Intestinal Α-glucosidase Research Articles

Antidiabetic Effects ofVigna nakashimaeExtract indb/dbMice

The inhibitory activity of Vigna nakashimae extract against intestinal α-glucosidase was investigated in vitro and in vivo. The extract exerted a significant inhibitory effect against intestinal α-glucosidases. With sucrose-loading, it reduced the peak responses of blood glucose significantly in normal mice. Next, it was administrated to 8-week-old db/db mice for 2 weeks, and then plasma glucose, triglyceride, and total cholesterol levels were measured. The extract significantly suppressed postprandial hyperglycemia and blood glycated hemoglobin in the db/db mice. In addition, it lowered fasting glucose and improved glucose tolerance. Furthermore, it led to significant decreases in plasma triglyceride levels. It reduced endoplasmic reticulum stress in thapsigargin-induced HepG2 cells. Taken together, these results suggest that Vigna nakashimae extract has hypoglycemic and hypolipidemic effects that occur via inhibition of α-glucosidase activity and endoplasmic reticulum stress.

α-Amylase and α-glucosidase inhibitory effects of Sclerocarya birrea [(A. Rich.) Hochst.] subspecies caffra (Sond) Kokwaro (Anacardiaceae) stem-bark extracts

Inhibition of intestinal α-amylase and α-glucosidase is an important strategy to control post-prandial hyperglycemia associated with type 2 diabetes mellitus. In vitro inhibitory effects of crude Sclerocarya birrea stem bark (SBSB) extracts against human urinary α-amylase and Bacillus steatothermophilus α-glucosidase were studied. Crude SBSB methanolic and acetone extracts inhibited human urinary α-amylase more potently than acarbose. Crude SBSB hexane extract was a strong inhibitor of α-glucosidase and weaker inhibitor of α-amylase. Furthermore, SBSB hexane extract significantly suppressed the rise in postprandial glucose level after oral administration of sucrose but failed to induce similar effects after oral administration of starch and glucose in both normal and diabetic rats. The results of this study suggest that the crude SBSB hexane extract may suppress the rise in postprandial hyperglycemia in vivo in part, through inhibition of alpha glucosidase. Keywords : Diabetic rats, alloxan, postprandial hyperglycemia, diabetes mellitus.

New icetexane diterpenes with intestinal α-glucosidase inhibitory and free-radical scavenging activity isolated from Premna tomentosa roots

New icetexane diterpenes ( 1– 2); 8, 11, 13-icetexatriene-10-hydroxy, 11, 12, 16-tri acetoxyl ( 1) and 8, 11, 13-icetexatriene-7, 10, 11-dihydroxy-12, 13-dihydrofuran ( 2) along with six known compounds namely acetoxy syranzaldehyde ( 3), syranzaldehyde ( 4), coniferaldehyde ( 5), lupeol ( 6), betulin ( 7), and 4-(4-methoxy phenyl)-2-butanone ( 8) were isolated from the roots of Premna tomentosa. The structures of compounds 1 and 2 were established by detailed spectral analysis using UV, IR, 1H NMR, 13C NMR, 1D, 2D and Mass. The newly isolated compounds were screened for rat intestinal α-glucosidase inhibitory and free radical (DPPH) scavenging potentiality. The new icetexane diterpenes ( 1, 2) and compound 3 were found to have significant α-glucosidase inhibitory and also free radical scavenging (DPPH) activities.

In Vitro and In Vivo Antihyperglycemic Effect of 2 Amadori Rearrangement Compounds, Arginyl‐Fructose and Arginyl‐Fructosyl‐Glucose

During the heat processing of raw ginseng to produce red ginseng, amino acid derivatives such as arginyl-fructose (AF) and arginyl-fructosyl-glucose (AFG) are formed at high levels, through amadori rearrangement, the early step of Maillard reaction, from arginine and glucose or maltose, respectively. However, very limited information is available about the effect of the structural difference between AF and AFG on various biological activities. This is the first report of the mode of action and effect of AF and AFG on the type 2 diabetes management related inhibition of postprandial hyperglycemia in vitro and in animal model. In our previous study, standards AF and AFG were chemically synthesized and in this study their inhibitory activities against rat intestinal α-glucosidases and porcine pancreatic α-amylase were investigated in vitro. The IC(50) value of the in vitro inhibitory activity of AF and AFG on rat intestinal sucrase was high and in similar levels (6.40 and 6.20 mM, respectively). Additionally, a mild pancreatic α-amylase inhibitory activity was observed, with IC(50) values 36.30 and 37.60 mM for AF and AFG, respectively. The effect of AF and AFG on the postprandial blood glucose increase after meal was investigated in Sprague Dawley rats fed on starch or sucrose meals. Both amadori compounds significantly reduced the postprandial blood glucose levels after starch or sucrose loading. These results indicate that AF and AFG, Maillard reaction products, may have antidiabetic effect by suppressing carbohydrate absorption in the gastrointestinal level, and thereby reducing the postprandial increase of blood glucose.

