Pancreatic Cholesterol Esterase Activity Research Articles

An In Vitro Study on the Effects of Selected Natural Dietary Fiber from Salad Vegetables for Lowering Intestinal Glucose and Lipid Absorption.

Salad vegetables are good sources of dietary fiber and are becoming increasingly popular among consumers. Therefore, these plants have the potential to be developed as functional foods. Using an in vitro model, this study investigated the physical properties and intestinal glucose and lipid absorption capacities of dry dietary fiber from vegetables typically consumed in salads (types of lettuce, including red oak, red coral, green oak, butterhead, and cos). Fiber was prepared from each type of lettuce using an enzymatic method and then characterized. Physical properties, including solubility and water-binding, swelling, cation-exchange, and oil-binding capacities, and antihyperglycemic and antihypercholesterolemic effects of fiber were investigated. The hydration capacity of total dietary fiber and insoluble fiber from the majority of sources was significantly different from that of cellulose. Adsorption and diffusion of glucose were directly proportional to incubation time, and the diffusion rate was significantly lower in the treatments containing fiber compared to the cellulose control. Fiber from these vegetables also inhibited amylase and alpha-glucosidase activities. Moreover, fiber from all sources exhibited significantly higher sodium cholate and cholesterol-binding capacity compared to cellulose, and also retarded pancreatic cholesterol esterase activity in a concentration-dependent manner. This study demonstrates that natural dietary fiber from salad vegetables can reduce glucose and lipid absorption and breakdown rates, thus preventing increases in postprandial blood glucose and cholesterol levels, which can be beneficial to human health.

Siamese neem flower extract suppresses cholesterol absorption by interfering NPC1L1 and micellar property in vitro and in intestinal Caco-2 cells.

Siamese neem (Azadirachta indica A. Juss var. siamensis Valeton) (A. indica) leaf extract, a traditional ayurvedic medicine, has been reported to exhibit antipyretic, antibacterial, antidyslipidemic, and antihyperglycemia effects. This study investigated the mechanism of hypocholesterolemic effect of methanolic extract of Siamese neem flowers in in vitro studies and in Caco-2 cells. Pancreatic cholesterol esterase and 3-hydroxy 3-methylglutaryl-CoA (HMG-CoA) reductase activities were assessed. Cholesterol micelle formation was prepared for in vitro cholesterol physicochemical property analyses, micelle size and solubility, and transport of cholesterol into the Caco-2 cells. The expression of niemann-pick C1 like 1 (NPC1L1), and its major regulator, peroxisome proliferator-activated receptor δ (PPARδ), were determined by western blot and real time polymerase chain reaction, respectively. A. indica flower extract inhibited pancreatic cholesterol esterase activity and increased cholesterol micelles size. Uptake of cholesterol into Caco-2 cells was inhibited by A. indica flower extract in a dose-dependent manner. In addition, A. indica extract inhibited HMG-CoA reductase activity, resulting in low level of intracellular cholesterol accumulation, together with increased cytosolic NPC1L1 protein expression and decreased PPARδ gene expression. In conclusion, A. indica flower extract has cholesterol-lowering effects by inhibiting intestinal cholesterol absorption, interfering micellar cholesterol formation, and attenuating cholesterol synthesis. As such, A. indica flower extract has potential for developing into nutraceutical product for prevention of hypocholesterolemia.

Screening for Biological Activities of Spirogyra neglecta Water Extract

The freshwater green algae, S. neglecta, has been commonly used as a Northern Thai local food due to the fact that it is composed of several nutritional components. The aim of the present study was to investigate the phytochemical properties and biological activities of an S. neglecta water extract for application as a functional food or pharmaceutical ingredient. The phenolic and flavonoid contents of S. neglecta and its biological activities, including anti-oxidant, pancreatic cholesterol esterase, anti-inflammatory, cytotoxic, and antibacterial activities, were investigated in vitro. The results showed that the S. neglecta extract contained 157.92 mg GAE/g extract of phenolics and 10.10 mg CE/g extract of flavonoids. The radical scavenging activity of the S. neglecta extract exhibited an IC50 of 7.46±1.17 µg/mL from DPPH assay and 224.20±1.06 µg/mL from ABTS assay. Meanwhile, trolox exhibited an IC50 of 7.03±1.08 µg/mL from DPPH assay and 5.24±1.10 µg/mL from ATBS assay. Interestingly, the S. neglecta extract at 10 mg/mL inhibited pancreatic cholesterol esterase activity by 60 %. Moreover, the release of TNF-α from macrophages was strongly reduced by incubation with the S. neglecta extract in a dose-dependent manner, and all of the study concentrations were non-toxic to primary fibroblast cells. In addition, the S. neglecta extract inhibited some gram-positive and -negative bacteria. In summary, S. neglecta extract could possibly be used as a potential functional food or pharmaceutical ingredient, for which further studies are required.

Identification of Lead Molecules in Garcinia mangostana L. Against Pancreatic Cholesterol Esterase Activity: An In Silico Approach.

Hypercholesterolemia is one of the major risk factors for the development and progression of atherosclerosis. Hence, inhibitors of cholesterol absorption have been investigated for decades as a strategy to prevent and treat cardiovascular diseases associated with hypercholesterolemia. Cholesterol esterase (CEase) in pancreatic juice plays a vital role in the hydrolysis of dietary cholesterol esters to cholesterol and fatty acids. Since inhibition of CEase might lead to a reduction of cholesterol absorption, an attempt is made in this study to identify lead molecules of Garcinia mangostana by the in silico approach. The study employed software applications viz., AutoDock 4.2 and GOLD Suite of Programs 5.2. The study revealed the efficacy of three compounds viz., epicatechin, euxanthone, and 1,3,5,6-tetrahydroxy-xanthone, which exhibited least binding energy in AutoDock and moderate scoring in GOLD. The molecular properties as well as biological activity of these three compounds were predicted by molinspiration prediction tool. The results show the crucial role of polyphenolic compounds to limit the activity of CEase. The drug-likeness prediction revealed the prospects of the identified lead molecules as potential drug candidates.

