Pancreatic lipase inhibitory constituents from Fructus Psoraleae.

Pancreatic lipase (PL), a crucial enzyme in the digestive system of mammals, has been proven as a therapeutic target to prevent and treat obesity. The purpose of this study is to evaluate and characterize the PL inhibition activities of the major constituents from Fructus Psoraleae (FP), one of the most frequently used Chinese herbs with lipid-lowering activity. To this end, a total of eleven major constituents isolated from Fructus Psoraleae have been obtained and their inhibition potentials against PL have been assayed by a fluorescence-based assay. Among all tested compounds, isobavachalcone, bavachalcone and corylifol A displayed strong inhibition on PL (IC50 < 10 µmol·L-1). Inhibition kinetic analyses demonstrated that isobavachalcone, bavachalcone and corylifol A acted as mixed inhibitors against PL-mediated 4-methylumbelliferyl oleate (4-MUO) hydrolysis, with the Ki values of 1.61, 3.77 and 10.16 µmol·L-1, respectively. Furthermore, docking simulations indicated that two chalcones (isobavachalcone and bavachalcone) could interact with the key residues located in the catalytic cavity of PL via hydrogen binding and hydrophobic interactions. Collectively, these finding provided solid evidence to support that Fructus Psoraleae contained bioactive compounds with lipid-lowering effects via targeting PL, and also suggested that the chalcones in Fructus Psoraleae could be used as ideal leading compounds to develop novel PL inhibitors.

Characterisation and antidiabetic utility of a novel hybrid peptide, exendin-4/gastrin/xenin-8-Gln.

Enteroendocrine derived hormones such as glucagon-like-peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), gastrin and xenin are known to exert complementary beneficial metabolic effects in diabetes. This study has assessed the biological activity and therapeutic utility of a novel GLP-1/gastrin/xenin hybrid peptide, namely exendin-4/gastrin/xenin-8-Gln hybrid, both alone and in combination with the stable GIP mimetic, (DAla2)GIP. Exendin-4/gastrin/xenin-8-Gln increased in vitro insulin secretion to a similar or superior extent, as the parent peptides. Insulinotropic effects were mainly linked to modulation of GLP-1 and neurotensin receptors. Exendin-4/gastrin/xenin-8-Gln also augmented the insulinotropic actions of (DAla2)GIP. Acute administration of exendin-4/gastrin/xenin-8-Gln in mice induced significant appetite suppressive, glucose lowering and insulin secretory effects, with a duration of biological action beyond 8 h. Twice daily administration of exendin-4, exendin-4/gastrin/xenin-8-Gln, either alone or in combination with (DAla2)GIP, reduced circulating glucose, increased plasma insulin as well as improving glucose tolerance, insulin sensitivity and metabolic response to GIP in high fat fed mice. Body weight, food intake, circulating glucagon and amylase activity were unaltered. All hybrid peptide treated high fat mice exhibited marked reductions in LDL-cholesterol and body fat mass. Energy expenditure and locomotor activity were increased in mice treated with exendin-4/gastrin/xenin-8-Gln in combination with (DAla2)GIP. Interestingly, exendin-4 and exendin-4/gastrin/xenin-8-Gln treatment, but not exendin-4/gastrin/xenin-8-Gln in combination with (DAla2)GIP, reduced pancreatic islet and beta-cell area when compared to high fat controls. These studies confirm that unimolecular multi-agonist peptide hormones exert beneficial metabolic effects in diabetes, highlighting their potential as novel treatment strategies.

Caco-2 Cell Conditions Enabling Studies of Drug Absorption from Digestible Lipid-Based Formulations.

