Intestinal Sucrase Research Articles

In Vitro and in Vivo Anti-Hyperglycemic Activities of Taxifolin and Its Derivatives Isolated from Pigmented Rice (Oryzae sativa L. cv. Superhongmi).

Superhongmi is a new rice variety, which was developed for the enrichment of bioactive compounds through cross-breeding three varieties of rice breeds in Korea. The high-performance liquid chromatography coupled with a photodiode array detector quadrupole and tandem time-of-flight mass spectrometry (HPLC/PDA/QTOF-MS) analysis has revealed that superhongmi bran extract contained four taxifolin derivatives as well as cyanidin 3-glucoside. The high-performance countercurrent chromatography (CCC) and reversed-phase HPLC led to the isolation of aforementioned five compounds, and spectroscopic analysis identified cyanidin 3-glucoside (1), along with (2R,3R)-taxifolin 3-O-β-d-glucopyranoside (2), (2R,3R)-4'-O-methyltaxifolin 3-O-β-d-glucopyranoside (a novel compound) (3), (2R,3R)-taxifolin (4), and (2R,3R)-4'-O-methyltaxifolin (5). Compound 2 had the highest rat small intestinal sucrase inhibitory activity (0.54 mM) relevant for potentially managing postprandial hyperglycemia, followed by compound 1 (0.97 mM) and compound 4 (1.74 mM, IC50). The anti-hyperglycemic effect of compound 4 (taxifolin), a main peak in HPLC analysis was investigated using a Sprague-Dawley (SD) rat model. Compared to a control, taxifolin treatment (p < 0.001) reduced significantly after sucrose loading the observed postprandial blood glucose and the maximum blood glucose (Cmax) by 15% (203.60 ± 15.86 to 172.30 ± 12.74). These results indicate that taxifolin derivatives that inhibit the activity of carbohydrate-hydrolyzing enzymes resulting in reduced dietary carbohydrate absorption can potentially be used as a strategy to manage diabetes.

Prebiotics Fructo-, Galacto-, and Mannan-Oligosaccharide Do Not Protect against 5-Fluorouracil–Induced Intestinal Mucositis in Rats

Prebiotics selectively stimulate the growth of beneficial bacteria within the gastrointestinal tract, and have been investigated in human and animal studies for their capacity to improve intestinal health. We investigated the prebiotics fructo-oligosaccharide (FOS), galacto-oligosaccharide (GOS), and mannan-oligosaccharide (MOS) for their potential to alleviate intestinal damage in rats. Female Dark Agouti rats (6-8 wk old, 110-150 g) were allocated to 1 of the following treatment groups (n=8/group): saline/water, saline/FOS, saline/GOS, saline/MOS, 5-fluorouracil (5FU)/water, 5FU/FOS, 5FU/GOS, and 5FU/MOS. Rats were pretreated with either 5% GOS, MOS, or FOS or vehicle (water) from day -12 to day 0. On day 0, rats received a single intraperitoneal injection of saline or 5FU. Metabolic data were recorded daily and all rats were killed on day 3. Histopathology was quantified in hematoxylin and eosin-stained sections. Intestinal sucrase and myeloperoxidase activity were quantified by biochemical assay. Fecal SCFAs-acetic, propionic, and butyric acid-were also measured. Statistical analysis was by repeated-measures, 2-factor ANOVA or Kruskal-Wallis and Mann-Whitney U test; P<0.05 was considered statistically significant. Body weight was significantly decreased in all treatment groups after 5FU injection, with no change in body weight observed in any prebiotic treatment group. Total food intake was lower by ≥7% in the GOS treatment group pre-5FU than in all other groups (P<0.05). Ileal villus height was 18% higher in GOS-treated rats pre-5FU than in respective water controls (P<0.05). Jejunal and ileal villus height and crypt depth were significantly decreased in all treatment groups after 5FU injection, with no prebiotic effect observed. SCFAs were differentially increased in prebiotic treatment groups compared with water-only controls (P<0.05). FOS, GOS, and MOS have differential effects in modifying small intestinal pathology and SCFA profiles in rats with healthy and damaged small intestinal mucosa.

