Digestion Of Dietary Fat Research Articles

Natural Polyphenol-Rich Inhibitors of Pancreatic Lipase for Obesity Management – A Systematic Review

Background: Obesity, a critical public health challenge, is associated with an increased risk of chronic diseases such as cardiovascular disease, diabetes, and cancer. Body mass index (BMI) categorizes obesity levels, with trends indicating a growing prevalence worldwide. Dietary choices and sedentary lifestyles contribute significantly to this condition, yet treatments remain limited by side effects. Pancreatic lipase, the primary enzyme in dietary fat digestion, presents a promising target for obesity management. Inhibitors of pancreatic lipase reduce fat absorption, lowering caloric intake and aiding in weight management. Synthetic inhibitors like orlistat are effective but lead to adverse gastrointestinal and systemic effects, creating a demand for safer alternatives. Methods: A thorough literature review was conducted using PubMed, Elsevier, ScienceDirect, and Google Scholar databases, employing search terms such as "herbal drugs," "polyphenols," "pancreatic lipase inhibitors," "antilipase," "natural products," and "antiobesity herbal drugs." Discussion and Conclusion: Polyphenol-rich plants such as Camellia sinensis (tea), Coffea (coffee), Punica granatum (pomegranate), Vitis vinifera (grape), and Curcuma longa (turmeric) exhibit natural pancreatic lipase inhibitory properties, offering therapeutic potential for obesity management. This review explores the bioactive compounds in these plants, emphasizing their efficacy and minimal side effects compared to synthetic drugs, and underscores the importance of further research in developing natural, polyphenol-based treatments for obesity.

In Vitro Efficacy of Formulated Protected Fat from Used Cooking Oil (UCO) on Gas Production, Nutrient Digestibility and Rumen Fermentation

This study was designed to determine in vitro gas production, nutrients digestibility, and rumen fermentation products of supplementary formulated dietary protected fat (PF) from used cooking oil (UCO). The dietary fat treatment was formulated from used cooking oil protected fat (UCOPF) and compared with other four dietary fat treatment were used cooking oil (UCO) and palm olein (PO which are active fat; palm olein protected fat (POPF) and commercial protected fat (CPF) which are inert fat added at 12 mg of dry matter (DM) in the 200 mg of basal diet (70:30 roughage to concentrate ratio). Control group contain basal diet without dietary fat supplement. Supplementation of dietary fat had no effect on gas production, pH, organic matter digestibility (OMD) and volatile fatty acid volatile fatty acids (VFA). The addition of fat in the form of oil and protected fat to in vitro setups up to 12 mg did not adversely affect the characteristics of rumen fermentation suggests that fat has a smaller impact on production of gas, digestibility of nutrients, and rumen fermentation products.

Synthesis and pancreatic lipase inhibition activity evaluation ofaurone derivatives with substituents on benzylidene ring

Pancreatic lipase is an essential enzyme for the digestion and absorption of dietary fat. Inhibiting this enzyme is one of the strategies in tackling obesity. To date, orlistat is the only Food and Drug Administration (FDA)-approved drug for obesity treatment via this mechanism. Therefore, there has been a growing interest in exploring novel compounds with natural structural frameworks that can give similar activity with fewer side effects. In this study, we describe the synthesis and pancreatic lipase inhibitory activity evaluation of 10 aurone derivatives with different substituents on the benzylidene ring. Aurone derivatives were synthesised through aldol condensation of benzofuranone and corresponding benzaldehyde derivatives with medium to good yields (45-73%). Pancreatic lipase inhibitory activities of synthesized compounds were determined by UV-Vis spectroscopy with quercetin and orlistat as references. Three aurones were found to have higher I% than quercetin at the same concentration (50 μg/ml). Compound 5c (2-(5’bromo-2’-hydroxybenzylidene)benzofuran-3(2H)-one) exhibited the greatest activity (I%=60.95%), better than quercetin (I%=27.20%) at the concentration of 50 μg/ml

