Ice plant (Mesembryanthemum crystallinum) improves hyperglycaemia and memory impairments in a Wistar rat model of streptozotocin-induced diabetes

BACKGROUND

Ice plant (Mesembryanthemum crystallinum) has been used as an anti-diabetic agent in Japan because it contains d-pinitol. The efficacy of ice plant in the regulation of blood glucose is unclear at present. Recently, memory impairment and development of Alzheimer's disease found in diabetic patients are thought to be caused by high blood glucose. The mechanism by which ice plant protects against the impairment of memory and learning abilities caused by high blood glucose remains unclear. The aim of this study was to evaluate the protection of ice plant water extracts (IPE) and D-pinitol against memory impairments in a Wistar rat model of streptozotocin (STZ)-induced diabetes. We hypothesised that IPE and D-pinitol could suppress blood glucose and elevate insulin sensitivity in these rats.

RESULTS

For memory evaluation, IPE and D-pinitol also improved the passive avoidance task and the working memory task. In addition, inhibition of acetylcholinesterase activity in hippocampus and cortex was found in this rat model administered IPE or D-pinitol. IPE and D-pinitol also markedly elevated superoxide dismutase activity against oxidative stress and reduced malondialdehyde production in hippocampus and cortex of the rats.

CONCLUSION

These findings indicated that IPE and D-pinitol possess beneficial effects for neural protection and memory ability in a rat model of diabetes.

Multiple pathogenic proteins implicated in neuronopathic Gaucher disease mice

Gaucher disease, a prevalent lysosomal storage disease (LSD), is caused by insufficient activity of acid β-glucosidase (GCase) and the resultant glucosylceramide (GC)/glucosylsphingosine (GS) accumulation in visceral organs (Type 1) and the central nervous system (Types 2 and 3). Recent clinical and genetic studies implicate a pathogenic link between Gaucher and neurodegenerative diseases. The aggregation and inclusion bodies of α-synuclein with ubiquitin are present in the brains of Gaucher disease patients and mouse models. Indirect evidence of β-amyloid pathology promoting α-synuclein fibrillation supports these pathogenic proteins as a common feature in neurodegenerative diseases. Here, multiple proteins are implicated in the pathogenesis of chronic neuronopathic Gaucher disease (nGD). Immunohistochemical and biochemical analyses showed significant amounts of β-amyloid and amyloid precursor protein (APP) aggregates in the cortex, hippocampus, stratum and substantia nigra of the nGD mice. APP aggregates were in neuronal cells and colocalized with α-synuclein signals. A majority of APP co-localized with the mitochondrial markers TOM40 and Cox IV; a small portion co-localized with the autophagy proteins, P62/LC3, and the lysosomal marker, LAMP1. In cultured wild-type brain cortical neural cells, the GCase-irreversible inhibitor, conduritol B epoxide (CBE), reproduced the APP/α-synuclein aggregation and the accumulation of GC/GS. Ultrastructural studies showed numerous larger-sized and electron-dense mitochondria in nGD cerebral cortical neural cells. Significant reductions of mitochondrial adenosine triphosphate production and oxygen consumption (28-40%) were detected in nGD brains and in CBE-treated neural cells. These studies implicate defective GCase function and GC/GS accumulation as risk factors for mitochondrial dysfunction and the multi-proteinopathies (α-synuclein-, APP- and Aβ-aggregates) in nGD.

Efficacy and safety of the dipeptidyl peptidase-4 inhibitor sitagliptin compared with α-glucosidase inhibitor in Japanese patients with type 2 diabetes inadequately controlled on sulfonylurea alone (SUCCESS-2): a multicenter, randomized, open-label, non-inferiority trial

We assessed the efficacy and safety of sitagliptin compared with α-glucosidase inhibitor (αGI) in 120 of Japanese patients with type 2 diabetes mellitus (T2DM) inadequately controlled on stable ≤2 mg/day glimepiride alone [mean hemoglobin A1c (HbA1c) 7.7%] by the randomized, active-controlled, non-inferiority trial. Patients were randomly assigned to receive additional sitagliptin or αGI for 24 weeks. The primary endpoint was change in HbA1c from baseline to week 12. After 12 weeks, sitagliptin reduced HbA1c by -0.44% (p < 0.001) relative to αGI. At 24 weeks, the reduction was almost identical between the groups (-0.091%, p = 0.47). Gastrointestinal disorders were more common with αGI than with sitagliptin, but only minor hypoglycaemia occurred in both groups at similar frequency. These data suggested that sitagliptin was not inferior to αGI for reduction of HbA1c in Japanese T2DM patients receiving glimepiride alone, and well tolerated with minimum risk of gastrointestinal symptoms and hypoglycaemia.