Studies on Riceberry rice (Oryza sativa L.) extract on the key steps related to carbohydrate and lipid digestion and absorption: A new source of natural bioactive substances

Riceberry rice (Oryza sativa L.), a new cross-breed from Hom Nin rice, a local non-glutinous purple rice, and Khoa Dawk Mali 105. The present study systematically assessed the effect of Riceberry rice extract (RBE) on the inhibition of key steps of carbohydrate and lipid digestion and absorption. The main anthocyanin identified in RBE was cyanidin-3-O-glucoside and peonidin-3-O-glucoside. In the step of carbohydrate digestion and absorption, RBE markedly inhibited intestinal maltase and sucrase. Kinetic analysis demonstrated that RBE was a mix-type competitive inhibitor against intestinal maltase. In Caco-2 cells, RBE had no effect on inhibition of glucose uptake but it could suppress mRNA expression of SGLT1. The results showed that RBE caused the reduction of lipid digestion and absorption by inhibiting pancreatic lipase, decreasing the micellar cholesterol solubility and binding of bile acid. Moreover, RBE showed non-competitive inhibition toward pancreatic lipase activity. In Caco-2 cells, RBE exhibited a significant reduction in cholesterol uptake and suppressed mRNA expression of NPC1L1 transporter. These findings provide important evidence that Riceberry rice may be a potential natural source for inhibiting the key steps of carbohydrate and lipid digestion and absorption.

Adventitious root cultures from leaf explants of Helicteres angustifolia L. as a novel source for production of natural bioactive compounds

In this study, adventitious roots of Helicteres angustifolia L. (H. angustifolia) were generated on Murashige and Skoog salt mixture (MS) medium with auxin and ascorbic acid as additives. The root initiation ratio reached 100% on MS medium supplemented with 3.0 mg/L NAA and 0.4 mg/L ascorbic acid at 28 °C. The root number reached 15 ± 2 per leaf explant with a length of 1.70 ± 0.52 cm. Moreover, the cultured roots exhibited similar functional groups with wild plant roots and produced abundant classes of phenolic secondary metabolites. The contents of total phenolics and flavonoids of the cultured roots reached 9.68 mg GAE/g and 25.66 mg RE/g, respectively. Compared to the wild plant roots, the cultured roots produced more gallic acid (1.97 ± 0.09 mg/g), catechol (0.17 ± 0.00 mg/g), caffeic acid (0.34 ± 0.01 mg/g), and quercetin (0.84 ± 0.02 mg/g). Additionally, the adventitious root extract showed dose-dependent antioxidant capability (IC50 of DPPH = 4.10 ± 0.27 mg/mL, IC50 of hydroxyl = 1.59 ± 0.07 mg/mL) and inhibition activities on rat intestinal maltase and sucrase (IC50 of maltase = 5.66 ± 0.20 mg/mL, IC50 of sucrase > 8.0 mg/mL). The adventitious root cultures are promising alternatives to produce bioactive phenolic compounds and functional foods of H. angustifolia.

Schlafen 3 knockout mice display gender-specific differences in weight gain, food efficiency, and expression of markers of intestinal epithelial differentiation, metabolism, and immune cell function.

Self-renewal and differentiation are essential for intestinal epithelium absorptive functioning and adaptation to pathological states such as short gut syndrome, ulcers, and inflammatory bowel disease. The rodent Slfn3 and its human analog Slfn12 are critical in regulating intestinal epithelial differentiation. We sought to characterize intestinal function in Slfn3 knockout (KO) mice. Male and female pair-fed Slfn3KO mice gained less weight with decreased food efficiency than wild type (WT) mice, with more pronounced effects in females. RNA sequencing performed on intestinal mucosa of Slfn3KO and WT mice showed gene ontology decreases in cell adhesion molecule signaling, tumor necrosis factor receptor binding, and adaptive immune cell proliferation/functioning genes in Slfn3KO mice, with greater effects in females. qPCR analysis of fatty acid metabolism genes, Pla2g4c, Pla2g2f, and Cyp3c55 revealed an increase in Pla2g4c, and a decrease in Pla2g2f in Slfn3KO females. Additionally, adipogenesis genes, Fabp4 and Lpl were decreased and ketogenesis gene Hmgcs2 was increased in female Slfn3KO mice. Sequencing did not reveal significant changes in differentiation markers, so qPCR was utilized. Slfn3KO tended to have decreased expression of intestinal differentiation markers sucrase isomaltase, dipeptidyl peptidase 4, villin 1, and glucose transporter 1 (Glut1) vs. WT males, although these trends did not achieve statistical significance unless data from several markers was pooled. Differentiation markers, Glut2 and sodium-glucose transporter 1 (SGLT1), did show statistically significant sex-dependent differences. Glut2 mRNA was reduced in Slfn3KO females, while SGLT1 increased in Slfn3KO males. Notch2 and Cdx2 were only increased in female Slfn3KO mice. Although Slfn3KO mice gain less weight and decreased food efficiency, their biochemical phenotype is more subtle and suggests a complex interplay between gender effects, Slfn3, and another regulatory pathway yet to be identified that compensates for the chronic loss of Slfn3.