PURPOSE: To identify conditions allowing the use of cell-based models for studies of drug absorption during in vitro lipolysis of lipid-based formulations (LBFs). METHODS: Caco-2 was selected as the cell-based model system. Monolayer integrity was evaluated by measuring mannitol permeability after incubating Caco-2 cells in the presence of components available during lipolysis. Pure excipients and formulations representing the lipid formulation classification system (LFCS) were evaluated before and after digestion. Porcine mucin was evaluated for its capacity to protect the cell monolayer. RESULTS: Most undigested formulations were compatible with the cells (II-LC, IIIB-LC, and IV) although some needed mucin to protect against damaging effects (II-MC, IIIB-MC, I-LC, and IIIA-LC). The pancreatic extract commonly used in digestion studies was incompatible with the cells but the Caco-2 monolayers could withstand immobilized recombinant lipase. Upon digestion, long chain formulations caused more damage to Caco-2 cells than their undigested counterparts whereas medium chain formulations showed better tolerability after digestion. CONCLUSIONS: Most LBFs and components thereof (undigested and digested) are compatible with Caco-2 cells. Pancreatic enzyme is not tolerated by the cells but immobilized lipase can be used in combination with the cell monolayer. Mucin is beneficial for critical formulations and digestion products.

[Effect of Electroacupuncture at "Weiwanxiashu" (EX-B 3) on Islet Morphology and the Expression of Pancreatic Glucagon-like Peptide-1 Receptor in Type 2 Diabetes Rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on pancreatic glucagon-like peptide-1 receptor (GLP-1 R), pancreatic and duodenal homeobox 1 (PDX-1) protein expression and blood glucose in type 2 diabetes rats, so as to explore the underlying mechanism of EA treatment in improving type 2 diabetes. METHODS: Sprague-Dawley rats were randomly divided into blank control group, model group, "Weiwanxiashu" (EX-B 3) group, "Xinshu" (BL 15) group, and "Shenshu" (BL 23) group, 12 rats in each group. Diabetes model was established by feeding the rat with high fat and high sugar diet combined with intraperitoneal injection of streptozotocin (35 mg/kg). All the EA groups received 2 Hz, 2 mA continuous wave treatment for 20 min everyday, 6 times per week lasting for 4 weeks. Fasting blood glucose was measured by Roche glucometer before and after treatment. Hematoxylin and eosin (HE) staining and Masson staining were used to detect pancreas morphology. GLP-1 R and PDX-1 protein expressions in the pancreas were detected by Western blot. RESULTS: Compared to the blank control group, fasting blood glucose was significantly increased in the model group(P<0.01), accompanied with shrunken islet area, reduced nucleus counts of islet ß cells, and compensatorily enlarged ß cell nucleus. Compared to the model group, EA intervention significantly reduced fasting blood glucose level only in the EX-B 3 group (P<0.05), partly restored pancreas morphology and nucleus counts of islet ß cells in the EX-B 3, BL 15, and BL 23 groups. Compared to the blank control group, GLP-1 R and PDX-1 expressions were decreased in the model group (P<0.01), while EA treatment could obviously increase GLP-1 R expression in the EX-B 3(P<0.01), BL 15 (P<0.01) and BL 23 (P<0.05) groups compared with the model group. The expression of GLP-1 R in the BL 15 group was the highest among the three EA groups (P<0.05,P<0.01), and that in the EX-B 3 group was higher than in the BL 23 group (P<0.05).There were no signifincant differences in the expression of PDX-1 protein among the three EA groups (P>0.05). CONCLUSIONS: EA treatment at EX-B 3 can reduce blood glucose via regulating pancreas function, increasing pancreatic GLP-1 R expression, and partly restoring the morphology of pancreas.

Effect of an aqueous extract of Cucurbita ficifolia Bouché on the glutathione redox cycle in mice with STZ-induced diabetes.