DPP-4 inhibitor and alpha-glucosidase inhibitor equally improve endothelial function in patients with type 2 diabetes: EDGE study

BACKGROUND

Alpha glucosidase inhibitor (GI) attenuates postprandial hyperglycemia (PPH) and reduces the risk of cardiovascular events in patients with impaired glucose tolerance or type 2 diabetes. Dipeptidyl peptidase 4 (DPP-4) inhibitors also attenuate PPH. PPH is one of the factors leading to endothelial dysfunction which is an early event in the pathogenesis of atherosclerosis. Furthermore, DPP-4 inhibitors protect endothelial function through a GLP-1-dependent mechanism. However, the impact of these two types of drugs on endothelial dysfunction in patients with type 2 diabetes has not been fully elucidated. We compared the effects of sitagliptin, a DPP-4 inhibitor, and voglibose, an alpha GI, on endothelial function in patients with diabetes.

METHODS

We conducted a randomized prospective multicenter study in 66 patients with type 2 diabetes who did not achieve the treatment goal with sulfonylurea, metformin or pioglitazone treatment; 31 patients received sitagliptin treatment and 35 patients, voglibose treatment. The flow-mediated dilatation (FMD) of the brachial artery was measured in the fasting state at baseline and after 12 weeks of treatment. The primary endpoint was a change in FMD (ΔFMD) from the baseline to the end of follow-up. The effects of sitagliptin and voglibose on FMD were assessed by ANCOVA after adjustment for the baseline FMD, age, sex, current smoking, diabetes duration and body mass index. Secondary efficacy measures included changes in HbA1c, GIP, GLP-1, C-peptide, CD34, lipid profile, oxidative stress markers, inflammatory markers and eGFR and any adverse events.

RESULTS

ΔFMD was significantly improved after 12 weeks of treatment in both groups, and there was no significant difference in ΔFMD between the two groups. There were no significant differences in changes in HbA1c, GIP, GLP-1, C-peptide, lipid profile, oxidative stress marker, inflammatory marker and eGFR between the two groups. Compared with voglibose, sitagliptin significantly increased the circulating CD34, a marker of endothelial progenitor cells. Adverse events were observed in 5 patients in only the voglibose group (diarrhea 1, nausea 1, edema 2 and abdominal fullness 1).

CONCLUSIONS

Sitagliptin improved endothelial dysfunction just as well as voglibose in patients with type 2 diabetes. Sitagliptin had protective effects on endothelial function without adverse events.

TRIAL REGISTRATION

registered at http://www.umin.ac.jp/ctrj/ under UMIN000003951.

Insulin-mimicking bioactivities of acylated inositol glycans in several mouse models of diabetes with or without obesity

Insulin-mimetic species of low molecular weight are speculated to mediate some intracellular insulin actions. These inositol glycans, which are generated upon insulin stimulation from glycosylphosphatidylinositols, might control the activity of a multitude of insulin effector enzymes. Acylated inositol glycans (AIGs) are generated by cleavage of protein-free GPI precursors through the action of GPI-specific phospholipase C (GPI-PLC) and D (GPI-PLD). We synthesized AIGs (IG-1, IG-2, IG-13, IG-14, and IG-15) and then evaluated their insulin-mimicking bioactivities. IG-1 significantly stimulated glycogen synthesis and lipogenesis in 3T3-L1 adipocytes and rat isolated adipocytes dose-dependently. IG-2 significantly stimulated lipogenesis in rat isolated adipocytes dose-dependently. IG-15 also enhanced glycogen synthesis and lipogenesis in 3T3-L1 adipocytes. The administration of IG-1 decreased plasma glucose, increased glycogen content in liver and skeletal muscles and improved glucose tolerance in C57B6N mice with normal diets. The administration of IG-1 decreased plasma glucose in STZ-diabetic C57B6N mice. The treatment of IG-1 decreased plasma glucose, increased glycogen content in liver and skeletal muscles and improved glucose tolerance in C57B6N mice with high fat-diets and db/db mice. The long-term treatment of IG-1 decreased plasma glucose and reduced food intake and body weight in C57B6N mice with high fat-diets and ob/ob mice. Thus, IG-1 has insulin-mimicking bioactivities and improves glucose tolerance in mice models of diabetes with or without obesity.