In Vitro and In Vivo Anti‐Hyperglycemic and Antioxidant Effects of Phenolic Compounds isolated from Oryza sativa L.(Keun‐nun‐Jami) Variety

Type 2 diabetes, one of the chronic diseases, is a problem in both developed and developing countries. In particular, excessive ingestion of grain, such as rice, can result in hyperglycemia and type 2 diabetes. Therefore, a Oryza sativa L. variety, Keun‐nun‐Jami (KNJM) extracts were investigated for their anti‐hyperglycemic effect using in vitro and animal models. In vitro study inhibitory activities of both ethyl alcohol extracts of bran and germ against rat intestinal sucrase and maltase were evaluated. Oxygen radical absorbance capacity (ORAC) was also investigated. Ethyl alcohol extract of KNJM bran (EKB) had the highest sucrase inhibitory activity followed by ethyl alcohol extract of KNJM germ (EKG). Taxifolin, a flavonol, was isolated from the extract of KNJM along with three unknown compounds using HPLC and semi‐prep HPLC systems. Their structures were elucidated by extensive spectroscopic analysis, including 1D and 2D NMR, and FTICR‐MS. Furthermore, post‐prandial blood anti‐hyperglycemic effect of the extacts and taxifolin were measured using SD (Sprague Dawley) rat model. Postprandial blood glucose levels were tested for 3 hr after sucrose and starch administration with or without 500 mg of EKB, EKG, and taxifolin, respectively. Similar to result in vitro study, EKB which has higher content of taxifolin than that of EKG had stronger anti‐hyperglycemic effect than that of EKG. These results indicate that taxifolin from KNJM serves to reduce post‐prandial blood glucose rise and slower absorption of glucose in the small intestine, via carbohydrate hydrolyzing enzymes inhibition. These findings suggest that EKB has better potential for this bioactivity and this observation possibly correlates with the taxifolin contents observed in both extracts. Selected variety of colored rice, KNJM may provide the potential to contribute as a dietary strategy for controlling postprandial hyperglycemia.Support or Funding InformationThis work was supported by a grant from the Next‐Generation BioGreen 21 Program (No.PJ01314003), Rural Development Administration, Republic of KoreaThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Biological interaction of newly synthesized astaxanthin-s-allyl cysteine biconjugate with Saccharomyces cerevisiae and mammalian α-glucosidase: In vitro kinetics and in silico docking analysis

In humans, alpha-glucosidase activity is present in sucrase-isomaltase (SI) and maltase-glucoamylase (MGAM). α-glucosidase is involved in the hydrolyses of disaccharide into monosaccharides and results in hyperglycemia. Subsequently chronic hyperglycemia induces oxidative stress and ultimately leads to the secondary complications of diabetes. Hence, identifying compounds with dual beneficial activity such as efficient antioxidant and α-glucosidase inhibition property has attracted the attention in recent years. Keeping these views, in the present study astaxanthin (AST; a natural antioxidant present in marine microalgae) was biconjugated with allyl sulfur amino acid such as s-allyl cysteine (SAC). The synthesized AST-SAC (with molecular weight of 883.28) was characterized using UV–visible spectrophotometer, ESI-MS, and NMR analysis. AST-SAC showed potent antioxidant property in vitro. AST-SAC inhibited Saccharomyces cerevisiae α-glucosidase (IC50 = 3.98 μM; Ki = 1 μM) and mammalian α-glucosidase [rat intestinal maltase (IC50 = 6.4 μM; Ki = 1.3 μM) and sucrase (IC50 = 1.6 μM; Ki = 0.18 μM)] enzyme activity in a dose-dependent manner. Kinetic analysis revealed that AST-SAC inhibited all the α-glucosidases in a competitive mode. In silico analysis determined the interaction of AST-SAC with the amino acids present in the active site of S. cerevisiae and human (MGAM and SI) α-glucosidases.