ETHNOPHARMACOLOGICAL IMPORTANCE: Cucurbita ficifolia is used in Mexican traditional medicine as an anti-diabetic and anti-inflammatory agent and its actions can be mediated by antioxidant mechanisms. Disturbance in the homeostasis of glutathione has been implicated in the etiology and progression of diabetes mellitus and its complications. MATERIAL AND METHODS: It was evaluated, the effect of an aqueous extract of Cucurbita ficifolia on glycemia, plasma lipid peroxidation; as well as levels of reduced (GSH) and oxidized (GSSG) glutathione and activities of enzymes involved in glutathione redox cycle: glutathione peroxidase (GPx) and glutathione reductase (GR) in liver, pancreas, kidney and heart homogenates of streptozotocin-induced diabetic mice. RESULTS: Increased blood glucose and lipid peroxidation, together with decreased of GSH concentration, GSH/GSSG ratio and its redox potential (E(h)), and enhanced activity of GPx and GR in liver, pancreas and kidney were the salient features observed in diabetic mice. Administration of the aqueous extract of Cucurbita ficifolia to diabetic mice for 30 days, used at a dose of 200 mg/kg, resulted in a significant reduction in glycemia, polydipsia, hyperphagia and plasma lipid peroxidation. Moreover, GSH was increased in liver, pancreas and kidney, and GSSG was reduced in liver, pancreas and heart, therefore GSH/GSSG ratio and its E(h) were restored. Also, the activities involved in the glutathione cycle were decreased, reaching similar values to controls. CONCLUSIONS: An aqueous extract of Cucurbita ficifolia with hypoglycemic action, improve GSH redox state, increasing glutathione pool, GSH, GSH/GSSG ratio and its E(h), mechanism that can explain, at least in part, its antioxidant properties, supporting its use as an alternative treatment for the control of diabetes mellitus, and prevent the induction of complications by oxidative stress.

An estimation of the manganese requirement for broilers from 1 to 21 days of age.

A dose-response experiment was conducted to find the sensitive and consistent biomarker for the estimation of dietary manganese (Mn) requirement and establish the optimal Mn level for broilers fed a practical corn-soybean meal diet from 1 to 21 days of age post-hatching. A total of 480 1-day-old Arbor Acres male chicks were randomly allotted to one of eight treatments with five replicates of 12 birds each and fed diets supplemented with 0, 20, 40, 60, 80, 100, 120, or 140 mg Mn/kg from reagent grade Mn sulfate. Tissue Mn concentrations, manganese-containing superoxide dismutase (MnSOD) activity, and MnSOD mRNA concentration within heart tissue were analyzed at 7, 14, and 21 days of age. Tissue Mn concentrations and heart MnSOD activity showed significant quadratic responses, and heart MnSOD mRNA concentration showed an asymptotic response to dietary supplemental Mn level, respectively. The estimate of dietary Mn for chicks from 1 to 21 days of age was 122-128 for heart Mn concentration, 141-159 for pancreas Mn concentration, 127-138 for liver Mn concentration, and 135-156 mg/kg for heart MnSOD activity, respectively. Heart MnSOD mRNA concentration was a consistent index for the estimation of the Mn requirement of broilers. Based on this index, the estimate of dietary Mn requirement for broilers from 1 to 21 days of age post-hatching was about 130 mg/kg, which was a little more than two times of the current NRC (1994) requirement.

Anti-diabetic effects including diabetic nephropathy of anti-osteoporotic trace minerals on diabetic mice.

OBJECTIVE: In our previous study to evaluate the effects of soluble silicon (Si) on bone metabolism, Si and coral sand (CS) as a natural Si-containing material suppressed peroxisome proliferator-activated receptor γ (PPARγ), which regulates both glucose and bone metabolism and increases adipogenesis at the expense of osteogenesis, leading to bone loss. In this study, we investigated the anti-diabetic effects of bone-seeking elements, Si and stable strontium (Sr), and CS as a natural material containing these elements using obese diabetic KKAy mice. METHODS: Weanling male mice were fed diets containing 1% Ca supplemented with CaCO(3) as the control and CS, and diets supplemented with 50 ppm Si or 750 ppm Sr to control diet for 56 d. The mRNA expressions related to energy expenditure in the pancreas and kidney were quantified by real-time polymerase chain reaction. RESULTS: At the end of feeding, plasma glucose, insulin, leptin, and adiponectin levels decreased significantly in three test groups, while pancreatic PPARγ and adiponectin mRNA expression levels increased significantly toward the normal level, improving the glucose sensitivity of ß-cells and inducing a significant decrease in insulin expression. The renal PPARγ, PPARα, and adiponectin expression levels, histologic indices of diabetic glomerulopathy, and plasma indices of renal function were also improved significantly in the test groups. CONCLUSION: Taken together, anti-osteoporotic trace minerals, Si and Sr, and CS containing them showed novel anti-diabetic effects of lowering blood glucose level, improving the tolerance to insulin, leptin, and adiponectin, and reducing the risk of glomerulopathy through modulation of related gene expression in the pancreas and kidney.