Trehalase activity in fungus-growing termite, Odontotermes feae (Isoptera: Termitideae) and inhibitory effect of validamycin

Trehalase is the hydrolytic enzyme that catalyzed the hydrolysis of trehalose to glucose. In this study, trehalase activity in the fungus-growing termite, Odontotermes feae Wasmann had been examined. Trehalase activity in digestive tract and carcass of O. feae was higher than that in wood-feeding termite, Coptotermes gestroi Wasmann. The intestinal tract of worker caste of O. feae was the main source of trehalase compared with that in salivary, fat body, and carcass. In particular, the highest activity was found in the midgut and hindgut parts. More specifically, the contents of midgut and hindgut had higher enzyme activity compared with that trehalase prepared from their epithelial tissue. The enzyme activity of gut trehalase in three different termite castes, worker, soldier, and reproductive, had been determined. The result showed that female alate had the highest activity, followed by worker, male alate, and soldier castes. Trehalose concentration in the reproductive caste was at lowest level, while soldier and worker contained the high trehalose concentration. This study indicates that high trehalase activity locates in the midgut and hindgut contents and change in trehalase activity in fungus-growing termite is caste-specific. Validamycin inhibited trehalase activity of O. feae in vivo and caused high mortality, indicating that this trehalase inhibitor is valuable tools for termite control.

Structural basis of pharmacological chaperoning for human β-galactosidase

GM1 gangliosidosis and Morquio B disease are autosomal recessive diseases caused by the defect in the lysosomal β-galactosidase (β-Gal), frequently related to misfolding and subsequent endoplasmic reticulum-associated degradation. Pharmacological chaperone (PC) therapy is a newly developed molecular therapeutic approach by using small molecule ligands of the mutant enzyme that are able to promote the correct folding and prevent endoplasmic reticulum-associated degradation and promote trafficking to the lysosome. In this report, we describe the enzymological properties of purified recombinant human β-Gal(WT) and two representative mutations in GM1 gangliosidosis Japanese patients, β-Gal(R201C) and β-Gal(I51T). We have also evaluated the PC effect of two competitive inhibitors of β-Gal. Moreover, we provide a detailed atomic view of the recognition mechanism of these compounds in comparison with two structurally related analogues. All compounds bind to the active site of β-Gal with the sugar-mimicking moiety making hydrogen bonds to active site residues. Moreover, the binding affinity, the enzyme selectivity, and the PC potential are strongly affected by the mono- or bicyclic structure of the core as well as the orientation, nature, and length of the exocyclic substituent. These results provide understanding on the mechanism of action of β-Gal selective chaperoning by newly developed PC compounds.

Ultrasound-assisted extraction of D-pinitol from carob pods using Response Surface Methodology

This study reports on the optimization of the conditions of extraction of D-pinitol compound from carob pods by using ultrasonication. For this purpose, the Box-Behnken design, which is a widely used form of Response Surface Methodology, was used to investigate the effects of parameters on the ultrasound-assisted extraction. Four independent variables, temperature (°C), ultrasonic power (W), dilution rate (material:water ratio) and time (min), were studied. The results showed that the highest D-pinitol concentration of 11.98 g/L was obtained with an extraction temperature of 50 °C, ultrasonic power of 207 W, a dilution rate of 1:4 and an extraction time of 120 min. It was found that the D-pinitol concentration of carob extract increased with the effect of ultrasonication during the extraction process. Therefore, ultrasound-assisted extraction could be used as an alternative to conventional hot water extraction with respect to the recovery of D-pinitol from carob pods with the advantages of lower extraction temperatures, shorter extraction time and reduced energy consumption.

[Effect of sequoyitol on expression of NOX4 and eNOS in aortas of type 2 diabetic rats]

The aim of the present study is to investigate the effects of sequoyitol (Seq) on expression of eNOS and NOX4 in aortas of type 2 diabetic rats. Type 2 diabetic rats induced by high fat and high sugar diet and low dose of streptozotocin (STZ, 35 mg x kg(-1)) and were administered Seq (12.5, 25 and 50 mg x kg(-1) x d(-1)) for 6 weeks. The fasting blood glucose (FBG) and body weight were tested. Acetylcholine (Ach) induced endothelium-dependent relaxation and sodium nitroprusside (SNP) induced endothelium-independent relaxation were measured in aortas for estimating endothelial function. Aortic morphological change was observed with HE staining. The level of serum insulin was measured by radioimmunoassay. The total antioxidative capacity (T-AOC), malondialdehyde (MDA) and NO levels in aortas were determined according to the manufacturer's instructions. In addition, the expressions of eNOS and NOX4 in aortas were measured by immunohistochemisty, real-time PCR or Western blotting. The results showed that Seq significantly decreased FBG and insulin resistance, and improved aortic endothelium-dependent vasorelaxation function. The expressions of NOX4 and MDA content were obviously decreased, while the expression of eNOS, the levels of NO and T-AOC increased significantly in aortas of diabetic rats with Seq treatment. In conclusion, Seq protects against aortic endothelial dysfunction of type 2 diabetic rats through down-regulating expression of NOX4 and up-regulating eNOS expression.