Total Synthesis of Natural Hyacinthacine C5 and Six Related Hyacinthacine C5 Epimers.

The total synthesis of natural (+)-hyacinthacine C5 was achieved, which allowed correction of its initially proposed structure, as well as six additional hyacinthacine C-type compounds. These compounds were readily accessible from two epimeric anti-1,2-amino alcohols. Keeping a common A-ring configuration, chemical manipulation occurred selectively on the B-ring of the hyacinthacine C-type products through methods of syn-dihydroxylation, SN2 ring-opening of a cyclic sulfate, and also employing either ( R)- or ( R, S)-α-methylallyl amine for the Petasis borono Mannich reaction. Our small analogue library was then assessed for its glycosidase inhibitory potency against a panel of glycosidases. (-)-6- Epi-hyacinthacine C5 and (+)-7- epi-hyacinthacine C5 (compound names are based on the corrected structure of hyacinthacine C5) proved most active, with inhibitory activities ranging between weak (IC50 = 130 μM) and moderate (IC50 = 9.9 μM) against the α-glucosidases of rat intestinal maltase, isomaltase, and sucrase, thus identifying potential new leads for future antidiabetic drug development.

Calorie Restriction Effect of Heat-Processed Onion Extract (ONI) Using In Vitro and In Vivo Animal Models.

Onion (Allium cepa L.) is widely consumed as food or medicinal plant due to its well-defined health benefits. The antioxidant and antihyperlipidemic effects of onion and its extracts have been reported well. However, very limited information on anti-hyperglycemic effect is available in processed onion extracts. In our previous study, we reported that Amadori rearrangement compounds (ARCs) produced by heat-processing in Korean ginseng can reduce carbohydrate absorption by inhibiting intestinal carbohydrate hydrolyzing enzymes in both in vitro and in vivo animal models. To prove the enhancement of anti-hyperglycemic effect and ARCs content by heat-processing in onion extract, a correlation between the anti-hyperglycemic activity and the total content of ARCs of heat-processed onion extract (ONI) was investigated. ONI has a high content of ARCs and had high rat small intestinal sucrase inhibitory activity (0.34 ± 0.03 mg/mL, IC50) relevant for the potential management of postprandial hyperglycemia. The effect of ONI on the postprandial blood glucose increase was investigated in Sprague Dawley (SD) rats fed on sucrose or starch meals. The maximum blood glucose levels (Cmax) of heat-processed onion extract were significantly decreased by about 8.7% (from 188.60 ± 5.37 to 172.27 ± 3.96, p < 0.001) and 14.2% (from 204.04 ± 8.73 to 175.13 ± 14.09, p < 0.01) in sucrose and starch loading tests, respectively. These results indicate that ARCs in onion extract produced by heat-processing have anti-diabetic effect by suppressing carbohydrate absorption via inhibition of intestinal sucrase, thereby reducing the postprandial increase of blood glucose. Therefore, enhancement of ARCs in onion by heat-processing might be a good strategy for the development of the new product on the management of hyperglycemia.

