Hyodeoxycholic Acid Research Articles

Epimeric Mixtures of Brassinosteroid Analogs: Synthesis, Plant Growth, and Germination Effects in Tomato (Lycopersicum esculentum Mill.)

Brassinosteroids (BRs) play an important role in the growth and development of plants. Herein, we describe the synthesis of epimeric mixtures of BR analogs with 24-norcholane type side chains, S/R configuration at C22 and A/B ring cis-type fusion. All epimeric mixtures were synthetized from hyodeoxycholic acid. The biological activity of mixtures was evaluated by using rice lamina inclination test and germination of tomato (Lycopersicum esculentum) seeds. The results show that these epimeric mixtures exhibit similar bioactivity to brassinolide in both bioassays. Thus, our results corroborate that the A/B junction has almost no effect on bioactivity and open the possibility of using epimeric mixtures instead of pure compounds. In this approach, the synthesized BR analogs maintain a good level of bioactivity, whereas the synthesis is shorter, cheaper and with higher yields. All these factors make this alternative very interesting for potential application.

Effect of a Flaxseed Lignan Intervention on Circulating Bile Acids in a Randomized, Crossover Trial

Abstract Objectives Health benefits of high-fiber foods may be attributed, in part, to microbial metabolites of plant compounds. Lignans and their microbial metabolites, the enterolignans [enterolactone (ENL) and enterodiol (END)], reduce serum lipids through a variety of mechanisms, including regulation of bile acid (BA) synthesis. BA, released into the gut lumen in response to dietary fat, undergo microbial metabolism to secondary (2°) BA, which have been positively associated with chronic disease, e.g., liver disease and colorectal cancer. Our aims were to evaluate the effects of a flaxseed lignan supplement on circulating BA and examine associations between enterolignans and 2° BA. Methods We conducted a randomized, crossover trial of a flaxseed lignan supplement (50 mg/d secoisolariciresinol diglucoside) compared to placebo in 46 healthy men and women (20-45 y). Each period lasted 60 days, separated by a 60-day washout period. Six primary and fourteen 2° BA species were measured in fasting plasma using LC-MS. ENL and END were measured in 24-h urines by GC-MS. Low- and high-ENL excreters were defined as below and above the median 24-h ENL excretion at the end of the flaxseed lignan intervention (23.4 µmol/24 h). Linear mixed models were used to a) test the effects of the intervention on individual BA concentrations, overall and stratified by low and high ENL excreters; and b) to cross-sectionally determine the association between plasma 2o BA and ENL and END. Results There was no significant effect of the flaxseed lignan intervention compared to placebo on BA concentrations overall, or by ENL-excreter status, after FDR adjustment. In the cross-sectional analysis, irrespective of treatment, six 2° BA were statistically significantly associated with ENL (FDR < 0.05), with two positive associations (isolithocholic and lithocholic acids), and four inverse associations (glycoursodeoxycholic, glycohyodeoxycholic, hyodeoxycholic, and muricholic acids). Conclusions The flaxseed lignan intervention and subsequent ENL production had no effect on plasma BA concentrations. However, the strong associations between ENL excretion and certain 2° BA concentrations suggests that the gut microbial communities capable of producing ENL may also play a role in 2° BA metabolism. Funding Sources NIH.

Potential contribution of faeces to resuspended PM1−10 in urban environment

Abstract The respirable fraction of resuspended urban road dust contains phosphorous at enhanced concentrations which may imply the potential presence of animal faeces. Specific biomarkers such as faecal sterols and bile acids are commonly used to verify the presence of faecal pollution in various environmental samples. The quantification of faecal materials in matrices is usually based on the analysis of bile acids which are persistent and refractory, and can be found in the digestive systems of all mammals and birds. In this study, by measuring the concentrations of bile acids in resuspended PM1−10 samples collected from paved roads on urban locations for the first time in aerosol science we have attempted to estimate the potential mass contribution of animals' faeces to the respirable fraction of road dust. A special sampling unit was applied for the collection of resuspended and respirable road dust in Veszprem and Budapest, Hungary. The concentrations of bile acids were determined by gas chromatography−mass spectrometry (GC−MS). Elemental phosphorous was found in the resuspended PM1−10 fraction in concentrations of 2 mg g−1 whereas the total concentrations of bile acids such as LCA (lithocholic acid), DCA (deoxycholic acid), CDCA (chenodeoxycholic acids), and HDCA (hyodeoxycholic acid) were in the order of 10 μg g−1. Based on the measured mass concentrations of bile acids, the estimated mass contribution of faeces to resuspended PM1−10 mass was found to be in the range of 0.02–0.54 m/m%. Our results imply that wind- or traffic-driven resuspension of dried animals’ faeces, which has never been considered as a potential source of urban PM1−10, is a detectable contributor to urban PM1−10 with all its potential health and epidemiological implications.

