Biosynthesis and regulatory mechanism of acarbose and its structural analogs: a review / 生物工程学报

Acarbose is widely used as α-glucosidase inhibitor in the treatment of type Ⅱ diabetes. Actinoplanes sp. is used for industrial production of acarbose. As a secondary metabolite, the biosynthesis of acarbose is quite complex. In addition to acarbose, a few acarbose structural analogs are also accumulated in the culture broth of Actinoplanes sp., which are hard to remove. Due to lack of systemic understanding of the biosynthesis and regulation mechanisms of acarbose and its structural analogs, it is difficult to eliminate or reduce the biosynthesis of the structural analogs. Recently, the advances in omics technologies and molecular biology have facilitated the investigations of biosynthesis and regulatory mechanisms of acarbose and its structural analogs in Actinoplanes sp.. The genes involved in the biosynthesis of acarbose and its structural analogs and their regulatory mechanism have been extensively explored by using bioinformatics analysis, genetic manipulation and enzymatic characterization, which is summarized in this review.

Synthesis and Biological Activity of Trolox Amide Derivatives

Abstract A series of Trolox amide derivatives were synthesized by modifying the carboxyl groups of Trolox. Thirty target compounds were obtained and characterized through nuclear magnetic resonance and mass spectrometry. Trolox derivatives were employed to explore the potential structure-antioxidant activity relationships. The antioxidant activities of these compounds were evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP) and hydroxyl radical assays. DPPH scavenging activity test results illustrated that compounds exhibited scavenging activities similar to L-ascorbic acid and Trolox, with compounds 14a, 18a, 24a and 26a in particular exhibiting higher scavenging activities than L-ascorbic acid. The results demonstrated that compounds displayed ABTS scavenging activities similar to L-ascorbic acid and Trolox, with compounds 26a and 29a in particular having potency twofold higher. FRAP assay results indicated that compounds 11a, 19a, 25a, 29a and 30a had activity similar to Trolox. The results revealed that compounds 6a and 19a had similarly high hydroxyl radical-scavenging activities as Trolox. The results of α-glucosidase experiments uncovered that compounds 10a, 25a, 28a and 29a had excellent inhibitory activity, which was similar to that of acarbose and different from Trolox. The results of acetylcholinesterase and butyrylcholinesterase experiments demonstrated that some compounds had weak anticholinesterase activities. 26a and 29a are important Trolox derivatives with better biological activity profiles and deserve further study

Antidiabéticos orais no diabetes gestacional: revisão de literatura / Oral antidiabetics in gestational diabetes: literature review

O diabetes mellitus gestacional (DMG) é um distúrbio metabólico por déficit na produção e/ou ação insulínica. Tem relação direta com um constante estado catabólico associado com maior resistência à ação da insulina. Doença de difícil controle, implica risco materno-fetal elevado. O objetivo é estudar a eficácia das drogas antidiabéticas orais sobre o controle glicêmico no DMG e sua segurança quanto aos desfechos gestacionais e perinatais. Trata-se de revisão de literatura descritiva baseada em dados de artigos, livros-texto e guidelines emitidos nos últimos cinco anos. O antidiabético oral pode ser uma boa alternativa no controle do DMG em fase inicial da doença, na presença de distúrbio metabólico e como complemento da terapia com insulina. Entretanto, por causa de sua passagem placentária, há preocupações com seus efeitos fetais e perinatais. Estudos comparativos destacam a metformina no manejo do DMG, considerando principalmente a segurança materno-fetal.(AU)

Gestational diabetes mellitus (GDM) is a metabolic disorder caused by deficit in production and/or insulin action. It is directly related to a constant catabolic state associated with greater resistance to insulin action. Disease difficult to control, implies high maternal-fetal risk. To study the efficacy of oral antidiabetic drugs on glycemic control in GDM and its safety regarding gestational and perinatal outcomes. Descriptive literature review based on data from articles, textbooks and guidelines issued in the last five years. Oral antidiabetic can be a good alternative in the control of GDM in the initial phase of the disease, in the presence of metabolic disorder and as a complement to insulin therapy. However, there are concerns about its placental passage and perinatal effects. Comparative studies highlight metformin in the management of DMG considering mainly maternal-fetal safety.(AU)

