Secondary bile acid metabolite; Endogenous Metabolite

Through FXR-mediated ACE2 modulation, Ursodeoxycholic acid (10 μM; 24 h) lowers SARS-CoV-2 infection in different cell types and reduces ACE2 and SHP levels in primary airways and damaged organoids [4].

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FXR regulates viral infection in vitro [4]
Our results show that suppressing FXR signalling with the clinically approved drug Ursodeoxycholic acid/UDCA—which is used as a first-line treatment in primary biliary cholangitis (PBC)—or with the over-the-counter drug ZGG reduces the expression of ACE2 in multiple cell types. To consider the relevance of this finding for COVID-19, we investigated whether the FXR-mediated downregulation of ACE2 could reduce susceptibility to SARS-CoV-2 infection in vitro. For this, we exposed gall bladder cholangiocyte, airway and intestinal organoids to physiological levels of CDCA, to simulate the baseline level of FXR activation that is present in vivo, and infected them with SARS-CoV-2 isolated from a patient’s nasopharyngeal swab in the absence or presence of UDCA or ZGG (Fig. 1e,f). Suppressing FXR signalling with UDCA or ZGG reduced viral infection in all three types of organoid (Fig. 1e,f and Extended Data Fig. 5a). We then investigated whether the observed reduction in viral infection was a direct result of the FXR-mediated downregulation of ACE2. First, we showed that knockdown of FXR using shRNAs decreases the expression of ACE2 and inhibits viral infection in cholangiocyte organoids independently of the presence of CDCA or that of UDCA or ZGG (Extended Data Fig. 4d). Accordingly, after knockdown, treatment with UDCA or ZGG had no effect on viral infection (Extended Data Fig. 4d). Next, to determine whether the modulation of ACE2 is the only mechanism by which UDCA and ZGG reduce SARS-CoV-2 infection, we treated HEK293T cells that had been genetically engineered to overexpress ACE2 independent of FXR (Extended Data Fig. 6a,b) with UDCA or ZGG, and then infected them with SARS-CoV-2. As expected, in the absence of ACE2 modulation, UDCA and ZGG did not affect viral replication (Extended Data Fig. 6c). Together, these results confirm that UDCA and ZGG reduce susceptibility to SARS-CoV-2 infection in multiple cell types in vitro through the FXR-mediated regulation of ACE2.

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To further explore the physiological and pharmacological implications of hepatic FATP inhibition by secondary bile acids we tested the effects of Ursodeoxycholic acid/UDCA on LCFA uptake by primary hepatocytes. Using a FACS-based LCFA uptake assay that allows for the gating of viable cells, we found that UDCA but not TUDCA inhibited LCFA uptake by primary human hepatocytes (Sup. Fig. 5). UDCA also inhibited LCFA uptake by primary mouse hepatocytes from C57Bl/6 animals without any detectable cytotoxic effects (Fig. 5A right). Importantly, this effect was entirely FATP5 dependent, as UDCA failed to inhibited LCFA uptake by primary hepatocytes from FATP5-null animals (Fig. 5A). As predicted form our stable cell line results, the secondary bile acid DCA inhibited hepatocyte LCFA uptake significantly (Fig. 5B) while LCA showed no inhibition of LCFA uptake by primary mouse hepatocytes (Fig. 5D). Further, DCA mediated inhibition was not associated with toxicity (Fig. 5B right) and, importantly, was primarily dependent on FATP5 as the effect was abolished in FATP5-null hepatocytes (Fig. 5B). We confirmed DCA inhibition of fatty acid uptake by primary hepatocytes using 14C-labeled oleate (Sup. Fig. 6). Subsequent assays focused on the uptake of radiolabeled metabolites by primary hepatocytes and demonstrated that DCA can inhibit the uptake of a wide range of fatty acids without affecting uptake of a 2-deoxy-D-[3H]glucose/glucose mix (Fig. 5C) [5].

In C57BL/6J wild-type mice, ursodeoxycholic acid (50, 150, and 450 mg/kg; orally; once daily for 21 days) salt induces weight loss [1]. In mice and hamsters, ursodeoxycholic acid (1% w/w or 416 mg/kg; port; 7 days) decreases ACE2 expression [4]. In hamsters, ursodeoxycholic acid (416 mg/kg; side wall; 7 days) is effective in reducing SARS-CoV-2 infection [4].