Long-Term β-galacto-oligosaccharides Supplementation Decreases the Development of Obesity and Insulin Resistance in Mice Fed a Western-Type Diet.

ScopeThe gut microbiota might critically modify metabolic disease development. Dietary fibers such as galacto‐oligosaccharides (GOS) presumably stimulate bacteria beneficial for metabolic health. This study assesses the impact of GOS on obesity, glucose, and lipid metabolism.Methods and resultsFollowing Western‐type diet feeding (C57BL/6 mice) with or without β‐GOS (7% w/w, 15 weeks), body composition, glucose and insulin tolerance, lipid profiles, fat kinetics and microbiota composition are analyzed. GOS reduces body weight gain (p < 0.01), accumulation of epididymal (p < 0.05), perirenal (p < 0.01) fat, and insulin resistance (p < 0.01). GOS‐fed mice have lower plasma cholesterol (p < 0.05), mainly within low‐density lipoproteins, lower intestinal fat absorption (p < 0.01), more fecal neutral sterol excretion (p < 0.05) and higher intestinal GLP‐1 expression (p < 0.01). Fecal bile acid excretion is lower (p < 0.01) in GOS‐fed mice with significant compositional differences, namely decreased cholic, α‐muricholic, and deoxycholic acid excretion, whereas hyodeoxycholic acid increased. Substantial changes in microbiota composition, conceivably beneficial for metabolic health, occurred upon GOS feeding.ConclusionGOS supplementation to a Western‐type diet improves body weight gain, dyslipidemia, and insulin sensitivity, supporting a therapeutic potential of GOS for individuals at risk of developing metabolic syndrome.

An Integrative Pharmacology-Based Analysis of Refined Qingkailing Injection Against Cerebral Ischemic Stroke: A Novel Combination of Baicalin, Geniposide, Cholic Acid, and Hyodeoxycholic Acid.

Stroke is the second leading cause of death after heart disease globally and cerebral ischemic stroke accounts for approximately 70% of all incident stroke cases. We selected four main compounds from a patent Chinese medicine, Qingkailing (QKL) injection, including baicalin from Scutellaria baicalensis Georgi (Huang Qin), geniposide from Gardenia jasminoides J. Ellis (Zhizi), and cholic acid and hyodeoxycholic acid from Bovis Calculus (Niuhuang) with a ratio of 4.4:0.4:3:2.6 m/m, to develop a more efficacious and safer modern Chinese medicine injection against ischemic stroke, refined QKL (RQKL). In this study, we investigated multiple targets, levels, and pathways of RQKL by using an integrative pharm\\acology combining experimental validation approach. In silica study showed that RQKL may regulate PI3K-Akt, estrogen, neurotrophin, HIF-1, MAPK, Hippo, FoxO, TGF-beta, NOD-like receptor, apoptosis, NF-kappa B, Wnt, chemokine, TNF, Toll-like receptor signaling pathways against ischemic stroke. The experimental results showed that RQKL improved neurological function and prevented infract volume and blood-brain-barrier damage. RQKL inhibited microgliosis and astrogliosis, and protected neurons from ischemic/reperfusion injury. RQKL also inhibited cell apoptosis and affecting the ratio of the anti-apoptosis protein B-cell lymphoma-2 (Bcl2) and pro-apoptosis protein Bcl2-associated X protein (Bax). Western blot analysis showed that RQKL activated AKT/PI3K signaling pathway and antibody array showed RQKL inhibited inflammatory response and decreased proinflammatory factor Tnf, Il6, and Il1b, and chemokines Ccl2, Cxcl2, and Cxcl3, and increased anti-inflammatory cytokine Il10. In conclusion, RQKL protected tissue against ischemic stroke through multiple-target, multiple signals, and modulating multiple cell-types in brain. This study not only promoted our understanding of the role of RQKL against ischemic stroke, but also provided a pattern for the study of Chinese medicine combining pharmaceutical Informatics and system biology methods.