[Effect of sequoyitol on expression of NOX4 and eNOS induced with glucose in human umbilical vein endothelial cells]

OBJECTIVE

To investigate the protective effect and mechanism of sequoyitol (Sep) on high glucose-induced human umbilical vein endothelial cells (HUVECs) injury.

METHODS

HUVECs were cultured with high glucose (30 mmol/L) in the presence or absence of sequoyitol (0.1, 1 and 10 micromol/L) for 24 h. Cell proliferation was measured by BrdU marking and cell cycle was detected by flow cytometry. 2', 7'-dichlorofluorescein diacetate was used to evaluate intracellular reactive oxygen species (ROS) levels. The NO, malonydialdehyde (MDA) and H2O2 levels were determined by colorimetric method according to the manufacturer's instructions. The expression of endothelial nitric oxide synthase (eNOS) and NADPH oxidase 4 (NOX4) were measured by real-time PCR and Western blot.

RESULTS

In the present study, we found that sequoyitol pretreatment for 1 h significantly decreased cell injury, promoted cell proliferation. Meanwhile sequoyitol significantly down-regulated NOX4 expression and decreased the level of ROS, MDA and H2O2 and obviously increased NO levels and up-regulated eNOS expression.

CONCLUSION

Sequoyitol alleviates high glucose-induced cell injuries in HUVECs via inhibiting oxidative stress and up-regulating eNOS expression.

[Quantitative determination of voglibose contents in its tablets with high-performance liquid chromatography-mass spectrometry]

OBJECTIVE

To develop a method for determination of voglibose contents in its tablets by high-performance liquid chromatography-mass spectrometry (HPLC-MS).

METHODS

The measurements were carried out on an Agilent ZORBAX Eclipse Plus C18 column (2.1×150mm 3.2μm) with a temperature of 40 degrees Celsius. A mixture of methanol and water (2:3,v/v) was used as a mobile phase at a flow rate of 0.25 ml/min. Voglibose was detected in an electrospray ionization (ESI) mode with MRM.

RESULTS

The calibration curves of voglibose showed good linearity in a range of 1.5804-2.6340 μg/ml (r=0.9990). The average recovery was 100.2% with RSD of 1.37% (n=6) for m/z 268.2/74.2.Linearity was obtained with r=0.9976 and the average recovery was 99.3% with RSD of 1.78% (n=6) for m/z 268.2/92.2.

CONCLUSION

HPLC-MS method is accurate,reproducible and can be used for quality control of voglibose tablets.

Integrated biological and chemical control of rice sheath blight by Bacillus subtilis NJ-18 and jinggangmycin

BACKGROUND

Sheath blight caused by Rhizoctonia solani Kühn is a major disease of rice that greatly reduces yield and grain quality and jinggangmycin is the most widely used fungicide to control this disease in China. Bacillus subtilis NJ-18 has broad antimicrobial activity to many phytopathogenic bacteria and fungi; it is especially effective against Rhizoctonia solani. Laboratory, greenhouse and field tests were conducted to determine the effect of combining the biological control agent Bacillus subtilis NJ-18 with the fungicide jinggangmycin for control of rice sheath blight.

RESULTS

Growth of NJ-18 in vitro was not affected by jinggangmycin. In a greenhouse experiment, disease control was greater with a mixture of NJ-18 and jinggangmycin than with either alone; a mixture of NJ-18 at 10(8)  cfu mL(-1) and jinggangmycin at 50 or 100 mg L(-1) reduced lesion length by 35% and 20%, respectively, and the combinations showed a synergistic action. In three field trials, disease control was significantly greater with a mixture of NJ-18 at 10(8)  cfu mL(-1) and jinggangmycin at 75 or 150 g a.i. ha(-1) than with either component alone.

CONCLUSION

The results of the study indicate that, when Bacillus subtilis NJ-18 strain was combined with jinggangmycin, there was an increased suppression of rice sheath blight, and thus could provide an alternative disease control option.