Chip-based drug screening for inhibiting α-glucosidase

Intestinal α-glucosidase performs a physiologically vital function in the digestive process of dietary carbohydrates. Administration of an α-glucosidase inhibitor may retard the digestion and absorption of carbohydrates. Consequently, the rise in postprandial blood glucose could be suppressed. This study developed a novel technology, called “after flowing through immobilized receptor (AFTIR),” for targeting components in herbal medicines with α-glucosidase-suppressing capability. As a result, we reveal that the AFTIR system is a highly-efficient drug screening platform, capable of purifying and identifying active components with α-glucosidase-suppressing capability in herbal medicines.

Antidiabetic effects of Allium ascalonicum methanolic extract in experimental diabetes

In the present study we have investigated the antidiabetic effects of bulbs of Persian shallot Allium ascalonicum L., (Alliaceae) methanolic extract (AAE) at doses of 500 and 250mg/kg bw, on Alloxan-induced diabetic male Wistar rats in comparision with Acarbose (as a reference drug), by measuring postprandial blood glucose (PBG), oral glucose tolerance test (OGTT), inhibition of rat intestinal α-glucosidases activities, changes in the levels of plasma lipids profiles antioxidant enzymes activities, including superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT), pancreatic Insulin and cardiac Glut-4 mRNAs expression. In diabetic Wistar rats, in short term period, effects of AAE on PBG showed significant reduction after 24h of oral administration. After 3 weeks of treatment, significant chronic decrease in the PBG was observed. For OGTT, the increase in PBG levels reduced mildly in AAE treated diabetic rats, at 1hour. Intestinal sucrase and maltase activities were inhibited by AAE, 17.41% and 14.62% respectively. In diabetic rats, AAE also increased the activities of SOD by 65%, GPx by 43% and CAT by 55%, showing strong antioxidant effects. AAE demonstrated antihyperlipidemic properties by reducing serum TG, LDL, VLDL and TC. In addition, we have observed increased expression of Ins and Glut-4 genes in diabetic rats treated with methanolic extract of Allium ascalonicum, compared to control group.

Inhibitory effects of five medicinal plants on ratalpha-glucosidase: Comparison with their effects on yeast alpha-glucosidase

The mammalian and yeast α-glucosidase inhibitory activities of Senna italica, Tinospora fragosa, Manilkara mochisia, Xanthocercis zambesiaca, Ozoroa cf. albicans, Peltophorum africanum, Cassia abbreviata were investigated using p-nitrophenyl glucopyranoside as a substrate. All the plant species tested had low inhibitory activity against rat intestinal α-glucosidase. The highest concentration of C. abbreviata resulted in no observable loss of rat intestinal α-glucosidase activity. At 2.5 mg/ml, X. zambesiaca managed only 25% inhibition of rat intestinal glucosidase activity. M. mochisia led to about 60% loss of activity at 5 mg/ml. On the other hand, all plant species tested had good inhibitory activity against Baker’s yeast α-glucosidase. These findings suggest that a chemical substance that inhibits yeast α-glucosidase activity will not necessarily inhibit mammalian α-glucosidase. The validatation of the antidiabetic activity of medicinal plant extracts, with the focus on the inhibition of carbohydrate-digesting enzymes, will require, in addition, investigation of mammalian enzymes. The antioxidant activity of these plant species was also investigated, with C. abbreviata and ascorbic acid as the positive controls. The IC50 values were estimated. P. africanum had good antioxidant activity with an IC50 value of 0.030 mg/ml, similar to the IC50 value resulting from the positive control, ascorbic acid. Key words: Diabetes mellitus, α-glucosidase activity, antioxidant activity, plant extracts.