Acarbose Add-on Therapy in Patients with Type 2 Diabetes Mellitus with Metformin and Sitagliptin Failure: A Multicenter, Randomized, Double-Blind, Placebo-Controlled Study

BACKGROUND: We evaluated the efficacy and safety of acarbose add-on therapy in Korean patients with type 2 diabetes mellitus (T2DM) who are inadequately controlled with metformin and sitagliptin. METHODS: A total of 165 subjects were randomized to metformin and sitagliptin (Met+Sita, n=65), metformin, sitagliptin, and acarbose (Met+Sita+Acarb, n=66) and sitagliptin and acarbose (Sita+Acarb, exploratory assessment, n=34) therapy in five institutions in Korea. After 16 weeks of acarbose add-on or metformin-switch therapy, a triple combination therapy was maintained from week 16 to 24. RESULTS: The add-on of acarbose (Met+Sita+Acarb group) demonstrated a 0.44%±0.08% (P<0.001 vs. baseline) decrease in glycosylated hemoglobin (HbA1c) at week 16, while changes in HbA1c were insignificant in the Met+Sita group (−0.09%±0.10%, P=0.113). After 8 weeks of triple combination therapy, HbA1c levels were comparable between Met+Sita and Met+Sita+Acarb group (7.66%±0.13% vs. 7.47%±0.12%, P=0.321). Acarbose add-on therapy demonstrated suppressed glucagon secretion (area under the curve of glucagon, 4,726.17±415.80 ng·min/L vs. 3,314.38±191.63 ng·min/L, P=0.004) in the absence of excess insulin secretion during the meal tolerance tests at week 16 versus baseline. The incidence of adverse or serious adverse events was similar between two groups. CONCLUSION: In conclusion, a 16-week acarbose add-on therapy to metformin and sitagliptin, effectively lowered HbA1c without significant adverse events. Acarbose might be a good choice as a third-line therapy in addition to metformin and sitagliptin in Korean subjects with T2DM who have predominant postprandial hyperglycemia and a high carbohydrate intake.

Autumn olive (Elaeagnus umbellata Thunb.) berry reduces fasting and postprandial glucose levels in mice

BACKGROUND/OBJECTIVES: Fasting and postprandial hyperglycemia should be controlled to avoid complications of diabetes mellitus. This study investigated the effects of autumn olive (Elaeagnus umbellata Thunb.) berry (AOB) on fasting and postprandial hyperglycemia in mice. MATERIALS/METHODS: In vitro α-glucosidase inhibitory effect of AOB was determined. Maltose solution (2 g/kg) with and without AOB extract at 500 mg/kg or acarbose at 50 mg/kg was orally administered to normal mice after overnight fasting and glucose levels were measured. To study the effects of chronic consumption of AOB, db/db mice received the basal diet or a diet containing AOB extract at 0.4% or 0.8%, or acarbose at 0.04% for 7 weeks. Blood glycated hemoglobin and serum glucose and insulin levels were measured. Expression of adiponectin protein in epididymal white adipose tissue was determined by Western blotting. RESULTS: In vitro inhibitory effect of AOB extract on α-glucosidase was 92% as strong as that of acarbose. The AOB extract (500 mg/kg) or acarbose (50 mg/kg) significantly suppressed the postprandial rise of blood glucose after maltose challenge and the area under the glycemic response curve in normal mice. The AOB extract at 0.4% or 0.8% of diet or acarbose at 0.04% of diet significantly lowered levels of serum glucose and blood glycated hemoglobin and homeostasis model assessment for insulin resistance values in db/db mice. The expression of adiponectin protein in adipose tissue was significantly elevated by the consumption of AOB at 0.8% of diet. CONCLUSIONS: Autumn olive (E. umbellata Thunb.) berry may reduce postprandial hyperglycemia by inhibiting α-glucosidase in normal mice. Chronic consumption of AOB may alleviate fasting hyperglycemia in db/db mice partly by inhibiting α-glucosidase and upregulating adiponectin expression.