The okra skin extract and its cholesterol‐lowering activities ő in vitro study (1045.28)

Okra [Abelmoschus esculentus (L.) Moench], also known as lady’s finger or gumbo, is an edible green vegetable that is widely used in cuisines around the world. It is rich in nutritive components such as dietary fibers, proteins, vitamins, minerals, antioxidants, and polyphenolic compounds. Several studies showed the health benefits of the okra in the prevention of hyperglycemia and hyperlipidemia. This in‐vitro study was aimed to investigate the effect of the okra skin extract on cholesterol‐lowering activities. The inhibitory effects of the extract on pancreatic cholesterol esterase activity and on the cholesterol micellization, also its effect on the binding ability to bile acids, were determined. The results showed that the okra skin extract inhibited pancreatic cholesterol esterase activity in the concentration‐dependent manner (R2=0.817, p <0.05, IC50 = 3.17 mg/mL). Moreover, the extract (ranging from 0.25‐2 mg/mL) also inhibited the cholesterol micellization in the concentration‐dependent manner (R2=0.827, p <0.05). In addition, the okra skin extract showed the ability to bind to bile acids (glycodeoxycholic acid, taurodeoxycholic acid, and taurocholic acid). We found that the binding efficacy of the extract (2 mg/mL) to glycodeoxycholic acid was significantly higher than binding to taurodeoxycholic acid and taurocholic acid (mean±SEM: 16.16±1.26% vs. 10.04±1.02% and 8.76±0.70%, p <0.05, respectively). In conclusion, the okra skin extract exhibited cholesterol‐lowering activities by inhibiting pancreatic cholesterol esterase activity, reducing the efficacy of cholesterol micellization, and binding to bile acids, which may result in delayed cholesterol absorption and increase cholesterol excretion. These findings may be useful for further studies in proposed mechanism on hypolipidemic acitivity of the okra.Grant Funding Source: Grants for Development of New Faculty Staff, Ratchadaphiseksomphot Endowment Fund, CU

Site-specific mutagenesis of an essential histidine residue in pancreatic cholesterol esterase

The histidine residue essential for the catalytic activity of pancreatic cholesterol esterase (carboxylester lipase) has been identified in this study using sequence comparison and site-specific mutagenesis techniques. In the first approach, comparison of the primary structure of rat pancreatic cholesterol esterase with that of acetylcholinesterase and cholinesterase revealed two conserved histidine residues located at positions 420 and 435. The sequence in the region around histidine 420 is quite different between the three enzymes. However, histidine 435 is located in a 22-amino acid domain that is 47% homologous with other serine esterases. Based on this sequence homology, it was hypothesized that histidine 435 is the histidine residue essential for catalytic activity of cholesterol esterase. The role of His435 in the catalytic activity of pancreatic cholesterol esterase was then studied by the site-specific mutagenesis technique. Substitution of the histidine in position 435 with glutamine, arginine, alanine, serine, or aspartic acid abolished the ability of cholesterol esterase to hydrolyze p-nitrophenyl butyrate and cholesterol [14C]oleate. In contrast, mutagenesis of the histidine residue at position 420 to glutamine had no effect on cholesterol esterase enzyme activity. The results of this study strongly suggested that histidine 435 may be a component of the catalytic triad of pancreatic cholesterol esterase.

Pancreatic cholesterol esterases. 1. Pancreatic cholesterol esterase induction during maturation

The activities of pancreatic cholesterol esterase from calf and cow pancreas were examined in detail. A 1300-fold enhancement of enzymatic activity was found after maturation, even though cholesterol esterase activity levels in other organs did not change from the juvenile to the adult species. Radioimmunoassays also showed that the calf pancreas contained at least 100-fold less cholesterol esterase protein. Decreased amounts of protein were not due to enhanced proteolysis, since cytosol from cow pancreas degrades exogenously added cholesterol esterase faster than that from calf pancreas. Rather, enhancement of pancreatic cholesterol esterase activity associated with bovine maturation was the result of specific, increased synthesis of a 72-kDa enzyme. This labile 72-kDa cholesterol esterase species was purified to homogeneity by a two-step process in 75% yield and is the major form of bovine pancreatic cholesterol esterase (99%). A much less abundant 67-kDa species, accounting for less than 1% of total pancreatic cholesterol esterase activity, was also purified to homogeneity in a similar two-step process. These results demonstrate that a specific form of pancreatic cholesterol esterase is induced during maturation, and they bear importantly on understanding juvenile cholesterol metabolism as related to dietary absorption of this sterol.

Some factors which influence the catalytic activity of pancreatic cholesterol esterase.

SummaryThese data indicate that pancreatic cholesterol esterase catalyzes both synthesis and hydrolysis of cholesteryl oleate at a single pH, but the reaction which predominates in presence of both substrates is governed by the electrolyte concentration. Rate of synthesis of 4C14-cholesteryl oleate is decreased in proportion to relative concentration of β-sitosterol.The authors acknowledge with gratitude the continued interest of Drs. R. E. Shipley and C. W. Pettinga.