Dose-dependent effects of Theobroma cacao in iron deficient anemia treatment in rats

The use of herb in the treatment of diseases, including nutrient-related diseases, remains the last resort in many villages. The lack of prescription for most of these herbs may negate the undoubtful efficacy of these herbs. Hence, this study seeks to propose an optimal dose of the aqueous extract of the stem bark of Theobroma cacao (TC) in the treatment of anemia and comparing the effect of this extract with that of Mangifera indica L (MI). Forty-eight weanling albino rats of both sexes (Rattus norvegicus) with a mean weight of 48.00 g ± 3.00 g were used in the study. Eight of the animals were placed on iron sufficient diet while the rest of the animals were placed on the iron deficient diet. After the four weeks, the animals were placed on iron deficient were confirmed to be iron deficient via their haematologic indexes. The iron deficient rats were then divided into nine sub groups. Each of the group of the animals was assigned different conditions for two weeks. 25, 50 and 75 mg/kg body weight of MI were administered to three of the groups. 25, 50 and 75 mg/kg body weight of TC were administered to three of the groups. A standard iron supplement drug was administered to one of the groups, the feed on one of the groups was changed to iron sufficient diet, and the last group was maintained on the iron deficient diet. The haematologic index, the intestinal disaccharidases of the animals were assayed after the treatments. The weight gained by the animal was also recorded. The iron sufficient diet and the aqueous extract from the two plants significantly increased the haematologic indexes assayed, packed cell volume, hemoglobin and red blood cell, in the animal after two weeks of administration. While increasing the dose of MI increased all the haematologic indexes in the animal, otherwise was the case for the aqueous extract of TC. Although given all the doses, the extract of MI seems to be more effective than TC, if the effect of the lowest dose, 25 mg/kg body weight is considered, TC is more effective as an anti anaemic substance than MI. The extract and iron sufficient diet also increased the activities of the intestinal lactase and sucrase in the animals. While the iron and phytochemicals in the extract seem to be acting in synergy in the increasing of the haematologic indexes, the iron content alone seems to be responsible their action on the intestinal disaccharidases. Just as proposed for MI, 25 mg/kg body weight of TC seems to be the optimal dose for the treatment.

Hydroxytyrosol nicotinate, a new multifunctional hypolipidemic and hypoglycemic agent

Hydroxytyrosol (HT) is a natural polyphenol antioxidant that exists in olive oil. In the study of multifunctional hypolipidemic of nicotinic derivatives, we found that hydroxytyrosol nicotinate (HT-N) incorporation of niacin with HT displayed α-glucosidase inhibitory activities in vitro, such as yeast α-glucosidase (IC50 = 117.72 μM) and rat intestinal α-glucosidases maltase (IC50 = 31.86 μM) and sucrase (IC50 = 22.99 μM), and had a good control of postprandial blood glucose (PBG). HT-N shown significantly hypoglycemic action by 16.9% and protection of pancreatic tissue in type 2 diabetic mellitus (T2DM) mouse model. HT-N also shown a potent antioxidant activity and property of anti-glycation in vitro, which were benefit for ameliorating diabetic complications. Moreover, HT-N exhibited much significant hypolipidemia, lowering plasma triglyceride (TG), total cholesterol (TC), and malonaldehyde (MDA) by 34.6%, 45.8% and 32.1% respectively, in hyperlipidemic mice induced by Triton WR 1339. The results indicated that HT-N has hypolipidemic, hypoglycemic and antioxidant actions. All these properties could be conducive to amelioration of oxidative stress, hyperlipidemia, and diabetes that HT-N may serve as a multifunctional potential therapeutic strategy in diabetic patients with hyperlipidemia.

Production and Utilization of L-Arabinose in China

L-arabinose is a newly developed low-caloric monosaccharide, which has many biomedical and health effects, especially intestinal sucrase inhibition effect. L-arabinose is mainly produced by chemical or enzymatic hydrolysis of hemicellulose. The taste of L-arabinose is quite similar to that of sucrose, with approximately 50% of the sweetness. As a functional additive, L-arabinose can be used in medical and pharmaceutical applications for the treatment of diseases such as diabetes, chronic constipation, mineral absorption disorder and secondary bile acid formation disorder. However, L-arabinose has not been widely used in functional foods due to high price and lack of publicity and guidance. A comprehensive review of L-arabinose physicochemical properties, production, applications field, market statue and development direction is presented in this paper.

Divergent synthesis of new α-glucosidase inhibitors obtained through a vinyl Grignard-mediated carbocyclisation.

