypercholesterolemia and cardiovascular diseases, but its role in CGS remains unclear. Our study aims to clarify mechanisms by which PCSK9 promotes CGS formation and explore the application of the PCSK9 inhibitor, alirocumab, in preventing and treating CGS.

APPROACH & RESULTS

The expressions of PCSK9 were notably increased in CGS patients' serum, bile, and liver tissues compared to those without gallstones. Moreover, among CGS patients, hepatic PCSK9 was positively correlated with hepatic cholesterol and negatively correlated with hepatic bile acids (BAs), suggesting PCSK9 was involved in disrupted hepatic cholesterol metabolism related to CGS. Mechanistically, in vitro experiments demonstrated that inhibition of PCSK9 enhanced nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Finally, inhibition of PCSK9 prevented CGS formation and dissolved the existing stones in CGS mice by elevating the conversion of cholesterol into BAs through PPARα-mediated CYP7A1 activation. Additionally, serum PCSK9 level may function as a prognostic signature to evaluate the therapeutic efficacy of PCSK9 inhibitors.

CONCLUSIONS

Inhibition of PCSK9 exerts preventive and therapeutic effects on CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs, which highlights the potential of PCSK9 inhibition as a promising candidate for preventing and treating CGS in clinical applications.

IMPACT AND IMPLICATIONS

PCSK9 plays a pivotal role in cholesterol metabolism and its inhibitors are approved for clinical use in cardiovascular diseases. Our study observes inhibition of PCSK9 prevents and dissolves CGS by activating PPARα-mediated CYP7A1 expression and facilitating the conversion of cholesterol into BAs. Mechanistically, PCSK9 inhibition enhanced the nuclear expression of PPARα by diminishing its lysosomal degradation and subsequently activated CYP7A1 transcription. Our study sheds light on the new function and mechanism of PCSK9 in CGS, providing a novel preventive and therapeutic target with potential clinical applications.

Modulating intestinal barrier function by sphingosine-1-phosphate receptor 1 specific agonist SEW2871 attenuated ANIT-induced cholestatic hepatitis via the gut-liver axis

Bile acid (BA) homeostasis throughout the enterohepatic circulation system is a guarantee of liver physiological functions. BA circulation disorders is one of the characteristic clinical manifestations of cholestasis, and have a closely relationship with intestinal barrier function, especially ileum. Here, our in vivo and in vitro studies showed that intestinal tight junctions (TJs) were disrupted by α-naphthylisothiocyanate (ANIT), which also down-regulated the protein expression of sphingosine-1-phosphate receptor 1 (S1PR1) in the top of villus of mice ileum. Activating S1PR1 by specific agonist SEW2871 could improve TJs via inhibiting ERK1/2/LKB1/AMPK signaling pathway in the ileum of ANIT-treated mice and ANIT-cultured Caco-2 cells. SEW2871 not only regained ileum TJs by activating S1PR1 in the epithelial cells of ileum mucosa, but also recovered ileum barrier function, which was further verified by the recovered BA homeostasis in mice ileum (content and tissue) by using of high-performance liquid chromatographytandem mass spectrometry (LC-MS/MS). Subsequently, the improved intestinal injury and inflammation further strengthened that SEW2871 modulated intestinal barrier function in ANIT-treated mice. Finally, our data revealed that along with the down-regulated levels of serum lipopolysaccharides (LPS), SEW2871 improved liver function and relieved hepatitis via blocking TLR4/MyD88/NF-kB signaling pathway in ANIT-treated mice. In conclusion, these results demonstrated that activating intestinal S1PR1 by SEW2871 could modulate intestinal barrier function, leading to the improvement of cholestatic hepatitis in ANIT-treated mice via the "gut-liver" axis.

Intestines-erythrocytes-mediated bio-disposition deciphers the hypolipidemic effect of berberine from Rhizoma Coptidis: A neglected insight

ETHNOPHARMACOLOGICAL RELEVANCE

Rhizoma Coptidis (RC), the dried rhizome of Coptis Chinensis Franch., can dispel dampness and heat within the body and has been traditionally used for the treatment of cardiovascular disease (CVD)-associated problems including hyperlipidemia in China. Berberine (BBR) is the main active component of RC, which has been shown to possess significant therapeutic potential. However, only 0.14% of BBR is metabolized in the liver, and the extremely low bioavailability (<1%) and blood concentration of BBR in experimental and clinical settings is insufficient to achieve the effects as observed under in vitro conditions, which imposes challenges to explain its excellent pharmacological actions. Intense efforts are currently being devoted to defining its specific pharmacological molecular targets, while the exploration from the perspective of its pharmacokinetic disposition has rarely been reported to date, which could hardly make a comprehensive understanding of its hypolipidemic enigma.

AIM OF THE STUDY

This study made a pioneering endeavor to unveil the hypolipidemic mechanism of BBR from RC focusing on its unique intestines-erythrocytes-mediated bio-disposition.