Postprandial Dizziness/Syncope Relieved by Alfa-Glucosidase Inhibitor: A Case Report / 대한평형의학회지

A 74-year-old man presented with positional vertigo and prandial dizziness and syncope. He had experienced episodes of frequent dizziness and loss of consciousness for several months. He underwent total gastrectomy with esophagojejunostomy and brown anastomosis 30 years ago. Thirteen years ago, subtotal colectomy with ileo-descending colostomy was done due to colon cancer. And he also had mitral valve replacement and maze operation due to severe mitral valve stenosis and atrial fibrillation. After cardiac operation, he has suffered from sudden dizziness with diaphoresis and chalky face, which usually occurs especially within 30 minutes from the onset of eating. Sometimes, this event was followed by several seconds of loss of consciousness, which caused recurrent events of falling. Neurological examination showed positional nystagmus compatible with benign paroxysmal positional vertigo arising from posterior semicircular canal of the right ear. The positional vertigo disappeared immediately after canalith repositioning maneuver. We tried to monitor vital signs and serum level of glucose during eating. Hyperglycemia (range, 210–466 mg/dL) was noted during eating, which was accompanied by postprandial and prandial hypotension, up to 60/40 mmHg. The patient was prescribed 100 mg of the alfa-glucosidase, acarbose to be taken half an hour before each meal. Eventually, the treatment with acarbose ameliorated the prandial dizziness and hypotension associated with hyperglycemia. Our patient suggests the acarbose could prevent postprandial dizziness and hypotension.

A non-linear mixed-effects model to describe the effect of acarbose intake on postprandial glycaemia in a single rat / Um modelo não linear de efeitos mistos para descrever o efeito da ingestão de acarbose na glicemia pós-prandial em um único rato

A non-linear mixed-effects model is proposed to assess the impact of acarbose over time on postprandial glycaemia in a single rat. The model is based on two compartments, one representing the entry of glucose in the blood and the other its exit. The rat was submitted to two treatments: ingestion of starch and ingestion of starch plus acarbose. The model showed great suitability, with inferences on the behavior of glucose levels in response to treatments and supplying a richer description than just the area under the curve. The marginal curves for the two treatments are similar during the first moments; however, after reaching the peak of glucose concentration, they progressively became separate due to acarbose treatment and reached the initial levels more quickly. The proposed model, albeit with a single sample unit, showed similar results to those with larger samples; in other words, acarbose significantly attenuates glycaemia after ingestion of starch.

Neste estudo, foi proposto um modelo não linear de efeitos mistos para verificar o impacto da acarbose ao longo do tempo na glicemia pós -prandial de um único rato. Adotou-se um modelo de dois compartimentos: um representando a entrada de glicose no sangue e outro, a saída. O rato foi submetido a dois tratamentos: ingestão de amido e de amido com adição de acarbose. O modelo proposto apresentou um ótimo ajuste, permitindo fazer inferências do comportamento da glicose para os tratamentos e fornecendo uma descrição muito mais rica do que simplesmente a área sob a curva. As curvas marginais para os dois tratamentos foram semelhantes nos primeiros tempos observados, porém, após o pico de concentração de glicose, elas se distanciaram progressivamente com o tratamento da acarbose atingindo os níveis iniciais mais rapidamente. O modelo adotado, com uma única unidade amostral, mostrou resultados similares a outros estudos com maior número de unidades amostrais, isto é, a acarbose pode atenuar consideravelmente a glicemia após ingestão de amido.