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Ursodeoxycholic acid (commercially available as ursodiol) is a naturally occurring bile acid that is used to treat a variety of hepatic and gastrointestinal diseases. Ursodiol can modulate bile acid pools, which have the potential to alter the gut microbiota community structure. In turn, the gut microbial community can modulate bile acid pools, thus highlighting the interconnectedness of the gut microbiota-bile acid-host axis. Despite these interactions, it remains unclear if and how exogenously administered ursodiol shapes the gut microbial community structure and bile acid pool in conventional mice. This study aims to characterize how ursodiol alters the gastrointestinal ecosystem in conventional mice. C57BL/6J wildtype mice were given one of three doses of ursodiol (50, 150, or 450 mg/kg/day) by oral gavage for 21 days. Alterations in the gut microbiota and bile acids were examined including stool, ileal, and cecal content. Bile acids were also measured in serum. Significant weight loss was seen in mice treated with the low and high dose of ursodiol. Alterations in the microbial community structure and bile acid pool were seen in ileal and cecal content compared to pretreatment, and longitudinally in feces following the 21-day ursodiol treatment. In both ileal and cecal content, members of the Lachnospiraceae Family significantly contributed to the changes observed. This study is the first to provide a comprehensive view of how exogenously administered ursodiol shapes the healthy gastrointestinal ecosystem in conventional mice. Further studies to investigate how these changes in turn modify the host physiologic response are important.[1]

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There is debate over the mortality and malignancy risk in people with primary biliary cirrhosis (PBC) and whether this risk is reduced by use of Ursodeoxycholic acid. To investigate this issue, we identified 930 people with PBC and 9,202 control subjects from the General Practice Research Database in the United Kingdom. We categorized regular ursodeoxycholic acid as treatment with 6 or more prescriptions and nonregular treatment as less than 6. We found a 2.7-fold increase in mortality for the PBC cohort compared with the general population [adjusted hazard ratio (HR), 2.69; 95% CI, 2.35-3.09]. In those having regular ursodeoxycholic acid (43%), the mortality increase was 2.2-fold (HR, 2.19; 95% CI, 1.66-2.87) and in those not treated 2.7-fold (HR, 2.69; 95% CI, 2.18-3.33). This apparent reduction in mortality was not explained by less severe disease in the ursodeoxycholic acid-treated group. The increased risk of primary liver cancer in ursodeoxycholic acid-treated patients was 3-fold (HR, 3.17; 95% CI, 0.64-15.62), in contrast to an 8-fold increase in those not treated (HR, 7.77; 95% CI, 1.30-46.65). Conclusion: We found that people with PBC had a 3-fold mortality increase when compared with the general population, which was somewhat reduced by regular treatment with Ursodeoxycholic acid. However, the observed effect of ursodeoxycholic acid was not statistically significant.[2]

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Bile acids are known to play important roles as detergents in the absorption of hydrophobic nutrients and as signaling molecules in the regulation of metabolism. We tested the novel hypothesis that naturally occurring bile acids interfere with protein-mediated hepatic long chain free fatty acid (LCFA) uptake. To this end, stable cell lines expressing fatty acid transporters as well as primary hepatocytes from mouse and human livers were incubated with primary and secondary bile acids to determine their effects on LCFA uptake rates. We identified Ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA) as the two most potent inhibitors of the liver-specific fatty acid transport protein 5 (FATP5). Both UDCA and DCA were able to inhibit LCFA uptake by primary hepatocytes in a FATP5-dependent manner. Subsequently, mice were treated with these secondary bile acids in vivo to assess their ability to inhibit diet-induced hepatic triglyceride accumulation. Administration of DCA in vivo via injection or as part of a high-fat diet significantly inhibited hepatic fatty acid uptake and reduced liver triglycerides by more than 50%. Conclusion: The data demonstrate a novel role for specific bile acids, and the secondary bile acid DCA in particular, in the regulation of hepatic LCFA uptake. The results illuminate a previously unappreciated means by which specific bile acids, such as UDCA and DCA, can impact hepatic triglyceride metabolism and may lead to novel approaches to combat obesity-associated fatty liver disease [5].

Modulation of FXR activity [4]
CDCA, ZGG and UDCA/Ursodeoxycholic acid were purchased from xxx and reconstituted following the manufacturer’s instructions. To modulate FXR activity, organoids were incubated with a final concentration of 10 μM CDCA, or 10 μM CDCA in combination with 10 μM of UDCA or ZGG.