Diabetes downregulates peptide transporter 1 in the rat jejunum: possible involvement of cholate-induced FXR activation.

Peptide transporter 1 (PepT1), highly expressed on the apical membrane of enterocytes, is involved in energy balance and mediates intestinal absorption of peptidomimetic drugs. In this study, we investigated whether and how diabetes affected the function and expression of intestinal PepT1. Diabetes was induced in rats by combination of high-fat diet and low dose streptozocin injection. Pharmacokinetics study demonstrated that diabetes significantly decreased plasma exposures of cephalexin and acyclovir following oral administration of cephalexin and valacyclovir, respectively. Single-pass intestinal perfusion analysis showed that diabetes remarkably decreased cephalexin absorption, which was associated with decreased expression of intestinal PepT1 protein. We assessed the levels of bile acids in intestine of diabetic rats, and found that diabetic rats exhibited significantly higher levels of chenodeoxycholic acid (CDCA), cholic acid (CA) and glycocholic acid (GCA), and lower levels of lithocholic acid (LCA) and hyodeoxycholic acid (HDCA) than control rats; intestinal deoxycholic acid (DCA) levels were unaltered. In Caco-2 cells, the 6 bile acids remarkably decreased expression of PepT1 protein with CDCA causing the strongest inhibition, whereas TNF-α, LPS and insulin little affected expression of PepT1 protein; short-chain fatty acids induced rather than decreased expression of PepT1 protein. Farnesoid X receptor (FXR) inhibitor glycine-β-muricholic acid or FXR knockdown reversed the downregulation of PepT1 expression by CDCA and GW4064 (another FXR agonist). In diabetic rats, the expression of intestinal FXR protein was markedly increased. Oral administration of CDCA (90, 180 mg·kg-1·d-1, for 3 weeks) dose-dependently decreased the expression and function of intestinal PepT1 in rats. In conclusion, diabetes impairs the expression and function of intestinal PepT1 partly via CDCA-mediated FXR activation.

Supplemental Clostridium butyricum Modulates Lipid Metabolism Through Shaping Gut Microbiota and Bile Acid Profile of Aged Laying Hens.

Probiotic Clostridium butyricum could affect lipid metabolism in broilers. However, it is not clear whether C. butyricum could improve lipid metabolism through shaping gut microbiota and bile acid (BA) profile of laying hens. We aimed to evaluate the contributions of gut microbiota and BA profile to the potential effect of C. butyricum on lipid metabolism of aged laying hens. A total of 192 60-week-old Hy-Line Brown laying hens were divided into two groups (eight replicates per group). Birds were fed a basal diet supplemented with 0 or 2.7 g/kg C. butyricum (1.0 × 109 CFU/g). Samples were collected at the end of week 8 of the experiment. The results showed elevated (P < 0.05) concentrations of glucagon-like peptide 1, insulin and thyroid hormones in serum responded to C. butyricum addition, which also decreased (P < 0.05) hepatic free fatty acids contents, as well as increased (P < 0.05) the expression of hepatic acyl-CoA oxidase, farnesoid X receptor (FXR) and PPARα. C. butyricum addition increased (P < 0.05) Bacteroidetes abundance but tended to decrease (P < 0.10) Firmicutes abundance in the ileum. Besides, C. butyricum addition resulted in higher (P < 0.05) abundances of Clostridia (Clostridiales) and Prevotellaceae, concurrent with an increasing trend (P < 0.10) of Bifidobacteriaceae abundance and decreased the abundances of several harmful bacteria such as Klebsiella (P < 0.05). Regarding ileal BA profile, there was a reduced (P < 0.05) content of tauro-α-muricholic acid, increased (P < 0.05) contents of tauroursodeoxycholic acid and lithocholic acid, along with increasing trends (P < 0.10) of glycochenodeoxycholic acid and hyodeoxycholic acid contents due to C. butyricum addition, which also increased (P < 0.05) ileal FXR expression. Collectively, supplemental C. butyricum accelerated hepatic fatty acid oxidation, and shaped gut microbiota and BA profile, thus reducing fat deposition in the liver of aged laying hens.