Increased glucose metabolism and alpha-glucosidase inhibition in Cordyceps militaris water extract-treated HepG2 cells

BACKGROUND/OBJECTIVES: Recent living condition improvements, changes in dietary habits, and reductions in physical activity are contributing to an increase in metabolic syndrome symptoms including diabetes and obesity. Through such societal developments, humankind is continuously exposed to metabolic diseases such as diabetes, and the number of the victims is increasing. This study investigated Cordyceps militaris water extract (CMW)-induced glucose uptake in HepG2 cells and the effect of CMW treatment on glucose metabolism. MATERIALS/METHODS: Colorimetric assay kits were used to determine the glucokinase (GK) and pyruvate dehydrogenase (PDH) activities, glucose uptake, and glycogen content. Either RT-PCR or western blot analysis was performed for quantitation of glucose transporter 2 (GLUT2), hepatocyte nuclear factor 1 alpha (HNF-1α), phosphatidylinositol 3-kinase (PI3k), protein kinase B (Akt), phosphorylated AMP-activated protein kinase (pAMPK), phosphoenolpyruvate carboxykinase, GK, PDH, and glycogen synthase kinase 3 beta (GSK-3β) expression levels. The α-glucosidase inhibitory activities of acarbose and CMW were evaluated by absorbance measurement. RESULTS: CMW induced glucose uptake in HepG2 cells by increasing GLUT2 through HNF-1α expression stimulation. Glucose in the cells increased the CMW-induced phosphorylation of AMPK. In turn, glycolysis was stimulated, and glyconeogenesis was inhibited. Furthermore, by studying the mechanism of action of PI3k, Akt, and GSK-3β, and measuring glycogen content, the study confirmed that the glucose was stored in the liver as glycogen. Finally, CMW resulted in a higher level of α-glucosidase inhibitory activity than that from acarbose. CONCLUSION: CMW induced the uptake of glucose into HepG2 cells, as well, it induced metabolism of the absorbed glucose. It is concluded that CMW is a candidate or potential use in diabetes prevention and treatment.

In vitro antioxidant activities of African birch [Anogeissus leiocarpus] leaf and its effect on the alpha-amylase and alpha-glucosidase inhibitory properties of acarbose

Objective: This study sought to determine the antioxidant activities of African birch leaf, to assess its interaction with key enzymes relevant to type 2 diabetes [aamylase and alpha-glucosidase] and to evaluate its effect on acarbose in vitro

Methods: One milligram per milliliter of aqueous extract of African birch and acarbose were separately prepared. At the same time, both the African extract and acarbose solution [50:50 v/v] were thoroughly mixed until homogeneity was attained. The phenolic phytoconstituents and antioxidant properties of African birch leaf were subsequently determined. Finally, the effects of African birch extract, acarbose solution and a mixture of acarbose and African birch extract on alpha-amylase and alpha-glucosidase activities were assessed in vitro

Results: The results showed that African birch extract demonstrated a remarkable antioxidant effect, as exemplified by its radical scavenging abilities, Fe2þ chelating ability and prevention of lipid peroxidation. Acarbose had significantly [p < 0.05] higher alpha-amylase [IC[50] = 11.77 mg/ml] and alpha-glucosidase [IC[50] = 9.05 mg/ml] activities compared to African birch extract [alpha-amylase [IC[50] = 242.17 mg/ml]; aglucosidase [IC[50] = 196.35 mg/ml]]. However, the combination of acarbose and African birch extract showed an additive effect on alpha-amylase inhibition, while a resultant synergistic action was observed against alpha-glucosidase inhibition

Hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus

BACKGROUND/OBJECTIVES: The primary objective of the treatment of diabetes mellitus is the attainment of glycemic control. Hyperglycemia increases oxidative stress which contributes to the progression of diabetic complications. Thus, the purpose of this study was to investigate the hypoglycemic and antioxidant effects of Daraesoon (Actinidia arguta shoot) in animal models of diabetes mellitus. MATERIALS/METHODS: Rats with streptozotocin-induced diabetes received an oral administration of a starch solution (1 g/kg) either with or without a 70% ethanol extract of Daraesoon (400 mg/kg) or acarbose (40 mg/kg) after an overnight fast and their postprandial blood glucose levels were measured. Five-week-old C57BL/6J mice were fed either a basal or high-fat/high-sucrose (HFHS) diet with or without Daraesoon extract (0.4%) or acarbose (0.04%) for 12 weeks after 1 week of adaptation to determine the effects of the chronic consumption of Daraesoon on fasting hyperglycemia and antioxidant status. RESULTS: Compared to the control group, rats that received Daraesoon extract (400 mg/kg) or acarbose (40 mg/kg) exhibited a significant reduction in the area under the postprandial glucose response curve after the oral ingestion of starch. Additionally, the long-term consumption of Daraesoon extract or acarbose significantly decreased serum glucose and insulin levels as well as small intestinal maltase activity in HFHS-fed mice. Furthermore, the consumption of Daraesoon extract significantly reduced thiobarbituric acid reactive substances and increased glutathione levels in the livers of HFHS-fed mice compared to HFHS-fed mice that did not ingest Daraesoon. CONCLUSIONS: Daraesoon effectively suppressed postprandial hyperglycemia via the inhibition of alpha-glucosidase in STZ-induced diabetic rats. Chronic consumption of Daraesoon alleviated fasting hyperglycemia and oxidative stress in mice fed a HFHS diet.

