Berberine (1) is an alkaloid used widely in the treatment of several diseases. However, its physicochemical properties, pharmacokinetics, and metabolism remain unclear, and conflicting data have been reported. In this study, the main physicochemical properties of 1 and its metabolites were evaluated, including lipophilicity, solubility, pKa, and albumin binding. A sensitive HPLC-ESIMS/MS method was developed and validated to identify 1 and its main metabolites in human plasma. This method was used to quantify their levels in the plasma of healthy volunteers and hypercholesterolemic patients following a single dose and chronic administration, respectively. In both cases, berberrubine (2) was found to be the main metabolite. Surprisingly, 2 is more lipophilic than 1, which suggests that this compound tautomerizes to a highly conjugated, electroneutral quinoid structure. This was confirmed by NMR studies. These results indicate that the higher plasma concentration of 2 was a consequence of a more efficient intestinal absorption, suggesting that berberrubine is potentially more pharmacologically active than berberine.

As patients decline from health to type 2 diabetes, glucose-stimulated insulin secretion (GSIS) typically becomes impaired. Although GSIS is driven predominantly by direct sensing of a rise in blood glucose by pancreatic β-cells, there is growing evidence that hypothalamic neurons control other aspects of peripheral glucose metabolism. Here we investigated the role of the brain in the modulation of GSIS. To examine the effects of increasing or decreasing hypothalamic glucose sensing on glucose tolerance and insulin secretion, glucose or inhibitors of glucokinase, respectively, were infused into the third ventricle during intravenous glucose tolerance tests (IVGTTs). Glucose-infused rats displayed improved glucose handling, particularly within the first few minutes of the IVGTT, with a significantly lower area under the excursion curve within the first 10 min (AUC0-10). This was explained by increased insulin secretion. In contrast, infusion of the glucokinase inhibitors glucosamine or mannoheptulose worsened glucose tolerance and decreased GSIS in the first few minutes of IVGTT. Our data suggest a role for brain glucose sensors in the regulation of GSIS, particularly during the early phase. We propose that pharmacological agents targeting hypothalamic glucose-sensing pathways may represent novel therapeutic strategies for enhancing early phase insulin secretion in type 2 diabetes.

Foodborne illnesses caused by pathogenic bacteria represent a widespread and growing problem to public health, and there is an obvious need for rapid detection of food pathogens. Traditional culture-based techniques require tedious sample workup and are time-consuming. It is expected that new and more rapid methods can replace current techniques. To enable large scale screening procedures, new multiplex analytical formats are being developed, and these allow the detection and/or identification of more than one pathogen in a single analytical run, thus cutting assay times and costs. We review here recent advancements in the field of rapid multiplex analytical methods for foodborne pathogenic bacteria. A variety of strategies, such as multiplex polymerase chain reaction assays, microarray-or multichannel-based immunoassays, biosensors, and fingerprint-based approaches (such as mass spectrometry, electronic nose, or vibrational spectroscopic analysis of whole bacterial cells), have been explored. In addition, various technological solutions have been adopted to improve detectability and to eliminate interferences, although in most cases a brief pre-enrichment step is still required. This review also covers the progress, limitations and future challenges of these approaches and emphasizes the advantages of new separative techniques to selectively fractionate bacteria, thus increasing multiplexing capabilities and simplifying sample preparation procedures.

As a continuation of previous efforts in mapping functional hot spots on the bile acid scaffold, we here demonstrate that the introduction of a hydroxy group at the C11β position affords high selectivity for FXR. In particular, the synthesis and FXR/TGR5 activity of novel bile acids bearing different hydroxylation patterns at the C ring are reported and discussed from a structure-activity standpoint. The results obtained led us to discover the first bile acid derivative endowed with high potency and selectivity at the FXR receptor, 3α,7α,11β-trihydroxy-6α-ethyl-5β-cholan-24-oic acid (TC-100, 7) which also shows a remarkable physicochemical and pharmacological profile. Compound 7 combines the excellent physicochemical properties of hydrophilic bile acids such as ursodeoxycholic acid, with the distinct ability to specifically bind and regulate FXR activity in vivo, thus providing a bona fide novel therapeutic agent to treat enterohepatic disorders such as cholestasis, NASH, and inflammatory bowel disease.