Hyodeoxycholic acid (HDCA) suppresses intestinal epithelial cell proliferation through FXR‐PI3K/AKT pathway, accompanied by alteration of bile acids metabolism profiles induced by gut bacteria

Bile acids (BAs) have been implicated in regulation of intestinal epithelial signaling and function. This study aimed to investigate the effects of hyodeoxycholic acid (HDCA) on intestinal epithelial cell proliferation and explore the underlying mechanisms. IPEC-J2 cells and weaned piglets were treated with HDCA and the contributions of cellular signaling pathways, BAs metabolism profiles and gut bacteria were assessed. In vitro, HDCA suppressed IPEC-J2 proliferation via the BAs receptor FXR but not TGR5. In addition, HDCA inhibited the PI3K/AKT pathway, while knockdown of FXR or constitutive activation of AKT eliminated the inhibitory effects of HDCA, suggesting that FXR-dependent inhibition of PI3K/AKT pathway was involved in HDCA-suppressed IPEC-J2 proliferation. In vivo, dietary HDCA inhibited intestinal expression of proliferative markers and PI3K/AKT pathway in weaned piglets. Meanwhile, HDCA altered the BAs metabolism profiles, with decrease in primary BA and increase in total and secondary BAs in feces, and reduction of conjugated BAs in serum. Furthermore, HDCA increased abundance of the gut bacteria associated with BAs metabolism, and thereby induced BAs profiles alternation, which might indirectly contribute to HDCA-suppressed cell proliferation. Together, HDCA suppressed intestinal epithelial cell proliferation through FXR-PI3K/AKT signaling pathway, accompanied by alteration of BAs metabolism profiles induced by gut bacteria.

Species Differences of Bile Acid Redox Metabolism: Tertiary Oxidation of Deoxycholate is Conserved in Preclinical Animals.

It was recently disclosed that CYP3A is responsible for the tertiary stereoselective oxidations of deoxycholic acid (DCA), which becomes a continuum mechanism of the host-gut microbial cometabolism of bile acids (BAs) in humans. This work aims to investigate the species differences of BA redox metabolism and clarify whether the tertiary metabolism of DCA is a conserved pathway in preclinical animals. With quantitative determination of the total unconjugated BAs in urine and fecal samples of humans, dogs, rats, and mice, it was confirmed that the tertiary oxidized metabolites of DCA were found in all tested animals, whereas DCA and its oxidized metabolites disappeared in germ-free mice. The in vitro metabolism data of DCA and the other unconjugated BAs in liver microsomes of humans, monkeys, dogs, rats, and mice showed consistencies with the BA-profiling data, confirming that the tertiary oxidation of DCA is a conserved pathway. In liver microsomes of all tested animals, however, the oxidation activities toward DCA were far below the murine-specific 6β-oxidation activities toward chenodeoxycholic acid (CDCA), ursodeoxycholic acid, and lithocholic acid (LCA), and 7-oxidation activities toward murideoxycholic acid and hyodeoxycholic acid came from the 6-hydroxylation of LCA. These findings provided further explanations for why murine animals have significantly enhanced downstream metabolism of CDCA compared with humans. In conclusion, the species differences of BA redox metabolism disclosed in this work will be useful for the interspecies extrapolation of BA biology and toxicology in translational researches. SIGNIFICANCE STATEMENT: It is important to understand the species differences of bile acid metabolism when deciphering biological and hepatotoxicology findings from preclinical studies. However, the species differences of tertiary bile acids are poorly understood compared with primary and secondary bile acids. This work confirms that the tertiary oxidation of deoxycholic acid is conserved among preclinical animals and provides deeper understanding of how and why the downstream metabolism of chenodeoxycholic acid dominates that of cholic acid in murine animals compared with humans.