Neuroinflammation and α-synuclein accumulation in response to glucocerebrosidase deficiency are accompanied by synaptic dysfunction

Clinical, epidemiological and experimental studies confirm a connection between the common degenerative movement disorder Parkinson's disease (PD) that affects over 1 million individuals, and Gaucher disease, the most prevalent lysosomal storage disorder. Recently, human imaging studies have implicated impaired striatal dopaminergic neurotransmission in early PD pathogenesis in the context of Gaucher disease mutations, but the underlying mechanisms have yet to be characterized. In this report we describe and characterize two novel long-lived transgenic mouse models of Gba deficiency, along with a subchronic conduritol-ß-epoxide (CBE) exposure paradigm. All three murine models revealed striking glial activation within nigrostriatal pathways, accompanied by abnormal α-synuclein accumulation. Importantly, the CBE-induced, pharmacological Gaucher mouse model replicated this change in dopamine neurotransmission, revealing a markedly reduced evoked striatal dopamine release (approximately 2-fold) that indicates synaptic dysfunction. Other changes in synaptic plasticity markers, including microRNA profile and a 24.9% reduction in post-synaptic density size, were concomitant with diminished evoked dopamine release following CBE exposure. These studies afford new insights into the mechanisms underlying the Parkinson's-Gaucher disease connection, and into the physiological impact of related abnormal α-synuclein accumulation and neuroinflammation on nigrostriatal dopaminergic neurotransmission.

Overview of current and upcoming strategies implied for the therapy of type 2 diabetes mellitus

Population explosion, urbanization, changes in lifestyle management, improper food habits and various other factors play focal contributors in the massive prevalence of type 2 diabetes mellitus in the developing countries. Although insulin is the cornerstone in the management of type 1 diabetes; insulin, anti-hyperglycemic and hypoglycemic agents are proved to be effective in type 2 diabetes, although their efficacy decreases with the progress of the disease. Moreover a significant number of side effects, mostly hypoglycemia and weight gain have put a bar in using these drugs confidently. Many novel therapeutic strategies with convincing efficacy and less adverse effects are currently emerging for providing efficient means of treatment of this disorder. This article mainly focuses on newer and unconventional pharmaceutical or biotechnical strategies that may or may not have been implied for the treatment of Type 2 Diabetes mellitus on a widescale basis so far. These strategies are supposed to be efficient in controlling glycemic levels and possess a significant potential to reduce the co-morbidities associated with this disease.

Efficacy of adding once- and thrice-daily voglibose in Japanese type 2 diabetic patients treated with alogliptin

We investigated the efficacy of once- and thrice-daily voglibose, an alpha-glucosidase inhibitor, as an add-on therapy to alogliptin, a dipeptidyl peptidase-4 inhibitor, on glycemic control in Japanese type 2 diabetic patients. In this 12-week, parallel-group, randomized, open-label, three-arm trial, 151 participants treated with alogliptin were randomly allocated to the following three arms; one was the group to initiate once-daily voglibose, another was to initiate thrice daily voglibose, and the other was the control group. The primary endpoint was the change of hemoglobin A1c levels at the end of the study, which was revealed to be significantly different among groups (p < 0.001). The once- and thrice-daily voglibose groups had a significantly greater reduction than the control group; the difference was -0.27% and -0.33% in the once- and thrice-daily voglibose group, respectively (both p < 0.001). No significant difference was observed between the two voglibose groups (p = 0.615). On the other hand, the increase of 1,5-anhydroglucitol levels were 3.3 and 5.5 μg/ml greater in the once- and thrice-daily voglibose groups than the control group (both p < 0.001). The thrice-daily voglibose group had a greater increase of 1,5- anhydroglucitol levels compared to the once-daily voglibose group (p = 0.005). In conclusion, once- and thrice-daily voglibose as an add-on to alogliptin significantly improved glycemic control in Japanese type 2 diabetic patients.

D-pinitol promotes apoptosis in MCF-7 cells via induction of p53 and Bax and inhibition of Bcl-2 and NF-κB

Development of drugs from natural products has been undergoing a gradual evoluation. Many plant derived compounds have excellent therapeutic potential against various human ailments. They are important sources especially for anticancer agents. A number of promising new agents are in clinical development based on their selective molecular targets in the field of oncology. D-pinitol is a naturally occurring compound derived from soy which has significant pharmacological activitites. Therefore we selected D-pinitol in order to evaluate apoptotic potential in the MCF-7 cell line. Human breast cancer cells were treated with different concentrations of D-pinitol and cytotoxicity was measured by MTT and LDH assays. The mechanism of apoptosis was studied with reference to expression of p53, Bcl-2, Bax and NF-kB proteins. The results revealed that D-pinitol significantly inhibited the proliferation of MCF-7 cells in a concentration-dependent manner, while upregulating the expression of p53, Bax and down regulating Bcl-2 and NF-kB. Thus the results obtained in this study clearly vindicated that D-pinitol induces apotosis in MCF-7 cells through regulation of proteins of pro- and anti-apoptotic cascades.