Identification of Novel Thiazolidinedione Based Pancreatic Lipase Inhibitors for the Management of Obesity Using In Silico Approach

AbstractAccumulation of excessive fat in the body is an indication of obesity, which is becoming an alarming health concern around the world. Pancreatic lipase has been found to have a promising role in the digestion of dietary fats thereby inhibition of pancreatic lipase can be a therapeutic strategy for the management of obesity. Literature showed the anti‐pancreatic lipase potential of thiazolidinediones thereby the current study is designed to identify substituted thiazolidinedione‐based molecules as pancreatic lipase inhibitors. A 3D QSAR model with R2 value of 0.7283 and Stability of 0.843 was generated to determine the nature of substitution necessary for the inhibitory activity. Based on the generated 3D QSAR, the activity of 352 novel‐designed molecules was predicted and further screened through pharmacokinetic parameters. These compounds were docked into the binding site of the pancreatic lipase which led to the identification of 14 hit molecules with dock score between −9.523 to −7.604 kcal/mol. The molecular simulation studies and free energy calculation of the hit compounds i. e. 87 and 80 revealed good stability and binding in the active site of pancreatic lipase. The current study provides 14 hit molecules, which can be synthesized and further evaluated to explore their anti‐pancreatic lipase inhibitory activity.

Characterisation of pancreatic lipase inhibitors from Brassica rapa L. ssp. chinensis.

Obesity has become a significant global health concern, affecting millions of people worldwide. One well-studied approach to identifying potential anti-obesity agents is the inhibition of pancreatic lipase (PL), an enzyme responsible for dietary fat digestion. This study investigated the inhibitory effects and mechanisms of galactolipid monogalactosyldiacylglycerol (MGDG), that was extracted from Brassica rapa ssp. chinensis on PL. Five different MGDG compounds were isolated and the results showed that compounds containing shorter fatty acid side chains and a higher degree of unsaturated bonds exhibit a greater inhibition effect on PL. Interestingly, both the kinetic study and the molecular docking prediction revealed a non-competitive inhibition of MGDG. Furthermore, the in vitro digestion model also showed that the consumption of MGDG extract with salad dressing was effective in delaying enzymatic fat digestion in a dose-dependent manner. These results suggest that MGDG from Brassica rapa ssp. chinensis may be a promising candidate for developing novel anti-obesity therapies.

Investigating the role of indole and quinazolinone-based hybrid analogues with ketoamide fragment and alkyl extension for potential PL inhibition

Pancreatic lipase (PL) is a key enzyme responsible for the digestion of dietary fat. Hence the inhibition of PL is an effective strategy for mitigating obesity. In this study, a novel series of 18 indolyl oxoacetamide–quinazolinone hybrid analogues (9a-h, 13aa-13fd) were designed, synthesized, and evaluated for PL inhibition activity. An approach of molecular hybridization was utilized by considering the PL inhibitory potential of indole, α-ketoamide, and quinazolinone scaffolds. A Propyl linker was attached for better binding at the PL active site, leading to enhanced PL inhibitory potential. Among all the synthesized analogues, 13be exhibited the highest PL inhibitory activity (IC50 = 4.71 ± 0.851 μM) with a docking score of -147.06 kcal/mol. The activities of all the synthesized analogues were compared with the orlistat (IC50 = 0.86 ± 0.090 µM). The most potent analogue, 13be revealed the competitive mode of enzyme inhibition with the Ki value of 1.826 µM. The molecular docking and dynamics simulation analysis also revealed the strong binding of 13be at the active site of PL. Interestingly, the potent analogue 13be when tested on RAW 264.7 cell line using MTT assay, was found to be nontoxic at a concentration range of 1-20 µM. Therefore, the current work validates the effectiveness of the molecular hybridization approach for designing indolyl oxoacetamide–quinazolinone hybrids for inhibiting PL.

Bridging the Gap from Enterotypes to Personalized Dietary Recommendations: A Metabolomics Perspective on Microbiome Research.