Effects of Onion (Allium cepa L.) Extract Administration on Intestinal α-Glucosidases Activities and Spikes in Postprandial Blood Glucose Levels in SD Rats Model

Diets high in calories and sweetened foods with disaccharides frequently lead to exaggerated postprandial spikes in blood glucose. This state induces immediate oxidant stress and free radicals which trigger oxidative stress-linked diabetic complications. One of the therapeutic approaches for decreasing postprandial hyperglycemia is to retard absorption of glucose by the inhibition of carbohydrate hydrolyzing enzymes, α-amylase and α-glucosidases, in the digestive organs. Therefore, the inhibitory activity of Korean onion (Allium cepa L.) extract against rat intestinal α-glucosidases, such as sucrase, maltase, and porcine pancreatic α-amylase were investigated in vitro and in vivo. The content of quercetin in ethyl alcohol extract of onion skin (EOS) was 6.04 g/100 g dried weight of onion skin. The in vitro half-maximal inhibitory concentrations (IC50) of EOS and quercetin, a major phenolic in onion, on rat intestinal sucrase were 0.40 and 0.11 mg/mL, respectively. The postprandial blood glucose lowering effects of EOS and quercetin were compared to a known type 2 diabetes drug (Acarbose), a strong α-glucosidase inhibitor in the Sprague-Dawley (SD) rat model. In rats fed on sucrose, EOS significantly reduced the blood glucose spike after sucrose loading. The area under the blood glucose-time curve (AUClast) in EOS-treated SD rats (0.5 g-EOS/kg) was significantly lower than in untreated SD rats (259.6 ± 5.1 vs. 283.1 ± 19.2 h·mg/dL). The AUClast in quercetin-treated SD rats (0.5 g-quercetin/kg) was similar to in EOS-treated group (256.1 ± 3.2 vs. 259.6 ± 5.1 h·mg/dL). Results from this study indicates that although quercetin does have blood glucose lowering potential via α-glucosidase inhibition, there are other bioactive compounds present in onion skin. Furthermore, the effects of two weeks administration of EOS in a high carbohydrate-dietary mixture (Pico 5053) on sucrase and maltase activities in intestine were evaluated in SD rat model. Compared to the upper and middle parts of intestine, the activities of sucrase in the lower parts of intestine remained significantly higher after two weeks of EOS treatment. These results indicate that EOS may improve exaggerated postprandial spikes in blood glucose and glucose homeostasis since it inhibits intestinal sucrase and thus delays carbohydrate absorption, although clinical trials are needed.

Mulberry Leaf Extract Reduces Postprandial Hyperglycemia with Few Side Effects by Inhibiting α-Glucosidase in Normal Rats

Mulberry (Morus alba L.) leaf extract (MLE) was investigated as a potent plant-derived α-glucosidase inhibitor with low α-amylase inhibitory activity. MLE was prepared by heating in an autoclave at 121 °C for 15 minutes, and its in vitro and in vivo antihyperglycemic activities were investigated. The adverse side effects of MLE were analyzed by measuring the weight and volume of the cecum, stool color, starch content in the cecum, and the integrity of intestinal transporting capacity. The in vitro inhibitory activity of MLE on intestinal α-glucosidase was potent and that on intestinal α-amylase was very weak compared with acarbose. Sugar loading tests with starch, maltose, and sucrose showed that MLE may reduce postprandial increases in blood glucose by acting as an intestinal α-glucosidase inhibitor. Feeding tests suggested that MLE may exhibit fewer adverse side effects than other α-glucosidase inhibitors, such as abdominal flatulence and meteorism, which are attributed to the impaired digestion of starch by strong inhibition of intestinal α-amylase. These results suggest that MLE could be used in the development of pharmaceutical foods to control the blood glucose levels of diabetic patients by inhibiting intestinal α-glucosidase with reduced side effects.

Identification of the genes involved in 1-deoxynojirimycin synthesis in Bacillus subtilis MORI 3K-85