MATERIALS AND METHODS

The fate of BBR in intestines and erythrocytes was probed by a rapid and sensitive LC/MS-IT-TOF method. To analyze the disposition of BBR, a reliable HPLC method was subsequently developed and validated for simultaneous determination of BBR and its key active metabolite oxyberberine (OBB) in whole blood, tissues, and excreta. Meanwhile, the enterohepatic circulation (BDC) of BBR and OBB was verified by bile duct catheterization rats. Finally, lipid overloading models of L02 and HepG2 cells were employed to probe the lipid-lowering activity of BBR and OBB at in vivo concentration.

RESULTS

The results showed that BBR underwent biotransformation in both intestines and erythrocytes, and converted into the major metabolite oxyberberine (OBB). The AUC_0-t ratio of total BBR to OBB was approximately 2:1 after oral administration. Besides, the AUC_0-t ratio of bound BBR to its unbound counterpart was 4.6:1, and this ratio of OBB was 2.5:1, indicative of abundant binding-type form in the blood. Liver dominated over other organs in tissue distribution. BBR was excreted in bile, while the excretion of OBB in feces was significantly higher than that in bile. Furthermore, the bimodal phenomenon of both BBR and OBB disappeared in BDC rats and the AUC_0-t was significantly lower than that in the sham-operated control rats. Interestingly, OBB significantly decreased triglycerides and cholesterol levels in lipid overloading models of L02 and HepG2 cells at in vivo-like concentration, which was superior to the prodrug BBR.

CONCLUSIONS

Cumulatively, BBR underwent unique extrahepatic metabolism and disposition into OBB by virtue of intestines and erythrocytes. BBR and OBB were mainly presented and transported in the protein-bound form within the circulating erythrocytes, potentially resulting in hepatocyte targeting accompanied by obvious enterohepatic circulation. The unique extrahepatic disposition of BBR via intestines and erythrocytes conceivably contributed enormously to its hypolipidemic effect. OBB was the important material basis for the hypolipidemic effect of BBR and RC.

Lipid-lowering activity of metformin-soluble soybean polysaccharide nanoparticles

Soybean dregs are one of the most important albeit underutilized byproducts in soybean processing. In this study, soluble soybean polysaccharides with lipid-lowering activity were extracted from soybean dregs and used as a wall material for embedding metformin. Metformin-soluble soybean polysaccharide nanoparticles (MET-SSPS-NPs) were prepared by electrostatic interaction. The lipid-lowering activity and possible mechanism of MET-SSPS-NPs were investigated. Western blotting was used to detect the expression levels of cell-related protein proprotein convertase subtilisin/kexin type 9 (PCSK9) and low-density lipoprotein receptor (LDLR) in vitro. The results showed that MET-SSPS-NPs lowered the expression of PCSK9 and improved LDLR levels. A high-fat diet (HFD) animal model was established to study the lipid-lowering effect of MET-SSPS-NPs by real-time quantitative PCR and western blotting. MET-SSPS-NPs significantly upregulated peroxisome proliferator-activated receptor gamma (PPARγ) expression and downregulated PCSK9, fatty acid-binding protein (FABP)7 and FABP5 expression more strongly than MET or SSPS alone. In conclusion, MET-SSPS-NPs can inhibit PCSK9 expression and improve the level of adipokines, providing a theoretical basis for the application of MET-SSPS-NPs in lipid lowering.

Apple polyphenol extract modulates bile acid metabolism and gut microbiota by regulating the circadian rhythms in daytime-restricted high fat diet feeding C57BL/6 male mice

The homeostasis of circadian clock linked to bile acid (BA) metabolism and gut microbiota has profound benefits in maintaining the health status of the host. The aim of this study was to investigate the prevention and regulation of apple polyphenol extract (APE) on BA metabolism and gut microbiota by means of modulation of circadian rhythms in mice. Eighty male C57BL/6 mice were randomized into four groups: 24-hour ad libitum standard chow group (AC), ad libitum HFD group (AF), restricted 12 h daytime HFD feeding group (DF), and daytime HFD feeding with APE treatment group (DP). Five weeks later, the mice were sacrificed at 6 h intervals over a 24 h period. The results showed that APE decreased body weight and induced daily rhythms of Cry1 and Rorα in the suprachiasmatic nucleus (SCN) and Clock, Cry1 and Cry2 in the ileum in daytime HFD mice. APE significantly increased the expression of hepatic FXR at ZT0 and BSEP at ZT12 and inhibited the expression of ileac FXR at ZT12, reduced levels of fecal TBAs, secondary BAs, and unconjugated BAs at ZT0. Meanwhile, APE regulated the diversity and composition of the gut microbiota, and increased the abundance of probiotics. Therefore, our work revealed that APE as a clock-regulating natural compound could modulate BA metabolism and gut microbiota and protect against circadian disruption in a clock-dependent manner.