Advances in high-throughput DNA sequencing have propelled research into the human microbiome and its link to metabolic health. We explore microbiome analysis methods, specifically emphasizing metabolomics, how dietary choices impact the production of microbial metabolites, providing an overview of studies examining the connection between enterotypes and diet, and thus, improvement of personalized dietary recommendations. Acetate, propionate, and butyrate constitute more than 95% of the collective pool of short-chain fatty acids. Conflicting data on acetate's effects may result from its dynamic signaling, which can vary depending on physiological conditions and metabolic phenotypes. Human studies suggest that propionate has overall anti-obesity effects due to its well-documented chemistry, cellular signaling mechanisms, and various clinical benefits. Butyrate, similar to propionate, has the ability to reduce obesity by stimulating the release of appetite-suppressing hormones and promoting the synthesis of leptin. Tryptophan affects systemic hormone secretion, with indole stimulating the release of GLP-1, which impacts insulin secretion, appetite suppression, and gastric emptying. Bile acids, synthesized from cholesterol in the liver and subsequently modified by gut bacteria, play an essential role in the digestion and absorption of dietary fats and fat-soluble vitamins, but they also interact directly with intestinal microbiota and their metabolites. One study using statistical methods identified primarily two groupings of enterotypes Bacteroides and Ruminococcus. The Prevotella-dominated enterotype, P-type, in humans correlates with vegetarians, high-fiber and carbohydrate-rich diets, and traditional diets. Conversely, individuals who consume diets rich in animal fats and proteins, typical in Western-style diets, often exhibit the Bacteroides-dominated, B-type, enterotype. The P-type showcases efficient hydrolytic enzymes for plant fiber degradation but has limited lipid and protein fermentation capacity. Conversely, the B-type features specialized enzymes tailored for the degradation of animal-derived carbohydrates and proteins, showcasing an enhanced saccharolytic and proteolytic potential. Generally, models excel at predictions but often struggle to fully elucidate why certain substances yield varied responses. These studies provide valuable insights into the potential for personalized dietary recommendations based on enterotypes.

Diet Quality and Fecal Bile Acid Composition

Background: Bile acids (BAs) are steroid metabolites generated by the liver from cholesterol. Their function is to support digestion of dietary fat, cholesterol, and fat-soluble vitamins. The gut microbiota metabolizes BAs that escape intestinal reabsorption to secondary BAs and other metabolites that are linked to increased risk of diseases including colorectal cancer (CRC). Diet plays a major role in BA metabolism and may be an important target for optimizing host-microbial BA metabolism for cancer prevention. Purpose: To examine fecal BA metabolites in relation to diet quality (Healthy Eating Index-2015, HEI-2015) among urban middle to older age adults. Methods: 135 participants were recruited from two academic medical centers. Stool, two 24-hour diet recalls, anthropometrics, and survey data were collected. Fecal BA profiling was completed using LC/MS. Diet quality was calculated using USDA's HEI-2015. Descriptive and inferential statistics were conducted. Results: Participants were 57% female, 51% African/American Black, mean age of 59.6 (±6.2) years and mean BMI of 31.4 (±6.9) kg/m2. Using USDA's cut-point for poor diet quality (HEI-2015 < 51 points), participants with poor diet quality were significantly more likely to be classified with obesity, self-report as African American/Black, report lower educational attainment, have increased secondary BAs, deoxycholic acid (DCA) and lithocholic acid (LCA), and lower 3-oxo-lithocholic acid and iso-allo-deoxycholic acid derivatives. In linear models, HEI-2015 (continuous) was a significant inverse predictor of DCA and LCA when controlling for BMI, race, and education. BMI was a significant positive predictor of DCA and LCA when controlling for HEI-2015, race, education. African American/Black was a significant inverse predictor of 3-oxo-lithocholic acid and iso-allo-deoxycholic acid when controlling for HEI-2015, BMI, and education. Conclusion. Poor diet quality and elevated BMI is associated with increased secondary BAs that have been linked to increased risk of CRC. Improving diet quality and reducing BMI may optimize host-microbial BA metabolism to prevent disease. African American/Black was an independent predicator of lower anti-inflammatory BA derivatives which warrants further investigation.