Comparison of Acarbose and Voglibose in Diabetes Patients Who Are Inadequately Controlled with Basal Insulin Treatment: Randomized, Parallel, Open-Label, Active-Controlled Study

We studied the efficacy and safety of acarbose in comparison with voglibose in type 2 diabetes patients whose blood glucose levels were inadequately controlled with basal insulin alone or in combination with metformin (or a sulfonylurea). This study was a 24-week prospective, open-label, randomized, active-controlled multi-center study. Participants were randomized to receive either acarbose (n=59, 300 mg/day) or voglibose (n=62, 0.9 mg/day). The mean HbA1c at week 24 was significantly decreased approximately 0.7% from baseline in both acarbose (from 8.43% +/- 0.71% to 7.71% +/- 0.93%) and voglibose groups (from 8.38% +/- 0.73% to 7.68% +/- 0.94%). The mean fasting plasma glucose level and self-monitoring of blood glucose data from 1 hr before and after each meal were significantly decreased at week 24 in comparison to baseline in both groups. The levels 1 hr after dinner at week 24 were significantly decreased in the acarbose group (from 233.54 +/- 69.38 to 176.80 +/- 46.63 mg/dL) compared with the voglibose group (from 224.18 +/- 70.07 to 193.01 +/- 55.39 mg/dL). In conclusion, both acarbose and voglibose are efficacious and safe in patients with type 2 diabetes who are inadequately controlled with basal insulin. (ClinicalTrials.gov number, NCT00970528)

The ingredients in Saengshik, a formulated health food, inhibited the activity of alpha-amylase and alpha-glucosidase as anti-diabetic function

BACKGROUND/OBJECTIVES: We investigated total 26 ingredients of Saengshik which will be commercially produced as an anti-diabetic dietary supplement. SUBJECTS/METHODS: Thirteen vegetables, nine cereals, three legumes and one seed were extracted with aqueous ethanol for 2 h at 60degrees C, and evaluated for their inhibitory effects against alpha-amylase and alpha-glucosidase and for total phenolic and flavonoid contents. RESULTS: All ingredients inhibited alpha-amylase activity except cabbage. Strong inhibitory activity of alpha-amylase was observed in leek, black rice, angelica and barley compared with acarbose as a positive control. Stronger inhibition of alpha-glucosidase activity was found in small water dropwort, radish leaves, sorghum and cabbage than acarbose. All Saengshik ingredients suppressed alpha-glucosidase activity in the range of 0.3-60.5%. Most ingredients contained total phenols which were in the range of 1.2-229.4 mg gallic acid equivalent/g dried extract. But, total phenolic contents were not observed in carrot, pumpkin and radish. All ingredients contained flavonoid in the range of 11.6-380.7 mg catechin equivalent/g dried extract. CONCLUSIONS: Our results demonstrate that Saengshik containing these ingredients would be an effective dietary supplement for diabetes.