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).

Potent microbial and tyrosinase inhibitors from stem bark of Bauhinia rufescens (Fabaceae)

The stem bark extracts of Bauhinia rufescens Lam. (Fabaceae) yielded 6-methoxy-7-methyl-8-hydroxydibenz[b,f]oxepin, alpha-amyrin acetate, beta-sitosterol 3-O-beta-D-xylopyranoside, 4-(2'-Hydroxyphenethyl)-5-methoxy-2-methylphenol, menisdaurin and sequoyitol. Their structures were determined using spectroscopic methods and comparisons with the literature data. For the antimicrobial assay Gram-positive and Gram-negative bacterial and fungal strains were tested, while the tyrosinase inhibition assay utilized L-DOPA as a substrate for the tyrosinase enzyme. 6-Methoxy-7-methyl-8-hydroxydibenz[b,f]oxepin, a-amyrin acetate, beta-sitosterol 3-O-D-xylopyranoside, menisdaurin and sequoyitol showed weak to moderate activities with minimum inhibition concentration (MIC) values in the range of 112.5-900 microg/mL against all bacterial strains, while the MIC values for the fungal strains were in the range of 28.1-450 microg/mL. In the tyrosinase inhibition assay, a-amyrin acetate was found to be moderately active against tyrosinase with an inhibition of 62% at 0.1 mg/mL. This activity was lower than that of the positive control, kojic acid (85%).

Metabolic phenotypes associated with high-temperature tolerance of Porphyra haitanensis strains

Colored mutants of Porphyra haitanensis have superior production and quality characteristics, with two mutants, Shengfu 1 (SF-1) and Shengfu 2 (SF-2), having good high-temperature tolerances. To understand the molecular aspects of high-temperature tolerance, this study comprehensively investigated the metabolic differences between the high-temperature tolerant strains and wild type. Nuclear magnetic resonance (NMR) methods identified 35 algal metabolites, including sugars, amino acids, carboxylic acids, aldehydes, amines, and nucleotides. The results indicated that the high-temperature tolerant strains had significantly different metabolic phenotypes from the wild type. The high-temperature tolerant mutants had significantly higher levels in a set of osmolytes consisting of betaine, taurine, laminitol, and isofloridoside than the wild type, indicating the particular importance of efficient osmoregulation for high-temperature resistance. These findings provided essential metabolic information about high-temperature adaptation for P. haitanensis and demonstrated NMR-based metabolomics as a useful tool for understanding the metabolic features related to resistance to stressors.

2-epi-5-epi-Valiolone synthase activity is essential for maintaining phycobilisome composition in the cyanobacterium Anabaena variabilis ATCC 29413 when grown in the presence of a carbon source

The cyclase 2-epi-5-epi-valiolone synthase (EVS) is reported to be a key enzyme for biosynthesis of the mycosporine-like amino acid shinorine in the cyanobacterium Anabaena variabilis ATCC 29413. Subsequently, we demonstrated that an in-frame complete deletion of the EVS gene had little effect on in vivo production of shinorine. Complete segregation of the EVS gene deletion mutant proved difficult and was achieved only when the mutant was grown in the dark and in a medium supplemented with fructose. The segregated mutant showed a striking colour change from native blue-green to pale yellow-green, corresponding to substantial loss of the photosynthetic pigment phycocyanin, as evinced by combinations of absorbance and emission spectra. Transcriptional analysis of the mutant grown in the presence of fructose under dark or light conditions revealed downregulation of the cpcA gene that encodes the alpha subunit of phycocyanin, whereas the gene encoding nblA, a protease chaperone essential for phycobilisome degradation, was not expressed. We propose that the substrate of EVS (sedoheptulose 7-phosphate) or possibly lack of its EVS-downstream products, represses transcription of cpcA to exert a hitherto unknown control over photosynthesis in this cyanobacterium. The significance of this finding is enhanced by phylogenetic analyses revealing horizontal gene transfer of the EVS gene of cyanobacteria to fungi and dinoflagellates. It is also conceivable that the EVS gene has been transferred from dinoflagellates, as evident in the host genome of symbiotic corals. A role of EVS in regulating sedoheptulose 7-phosphate concentrations in the photophysiology of coral symbiosis is yet to be determined.