Inquiry on a Potential Anti-Obesity Agent

This study introduces a practical work activity that allows students to investigate the inhibitory effects of seed extracts on pancreatic lipase activity. The activity is related to the issue of the ongoing global obesity epidemic and involves the use of materials and chemicals readily available in high school laboratories. We show how the activity can help students understand how scientists can control the reaction rates of key enzymes involved in the digestion of dietary fat, to combat obesity. The activity also illustrates how instructional scaffolding can help students understand important procedures related to the design, measurement, and handling of data which are critical in ensuring success among students performing scientific investigations.

The Effect of Different Zinc Sources on Biochemical Parameters, Intestinal Morphology, Carcass Characteristics and Performance in Finishing Lambs.

To investigate the effect of different sources of zinc supplements on blood serum parameters, nutrient digestibility, growth performance, carcass characteristics, and intestinal morphology, 18 male Zandi lambs (with initial body weight of 31 ± 1.2kg and 120 ± 8days old) were divided into three groups, six animals each in a completely random design. Experimental treatments include (1) control treatment of basal diet without zinc supplementation, (2) basal diet with 40mg/kg of zinc supplementation from zinc sulfate source, and (3) basal diet with 40mg/kg of zinc supplementation with origin it was organic (Zn-peptide). All lambs were kept in individual pens with cemented floor and provision of individual feeding and watering. Mean daily weight gain increased with zinc supplementation (P < 0.05), but feed intake and feed conversion ratio were not affected by zinc supplementation in the diet. Zinc supplementation increased the apparent digestibility of the dry matter (P < 0.05), but the digestibility of dietary fat, neutral detergent fiber (NDF), and acid detergent fiber (ADF) were not affected by zinc supplementation. In this experiment, the addition of organic and inorganic supplements to the diet of fattening lambs had no significant effect on serum triglyceride, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and glucose concentrations, and carcass traits. The concentration of aspartate aminotransferase (AST) enzyme in the zinc sulfate group was significantly higher than the control and organic zinc groups (P < 0.05). Concentrations of blood urea nitrogen were lower in zinc fed lambs, compared to control (P ≤ 0.05). The villi width in the duodenum was higher in the zinc supplementation treatments (P < 0.05). Also, in the ileum section, the height of the villi in the treatment of zinc sulfate supplement was higher, compared to the complement and control (P < 0.05). The results of this study showed that Zn supplementation, regardless of its source, improved growth performance in fattening lambs. However, no effect was observed on feed intake and efficiency, carcass traits, and blood parameters.

In vitro anti-obesity activity by pancreatic lipase inhibition - Simple HPLC approach using EVOO as natural substrate.

Pancreatic lipase (PL) is a key lipolytic enzyme in humans for the digestion and absorption of dietary fats. Thereby, PL is a well-recognized target in the management of obesity and its inhibition attracts the interest of researchers globally. The screening of new natural PL inhibitors as alternative strategy to the synthesis of chemical ones represents nowadays a hot topic in research. The main challenge in this matter is the lack of a universal analytical method allowing the monitoring of PL activity and the reliable quantification of lipid digestion products. The (normal phase)-high-performance liquid chromatography-evaporative light scattering detector [(NP)-HPLC-ELSD] method proposed in this work represents a direct and rapid strategy to simultaneously quantify the products obtained from in vitro PL digestion. As one of the main novelties, the triacylglycerol (TAG) fraction from extra-virgin olive oil was selected as natural substrate. The PL activity was measured by monitoring the levels of remaining TAGs and formed free fatty acids (FFAs), using Orlistat as known inhibitor. The method validation confirmed the adequacy of the analytical method for quantitative purposes, showing high recovery percentage values (between 99% and 103%) and low relative standard deviation (RSD%) values (between 2% and 7%) for triolein and oleic acid standard solutions, as well as appreciably low limit of detection (LOD) and limit of quantification (LOQ) values (respectively 58 and 177 ng mL-1 for triolein; 198 and 602 ng mL-1 for oleic acid). Finally, the developed HPLC-ELSD method was successfully applied to evaluate the inhibitory effect of a polyphenolic extract obtained from apple pomace. The results showed a comparable inhibition degree between a 4.0mg mL-1 apple pomace solution and a 1.0μg mL-1 Orlistat solution. The proposed innovative method reveals highly sensitive and simple to follow the fate of PL digestion, thus opening the way to further investigations in the research of new potentially anti-obesity compounds. © 2022 Society of Chemical Industry.