ChIP [4]
Approximately 6 × 106 cells were used for each ChIP, and cells were incubated with fresh medium with 100 μM of CDCA, UDCA/Ursodeoxycholic acid or ZGG 2 h before collection. ChIP was performed using the True Micro ChiP kit according to the manufacturer’s instructions. In brief, following pre-clearing, the lysate was incubated overnight with the FXR antibody (Supplementary Table 1) or non-immune IgG. ChIP was completed and immunoprecipitated DNA was purified using MicroChip DiaPure columns. Samples were analysed by qPCR using the ΔΔCt approach as previously described51 (see Supplementary Table 3 for primer sequences). Primers flanking the FXRE on the well-known FXR target gene OSTα (also known as SLC51A; ref. 54) were used as a positive control, whereas primers flanking a site distant from the FXRE on the ACE2 promoter were used as a negative control. The results were normalized to the enrichment observed with non-immune IgG ChIP controls.

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Luciferase reporter [4]
Two different fragments containing the FXRE IR-1 in the ACE2 gene and in the SHP gene (also known as NR0B2) were amplified using human genomic DNA as a template and inserted onto a pGL3-promoter luciferase vector. The ACE2 and SHP IR-1 mutants were generated using a site-directed mutagenesis approach. Sequences of primers used are reported in Supplementary Table 4. These gene reporter constructs were co-transfected with a commercially available FXR expression plasmid into HEK293 cells using TransIT-293 Transfection Reagent. Twenty-four hours after transfection, cells were treated with 50 μM of CDCA, UDCA/Ursodeoxycholic acid and ZGG in fresh medium for 8 h. Luciferase activity was determined with the GLO-Luciferase Reporter Assay System and values were normalized to the empty pGL3 vector.

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Cytotoxicity and viability [4]
Primary organoids were treated with 0.1 μM–100 μM of CDCA, UDCA/Ursodeoxycholic acid or ZGG and the percentage of viable cells was counted using trypan blue and a Countess II cell counter. Cellular viability in primary organoids treated with 10 μM of CDCA, UDCA or ZGG was measured using the resazurin-based assay PrestoBlue using SoftMax Pro 5.4.4 on a SpectraMax M2.

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Luciferase reporter for SARS-CoV-2 replication [4]
A luciferase reporter for SARS-CoV-2 protease activity during viral replication was generated as previously described28 In brief, HEK293T reporter cells stably expressing ACE2, renilla luciferase (Rluc) and SARS-CoV-2 papain-like protease-activatable circularly permuted firefly luciferase (FFluc) were seeded in flat-bottomed 96-well plates. The following morning, cells were treated with the indicated doses of CDCA, UDCA/Ursodeoxycholic acid and ZGG, and infected with SARS-CoV-2 at a MOI of 0.01. The SARS-CoV-2 RdRp inhibitor remdesivir and a neutralizing antibody cocktail blocking the interaction between SARS-CoV-2 spike and ACE2 (REGN-COV2) were included as positive controls. After 24 h, cells were lysed in Dual-Glo Luciferase Buffer diluted 1:1 with PBS and 1% NP-40. Lysates were then transferred to opaque 96-well plates, and viral replication quantified as the ratio of FFluc/Rluc activity measured using the Dual-Glo kit according to the manufacturer’s instructions. FFluc/Rluc ratios were expressed as a fraction of the maximum, then analysed using the Sigmoidal, 4PL, X is log(concentration) function in GraphPad Prism.

Animal/Disease Models: 5weeks old C57BL/6J WT mice (male and female) [1]
Doses: 50, 150 and 450 mg/kg dissolved in corn oil
Route of Administration: po (oral gavage); one time/day for 21 days
Experimental Results: Mice in the 50 mg/kg and 450 mg/kg groups continued to lose significant weight over a week. At the 50 mg/kg dose, this weight loss persisted throughout the experiment. At the 450 mg/kg dose, weight loss was initially noted during the first and third weeks of ursodiol administration. At the 150 mg/kg dose, there was no significant difference in body weight compared to untreated mice.

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Animal/Disease Models: FVB/N mice and Syrian golden hamsters [4]
Doses: 1% w/w for mice, 416 mg/kg for hamsters.
Route of Administration: feed or po (oral gavage), 7 days.
Experimental Results: ACE2 expression diminished.