Efficient synthesis of cholic acid derivates through stereoselective C–H functionalization from hyodeoxycholic acid

Five cholic acid derivatives (including allo-ω-muricholic acid and CDCA) were synthesized from hyodeoxycholic acid via selective oxidation of C3- or C6-hydroxyl groups by IBX and NBS oxidants and stereocontrolled conversion. The hydroxyl group could be introduced through hydrolyzing α-Br keto with K2CO3 aqueous solution or through oxidizing the double bond by monoperoxyphthalic acid. The reduction of C6-O6 carbonyl to methylene could undergo with PTSH, NaBH3CN and ZnCl2 only at 5β configuration. A feasible synthetic route of CDCA from HDCA has been established to avoid the epimerization with the yield of 45% (8 steps). These strategies provided good yields, stereoselectivity and reproducibility for the preparation of cholic acid derivates and CDCA.

Dietary bile acids regulate the hepatic lipid homeostasis in tiger puffer fed normal or high-lipid diets

Bile acid (BA) plays an important role in lipid metabolism. Tiger puffer has a unique lipid storage pattern; storing lipid predominantly in the liver. The present study aimed to investigate the effects of dietary BA supplementation on hepatic lipid accumulation and metabolism in tiger puffer fed normal or high-lipid diets. An 8-week feeding trial was conducted in an indoor flow-through seawater system. Two diets with suitable (8.5%, diet C) or high lipid level (12.5%, diet HL) were prepared. BA, a porcine bile extract mainly comprised of hyodeoxycholic acid was supplemented into the two diets at the level of 0.02% to formulate diet CBA and diet HLBA, respectively. A fifth diet was prepared by supplementing an excess level of porcine bile extract (0.10%) into diet C (diet CHBA). Each diet was randomly fed to triplicate tanks. Dietary BA supplementation did not significantly affect fish growth performances. Dietary BA tended to decrease the whole-body lipid content, liver lipid content, hepatosomatic index, and viscerasomatic index in both fish fed with normal diets and fish fed with high-lipid diets. Similar results were observed for the contents of triacylglycerol, total cholesterol, and low-density lipoprotein-cholesterol in serum. The quantitative bile acid metabolomics analysis showed that taurocholic acid and taurochenodeoxycholic acid were dominantly abundant in the gallbladder. Dietary BA supplementation increased the concentration of taurohyodeoxycholic acid, glycohyodeoxycholic acid, and glycocholic acid, but affected some other BAs in various patterns. Dietary BA regulated hepatic transcription of lipid metabolism-related genes differentially in fish fed normal diets and fish fed high-lipid diets, decreasing the transcription of lipogenic genes in fish fed normal diets but increasing the transcription of genes related to lipid digestion and lipid/cholesterol transport in fish fed high-lipid diets. In conclusion, dietary BA supplementation tended to reduce the lipid accumulation in juvenile tiger puffer. However, at the transcription level the regulation of lipid metabolism by dietary BA seemed very different between fish fed normal diets and fish fed high-lipid diets. This study contributes to the general knowledge of bile physiology under different nutritional conditions in teleost and is beneficial to lipid management in tiger puffer farming.

Structurally different mixed linkage β-glucan supplements differentially increase secondary bile acid excretion in hypercholesterolaemic rat faeces.

Mixed linkage (1→3),(1→4)-β-d-glucan (BG) is a soluble fibre available from oat and barley grains that has been gaining interest due to its health-promoting role in cardiovascular diseases and its ability to modulate the glycaemic index which is beneficial for people with diabetes. This study investigates the effect of three purified barley BGs, with different molecular weight and block structure, on faecal bile acid excretion in hypercholesterolaemic rats. Wistar rats (48 male) were divided in four groups: Control group fed with the cellulose-rich diet (CON); Glucagel group fed with the commercial BG (GLU, 100 kDa), and rats fed with low molecular weight BG (LBG, 150 kDa) and medium molecular weight BG (MBG, 530 kDa). The bile acid profiles of rat faecal samples were measured using gas chromatography-mass spectrometry (GC-MS). A metabolite profiling approach led to the identification of 7 bile acids and 45 other compounds such as sterols, fatty acids and fatty alcohols. Subsequent application of ANOVA-simultaneous component analysis and Principal Component Analysis revealed that all three BG diets increased bile acid faecal excretion compared to the control group. The bile acid excretion was found to be different in all three BG diets and the MBG group showed a significantly higher level of faecal secondary bile acids, including deoxycholic acid, hyodeoxycholic acid, and lithocholic acid. We hypothesise that the hydrophobic surface of the secondary bile acids, which are known to cause colon cancer, has high affinity to the hydrophobic surfaces of cellulosic blocks of the BG. This in vivo study demonstrates that the molecular weight and/or block structures of BG modulate the excretion of secondary bile acids. This finding suggests that developing diets with designed BGs with an optimal molecular structure to trap carcinogenic bile acids can have a significant impact on counteracting cancer and other lifestyle associated diseases.