Effect of exogenous bile salts supplementation on the performance and hepatic lipid metabolism of aged laying hens.

Bile acids (BA), a series of hydroxylated steroids secreted by the liver, are involved in the digestion and absorption of dietary fats. In the present study, the effect of exogenous BAs on the performance and liver lipid metabolism of laying hens was investigated. Three hundred and sixty 50-wk-old Hy-line Brown hens were randomly allocated into three groups and subjected to one of the following treatments: fed with the basal diet (control, Con), the basal diet supplemented with 0.1 g/kg (0.1 g/kg BAs), or 0.2 g/kg (0.2 g/kg BAs) porcine BAs. Laying performance, egg quality, and blood parameters were measured during the 8-wk experimental period. The expression of genes related to hepatic lipid metabolism was determined at the end of experiment. The results showed that BAs treatments had no influence (P > 0.05) on laying rate, egg weight, and feed efficiency. BAs treatment, however, significantly decreased mortality of hens (P = 0.006). BAs treatment showed a transient negative influence on eggshell quality at week 4 but not at week 8. The yolk color on week 8 was increased by BAs treatments (P < 0.0001) compared to control. The duodenum index showed a tendency to be increased (P = 0.053) and jejunum index were increased (P = 0.007) by BAs treatment. Compared to control, BAs treatments decreased lipid droplet content (P < 0.0001) and TG content (P = 0.002) of liver. Fatty acid synthase activity was also decreased as an effect of BAs dietary supplementation. Compared to the control group, 0.1 g/kg BAs treatment increased (P < 0.05) the mRNA expression of genes Farnesoid X receptor (FXR) (P = 0.042), cytochrome P450 family 7 subfamily A member 1 (CYP7A1) (P = 0.002), and cytochrome P450 family 8 subfamily B member 1 (CYP8B1) (P = 0.017), fatty acid synthase (FAS) (P = 0.020), acetyl-CoA carboxylase (ACC) (P = 0.032), sterol regulatory element binding protein-1c (SREBP-1c) (P = 0.037), proliferator-activated receptor gamma (PPARγ) (P = 0.002), apolipoprotein B (APO-B) (P = 0.020), and very low density lipoprotein receptor (VLDLR) (P = 0.024). In conclusion, the addition of exogenous BAs reduces lipid accumulation in liver. BA supplementation reduces the mortality of hens and improves egg yolk color, with no unfavorable effect on laying performance. The result suggests that suppressed FAS activity is involved in the reduced hepatic lipid accumulation by BAs treatment.

Cholestasis associated to inborn errors in bile acid synthesis

Several metabolic pathways are involved in the biotransformation of C27 neutral cholesterol to C24 primary bile acids (BAs), mainly cholic acid (CA) and chenodeoxycholic acid (CDCA), which are then conjugated with glycine or taurine. This process can start with the modification of the steroid ring or the shortening of the side chain and involves enzymes present in different subcellular compartments. Inborn errors affecting the biogenesis of organelles, such as peroxisomes, or the expression or function of specific enzymes of these convergent routes result in: i) the lack of mature C24-BAs, with the subsequent impairment in digestion and absorption of dietary fat and liposoluble vitamins, such as vitamin K, which may account for a deficient hepatic synthesis of several coagulation factors; ii) the accumulation of intermediate metabolites, which may affect hepatocyte physiology, causing cholestasis as a commonly shared alteration besides other deleterious hepatic events; and iii) extrahepatic clinical manifestations due to accumulation of toxic metabolites in other territories, such as the nervous system, causing neurological disorders. In general, diseases whose primary alteration is a genetic defect in BA synthesis are diagnosed in children or young individuals with a very low incidence. The symptomatology can markedly vary among individuals, ranging from mild to severe conditions. Oral therapy, based on the enrichment of the BA pool with natural C24-BAs, such as CA, CDCA, glyco-CA, or ursodeoxycholic acid (UDCA), depending on the exact deficiency causing the disease, may be beneficial in preventing life-threatening situations. In contrast, in other cases, a liver transplant is the only option for these patients. This review describes the updated information on the genetic and molecular bases of these diseases and the current approaches to achieve a selective diagnosis and specific treatment.