Four new α-glucosidase inhibitors have been synthesised through 5-8 synthetic steps from a common synthetic intermediate obtained through a recently developed carbocyclisation. The compounds were designed as hybrids of the known glucosidase inhibitors valienamine, voglibose and miglitol. All four compounds showed activity against rat intestinal sucrase with the most potent inhibitor acting at low micromolar concentration. The newly synthesised compounds were not as potent as miglitol against sucrase but showed greater selectivity towards the tested glycosidases. The most potent inhibitors were docked into a homology model built for this study of rat intestinal sucrase explaining the difference in potency between two diastereoisomers with varying orientation of a secondary amine.

New research highlights: Impact of chronic ingestion of white kidney beans (Phaseolus vulgaris L. var. Beldia) on small-intestinal disaccharidase activity in Wistar rats.

The chronic ingestion of raw or undercooked kidney beans (Phaseolus vulgaris L.) is involved in the pathogenesis of multiple organ dysfunction; the underlying mechanisms are still poorly understood. The objective of this study was to assess the gavage effects of a raw Beldia bean variety on the brush border disaccharidase activities in the jejunal mucosa of Wistar rats. Twenty young adult male rats were randomly assigned into 2 groups of 10 rats each: Control, rats were gavaged with 300 mg of a rodent pellet flour suspension (RPFS); Experimental, rats were orogastrically fed a dose of 300 mg Beldia bean flour suspension (BBFS). Prior to determining the disaccharidase activity by Dahlqvist method, the blood and stool specimens were collected on day 10. The sera and feces were screened for the presence of lectins by serologic and hemagglutination assays. The results showed that the brush border maltase and sucrase activities were significantly diminished but lactase activity did not undergo any change in BBFS-gavaged animals as compared with control. Preliminary immunobiochemical assays revealed the absence of lectins in the systemic circulation and feces of rats, but further work is required to prove this. Overall, the dietary administration of BBFS caused depression of the activity of the small intestinal enzymes maltase and sucrase.

Sugar Metabolism in Hummingbirds and Nectar Bats.

Hummingbirds and nectar bats coevolved with the plants they visit to feed on floral nectars rich in sugars. The extremely high metabolic costs imposed by small size and hovering flight in combination with reliance upon sugars as their main source of dietary calories resulted in convergent evolution of a suite of structural and functional traits. These allow high rates of aerobic energy metabolism in the flight muscles, fueled almost entirely by the oxidation of dietary sugars, during flight. High intestinal sucrase activities enable high rates of sucrose hydrolysis. Intestinal absorption of glucose and fructose occurs mainly through a paracellular pathway. In the fasted state, energy metabolism during flight relies on the oxidation of fat synthesized from previously-ingested sugar. During repeated bouts of hover-feeding, the enhanced digestive capacities, in combination with high capacities for sugar transport and oxidation in the flight muscles, allow the operation of the “sugar oxidation cascade”, the pathway by which dietary sugars are directly oxidized by flight muscles during exercise. It is suggested that the potentially harmful effects of nectar diets are prevented by locomotory exercise, just as in human hunter-gatherers who consume large quantities of honey.

Effect of Oral Insulin on the Development of Small Intestine Carbohydrate Hydrolysis and Absorption in Suckling Rats

The study is conducted to reveal the effect of oral insulin on the development of carbohydrate hydrolysis and transport in the small intestine in suckling rats. Oral insulin administration (5 U/kg/day) from the 1st to the 21st day of postnatal life resulted in induction of the carbohydrate assimilation in the small intestine of growing rats. Oral insulin increased intestinal maltase, sucrase and lactase activity as well as absorption of free and hydrolysis-dependent glucose from maltose in the small intestine of suckling rats. The effect was age-dependent and was clearly expressed during the second half of the milk nutrition period. After weaning oral insulin effect on the intestinal carbohydrate digestion and absorption was absent. These data show oral insulin keeps its biological activity in the intestinal cavity and they suggest involvement of milk insulin in the hydrolysis and absorption of carbohydrates in the small intestine.

Investigation of Antihyperglycaemic Activity of Banana (Musa sp. Var. Nanjangud rasa bale) Flower in Normal and Diabetic Rats.