Eupatilin, isolated from Artemisia princeps Pampanini, enhances hepatic glucose metabolism and pancreatic beta-cell function in type 2 diabetic mice.

Eupatilin (5,7-dihydroxy-3',4',6-trimethoxyflavone) was isolated from Artemisia princeps to investigate the dose-response effects on blood glucose regulation and pancreatic beta-cell function in type 2 diabetic mice. Db/db mice were divided into control (eupatilin-free, AIN-76 standard diet), low-Eupa (0.005g/100g diet) and high-Eupa (0.02g/100g diet) groups. The supplementation of eupatilin for 6 weeks significantly lowered fasting blood glucose concentration while it increased hepatic glycogen content. In particular, high-Eupa reduced hemoglobin A(1c) and plasma glucagon levels along with a simultaneous increase in plasma insulin and adiponectin levels. The supplementation of eupatilin significantly lowered hepatic glucose-6-phosphatase and phosphoenolpyruvate carboxykinase activities, while it increased glucokinase activity in the liver. The pancreatic insulin concentration was higher in the eupatilin-supplemented groups. Also the pancreatic insulin concentration of eupatilin groups was higher than the control group. These results suggest that eupatilin played the role of an antidiabetic functional component in A. princeps by enhancing hepatic and plasma glucose metabolism as well as by increasing insulin secretion in type 2 diabetic mice.

The effect of ginseng on bile-pancreatic secretion in the rat. Increase in proteins and inhibition of total lipids and cholesterol secretion.

Ginseng is one of the most popular herbal remedies. Studies were performed in anaesthetized rats to examine the effect of ginseng on bile secretion. Male Sprague-Dawley rats were anaesthetized with intraperitoneal (i.p.) urethane (1.25 g kg(-1)) and equipped with biliary cannulas inserted into the bile duct through the sphincter of Oddi. Rats were treated with a single i.p. injection of ginseng at 25, 50 or 100 mg kg(-1) (1 ml(-1)) 30 min before bile collection; the control group received i.p. saline only at 1 ml(-1)volume. The effect of multiple doses of ginseng on bile volume and biliary composition was also studied. Ginseng was given in the higher dose of 100 mg kg(-1) (1 ml(-1), i.p.) every 12 hours for 2 days. Bile was collected in 15 min fractions for 90 min. Bile flow (bile-pancreatic juice), biliary excretion of total proteins, cholesterol and total lipids were measured. The single administration of different doses (25, 50 and 100 mg kg (-1)) of ginseng reduced basal bile secretion in a dose-dependent manner. Single-dose administration of ginseng at 100 mg kg(-1) caused 32.9% reduction in basal bile flow. Meanwhile, mean basal bile flow was reduced by 15.1% in rats treated with multiple doses of ginseng at 100 mg kg(-1) for two days. Biliary protein concentrations were significantly increased after single- or multiple-dose administration of ginseng, but protein output was only significantly increased (33%) in rats treated with ginseng (100 mg kg(-1)) twice a day for 2 days. Biliary total lipids and cholesterol concentration and outputs were significantly reduced after single or multiple administration of ginseng. In conclusion, administration of ginseng in the rat resulted in a reduction of bile flow and in bile secretion of total lipids and cholesterol, while it increased the secretion of proteins in a dose-dependent manner. The precise mechanisms underlying these effects remain to be elucidated. The findings indicate the need for clinical trials for the effect of this herb on bile composition and flow in man in view of a possible modulatory effect for the herb on gallstone formation.