Natural mimetic 4-benzyloxychalcones as potent pancreatic lipase inhibitors: Virtual screening, synthesis and biological evaluation

Pancreatic lipase is a well-known target for obesity drug development. The inhibition of this enzyme mitigates the digestion and absorption of dietary fat. Despite some inconvenient side effects, orlistat is currently the only medication with FDA approval that works by inhibition of pancreatic lipase. Several natural flavonoids, including chalcones, have been reported to possess promising lipase inhibitory activity. In this paper, we describe the evaluation of the lipase inhibitory activity of our in-house natural mimetic chalcone library via virtual screening, followed by the synthesis and biological evaluation of the hits. Compound C82 showed low-micromolar activity against pancreatic lipase in vitro (IC 50 = 1.01 ± 0.86 µM). The interaction of C82 and lipase was additionally confirmed by a fluorescence quenching study. • Natural mimetic 4-benzyloxychalcone derivatives were identified as potential pancreatic lipase by computational methods. • Six 4-benzyloxychalcone derivatives were synthesized and evaluated for in vitro pancreatic lipase inhibitory activity. • Compound C82 showed low-micromolar activity • The interaction of compound C82 and pancreatic lipase was confirmed by a fluorescence quenching experiment.

Visual Identification of Trichosporon asahii, a Gut Yeast Associated with Obesity, Using an Enzymatic NIR Fluorescent Probe.

Lipase found in the gut microbiota participates in the digestion and absorption of dietary fats. As such, the gut microbiota is involved in the regulation of the host metabolism, affecting the levels of lipids and free fatty acids, ultimately resulting in obesity. In this study, an enzymatic activatable near-infrared fluorescent probe, DDAO-C6, was developed for visually sensing endogenous lipase from gut microbes. Using DDAO-C6, a cultivated intestinal yeast strain was rapidly identified from human feces that exhibited high lipase expression and was identified as Trichosporon asahii Y2. We then determined that the colonization of the gut of mice with T. asahii Y2 increased lipase activity in the digestive tract and promoted obesity and hyperlipidemia when the mice were fed high fat diets. Above all, the present research resulted in a fluorescence visualization tool for the functional investigation of gut microbiota associated with obesity and disorders of lipid metabolism.

Free Linoleic Acid and Oleic Acid Reduce Fat Digestion and Absorption In Vivo as Potent Pancreatic Lipase Inhibitors Derived from Sesame Meal

Pancreatic lipase catalyzes the cleavage of triacylglycerols at the oil–water interface, and is known as the dominant determiner of dietary fat digestion. Reducing dietary fat digestion and absorption by modulating the activity of pancreatic lipase has become a favorable strategy to tackle obesity. Orlistat is, at present, the only pancreatic lipase inhibitor approved for the treatment of obesity; however, an array of gastrointestinal adverse effects associated with orlistat limits its tolerability. As a safe alternative to orlistat, a number of natural product-derived compounds with varying degrees of pancreatic lipase inhibitory activity have been reported. We herein reported that bioactivity-guided fractionation of sesame meal led to the identification of free linoleic acid and oleic acid as potent inhibitors of porcine pancreatic lipase in vitro with an IC50 of 23.1 µg/mL (82.4 µM) and 11.7 µg/mL (41.4 µM), respectively. In rats, a single oral dose of the mixture of these fatty acids significantly suppressed the elevation of blood triacylglycerol level following fat intake. These results substantiate the role of free linoleic acid and oleic acid as a novel class of natural product-derived functional molecules that act as pancreatic lipase inhibitors, and their potential for healthy, routine-based weight management.