1-Deoxynojirimycin (DNJ), a D-glucose analogue with a nitrogen atom substituting for the ring oxygen, is a strong inhibitor of intestinal α-glucosidase. DNJ has several promising biological activities, including its antidiabetic, antitumor, and antiviral activities. Nevertheless, only limited amounts of DNJ are available because it can only be extracted from some higher plants, including the mulberry tree, or purified from the culture broth of several types of soil bacteria, such as Streptomyces sp. and Bacillus sp. In our previous study, a DNJ-producing bacterium, Bacillus subtilis MORI, was isolated from the traditional Korean fermented food Chungkookjang. In the present study, we report the identification of the DNJ biosynthetic genes in B. subtilis MORI 3K-85 strain, a DNJ-overproducing derivate of the B. subtilis MORI strain generated by γ-irradiation, xhe genomic DNA library of B. subtilis MORI 3K-85 was constructed in Escherichia coli, and clones showing α-glucosidase inhibition activity were selected. After DNA sequencing and a series of subcloning, we were able to identify a putative Operon which consists of gabT1, yktc1, and gutB1 genes predicted to encode putative transaminase, phosphatase, and oxidoreductase, respectively. When a recombinant plasmid containing this Operon sequence was transformed into an E. coli strain, the resulting transformant was able to produce DNJ into the culture medium. Our results indicate that the gabT1, yktc1, and gutB1 genes are involved in the DNJ biosynthetic pathway in B. subtilis MORI, suggesting the possibility of employing these genes to establish a large-scale microbial DNJ overproduction system through genetic engineering and process optimization.

Mapping the intestinal alpha-glucogenic enzyme specificities of starch digesting maltase-glucoamylase and sucrase-isomaltase

Inhibition of intestinal α-glucosidases and pancreatic α-amylases is an approach to controlling blood glucose and serum insulin levels in individuals with Type II diabetes. The two human intestinal glucosidases are maltase-glucoamylase and sucrase-isomaltase. Each incorporates two family 31 glycoside hydrolases responsible for the final step of starch hydrolysis. Here we compare the inhibition profiles of the individual N- and C-terminal catalytic subunits of both glucosidases by clinical glucosidase inhibitors, acarbose and miglitol, and newly discovered glucosidase inhibitors from an Ayurvedic remedy used for the treatment of Type II diabetes. We show that features of the compounds introduce selectivity towards the subunits. Together with structural data, the results enhance the understanding of the role of each catalytic subunit in starch digestion, helping to guide the development of new compounds with subunit specific antidiabetic activity. The results may also have relevance to other metabolic diseases such as obesity and cardiovascular disease.

Persimmon leaf (Diospyros kaki), a potent -glucosidase inhibitor and antioxidant: Alleviation of postprandial hyperglycemia in normal and diabetic rats

This research aims to investigate the α-glucosidase (baker’s yeast and rat intestinal acetone powder) inhibitory potential of Diospyros kaki Thunb. (Ebenaceae) leaf extract (DKLE) along with its antioxidant activity against metal-catalysed protein oxidation by pro-oxidant model (Fe2+/ascorbate) in rat liver homogenates, in vitro. DKLE evidenced the outstanding inhibitory effect with IC50 values of 1.22 and 32 µg/ml for baker’s yeast and rat intestinal α-glucosidase enzymes. The inhibition mode of this extract was determined by measuring enzyme activity in different concentrations of substrate for Lineweaver-Burk plot analysis. Its inhibition was found to be noncompetitive. The addition of Fe2+/ascorbate to the liver homogenate significantly increased the extent of lipid peroxidation which was significantly lowered with the extract treatment. Furthermore, DKLE ability to alleviate postprandial hyperglycemia in normal and streptozotocin (STZ)-induced diabetic rats was scrutinized. Oral administration of this leaf extract (250 to 1000 mg/kg body wt.) considerably decreased blood glucose in normal and diabetic rats after glucose and maltose loading in a dose-dependent manner. These results propose that DKLE might show an anti-diabetic effect by suppressing carbohydrate and glucose absorption from the intestine and can reduce the postprandial blood glucose rise. Key words: Diospyros kaki, α-glucosidase, antioxidant, diabetic rats, postprandial hyperglycemia, streptozotocin.

Inhibitory Activity of Cinnamon Bark Species and their Combination Effect with Acarbose against Intestinal α-glucosidase and Pancreatic α-amylase

Inhibition of α-glucosidase and pancreatic α-amylase is one of the therapeutic approaches for delaying carbohydrate digestion, resulting in reduced postprandial glucose. The aim of this study was to evaluate the phytochemical analysis and the inhibitory effect of various cinnamon bark species against intestinal α-glucosidase and pancreatic α-amylase. The results showed that the content of total phenolic, flavonoid, and condensed tannin ranged from 0.17 to 0.21 g gallic acid equivalent/g extract, from 48.85 to 65.52 mg quercetin equivalent/g extract, and from 0.12 to 0.15 g catechin equivalent/g extract, respectively. The HPLC fingerprints of each cinnamon species were established. Among cinnamon species, Thai cinnamon extract was the most potent inhibitor against the intestinal maltase with the IC(50) values of 0.58 ± 0.01 mg/ml. The findings also showed that Ceylon cinnamon was the most effective intestinal sucrase and pancreatic α-amylase inhibitor with the IC(50) values of 0.42 ± 0.02 and 1.23 ± 0.02 mg/ml, respectively. In addition, cinnamon extracts produced additive inhibition against intestinal α-glucosidase and pancreatic α-amylase when combined with acarbose. These results suggest that cinnamon bark extracts may be potentially useful for the control of postprandial glucose in diabetic patients through inhibition of intestinal α-glucosidase and pancreatic α-amylase.