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Animal/Disease Models: Syrian golden hamster, SARS-CoV-2 infection model [4]
Doses: 416 mg/kg
Route of Administration: po (oral gavage), 7 days
Experimental Results: n = 6 of 9 sentinel animals prevented SARS -Transmission of CoV-2 (33% infected vs. 67% uninfected).\n

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\n\nUrsodiol/Ursodeoxycholic acid dosing experiment and sample collection [1]
\nGroups of 5 week old C57BL/6J WT mice (male and female) were treated with ursodiol/Ursodeoxycholic acid at three distinct doses (50, 150, and 450 mg/kg dissolved in corn oil) given daily via oral gavage for 21 day. These distinct doses were selected for a proof of concept experiment in order to achieve sufficient intestinal concentrations of ursodiol to alter the life cycle of Clostridioides difficile in vivo. The total volume gavaged was consistent between the three distinct doses in order to control for the volume of corn oil administered. Ursodiol dosing was adjusted once weekly, based on current weight. Two independent experiments were performed, with a total of n = 8 mice (female/male) per treatment group. Mice were weighed daily over the course of the experiment. Fecal pellets were collected twice daily, flash-frozen and stored at -80°C until further analysis. A control group of mice were necropsied prior to initiating any treatments (pretreatment group). This pretreatment group serves as a microbiome and bile acid metabolome baseline prior to mice receiving ursodiol treatment. An additional control group of mice underwent daily handling similar to the treatment groups, but were not administered ursodiol (no treatment control). Necropsy was performed at day 21 in all ursodiol treated mice and the no treatment control mice. Gastrointestinal contents and tissue from the ileum and cecum were collected, flash frozen in liquid nitrogen, and stored at -80°C until further analysis. Serum and bile aspirated from the gallbladder was obtained flash frozen in liquid nitrogen, and stored at -80°C until further analysis.\n

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\nMice [4]
\nMice were housed in a 12 h–12 h dark–light cycle, with a humidity of 45–65% and temperature of 20–24 °C. Age-matched female mice were used. Mice were assigned randomly to treatment and control groups. Mice in the treatment group received chow supplemented with 1% w/w UDCA/Ursodeoxycholic acid and 1% w/w cholic acid, whereas mice in the control group received chow supplemented with 1% w/w cholic acid58. Cholic acid was used to activate FXR and study the effects of UDCA on FXR activation19. The mice were fed ad libitum for seven days. Data were analysed blinded to the identity of the experimental groups.\n

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\n\nHamsters [4]
\nGolden Syrian hamsters were purchased from Janvier Labs. Hamsters were housed in a 12 h–12 h dark–light cycle, with a humidity of 45–65% and temperature of 20–24 °C. Age-matched male hamsters were used, weighing between 80 g and 100 g. Hamsters were assigned randomly to treatment and control groups. Hamsters in the treatment groups received a daily oral regimen of UDCAUrsodeoxycholic acid (416 mg per kg) by oral gavage, whereas those in the control group received vehicle only. The hamsters were fed ad libitum and treatment continued for seven days to achieve a similar blood concentration of UDCA to that observed in patients taking UDCA29 (Extended Data Fig. 9a). [4]
\n\nFor testing the effects of Ursodeoxycholic acid/UDCA against SARS-CoV-2 infection, one hamster was directly inoculated by the intranasal route with 1 × 102 plaque-forming units (PFU) in 100 µl PBS. Each infected hamster was placed on one side of a transmission cage. The cage was divided with an aerated barrier that allowed the infected hamster to be co-housed with previously treated uninfected hamsters housed on the other side, permitting us to study viral infection by aerosol transmission. Daily swabs were collected from all hamsters to monitor the infection by qPCR for the viral N gene. On day 4 after infection, the hamsters were euthanized and lungs and nasal turbinates were collected for quantification of viral infection. The experiment was repeated n = 3 times for a total of n = 9 UDCA and n = 6 vehicle hamsters. Data were analysed blinded to the identity of the experimental groups.\n\n

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\n\nAnimal Experiments [5]
\nThe generation of FATP5 null mice has been described previously Mice were fed standard chow prior to the high-fat diet experiments (60% calories from fat). All experiments were performed with individually housed animals. For the bile acid injection experiments mice were injected subcutaneously with 3.2mg/kg DCA or LCA in 20 μl DMSO on the back above the right hip once a day for 7 weeks while consuming a high-fat diet. For bile acid feeding experiments 5mg/g Ursodeoxycholic acid/UDCA, 0.5mg/g DCA or 0.5mg/g LCA in high fat food were mixed. The mice were fed the supplemented high fat diet for 7 weeks. Their food intake and body weight were recorded once a week. During this time, the mice had ad libitum access to water and high fat food. For tissue and plasma collection, mice were fasted 4 hours prior to euthanization. After euthansia by CO2 asphyxiation, subcutaneous injection sites were examined to verify that no bile acid precipitates had accumulated. Liver and other organs were removed, lysed and the protein and TAG concentrations of organ lysates were assayed using the BCA protein assay kit and infinity TAG kit respectively. All procedures were approved by the UC Berkeley ACUC.\n