Bile acids induce Ca2+ signaling and membrane permeabilizations in vagal nodose ganglion neurons

Bile acids (BAs) play an important role in the digestion of dietary fats and act as signaling molecules. However, due to their solubilizing properties, high concentrations in the gut may negatively affect gut epithelium and possibly afferent fibers innervating the gastrointestinal tract (GI). To determine the effect of BAs on intracellular Ca2+ and membrane permeabilization we tested a range of concentrations of two BAs on vagal nodose ganglion (NG) neurons, Chinese Hamster Ovary (CHO), and PC12 cell lines. NG explants from mice were drop-transduced with the genetically encoded Ca2+ indicator AAV9-Syn-jGCaMP7s and used to measure Ca2+ changes upon application of deoxycholic acid (DCA) and taurocholic acid (TCA). We found that both BAs induced a Ca2+ increase in NG neurons in a dose-dependent manner. The DCA-induced Ca2+ increase was dependent on intracellular Ca2+ stores. NG explants, with an intact peripheral part of the vagus nerve, showed excitation of NG neurons in nerve field recordings upon exposure to DCA. The viability of NG neurons at different BA concentrations was determined, and compared to CHO and PC12 cells lines using propidium iodide labeling, showing threshold concentrations of BA-induced cell death at 400–500 μM. These observations suggest that BAs act as Ca2+-inducing signaling molecules in vagal sensory neurons at low concentrations, but induce cell death at higher concentrations, which may occur during inflammatory bowel diseases.

Bile acids directly bind and allosterically regulate the epithelial sodium channel

Bile acids are critical for the digestion and absorption of dietary fats and have important roles as signaling molecules. Bile acids are normally restricted to the enterohepatic circulation, but can be elevated in the blood and urine of patients with advanced liver diseases. The epithelial sodium channel (ENaC) mediates Na+ transport in the biliary epithelium, where it regulates bile viscosity, and in the aldosterone‐sensitive distal nephron, where it regulates extracellular fluid volume. We previously showed that bile acid regulation of ENaC depends on the position and stereochemistry of specific functional groups, but not on their chemico‐physical properties. To determine whether bile acids regulate ENaC in ex vivo native tissues, we performed patch clamp experiments on isolated split open renal tubules from mice, using recording pipettes backfilled with taurocholic acid (t‐CA) or taurohyodeoxycholic acid (t‐HDCA). Consistent with in vitro experiments, t‐CA increased ENaC open probability (PO) by 2‐fold while t‐HDCA decreased ENaC PO by nearly two‐thirds. To determine whether bile acids regulate ENaC through direct binding, we performed photoaffinity labeling experiments. We employed a bile acid derivative (p‐DCA) with diazirine and terminal alkyne groups that facilitate uv‐crosslinking and affinity purification, respectively. Using cultured Fisher Rat Thyroid cells transfected with ENaC, we found that the deoxycholic acid derivative (p‐DCA) crosslinked to the α, β, and γ subunits. To determine whether crosslinking was specific, we performed experiments in the presence of competing bile acids. Crosslinking to the β subunit was significantly reduced in the presence of deoxycholic acid (DCA). Crosslinking to the γ subunit was significantly reduced by taurocholic acid (t‐CA). These data suggest direct binding and multiple sites. To determine the effect of subunit composition on regulation, we measured the effect of t‐CA on Li+ currents in Xenopusoocytes expressing different functional ENaC subunit combinations. Channels composed of α subunits alone were strongly activated by t‐CA, followed by αβγ‐ and αβ‐ channels, suggesting that the α subunit is sufficient for ENaC sensitivity to t‐CA. Our data are consistent with bile acids directly binding all three ENaC subunits at multiple sites. Bile acid moieties provide for selective preferences for each of the sites, resulting in distinct effects for each bile acid.