Treatment with acarbose in severe hypoglycaemia due to late dumping syndrome / Tratamiento con acarbosa en la hipoglicemia severa debido al síndrome de dumping tardío

BACKGROUND: We present a case of recurrent loss of consciousness, which was finally accurately diagnosed as late dumping syndrome twelve years after subtotal gastrectomy and successfully treated with acarbose. A 66-year old lean male was found unconscious repeatedly within one year. Oral glucose tolerance tests performed before and after acarbose treatment verified the diagnosis of late dumping syndrome. Acarbose can be used as a successful treatment modality for reactive hypoglycaemia due to late dumping syndrome by influencing the release of hormone.

ANTECEDENTES: Presentamos un caso de pérdida recurrente de conciencia, que fue finalmente diagnosticado con precisión como síndrome de dumping tardío, doce años después de la gastrectomía subtotal, y tratado con éxito con acarbosa. Un hombre magro de 66 años de edad fue encontrado inconsciente repetidas veces en un año. Las pruebas orales de tolerancia a la glucosa realizadas antes y después del tratamiento con acarbosa verificaron el diagnóstico de síndrome de dumping tardío. La acarbosa puede utilizarse como una modalidad de tratamiento acertado para la hipoglicemia reactiva debido al síndrome de dumping tardío por la influencia en la liberación de hormonas.

comparison of ezetimibe and acarbose in decreasing liver transaminase in nonalcoholic fatty liver disease: a randomized clinical trial

Ezetimibe inhibits the resorption of dietary and biliary cholesterol in the small intestine and decreases insulin resistance in patients with nonalcoholic fatty liver disease [NAFLD]. Acarbose has been used in type 2 diabetes mellitus and metabolic syndrome. This study aims to compare the therapeutic effects of ezetimibe and acarbosein decreasing liver transaminase levels in patients with NAFLD. This was a single center, double-blind, parallel-group study conducted at Bu-Ali Sina Hospital, Qazvin, Iran. In this trial, we enrolled, by simple randomization, a total of 62 patients diagnosed with NASH. There were 29 patients treated with ezetimibe and 33 who were treated with acarbose over a ten-week period. Ezetimibe treatment significantly reduced ALT, AST, triglycerides, total cholesterol, low-density lipoprotein [LDL] cholesterol, high-sensitivity C-reactive protein [hsCRP], and serum insulin levels and the insulin resistance homeostasis model assessment [HOMA-IR] index compared to patients treated with acarbose [p<0.001]. Ezetimibe treatment decreased ALT [p=0.05], AST [p=0.01], total cholesterol [p=0.01], HDL cholesterol [p=0.03] and LDL cholesterol [p=0.03] levels to a significantly higher extent. Both ezetimibe and acarbose improved metabolic and biochemical abnormalities in patients with NASH, however these effects were more prominent with ezetimibe

Lotus leaf alleviates hyperglycemia and dyslipidemia in animal model of diabetes mellitus

The purpose of this study was to investigate the effects of lotus leaf on hyperglycemia and dyslipidemia in animal model of diabetes. Inhibitory activity of ethanol extract of lotus leaf against yeast alpha-glucosidase was measured in vitro. The effect of lotus leaf on the postprandial increase in blood glucose levels was assessed in streptozotocin-induced diabetic rats. A starch solution (1 g/kg) with and without lotus leaf extract (500 mg/kg) was administered to the rats after an overnight fast, and postprandial plasma glucose levels were monitored. Four-week-old db/db mice were fed a basal diet or a diet containing 1% lotus leaf extract for 7 weeks after 1 week of acclimation to study the chronic effect of lotus leaf. After sacrifice, plasma glucose, insulin, triglycerides (TG), total cholesterol (CHOL), high-density lipoprotein (HDL)-CHOL, and blood glycated hemoglobin levels were measured. Lotus leaf extract inhibited alpha-glucosidase activity by 37.9%, which was 1.3 times stronger than inhibition by acarbose at a concentration of 0.5 mg/mL in vitro. Oral administration of lotus leaf extract significantly decreased the area under the glucose response curve by 35.1% compared with that in the control group (P < 0.01). Chronic feeding of lotus leaf extract significantly lowered plasma glucose and blood glycated hemoglobin compared with those in the control group. Lotus leaf extract significantly reduced plasma TG and total CHOL and elevated HDL-CHOL levels compared with those in the control group. Therefore, we conclude that lotus leaf is effective for controlling hyperglycemia and dyslipidemia in an animal model of diabetes mellitus.