Absorption, Distribution and Excretion
Under normal circumstances, endogenous ursodeoxycholic acid (UDCA) accounts for only a small portion (approximately 5%) of the total bile acid pool in the human body. After oral administration, most UDCA is absorbed via passive diffusion, but absorption is not complete. After absorption, approximately 50% of UDCA is extracted by the liver in the absence of liver disease. The extraction rate decreases with increasing severity of liver disease. With long-term use of UDCA, it becomes the main bile acid in bile and plasma. At long-term doses of 13 to 15 mg/kg/day, UDCA accounts for 30-50% of bile and plasma bile acids. UDCA is primarily excreted in feces. Renal excretion is a secondary route of excretion. After treatment, urinary excretion increases, but remains below 1% except in cases of severe cholestatic liver disease.
The volume of distribution of ursodeoxycholic acid (UDCA) has not been determined; however, since UDCA is mainly distributed in the bile of the gallbladder and small intestine, its volume of distribution is expected to be small.
Metabolism/Metabolites
After administration, ursodeoxycholic acid (UDCA) enters the portal vein and then the liver, where it conjugates with glycine or taurine. UDCA also enters the bile. The glycine or taurine conjugates are absorbed in the small intestine via passive and active mechanisms. These conjugates can also be deconjugated by intestinal enzymes in the ileum, generating free UDCA, which can be reabsorbed and reconjugated in the liver. Unabsorbed ursodeoxycholic acid (UDCA) enters the colon and undergoes 7-dehydroxylation by intestinal bacteria to generate lithocholic acid. Some UDCA isomerizes to chenodeoxycholic acid via a 7-oxo intermediate. Chenodeoxycholic acid also undergoes 7-dehydroxylation to generate lithocholic acid. These metabolites have low solubility and are mainly excreted in feces. A small amount of lithocholic acid is reabsorbed, conjugated with glycine or taurine in the liver, and sulfated at position 3. The resulting sulfated lithocholic acid conjugate is excreted via bile and ultimately in feces.

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Biological half-life
Estimated half-life is 3.5 to 5.8 days.

Hepatotoxicity
In multiple clinical trials targeting various diseases, ursodeoxycholic acid (UDCA) has not been found to cause elevated serum enzymes, worsening of primary liver disease, or clinically significant liver injury. However, a few reports have indicated clinical decompensation in patients with advanced liver disease and cirrhosis after initiation of UDCA, but the cause is unclear. At least one patient experienced a recurrence of jaundice after restarting UDCA. Therefore, UDCA has beneficial effects on a variety of liver diseases, and there is no conclusive evidence that it is associated with clinically significant acute liver injury in non-cirrhotic patients. There are concerns that UDCA may be harmful to patients with advanced liver disease (Child-Pugh B and C), and these patients may not be able to take UDCA. Probability Score: D (Possibly a rare cause of acute decompensation in pre-existing liver disease). Pregnancy and Lactation Effects ◉ Overview of Use During Lactation Ursodeoxycholic acid is naturally present in breast milk. Because the levels of ursodeoxycholic acid (UDCA) in breast milk are low after exogenous administration, and the infant's intake is minimal, no adverse effects are expected on breastfed infants. UDCA has been used in newborns and is safe and effective in treating neonatal jaundice. No special precautions are required.
◉ Effects on Breastfed Infants
One breastfed infant (feeding extent not specified) developed normally in the first 6 months after birth, with the mother taking 750 to 1000 mg of UDCA daily.
Seven women took 14 mg/kg of UDCA daily near delivery and postpartum. They reported no adverse reactions in their breastfed infants in the early postpartum period.
A mother with primary biliary cirrhosis was reported to take 250 mg of UDCA orally three times daily and breastfed her infant normally, but the extent and duration of breastfeeding were not specified.
A woman with primary biliary cirrhosis experienced severe itching and elevated serum bile acids 3 weeks postpartum. Ursodeoxycholic acid was started at 500 mg daily (7.5 mg/kg) and gradually increased to 1500 mg daily (25 mg/kg) over the next 8 weeks. Her breastfed infant (feeding extent not specified) had normal psychomotor development, and no significant side effects were observed.
A retrospective analysis of medical records of pregnant women diagnosed with primary biliary cirrhosis at a hospital in Ankara, Turkey, found that 8 patients received ursodeoxycholic acid postpartum at a dose of 13-15 mg/kg daily. "Most" of these patients breastfed their infants (feeding extent not specified). No side effects were reported in the infants.
A woman breastfed her 8-day-old premature infant 10 times a day for approximately 15 minutes each time. The infant was born by cesarean section at 34 weeks of gestation, weighing 3600 grams. She was diagnosed with cholestasis, type 1 diabetes, and hypothyroidism. She received ursodeoxycholic acid (500 mg daily), insulin Lantus and insulin aspart, and levothyroxine sodium. She also took cefuroxime, flurbiprofen, and a combination of acetaminophen, disopyrfenone, and caffeine. The mother took ursodeoxycholic acid for 12 days, cefuroxime and combination analgesics for 10 days, and flurbiprofen for 15 days. No adverse reactions were observed during ursodeoxycholic acid treatment.
Twenty lactating women with cholestasis received ursodeoxycholic acid at daily doses of 500 to 1500 mg or 13 to 15 mg/kg, depending on their condition. Ursodeoxycholic acid was discontinued 3 days postpartum. No significant side effects were observed in any newborns according to early postnatal clinical examination criteria; no postnatal developmental delays were observed during a 1-year follow-up with routine pediatric examinations.
◉ Effects on Lactation and Breast Milk
As of the revision date, no relevant published information was found.