Comparison of glycemic variability in patients with type 2 diabetes given sitagliptin or voglibose: a continuous glucose monitoring-based pilot study

OBJECTIVE

This study compared glycemic variability in patients with type 2 diabetes given sitagliptin or voglibose.

PATIENTS AND METHODS

Seventeen type 2 diabetes patients were given sitagliptin 50 mg/day or voglibose 0.9 mg/day for 2 months and were hospitalized for a 4-day evaluation by continuous glucose monitoring (CGM). On discharge, they were crossed over to the other regimen for 2 months of treatment/4 days of evaluation. The CGM data were used to compare each parameter for glycemic variability.

RESULTS

The average glucose levels with sitagliptin and voglibose were significantly different at 138.6 and 152.6 mg/dL for 24 h (P=0.014) and 147.2 and 160.9 mg/dL for during daytime (P=0.050), respectively. The patients' glucose levels with sitagliptin and voglibose were significantly different at 125.3 and 139.7 mg/dL before breakfast (P=0.015) and 112.7 and 131.4 mg/dL before lunch (P=0.049), respectively. The time from before meal to postprandial peak glucose levels was significantly longer after dinner with voglibose than with sitagliptin (91.5 and 122.3 min, respectively; P=0.012). All of the slopes of glucose elevation were significantly lower with voglibose after each meal, with that after breakfast, lunch, and dinner being 1.16 and 0.86 mg/dL/min (P=0.031), 0.70 and 0.45 mg/dL/min (P=0.048), and 1.06 and 0.73 mg/dL/min (P=0.028), respectively.

CONCLUSIONS

This CGM-based pilot study revealed that sitagliptin significantly lowered 24-h and daytime mean glucose levels and glucose levels before breakfast and lunch compared with voglibose, whereas the time from before dinner to peak postprandial glucose levels was significantly longer, and the slope of postprandial elevation of glucose level was significantly lower after each meal, with voglibose compared with sitagliptin.

Loss of β-glucocerebrosidase activity does not affect alpha-synuclein levels or lysosomal function in neuronal cells

To date, a plethora of studies have provided evidence favoring an association between Gaucher disease (GD) and Parkinson’s disease (PD). GD, the most common lysosomal storage disorder, results from the diminished activity of the lysosomal enzyme β-glucocerebrosidase (GCase), caused by mutations in the β-glucocerebrosidase gene (GBA). Alpha-synuclein (ASYN), a presynaptic protein, has been strongly implicated in PD pathogenesis. ASYN may in part be degraded by the lysosomes and may itself aberrantly impact lysosomal function. Therefore, a putative link between deficient GCase and ASYN, involving lysosomal dysfunction, has been proposed to be responsible for the risk for PD conferred by GBA mutations. In this current work, we aimed to investigate the effects of pharmacological inhibition of GCase on ASYN accumulation/aggregation, as well as on lysosomal function, in differentiated SH-SY5Y cells and in primary neuronal cultures. Following profound inhibition of the enzyme activity, we did not find significant alterations in ASYN levels, or any changes in the clearance or formation of its oligomeric species. We further observed no significant impairment of the lysosomal degradation machinery. These findings suggest that additional interaction pathways together with aberrant GCase and ASYN must govern this complex relation between GD and PD.

[Effects of sequoyitol on expression of NADPH oxidase subunits p22 phox and p47 phox in rats with type 2 diabetic liver disease]

This study is to observe the effects of sequoyitol on the expression of NADPH oxidase subunits p22 phox and p47 phox in rats with type 2 diabetic liver diseases. The model of high fat and high sugar diet as well as intraperitoneal injection of small dose of streptozotocin (STZ, 35 mg x kg(-1)) induced diabetic rat liver disease was used. After sequoyitol (50, 25 and 12.5 mg x kg(-1)) was administrated for 6 weeks, the contents of blood glucose (BG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total antioxidant capacity (T-AOC), hydrogen peroxide (H2O2), NO and insulin (Ins) were measured, liver p22 phox and p47 phox mRNA content was determined with real-time PCR and the expression of p22 phox and p47 phox protein was examined by Western blotting. In addition, pathological changes in liver were observed with HE staining. Sequoyitol could reduce the content of fasting blood glucose, ALT, AST, Ins and H2O2, restore insulin sensitive index (ISI) and weight, elevate liver tissue T-AOC and NO content, reduce the NADPH oxidase subunit liver tissue p22 phox and p47 phox mRNA and protein expression, as well as ameliorate liver pathologic lesions. The results showed that sequoyitol can ease the type 2 diabetic rat liver oxidative stress by lowering NADPH oxidase expression.