Astaxanthin attenuates d-galactose-induced brain aging in rats by ameliorating oxidative stress, mitochondrial dysfunction, and regulating metabolic markers.

Astaxanthin (AX) is a red-colored xanthophyll carotenoid with potent antioxidant, anti-inflammatory, and neuroprotective properties. However, the underlying in vivo mechanism by which AX protects the brain from oxidative stress remains unclear. In this study, we investigated the protective effect of AX on brain oxidative damage in a d-galactose-induced rat model of aging. We also explored its possible mechanism of action by analyzing the resulting serum metabolic profiles. Our results showed that AX significantly increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) by 26%, 30%, and 53%, respectively. AX also significantly increased the mitochondrial membrane potential by 18% when compared with the model group. Additionally, treatment with AX (15 mg kg-1) increased the activities of respiratory chain complexes I and IV by 50.17% and 122.87%, respectively. Furthermore, AX also improved age-related morphological changes in the cerebral cortex and hippocampus. Significant differences in serum metabolic profiles were observed between the d-galactose and AX treatment groups. AX corrected amino acid metabolic problems by increasing the levels of N-acetyl-l-leucine, N-acetyl-l-tyrosine, and methionine sulfoxide to protect nerve cells. This also allowed AX to regulate the pentose phosphate pathway by acting on ergotoxine, d-xylose-5-phosphoric, and thiamine, to against oxidative stress and apoptosis. Moreover, AX reduced the levels of both hyodeoxycholic acid and chenodeoxycholic acid though the primary bile acid biosynthesis pathway, resulting in improved brain mitochondrial dysfunction. In conclusion, AX likely enhances the brain's antioxidant defenses through these potential metabolic means, enabling the brain to resist mitochondrial dysfunction, improve neuronal damage, and protect the electron transmission of mitochondrial respiratory chain, thus preventing brain aging.

A combination of Omega-3 PUFAs and COX inhibitors: A novel strategy to manage obesity-linked dyslipidemia and adipose tissue inflammation

We previously reported that fish oil in combination with cyclooxygenase (COX) inhibitors exerts enhanced hypolipidemic and anti-inflammatory effects in mice. Here, we sought to determine the effects of omega-3 polyunsaturated fatty acids (ω-3 PUFAs) in combination with naproxen (NX), a COX inhibitor, on dyslipidemia and gene expression in adipose tissue (AT) in humans. Obese dyslipidemic patients were randomly assigned to one of these interventions for 12 wk: 1) Standard nutrition counseling (control), 2) ω-3 PUFAs (2 g twice daily), 3) NX (220 mg twice daily), and 4) ω-3 PUFAs (2 g twice daily) + NX (220 mg twice daily). The serum triglycerides showed a trend towards a reduction and a significant reduction (P<0.05) in ω-3 and ω3 + NX-treated subjects, respectively, compared to control. The mRNA expression of vascular cell adhesion molecule-1 (Vcam1), an inflammatory marker, increased significantly in AT of ω-3 PUFA-treated subjects but not in ω-3 PUFAs+NX-treated group. The plasma level of glycine-conjugated hyodeoxycholic acid, a secondary bile acid with hypolipidemic property, increased significantly in ω-3 PUFAs + NX-treated group. Our data suggest that combining NX with ω-3 PUFAs increases their effectiveness in reducing serum TG and favorably altering AT gene expression and plasma bile acid profile.

Decrease in major secondary bile acid, hyodeoxycholic acid, was the main alteration in hepatic bile acid compositions in a hypertensive nonalcoholic fatty liver disease model.