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Protein Binding
In healthy individuals, unconjugated ursodeoxycholic acid binds to plasma proteins at least 70%. There is currently no information regarding the protein binding of conjugated ursodeoxycholic acid.

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Toxicity Overview
Usodeoxycholic acid has been shown to have potentially toxic molecular properties. Ursodeoxycholic acid breaks down into toxic lithocholic acid. After absorption in the small intestine, ursodeoxycholic acid is conjugated in the liver. After conjugation, ursodeoxycholic acid is not further broken down in the liver or intestinal mucosa. It can be oxidized or reduced to produce 7-ketolithocholic acid or lithocholic acid. Lithocholic acid is toxic to hepatocellular cells and can even lead to liver failure in those with impaired sulfation. It can also cause segmental bile duct injury, hepatocellular failure, and death.

[1]. Secondary bile acid ursodeoxycholic acid alters weight, the gut microbiota, and the bile acid pool in conventional mice. PLoS One. 2021;16(2):e0246161.

[2]. Influence of ursodeoxycholic acid on the mortality and malignancy associated with primary biliary cirrhosis: a population-based cohort study. Hepatology. 2007 Oct;46(4):1131-7.

[3]. Use of ursodeoxycholic acid in liver diseases. J Gastroenterol Hepatol. 2001 Jan;16(1):3-14.

[4]. FXR inhibition may protect from SARS-CoV-2 infection by reducing ACE2. Nature. 2022 Dec 5.

[5]. Specific Bile Acids Inhibit Hepatic Fatty Acid Uptake in Mice. Hepatology. 2012 Oct;56(4):1300-10.

Ursodeoxycholic acid (UDCA) is a diastereomer of chenodeoxycholic acid. It is a mammalian bile acid, first discovered in bears, and is apparently a precursor or product of chenodeoxycholic acid. Taking UDCA can alter bile composition and may dissolve gallstones. It is used as a choleretic agent.

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Pharmacodynamics
Usodeoxycholic acid (UDCA) is a secondary bile acid with cell-protective, immunomodulatory, and choleretic effects. It reduces cholesterol content in bile lipids. UDCA inhibits intestinal cholesterol absorption and cholesterol secretion into bile, thereby reducing bile cholesterol saturation. UDCA increases bile acid flow and promotes bile acid secretion.