Ct‐MGAM Activity Adapts to Various Botanical Food Starch Intakes by Alternative Splicing

Maltase‐Glucoamylase (MGAM) is one of the intestinal mucosal α‐glucosidases responsible for the final digestion of starch to free glucose. In humans membrane‐bound MGAM is formed by two subunits: a N‐terminal (Nt‐MGAM) subunit with slow activity against αamylase pretreated α‐Limit Dextrins (α‐LDx); and a C‐terminal (Ct‐MGAM) subunit with fast activity against α‐LDx and substrate inhibition by the shortest glucans. In mammals, including humans, the 3′‐region of the MGAM gene coding the Ct subunit contains from 4 to 6 paralogous copies, each for a varied subunit. Although expression of mRNA from these copies has been observed, the biological significance of the variable 3′ Ct regions undocumented. Here we report 4 different mRNAs coding for Ct‐MGAM, each by alternative splicing. The recombinant expression of these 4 subunits produced active enzymes with differences in their kinetic properties of catalysis. These observations indicate that variable Ct‐MGAM subunits are the result of alternative splicing arising from paralogous duplications in the MGAM gene's 3′‐region. The resulting “splicoform” Ct‐MGSM enzymes may be a mechanism for efficient digestion of glucans with variable α‐LDx structures generated by αamylase from starches of different botanical origin. Supported by CNRC/ARS/USDA and CONACYT‐Mexico.

Biological evaluation of 3′-O-alkylated analogs of salacinol, the role of hydrophobic alkyl group at 3′ position in the side chain on the α-glucosidase inhibitory activity

Four analogs with 3'-O-alkyl groups (9a: CH(3), 9b: C(2)H(5), 9c: C(13)H(27) or 9d: CH(2)Ph) instead of the 3'-O-sulfate anion in salacinol (1), a naturally occurring potent α-glucosidase inhibitor, were synthesized by the coupling reaction of 1,4-dideoxy-1,4-epithio-d-arabinitols (18a and 18b) with appropriate epoxides (10a-10d). These analogs showed equal or considerably higher inhibitory activity against rat small intestinal α-glucosidases than the original sulfate (1), and one of them (9d) was found more potent than currently used α-glucosidase inhibitors as antidiabetics. Thus, introduction of a hydrophobic moiety at the C3' position of this new class of inhibitor was found beneficial for onset of stronger inhibition against these enzymes.

Inhibitory effect of hydro-methanolic extract of seed of Holarrhena antidysenterica on alpha-glucosidase activity and postprandial blood glucose level in normoglycemic rat

The present experiment was conducted to search out the effect of hydro-methanolic extract of seed of Holarrhena antidysenterica on intestinal α-glucosidase activity in dose dependent manner and on the management of postprandial hyperglycemia in starch loaded rats. Activity of intestinal α-glucosidase was measured by in vitro method. Fasting blood glucose level was determined by single touch glucometer. Total phenol and flavonoids of seed extract of Holarrhena antidysenterica were estimated using gallic acid and quercetin standard curves, respectively. The degree of elevation in blood glucose level after starch administration was significantly (p<0.05) less by the extract in respect to the control. The said extract also inhibited α-glucosidase activity having an IC(50) of 0.52mg/ml. Phytochemical study revealed that the extract is rich in phenolic compounds (60.23mg of gallic acid equivalent/g of extract) and flavonoids (360.23mg of quercetin equivalent/g of the extract). The extract exerts its antihyperglycemic effect by retarding the carbohydrate absorption from intestine through the inhibition in α-glucosidase activity and therefore resists postprandial hyperglycemia.