Natural Products Targeting Liver X Receptors or Farnesoid X Receptor

Nuclear receptors (NRs) are a superfamily of transcription factors induced by ligands and also function as integrators of hormonal and nutritional signals. Among NRs, the liver X receptors (LXRs) and farnesoid X receptor (FXR) have been of significance as targets for the treatment of metabolic syndrome-related diseases. In recent years, natural products targeting LXRs and FXR have received remarkable interests as a valuable source of novel ligands encompassing diverse chemical structures and bioactive properties. This review aims to survey natural products, originating from terrestrial plants and microorganisms, marine organisms, and marine-derived microorganisms, which could influence LXRs and FXR. In the recent two decades (2000-2020), 261 natural products were discovered from natural resources such as LXRs/FXR modulators, 109 agonists and 38 antagonists targeting LXRs, and 72 agonists and 55 antagonists targeting FXR. The docking evaluation of desired natural products targeted LXRs/FXR is finally discussed. This comprehensive overview will provide a reference for future study of novel LXRs and FXR agonists and antagonists to target human diseases, and attract an increasing number of professional scholars majoring in pharmacy and biology with more in-depth discussion.

Diammonium Glycyrrhizinate Ameliorates Obesity Through Modulation of Gut Microbiota-Conjugated BAs-FXR Signaling

Obesity is a worldwide epidemic metabolic disease. Gut microbiota dysbiosis and bile acids (BAs) metabolism disorder are closely related to obesity. Farnesoid X-activated receptor (FXR), served as a link between gut microbiota and BAs, is involved in maintaining metabolic homeostasis and regulating glucose and lipid metabolism. We previously reported that diammonium glycyrrhizinate (DG) could alter gut microbiota and prevent non-alcoholic fatty liver disease. However, it remains ambiguous how DG affects the gut microbiota to regulate host metabolism. In this present study, 16S rRNA Illumina NovaSeq and metabolomic analysis revealed that DG treatment suppressed microbes associated with bile-salt hydrolase (BSH) activity, which, in turn, increased the levels of taurine-conjugated BAs accompanied by inhibition of ileal FXR-FGF15 signaling. As a result, several obesity-related metabolism were improved, like lower serum glucose and insulin levels, increased insulin sensitivity, few hepatic steatosis and resistance to weight gain. Additionally, decreased level of serum lipopolysaccharide was observed, which contributed to a strengthened intestinal barrier. The effect of DG on weight loss was slightly enhanced in the antibiotics-treated obese mice. Collectively, the efficacy of DG in the treatment of obesity might depend on gut microbiota-conjugated BAs-FXR axis. Hence, it will provide a potential novel approach for the treatment of obesity.

Toxic effects of copper on the jejunum and colon of pigs: mechanisms related to gut barrier dysfunction and inflammation influenced by the gut microbiota

Copper (Cu) is an essential trace mineral, but its excessive intake can lead to potentially toxic effects on host physiology. The mammalian intestine harbors various microorganisms that are associated with intestinal barrier function and inflammation. In this study, the influences of Cu on barrier function, microbiota, and its metabolites were examined in the jejunum and colon of pigs. Here, we identified that the physical and chemical barrier functions were impaired both in the jejunum and colon, as evidenced by the decreased expression of tight junction proteins (ZO-1, Occludin, Claudin-1, and JAM-1) and mucous secretion-related genes, positive rate of Muc2, and secretion of SIgA and SIgG. Additionally, inflammatory cytokines were overexpressed in the jejunum and colon. Furthermore, Cu might increase the abundances of Mycoplasma, Actinobacillus and unidentified_Enterobacteriaceae in the jejunum, which significantly affected pentose and glucoronate interconversions, histidine metabolism, folate biosynthesis, porphyrin metabolism, and purine metabolism. Meanwhile, the abundances of Lactobacillus and Methanobrevibacter were remarkably decreased and Streptococcus, unidentified_Enterobacteriaceae, and unidentified_Muribaculaceae were significantly increased in the colon, with an evident impact on glycerophospholipid metabolism, retinol metabolism, and steroid hormone biosynthesis. These findings revealed that excess Cu had significant effects on the microbiota and metabolites in the jejunum and colon, which were involved in intestinal barrier dysfunction and inflammation.

Flavonoids from Whole-Grain Oat Alleviated High-Fat Diet-Induced Hyperlipidemia via Regulating Bile Acid Metabolism and Gut Microbiota in Mice

A high-fat diet (HFD) causes hyperlipidemia, which worsens disturbances in bile acid (BA) metabolism and gut microbiota. This study aimed to investigate the regulation of flavonoids from whole-grain oat (FO) on BA metabolism and gut microbiota in HFD-induced hyperlipidemic mice. The experiment results showed that FO improved serum lipid profiles and decreased body weight and lipid deposition in HFD-fed mice. Through real-time qualitative polymerase chain reaction (RT-qPCR) and Western blot assays, by up-regulating the expression of PPARα, CPT-1, CYP7A1, FXR, TGR5, NTCP, and BSTP, and down-regulating those of SREBP-1c, FAS, and ASBT, FO suppressed lipogenesis, promoted lipolysis and BA synthesis, and efflux to faeces via the FXR pathway. 16s rRNA sequencing revealed that FO significantly increased Akkermansia and significantly decreased Lachnoclostridium, Blautia, Colidextribacter, and Desulfovibrio. Spearman's correlation analysis showed that these bacteria were strongly correlated with hyperlipidemia-related parameters. Therefore, our results indicated that FO possessed an antihyperlipidemic effect via regulating the gut-liver axis, i.e., BA metabolism and gut microbiota.