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Usodeoxycholic acid is a bile acid found in the bile of bears, existing in a form bound to taurine.
Usodeoxycholic acid (UDCA), also known as ursodeoxycholic acid, is a naturally occurring bile acid, present in relatively small amounts in the human bile acid pool. Ursodeoxycholic acid (UDCA) has been used to treat liver diseases for decades, with its application in traditional medicine dating back over a century. Originally isolated from the bile of the Chinese black bear, UDCA is formed by the 7β-epimerization of the primary bile acid, chenodeoxycholic acid. Due to its hydrophilicity, UDCA is less toxic than bile acids or chenodeoxycholic acid. Ursodeoxycholic acid (UDCA) was first approved by the U.S. Food and Drug Administration (FDA) in 1987 for dissolving gallstones and in 1996 for treating primary biliary cirrhosis. UDCA's mechanism of action is to displace hydrophobic or more toxic bile acids in the bile acid pool. Ursodeoxycholic acid is a bile acid. Ursodeoxycholic acid (also known as ursodeoxycholic acid) is a naturally occurring bile acid used to dissolve cholesterol stones and treat cholestatic liver diseases, including primary biliary cirrhosis. Ursodeoxycholic acid (UDCA) has been associated with rare, transient, mild elevations in serum transaminases during treatment, as well as rare jaundice and exacerbations of liver disease in patients with pre-existing cirrhosis. It has been reported that ursodeoxycholic acid is present in beavers; relevant data is available from LOTUS—a database of natural products. UDCA is a synthetic derivative of ursodeoxycholic acid, a bile acid produced and secreted by the liver and stored in the gallbladder. UDCA is also produced in the liver of the Chinese black bear and has been used for centuries to treat liver disease. This drug dissolves or prevents cholesterol gallstones by inhibiting hepatic cholesterol production and lowering bile cholesterol. UDCA also reduces intestinal cholesterol absorption. UDCA is a small molecule drug currently in Phase IV clinical trials (covering all indications). It was first approved in 1987 for the treatment of primary biliary cirrhosis and biliary cirrhosis, and has 25 investigational indications. UDCA is a diastereomer of chenodeoxycholic acid. It is a mammalian bile acid, originally found in bears, and is apparently a precursor or product of chenodeoxycholate. Administration of ursodeoxycholate alters bile composition and may dissolve gallstones. It is used as a choleretic agent and choleretic drug. Ursodeoxycholate (trade name: ursodeoxycholic acid) is a naturally occurring bile acid used to treat a variety of liver and gastrointestinal diseases. Ursodeoxycholate can modulate the bile acid pool, potentially altering the structure of the gut microbiota. In turn, the gut microbiota can modulate the bile acid pool, highlighting the interrelationships of the gut microbiota-bile acid-host axis. Despite these interactions, whether and how exogenous ursodeoxycholate affects the gut microbiota structure and bile acid pool in conventional mice remains unclear. This study aimed to elucidate how ursodeoxycholate alters the gastrointestinal ecosystem in conventional mice. C57BL/6J wild-type mice were administered three doses of ursodeoxycholate (50, 150, or 450 mg/kg/day) by gavage for 21 days. Changes in gut microbiota and bile acids were examined in feces, ileum and cecum contents. Serum bile acid levels were also examined. Mice treated with low and high doses of ursodeoxycholic acid showed significant weight loss. The microbial community structure and bile acid pool in the ileum and cecum contents were altered compared to pretreatment levels; similar longitudinal changes were observed in feces after 21 days of ursodeoxycholic acid treatment. Members of the Lachnospiraceae family made significant contributions to the observed changes in the ileum and cecum contents. This study provides the first comprehensive account of how exogenous ursodeoxycholic acid shapes a healthy gastrointestinal ecosystem in conventional mice. Further research into how these changes, in turn, affect the host’s physiological responses is crucial. [1] Ursodeoxycholic acid is currently the only drug approved for the treatment of chronic cholestatic liver disease. It has cytoprotective, anti-apoptotic, membrane-stabilizing, antioxidant and immunomodulatory effects. Long-term use of ursodeoxycholic acid can prolong the survival of patients with primary biliary cirrhosis (PBC) and delay liver transplantation. There is evidence that ursodeoxycholic acid may even prevent the progression of histological staging of primary biliary cholangitis (PBC). It also has beneficial effects on primary sclerosing cholangitis, intrahepatic cholestasis of pregnancy, cystic fibrosis-related liver disease, chronic graft-versus-host disease, total parenteral nutrition-related cholestasis, and various pediatric cholestatic liver diseases. This review discusses the current understanding of the mechanism of action of ursodeoxycholic acid and its role in the treatment of various liver diseases. [3]