We report on the relationship between the structure-pharmacokinetics, metabolism, and therapeutic activity of semisynthetic bile acid analogs, including 6a-ethyl-3a,7a-dihydroxy-5b-cholan-24-oic acid (a selective farnesoid X receptor [FXR] receptor agonist), 6a-ethyl-23(S)-methyl-3a,7a,12a-trihydroxy-5b-cholan-24-oic acid (a specific Takeda G protein-coupled receptor 5 [TGR5] receptor agonist), and 6a-ethyl-3a,7a-dihydroxy-24-nor-5b-cholan-23-sulfate (a dual FXR/TGR5 agonist). We measured the main physicochemical properties of these molecules, including ionization constants, water solubility, lipophilicity, detergency, and protein binding. Biliary secretion and metabolism and plasma and hepatic concentrations were evaluated by high-pressure liquid chromatography-electrospray-mass spectrometry/mass spectrometry in bile fistula rat and compared with natural analogs chenodeoxycholic, cholic acid, and taurochenodexycholic acid and intestinal bacteria metabolism was evaluated in terms of 7a-dehydroxylase substrate-specificity in anaerobic human stool culture. The semisynthetic derivatives detergency, measured in terms of their critical micellar concentration, was quite similar to the natural analogs. They were slightly more lipophilic than the corresponding natural analogs, evaluated by their 1-octanol water partition coefficient (log P), because of the ethyl group in 6 position, which makes these molecules very stable toward bacterial 7-dehydroxylation. The hepatic metabolism and biliary secretion were different: 6a-ethyl-3a,7a-dihydroxy-5b-cholan-24-oic acid, as chenodeoxycholic acid, was efficiently conjugated with taurine in the liver and, only in this form, promptly and efficiently secreted in bile. 6a-Ethyl-23(S)-methyl-3a,7a,12a-trihydroxy-5b-cholan-24-oic acid was poorly conjugated with taurine because of the steric hindrance of the methyl at C23(S) position metabolized to the C23(R) isomer and partly conjugated with taurine. Conversely, 6a-ethyl-3a,7a-dihydroxy-24-nor-5b-cholan-23-sulfate was secreted in bile unmodified and as 3-glucuronide. Therefore, minor structural modifications profoundly influence the metabolism and biodistribution in the target organs where these analogs exert therapeutic effects by interacting with FXR and/or TGR5 receptors.

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Key points• Although diarrhoeal diseases represent a significant health and economic burden to society, therapeutic options remain limited.• While several bile acids are known to stimulate epithelial Cl − secretion, the major driving force for fluid secretion in the intestine, the effects of ursodeoxycholic acid (UDCA) on epithelial transport function are not well described.• We report that in contrast to other bile acids, UDCA exerts anti-secretory actions on colonic epithelial cells in vitro.• In contrast, in vivo administration of UDCA enhances epithelial secretory function, an affect we ascribe to being due to its bacterial metabolism to lithocholic acid. In keeping with this hypothesis, in vivo administration of a metabolically stable analogue of UDCA, 6α-methyl-UDCA, was anti-secretory.• Our findings reveal novel anti-secretory actions of UDCA and suggest that metabolically stable analogues of bile acid may be useful for development as a new class of anti-diarrhoeal drug.Abstract Dihydroxy bile acids, such as chenodeoxycholic acid (CDCA), are well known to promote colonic fluid and electrolyte secretion, thereby causing diarrhoea associated with bile acid malabsorption. However, CDCA is rapidly metabolised by colonic bacteria to ursodeoxycholic acid (UDCA), the effects of which on epithelial transport are poorly characterised. Here, we investigated the role of UDCA in the regulation of colonic epithelial secretion. Cl − secretion was measured across voltage-clamped monolayers of T 84 cells and muscle-stripped sections of mouse or human colon. Cell surface biotinylation was used to assess abundance/surface expression of transport proteins. Acute (15 min) treatment of T 84 cells with bilateral UDCA attenuated Cl − secretory responses to the Ca 2+ and cAMP-dependent secretagogues carbachol (CCh) and forskolin (FSK) to 14.0 ± 3.8 and 40.2 ± 7.4% of controls, respectively (n = 18, P < 0.001). Investigation of the molecular targets involved revealed that UDCA acts by inhibiting Na + /K + -ATPase activity and basolateral K + channel currents, without altering their cell surface expression. In contrast, intraperitoneal administration of UDCA (25 mg kg −1 ) to mice enhanced agonist-induced colonic secretory responses, an effect we hypothesised to be due to bacterial metabolism of UDCA to lithocholic acid (LCA). Accordingly, LCA ( agonist-induced secretory responses in vitro and a metabolically stable UDCA analogue, 6α-methyl-UDCA, exerted anti-secretory actions in vitro and in vivo. In conclusion, UDCA exerts direct anti-secretory actions on colonic epithelial cells and metabolically stable derivatives of the bile acid may offer a new approach for treating intestinal diseases associated with diarrhoea.

Sulphate-bicarbonate-calcium water consumption has a positive effect on lithogenic risk and intestinal transit and allows maintenance of a stable body weight despite a high food intake.