Previous findings on hepatic bile acid compositions in nonalcoholic fatty liver disease (NAFLD) have been inconsistent and complicated. The aim of this study was to investigate the effects of steatosis on hepatic bile acid composition in a hypertensive NAFLD model without obesity and diabetes mellitus and compare hepatic bile acid composition between hypertensive rats with and without steatosis. Two groups of hypertensive rats were studied: spontaneously hypertensive rats (SHR) fed with a normal diet (SHR-N) or a choline-deficient diet (SHR-CD). Two groups of normotensive rats were studied: Wistar Kyoto rats (WKY) fed a normal diet (WKY-N) or a choline-deficient diet (WKY-CD). Hepatic bile acid analysis was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry. Regarding bile acid composition, the hyodeoxycholic acid (HDCA) species in the SHR-CD group showed the largest change in bile acid composition, significantly decreasing to 21.9% of that found in the SHR-N group. In the WKY-CD group, no reduction of HDCA species was observed. We demonstrated that the decrease in HDCA species was the main alteration in a hypertensive NAFLD model. It was suggested that the decrease in HDCA species in the SHR-CD group was caused by dysbiosis.

Iron overload reduces synthesis and elimination of bile acids in rat liver

Excessive iron accumulation in the liver, which accompanies certain genetic or metabolic diseases, impairs bile acids (BA) synthesis, but the influence of iron on the complex process of BA homeostasis is unknown. Thus, we evaluated the effect of iron overload (IO) on BA turnover in rats. Compared with control rats, IO (8 intraperitoneal doses of 100 mg/kg every other day) significantly decreased bile flow as a consequence of decreased biliary BA secretion. This decrease was associated with reduced expression of Cyp7a1, the rate limiting enzyme in the conversion of cholesterol to BA, and decreased expression of Bsep, the transporter responsible for BA efflux into bile. However, IO did not change net BA content in faeces in response to increased intestinal conversion of BA into hyodeoxycholic acid. In addition, IO increased plasma cholesterol concentrations, which corresponded with reduced Cyp7a1 expression and increased expression of Hmgcr, the rate-limiting enzyme in de novo cholesterol synthesis. In summary, this study describes the mechanisms impairing synthesis, biliary secretion and intestinal processing of BA during IO. Altered elimination pathways for BA and cholesterol may interfere with the pathophysiology of liver damage accompanying liver diseases with excessive iron deposition.

Identify liver X receptor β modulator building blocks by developing a fluorescence polarization-based competition assay

The liver X receptors (LXRs) of the nuclear receptor family are promising therapeutic targets of multiple diseases like lipid disorders, chronic inflammation, as well as different human cancers. To date, no LXR agonists or antagonists can be used in clinics, emphasizing the importance for discovering new LXR modulators. Fragment-based lead discovery (FBLD) is powerful for designing new scaffolds and new mechanistic drugs, but fragment screening has not been applied to LXRs yet, which might be due to the lack of a specific fragment screening method against the dynamic and hydrophobic ligand binding domain (LBD) of LXRs. Herein, a series of fluorescent tracers were designed, synthesized and tested. The tracer based on hyodeoxycholic acid exhibited a good capability for competitively detecting the ligand binding of LXRβ using a fluorescence polarization approach. Then, 1074 fragments were screened against the LBD of LXRβ (LXRβ-LBD), resulting in 27 binding hits. These fragment hits were further tested using the co-activator recruitment assay and reporter gene assay, and efforts in X-ray crystallography fortunately solved a co-crystal structure of LXRβ-LBD with the fragment F3 (tert-butyl-7-amino-3,4-dihydroisoquinoline-2(1H)-carboxylate). The fluorescence-based fragment screening tool and the newly identified LXRβ binding fragments provide the basis for developing novel LXRβ modulators.

The effects of dietary supplementation with hyodeoxycholic acid on the differentiation and function of enteroendocrine cells and the serum biochemical indices in weaned piglets.