Comparison of antioxidant, alpha-glucosidase inhibition and anti-inflammatory activities of the leaf and root extracts of Smilax china L / 한국영양학회지

This study was conducted in order to compare the biological activities of leaf and root water extracts of Smilax china L. (SC) by measuring the total polyphenol and flavonoid contents, anti-oxidant activity, inhibitory effect on alpha-glucosidase, and anti-inflammatory gene expression. The total polyphenol and flavonoid contents of SC leaf (SCLE) and root (SCRE) water extracts were 127.93 mg GAE/g and 39.50 mg GAE/g and 41.99 mg QE/g and 1.25 mg QE/g, respectively. The anti-oxidative activities of SCLE and SCRE were measured using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity assay and reducing power assay. Both SCLE and SCRE scavenged radicals in a concentration-dependent manner, and SCLE showed stronger radical scavenging activity and reducing power than SCRE; however, both SCLE and SCRE exhibited lower activities than ascorbic acid. Compared to the anti-diabetic drug acarbose, which was used as a positive control, SCLE and SCRE exhibited low alpha-glucosidase inhibition activities; nevertheless, the activity of SCLE was 3.7 fold higher than that of SCRE. Finally, SCLE caused significantly decreased expression of the LPS-induced cytokines, iNOS, and COX-2 mRNA in RAW264.7 cells, indicating anti-inflammatory activity. These results indicate that SCLE might be a potential candidate as an anti-oxidant, anti-diabetic, and anti-inflammatory agent.

Chamnamul Pimpinella brachycarpa (Kom.) Nakai ameliorates hyperglycemia and improves antioxidant status in mice fed a high-fat, high-sucrose diet

Chronic consumption of a high-fat, high-sucrose (HFHS) diet increases insulin resistance and results in type 2 diabetes mellitus in C57BL/6J mice. Hyperglycemia in diabetics increases oxidative stress, which is associated with a high risk of diabetic complications. The purpose of this study was to examine the hypoglycemic and antioxidant effects of chamnamul [Pimpinella brachycarpa (Kom.) Nakai] in an animal model of type 2 diabetes. The alpha-glucosidase inhibitory activity of a 70% ethanol extract of chamnamul was measured in vitro. Five-week-old male C57BL/6J mice were fed a basal or HFHS diet with or without a 70% ethanol extract of chamnamul at a 0.5% level of the diet for 12 weeks after 1 week of adaptation. After sacrifice, serum glucose, insulin, adiponectin, and lipid profiles, and lipid peroxidation of the liver were determined. Homeostasis model assessment for insulin resistance (HOMA-IR) was determined. Chamnamul extract inhibited alpha-glucosidase by 26.7%, which was 78.3% the strength of inhibition by acarbose at a concentration of 0.5 mg/mL. Serum glucose, insulin, and cholesterol levels, as well as HOMA-IR values, were significantly lower in the chamnamul group than in the HFHS group. Chamnamul extract significantly decreased the level of thiobarbituric acid reactive substances and increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver compared with the HFHS group. These findings suggest that chamnamul may be useful in prevention of hyperglycemia and reduction of oxidative stress in mice fed a HFHS diet.

Structural insight into substrate specificity of human intestinal maltase-glucoamylase

Human maltase-glucoamylase (MGAM) hydrolyzes linear alpha-1,4-linked oligosaccharide substrates, playing a crucial role in the production of glucose in the human lumen and acting as an efficient drug target for type 2 diabetes and obesity. The amino- and carboxyl-terminal portions of MGAM (MGAM-N and MGAM-C) carry out the same catalytic reaction but have different substrate specificities. In this study, we report crystal structures of MGAM-C alone at a resolution of 3.1 Å, and in complex with its inhibitor acarbose at a resolution of 2.9 Å. Structural studies, combined with biochemical analysis, revealed that a segment of 21 amino acids in the active site of MGAM-C forms additional sugar subsites (+ 2 and + 3 subsites), accounting for the preference for longer substrates of MAGM-C compared with that of MGAM-N. Moreover, we discovered that a single mutation of Trp1251 to tyrosine in MGAM-C imparts a novel catalytic ability to digest branched alpha-1,6-linked oligosaccharides. These results provide important information for understanding the substrate specificity of alpha-glucosidases during the process of terminal starch digestion, and for designing more efficient drugs to control type 2 diabetes or obesity.