Background:The vital enzymes of starch digestion and absorption are intestinal α-glucosidases and their inhibition improves postprandial hyperglycaemia, constituting an effective mode of therapy in diabetes.Objectives:The present study was designed to assess the inhibitory potential of ethanol extract of banana flower (EF) on mammalian α-glucosidases and its pharmacological effects on postprandial hyperglycaemia in normal and alloxan-induced diabetic rats.Materials and Methods:EF was evaluated for its inhibitory potential and mode of inhibition on mammalian α-glucosidases. Further, the role of EF and its constituents Umbelliferone (C1) and Lupeol (C2) on glucose uptake using isolated rat hemi-diaphragm and insulinotropic activity using RINm5F (rat insulinoma) cell lines were determined. The phytocomponents in EF were also evaluated using GC-MS.Results:EF illustrated a dose-dependent inhibition for rat intestinal sucrase, maltase and p-nitrophenyl-α-D-glucopyranoside (pNPG) hydrolysis (IC50 values: 18.76±0.22, 25.54±0.10 and 76.42±1.12 µg/ml, respectively) and the mode of inhibition was non-competitive with low Ki values. Oral administration (100-200 mg/kg b.wt.) of EF significantly improved the maltose/glucose-induced postprandial hyperglycaemia in normal and alloxan-induced diabetic rats. EF, C1 and C2 exhibited stimulation of glucose uptake and a dose-dependent glucose-induced insulin secretion at both 4.5 and 16.7 mM glucose concentrations. Further, GC-MS analysis revealed significant levels of steroids (25.61%), diazoprogesterone (21.31%), sesquiterpene (11.78%) and other phytocomponents.Conclusion:EF inhibited α-glucosidases besides promoting glucose uptake and insulin secretion, resulting in antihyperglycaemic effect determining EF as a potent anti-diabetic agent.Abbreviations used: mg/dl: milligramsper deciliter, mM: millimolar, b.wt.: body weight.

The inhibitory activity of herbal medicines on the keys enzymes and steps related to carbohydrate and lipid digestion

BackgroundObesity and overweight are consistently associated with metabolic disorders including hyperglycemia and hyperlipidemia. Herbal medicines have been currently suggested as an alternative source of potentially useful antihyperglycemic, antihyperlipidemic, antioxidant activities. The objective of this study was to assess the in vitro inhibitory effects of eleven herbal medicines on carbohydrate and lipid digestive enzymes and the key steps of lipid digestion including the inhibition of micelle formation and the ability to bind bile acid. In addition, antioxidant activity of herbal medicines was also investigated.Methodsα-Glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase inhibitory activities of aqueous extract of herbal medicines were measured using the enzymatic colorimetric assay. The formation of cholesterol micelles was determined using the cholesterol assay kit. The bile acid binding was measured using the colorimetric assay. Antioxidant activities were assessed by using four methods including Trolox equivalent antioxidant capacity (TEAC), oxygen radical absorbance capacity ORAC), superoxide radical scavenging activity (SRSA), and hydroxyl radical scavenging activity (HRSA).ResultsThe extracts (1 mg/mL) markedly inhibited intestinal maltase (5.16 − 44.33 %), sucrase (1.25–45.86 %), pancreatic α-amylase (1.75–12.53 %), pancreatic lipase (21.42–85.93 %), and pancreatic cholesterol esterase (2.92–53.35 %). The results showed that all extracts exhibited the inhibitory activity against pancreatic lipase with the IC50 values ranging from 0.015 to 4.259 mg/mL. In addition, the incorporation of cholesterol into micelles was inhibited by the extracts (6.64–33.74 %). The extracts also bound glycodeoxycholic acid (9.9–15.08 %), taurodeoxycholic acid (12.55–18.18 %), and taurocholic acid (11.91 − 18.4 %). Furthermore, the extracts possessed various antioxidant activities including the TEAC values (0.50 − 4.70 μmol trolox/mg dried extract), the ORAC values (9.14–44.41 μmol trolox/mg dried extract), the SRSA (0.31 − 18.82 mg trolox/mg dried extract), and the HRSA (0.05–2.29 mg trolox/mg dried extract). The findings indicated that Syzygium aromaticum, Phyllanthus amarus, Thunbergia laurifolia were the effective promising antihyperglycemic and antihyperlipidemic agents. Statistical analysis demonstrated strong positive significant correlations between the contents of phenolic compounds and % inhibition of pancreatic lipase (r = 0.885, p < 0.001), % inhibition of pancreatic cholesterol esterase (r = 0.761, p < 0.001), and the TEAC value (r = 0.840, p < 0.001). Furthermore, there was a strongly positive correlation between the TEAC value and % inhibition of pancreatic cholesterol esterase (r = 0.851, p < 0.001) and % inhibition of pancreatic lipase (r = 0.755, p < 0.001).ConclusionsThree herbal medicines including Syzygium aromaticum, Thunbergia laurifolia, and Phyllanthus amarus markedly inhibited the intestinal α-glucosidase, pancreatic α-amylase, pancreatic lipase, and pancreatic cholesterol esterase. They also reduced formation of cholesterol micelle and bound bile acid. The findings indicate that these herbal medicines might be a promising agent for antihyperglycemic, antihyperlipidemic, and antioxidant activities.