Molecular Regulation of Bile Acid Homeostasis.

Bile acids have been known for decades to aid in the digestion and absorption of dietary fats and fat-soluble vitamins in the intestine. The development of gene knockout mice models and transgenic humanized mouse models have helped us understand other functions of bile acids, such as their role in modulating fat, glucose, and energy metabolism, and in the molecular regulation of the synthesis, transport, and homeostasis of bile acids. The G-protein coupled receptor TGR5 regulates the bile acid induced alterations of intermediary metabolism, whereas the nuclear receptor FXR regulates bile acid synthesis and homeostasis. However, this review indicates that unidentified factors in addition to FXR must exist to aid in the regulation of bile acid synthesis and homeostasis. SIGNIFICANCE STATEMENT: This review captures the present understanding of bile acid synthesis, the role of bile acid transporters in the enterohepatic circulation of bile acids, the role of the nuclear receptor FXR on the regulation of bile acid synthesis and bile acid transporters, and the importance of bile acids in activating GPCR signaling via TGR5 to modify intermediary metabolism. This information is useful for developing drugs for the treatment of various hepatic and intestinal diseases, as well as the metabolic syndrome.

The effect of feed processing of novel unheated, low trypsin inhibitor soybeans on the performance of young female turkeys reared from hatch to 21 days of age

The objective of this study was to evaluate the effects of dietary inclusion of a novel low trypsin inhibitor soybean (LTI) fed as mash or crumbled pellet form on the productive performance and digestibility in turkey poults from hatch to 21 d. A total of 336 Hybrid Converter turkey poults were allocated in groups of 7 to 6 treatments, each with 8 replicate cages. Treatments were arranged as a 3 × 2 factorial with inclusion level of the low trypsin-inhibitor soybean (0, 20, and 40% LTI) and feed form (mash and crumbled pellet). A single batch of feed was mixed for each inclusion level and divided into 2 aliquots: one remaining as mash and the other conditioned at 82°C for approximately 30 s, pelleted and then crumbled. On d 7, 14, and 21 posthatching, BW, and feed intake (FI) were recorded and BW gain (BWG) and feed conversion ratio (FCR) calculated. Excreta samples were collected from d 19 to 21 and pooled by cage. At d 21, intestines were excised, pancreas weights recorded (PRW), and ileal contents collected. There were no interactions (linear, P > 0.05) between LTI inclusion and feed form on BW, BWG, FI, or FCR at d 7 or 21. Increasing LTI resulted in a linear reduction in BW at 7, 14, and 21 d (P < 0.006). Poults fed crumbles were significantly heavier at d 21 than those fed mash feed (P < 0.027) with no interaction of LTI level with feed form. FCR was not significantly greater with increasing LTI. However, poults fed crumbles had a better, lower FCR that those fed mash feed from d 0 to 21 (P < 0.018). There was a significant interaction between feed form and LTI level at 14 d (P < 0.031), but not 7 or 21 d. Pancreatic hypertrophy (PRW) increased linearly with increasing LTI (P < 0.001) with a significant linear interaction with feed form (P < 0.001). Poults fed crumbles had less pancreatic hypertrophy. At 21 d of age, dietary fat digestibility (ALD, %) was linearly reduced with increasing LTI (P < 0.001). However, poults fed crumbles had significantly better fat absorption than poults fed mash (91.2 vs. 85.8%) (P < 0.001), and there was a significant linear interaction between feed form and LTI level (P < 0.001). AMEn was significantly better for the poults fed crumbles compared to mash (3228 vs. 3132 kcal/kg) (P < 0.001), and there was a significant linear interaction between feed form and LTI level (P < 0.001). Based on the results this trial, it is possible to include up to 20% unheated full fat LTI soybeans into poult starter diets after pelleting. Pelleting improves nutrient utilization, allowing for greater incorporation of the LTI soybean in the crumbled diet compared to the mash diet.