Bile acid, a cholesterol metabolite, promotes gastrointestinal tract digestion and absorption of cholesterol, lipids, and fat-soluble vitamins. It is a signaling regulatory molecule that influences a variety of endocrinal and metabolic activities. This study investigated the effects hyodeoxycholic acid (HDCA) as a dietary supplement on endocrine cell differentiation and function and weaned piglet serum biochemical indices. Sixteen piglets (Duroc × [Landrace × Yorkshire]) were individually housed and weaned at 21 days of age (body weight of 6.14 ± 0.22 kg). Uniform weight animals were randomly assigned to one of two treatments (eight replicate pens per treatment and one piglet per pen). The treatments were 1) base diet (control); and 2) base diet supplemented with 2 g/kg of HDCA. Control and HDCA piglet numbers of CgA-positive cells per crypt did not differ. HDCA CgA-positive cells numbers decreased (P < 0.05) in the jejunal villi, showed a tendency to decrease (P < 0.10) in the ileal villi, and showed tendency toward an increase (P < 0.10) in the duodenal villi compared to the controls. The HDCA diet led to a decline in GLP-2 (P < 0.01) concentrations, but did not affect plasma GLP-1. HDCA supplementation increased (P < 0.05) the mRNA expression of jejunal Insm1, Sst, PG, and Gast, but decreased (P < 0.05) duodenal expression of Insm1, jejunal Pdx1, and ileal NeuroD1. HDCA elevated GLO and IgA (P < 0.05) serum concentrations and decreased the A/G ratio (P < 0.05). TP and IgG serum levels tended to increase compared to the control group. These results indicate that dietary HDCA at 2 g/kg may regulate enteroendocrine cell differentiation and play a role in increasing weaned piglet humoral immunity.

Hyodeoxycholic acid protects the neurovascular unit against oxygen-glucose deprivation and reoxygenation-induced injury in vitro

Calculus bovis is commonly used for the treatment of stroke in traditional Chinese medicine. Hyodeoxycholic acid (HDCA) is a bioactive compound extracted from calculus bovis. When combined with cholic acid, baicalin and jas-minoidin, HDCA prevents hypoxia-reoxygenation-induced brain injury by suppressing endoplasmic reticulum stress-mediated apoptotic signaling. However, the effects of HDCA in ischemic stroke injury have not yet been studied. Neurovascular unit (NVU) dysfunction occurs in ischemic stroke. Therefore, in this study, we investigated the effects of HDCA on the NVU under ischemic conditions in vitro. We co-cultured primary brain microvascular endothelial cells, neurons and astrocytes using a transwell chamber co-culture system. The NVU was pre-treated with 10.16 or 2.54 μg/mL HDCA for 24 hours before exposure to oxygen-glucose deprivation for 1 hour. The cell counting kit-8 assay was used to detect cell activity. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to assess apoptosis. Enzyme-linked immunosorbent assay was used to measure the expression levels of inflammatory cytokines, including interleukin-1β, interleukin-6 and tumor necrosis factor-α, and neurotrophic factors, including brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor. Oxidative stress-related factors, such as superoxide dismutase, nitric oxide, malondialdehyde and γ-glutamyltransferase, were measured using kits. Pretreatment with HDCA significantly decreased blood-brain barrier permeability and neuronal apoptosis, significantly increased transendothelial electrical resistance and γ-glutamyltransferase activity, attenuated oxidative stress damage and the release of inflammatory cytokines, and increased brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor expression. Our findings suggest that HDCA maintains NVU morphological integrity and function by modulating inflammation, oxidation stress, apoptosis, and the expression of neurotrophic factors. Therefore, HDCA may have therapeutic potential in the clinical management of ischemic stroke. This study was approved by the Ethics Committee of Experimental Animals of Beijing University of Chinese Medicine (approval No. BUCM-3-2016040201-2003) in April 2016.

Bile acids: Lipase-catalyzed synthesis of new hyodeoxycholic acid derivatives

In this work we present an efficient, environmentally friendly approach to the synthesis of a series of hyodeoxycholic acid derivatives applying Biocatalysis. Fifteen acetyl and ester derivatives, twelve of them new, were obtained through an enzymatic strategy in a fully regioselective way and in very good to excellent yield. In order to find the optimal reaction conditions, the influence of several parameters such as enzyme source, alcohol or acylating agent:substrate ratio, enzyme:substrate ratio, temperature and reaction solvent was considered. The excellent results obtained made this procedure very efficient, particularly considering the low amount of enzyme required. In addition, this methodology uses mild reaction conditions and has reduced environmental impact, making biocatalysis a suitable way to obtaining these bile acids derivatives.