Modulation of digestive enzyme activities in the avian digestive tract in relation to diet composition and quality.

In nature, birds are faced with variable food sources that may differ in composition (protein vs. carbohydrates) and quality (highly digestible material vs. indigestible fiber). Studies in passerine birds and some commercial poultry demonstrate that the gastrointestinal tract can respond to varying diet composition and quality by changing morphology and/or activities of digestive enzymes. However, studies in additional avian species are warranted to understand generalities of these trends. We first fed juvenile mallards (Anas platyrhynchos), chickens (Gallus gallus), and quails (Coturnix coturnix) on either high-carbohydrate or high-protein diets. For the most part, birds fed the high-carbohydrate diet had higher small intestinal and cecal disaccharidase activities (maltase and sucrase). However, only mallards exhibited higher small intestinal aminopeptidase-N (APN) activities when fed the high-protein diet. These results differ from passerine birds, which largely modulate small intestinal proteases, but not disaccharidases. In another trial, we fed Canada geese (Branta canadensis) diets that varied in both their protein and fiber concentrations for approximately 3.5months. Birds fed the high-fiber diets had significantly longer small intestines and caeca compared to those fed low-fiber diets. Additionally, geese fed the high-fiber diets exhibited lower mass-specific activities of small intestinal sucrase, and higher activities of APN when summed across the small intestine and ceca. Similar to the avian species above, geese fed the high-protein diets did not exhibit flexibility in their small intestinal APN activities. Overall, these experiments demonstrate that responsiveness of the avian digestive tract to diet composition may have phylogenetic or ecological constraints. Studies on other avian taxa are needed to understand these patterns.

Intestinal Sucrase as a Novel Target Contributing to the Regulation of Glycemia by Prebiotics.

Inulin-type fructans (ITF) are known for their capacity to modulate gut microbiota, energy metabolism and to improve glycemia in several animal models of obesity, and in humans. The potential contribution of ITF as modulators of sugar digestion by host enzymes has not been evaluated yet. A sucrose challenge has been performed on naive mice fed a standard diet supplemented with or without native chicory inulin (Fibruline 5%) for 3 weeks. The area under the curve of glycemia as well as sucrase activity in the small intestine were lowered after inulin treatment. Pyrosequencing of the 16S rRNA gene confirmed important changes in gut microbiota (mostly in favor of Blautia genus) due to inulin extract supplementation. Interestingly, the suppressive effect of inulin extract on postprandial glycemia also occurred when inulin was directly added to the sucrose solution, suggesting that the effect on sucrose digestion did not require chronic inulin administration. In vitro tests confirmed a direct inhibition of sucrase enzyme by the inulin extract, thereby suggesting that native chicory inulin, in addition to its well-known prebiotic effect, is also able to decrease the digestibility of carbohydrates, a phenomenon that can contribute in the control of post prandial glycemia. We may not exclude that the sucrose escaping the digestion could also contribute to the changes in the gut microbiota after a chronic treatment with inulin.