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Prophylaxis of SARS-CoV-2 infection by modulating viral host receptors (e.g., angiotensin-converting enzyme 2 (ACE2)) ¹ may represent a new approach to COVID-19 chemoprevention as a complement to vaccination ^2,3. However, the mechanism by which ACE2 expression is controlled remains unclear. This study demonstrates that the farnesoid X receptor (FXR) is a direct regulator of ACE2 transcription in various COVID-19-affected tissues, including the gastrointestinal and respiratory systems. We then used the over-the-counter compound Z-cougurone and the off-patent drug ursodeoxycholic acid (UDCA) to reduce FXR signaling and downregulate ACE2 expression in human lung, bile duct cells, intestinal organoids, and corresponding tissues in mice and hamsters. We found that UDCA-mediated ACE2 downregulation reduced susceptibility to SARS-CoV-2 infection in vitro, in vivo, and in vitro perfused human lung and liver. Furthermore, we found that UDCA reduced ACE2 expression in human nasal epithelial cells. Finally, using retrospective registry data, we determined the association between UDCA treatment and favorable clinical outcomes after SARS-CoV-2 infection and confirmed these findings in an independent liver transplant recipient validation cohort. In summary, we demonstrate that FXR plays a role in controlling ACE2 expression and provide evidence that modulating this pathway may contribute to reducing SARS-CoV-2 infection, paving the way for future clinical trials. [4]

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Bile acids are known to play an important role as detergents in the absorption of hydrophobic nutrients and as signaling molecules in metabolic regulation. We tested a novel hypothesis that naturally occurring bile acids interfere with protein-mediated uptake of long-chain free fatty acids (LCFAs) in the liver. To this end, we incubated stable cell lines expressing fatty acid transporters, as well as primary hepatocytes from mouse and human livers, with primary and secondary bile acids to determine their effects on LCFA uptake. We found that ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA) were the two most potent inhibitors of liver-specific fatty acid transporter 5 (FATP5). Both UDCA and DCA inhibited the uptake of long-chain fatty acids (LCFAs) by primary hepatocytes in an FATP5-dependent manner. Subsequently, we treated mice in vivo with these secondary bile acids to evaluate their ability to inhibit diet-induced hepatic triglyceride accumulation. In vivo injection of DCA or its use as part of a high-fat diet significantly inhibited the uptake of fatty acids in the liver and reduced liver triglyceride levels by more than 50%. Conclusion: These data suggest that specific bile acids, particularly the secondary bile acid DCA, play a novel role in regulating hepatic LCFA uptake. The results reveal a previously unrecognized way in which specific bile acids such as ursodeoxycholic acid (UDCA) and deoxycholic acid (DCA) affect hepatic triglyceride metabolism and may provide new approaches to combat obesity-related fatty liver disease. [5]

C24H39O4-.NA+

414.55386

414.274

C, 69.53; H, 9.48; Na, 5.55; O, 15.44

2898-95-5

Ursodeoxycholic acid;128-13-2

23707110

White to off-white solid powder

2.98E-14mmHg at 25°C

3.143

2

4

4

29

612

10

C[C@H](CCC(=O)[O-])[C@H]1CC[C@@H]2[C@@]1(CC[C@H]3[C@H]2[C@H](C[C@H]4[C@@]3(CC[C@H](C4)O)C)O)C.[Na+]

WDFRNBJHDMUMBL-FUXQPCDDSA-M

InChI=1S/C24H40O4.Na/c1-14(4-7-21(27)28)17-5-6-18-22-19(9-11-24(17,18)3)23(2)10-8-16(25)12-15(23)13-20(22)26;/h14-20,22,25-26H,4-13H2,1-3H3,(H,27,28);/q;+1/p-1/t14-,15+,16-,17-,18+,19+,20+,22+,23+,24-;/m1./s1

sodium;(4R)-4-[(3R,5S,7S,8R,9S,10S,13R,14S,17R)-3,7-dihydroxy-10,13-dimethyl-2,3,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydro-1H-cyclopenta[a]phenanthren-17-yl]pentanoate

2898-95-5; Ursodeoxycholate sodium; Sodium Ursodeoxycholate; Ursodeoxycholic Acid Sodium Salt; YKU915YJNV; Ursodeoxycholic acid (sodium); Cholan-24-oic acid, 3,7-dihydroxy-, sodium salt (1:1), (3alpha,5beta,7beta)-; 2898-95-5 (sodium);

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment, avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO : ~125 mg/mL (~301.53 mM)
H2O : ≥ 100 mg/mL (~241.23 mM)

Solubility in Formulation 1: ≥ 2.08 mg/mL (5.02 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.08 mg/mL (5.02 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.08 mg/mL (5.02 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)