In Vitro and in Vivo Anti-Hyperglycemic Effects of Omija (Schizandra chinensis) Fruit

The entrocytes of the small intestine can only absorb monosaccharides such as glucose and fructose from our diet. The intestinal absorption of dietary carbohydrates such as maltose and sucrose is carried out by a group of α-glucosidases. Inhibition of these enzymes can significantly decrease the postprandial increase of blood glucose level after a mixed carbohydrate diet. Therefore, the inhibitory activity of Omija (Schizandra chinensis) extract against rat intestinal α-glucosidase and porcine pancreatic α-amylase were investigated in vitro and in vivo. The in vitro inhibitory activities of water extract of Omija pulp/skin (OPE) on α-glucosidase and α-amylase were potent when compared to Omija seeds extract (OSE). The postprandial blood glucose lowering effect of Omija extracts was compared to a known type 2 diabetes drug (Acarbose), a strong α-glucosidase inhibitor in the Sprague-Dawley (SD) rat model. In rats fed on sucrose, OPE significantly reduced the blood glucose increase after sucrose loading. Furthermore, the oxygen radical absorbance capacity (ORAC) of OSE and OPE was evaluated. OPE had higher peroxyl radical absorbing activity than OSE. These results suggest that Omija, which has high ORAC value with α-glucosidase inhibitory activity and blood glucose lowering effect, could be physiologically useful for treatment of diabetes, although clinical trials are needed.

Inhibitory activities of Ficus benghalensis bark against carbohydrate hydrolyzing enzymes - An in vitro study

The present study evaluated the effect of Ficus benghalensis Linn. (Moraceae) stem bark on porcine pancreatic α-amylase, rat intestinal α-glucosidase and sucrase. Further, the effect of heat treatment was also studied. Both untreated and heattreated samples inhibited α-amylase to a significant extent. Further, the aqueous extracts prepared form untreated and heat treated samples exhibited significant inhibition (p ≤ 0.05) of α-glucosidase and sucrase in a dose dependent manner. Heat treatment of the sample increased α-glucosidase and sucrase inhibitory activities at lower concentrations, however no statistical differences were observed at higher concentrations. Consequently, the untreated extracts showed IC50 values of 158 and 193 μg mL-1 for α-glucosidase and sucrase respectively while, the heat-treated extracts showed the IC50 values 77 and 141 μg mL-1 respectively. Further, a significant correlation (p ≤ 0.05; r = 0.698) was observed between α-glucosidase and sucrase inhibitory activities of both untreated and heat-treated extracts. The results clearly demonstrate that inhibition of carbohydrate hydrolyzing enzymes is one of the mechanism through which F. benghalensis bark exerts its hypoglycemic effect in vivo.

Isolation, structure identification and SAR studies on thiosugar sulfonium salts, neosalaprinol and neoponkoranol, as potent α-glucosidase inhibitors

Two hitherto missing members of sulfonium salts family in Salacia genus plants as a new class of α-glucosidase inhibitors, neoponkoranol (7) and neosalaprinol (8), were isolated from the water extracts, and their structures were unambiguously identified. For further SAR studies on this series of sulfonium salts, several epimers of 7 and 8 were synthesized, and their inhibitory activities against rat small intestinal α-glucosidases were evaluated. Among them, 3′-epimer of 7 was found most potent in this class of molecules, and revealed as potent as currently used antidiabetics, voglibose and acarbose.

Cyanidin-3-rutinoside alleviates postprandial hyperglycemia and its synergism with acarbose by inhibition of intestinal α-glucosidase

The inhibitory activity on intestinal α-glucosidase by cyanidin-3-rutinoside was examined in vitro and in vivo. The IC50 values of cyanidin-3-rutinoside against intestinal maltase, and sucrase were 2,323 ± 14.8 and 250.2 ± 8.1 µM, respectively. The kinetic analysis revealed that intestinal sucrase was inhibited by cyanidin-3-rutinoside in a mixed-type manner. The synergistic inhibition also found in combination of cyanidin-3-rutinoside with acarbose against intestinal maltase and sucrase. The oral administration of cyanidin-3-rutinoside (100 and 300 mg/kg) plus maltose or sucrose to normal rats, postprandial plasma glucose was markedly suppressed at 30–90 min after loading. Furthermore, the normal rats treated with acarbose and cyanidin-3-rutinoside (30 mg/kg) showed greater reduction of postprandial plasma glucose than the group treated with acarbose alone. These results suggest that cyanidin-3-rutinoside retards absorption of carbohydrates by inhibition of α-glucosidase which may be useful as a potential inhibitor for prevention and treatment of diabetes mellitus.