Glycemic variability in insulin treated type 2 diabetes with well-controlled hemoglobin A1c and its response to further treatment with acarbose / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Glycemic variability, an HbA1c-independent risk factor, has more deleterious effects than sustained hyperglycemia in the development of diabetic complications. This study analyzed the characteristics of glycemic variability in type 2 diabetes mellitus (T2DM) with HbA1c < 6.5% in duration of twice daily premixed insulin treatment and the effect of further treatment with acarbose.</p><p><b>METHODS</b>Eighty-six T2DM patients who used premixed insulin analogue (insulin aspart 30) twice daily and had HbA1c < 6.5% and 20 controlled subjects with normal glucose regulation (NGR) were monitored using the continuous glucose monitoring (CGM) system. The mean amplitude of glycemic excursions (MAGE), mean of daily differences (MODD) were used for assessing intra-day, inter-day glycemic variability. Hypoglycemia was defined as glucose level < 3.9 mmol/L for at least 15 minutes in CGM. According to reference values of MAGE, T2DM patients were classified into two groups: low-MAGE group with MAGE < 3.4 mmol/L (L-MAGE) and high-MAGE group with MAGE ≥ 3.4 mmol/L (H-MAGE). H-MAGE group received further treatment with acarbose for 2 weeks and was monitored a second time with CGM system.</p><p><b>RESULTS</b>After first CGM, L-MAGE group had 41 cases, and H-MAGE group had 45 cases. The MAGE and MODD of T2DM group were all higher than those of subjects with NGR (P < 0.01). Twenty-four percent (n = 11) in H-MAGE group had a total of 13 hypoglycemic events, 10 of the 13 events occurred at night, meanwhile 5% (n = 2) in L-MAGE group had a total of 2 hypoglycemic events, which also occurred at night (hypoglycemic events: 24% vs. 5%, χ(2) = 6.40, P < 0.01). MAGE value was correlated with hypoglycemia value and 2-hour postprandial plasma glucose value (r = -0.32 and 0.26, respectively, P < 0.05). After further acarbose therapy and secondly CGM, MAGE and MODD values in H-MAGE group were all significantly decreased (40%, P < 0.01, and 15%, P < 0.05, respectively), but remained higher than in the subjects with NGR (P < 0.05); 2% (n = 1) had a total of 1 hypoglycemic event, incidence significantly decreased (2% vs. 24%, χ(2) = 9.61, P < 0.01).</p><p><b>CONCLUSIONS</b>CGM system can detect the glycemic variability and asymptomatic hypoglycemic events of T2DM with well-controlled HbA1c in duration of insulin treatment. Combination therapy of premixed insulin twice daily with acarbose can flat glycemic variability and decrease hypoglycemic events.</p>

A Case of Postprandial Hypotension in the Intensive Care Unit Treated With Acarbose

Postprandial hypotension (PPH) has not been described as a cause of hypotension after the return of spontaneous circulation (ROSC) in the intensive care unit (ICU). A 74 year old man underwent cardiopulmonary resuscitation (CPR) due to monomorphic ventricular tachycardia. After the ROSC, inotropic agents were not reduced but increased. PPH had occurred, according to the flow sheet, so a provocation test was performed. We noted hypotension but no serum hypoglycemia or tachycardia. The hypotension was diagnosed as PPH. We chose acarbose for treatment; thus, the inotropic agents were discontinued. This is the first case in which hypotension occurred in a patient recovering after CPR in the ICU and that the PPH was treated with acarbose. PPH should be considered and treated to manage hypotension in elderly patients in the ICU.