Long-term safety of linagliptin monotherapy in Japanese patients with type 2 diabetes

AIMS

In a phase III study conducted among Japanese patients with type 2 diabetes mellitus (T2DM), linagliptin 5 and 10 mg showed clinically meaningful improvements in glycaemic parameters after 12 and 26 weeks compared with placebo and voglibose, respectively. This extension study assessed long-term tolerability of linagliptin over 52 weeks.

METHODS

Japanese patients with T2DM who completed either phase of a 12-week/26-week study comparing linagliptin monotherapy with placebo or voglibose were eligible to enrol. In the extension study, the comparator groups switched to linagliptin 5 or 10 mg, while the linagliptin groups maintained dosage.

RESULTS

In all, 540 patients received at least one dose of linagliptin 5 or 10 mg and 494 completed the extension. Long-term treatment with linagliptin was well tolerated; adverse events (AEs) of special interest and serious AEs occurred in small percentages of patients. Drug-related AEs occurred in 10.2 and 10.6% of patients in the linagliptin 5- and 10-mg groups, respectively, and discontinuations due to drug-related AEs occurred in 1.1 and 0.7%, respectively. Only one (0.4%) patient in each dose group experienced investigator-defined hypoglycaemia during the treatment period (both events were non-severe). Body weight was not clinically altered in either group. The glycated haemoglobin A1c profiles over time were similar with linagliptin 5 and 10 mg.

CONCLUSIONS

These findings provide evidence for the safety and tolerability of oral linagliptin at either 5 or 10 mg for up to 52 weeks for the treatment of Japanese patients with T2DM, without clinically relevant increase in the risk of hypoglycaemia or weight gain.

Regioselective opening of myo-inositol orthoesters: mechanism and synthetic utility

Acid hydrolysis of myo-inositol 1,3,5-orthoesters, apart from orthoformates, exclusively affords the corresponding 2-O-acyl myo-inositol products via a 1,2-bridged five-membered ring dioxolanylium ion intermediate observed by NMR spectroscopy. These C-2-substituted inositol derivatives provide valuable precursors for rapid and highly efficient routes to 2-O-acyl inositol 1,3,4,5,6-pentakisphosphates and myo-inositol 1,3,4,5,6-pentakisphosphate with biologically interesting and anticancer properties. Deuterium incorporation into the α-methylene group of such alkyl ester products (2-O-C(O)CD2R), when the analogous alkyl orthoester is treated with deuterated acid, is established utilizing the novel orthoester myo-inositol 1,3,5-orthobutyrate as an example. Such deuterated ester products provide intermediates for deuterium-labeled synthetic analogues. Investigation into this selective formation of 2-O-ester products and the deuterium incorporation is presented with proposed mechanisms from NMR experiments.

Antihepatotoxic activity of a quantified Desmodium adscendens decoction and D-pinitol against chemically-induced liver damage in rats

ETHNOPHARMACOLOGICAL RELEVANCE

The isolation of D-pinitol (or 3-O-methyl-D-chiro-inositol) from an aqueous decoction of Desmodium adscendens (Fabaceae) leaves and twigs is reported. The protective and curative effect of this decoction, in which d-pinitol was quantified, and of pure D-pinitol, against chemically-induced liver damage in rats has been evaluated.

MATERIALS AND METHODS

Enzyme levels of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP), which are among the usual biomarkers for liver damage, were determined in serum samples of experimental animals. The protective effects against D-galactosamine-induced and ethanol-induced liver damage of a decoction of D. adscendens, quantified on its main constituent D-pinitol, was investigated in rats. In addition, the curative effects of pure D-pinitol and D. adscendens against chronic D-galactosamine-induced and acute acetaminophen-induced hepatotoxicity in rats was studied. Silymarin was used as positive control.

RESULTS

In a first experiment evaluating the protective effect against acute D-galactosamine-induced liver damage in rats, a significant decrease of AST and ALT was observed for the D. adscendens decoction at a dose equivalent to 5 mg/kg/day and 20 mg/kg/day D-pinitol, as well as 20 mg/kg/day pure D-pinitol. With respect to chronic ethanol-induced liver damage in rats, the protective effects of D. adscendens at doses equivalent to 2 mg/kg/day and 10 mg/kg/day D-pinitol, were not observed for serum AST and ALT levels. However, with respect to reduced mortality of animals, statistical analysis showed a trend towards significance for the Desmodium group receiving a dose equivalent to 10 mg/kg/day D-pinitol, versus the untreated hepatotoxic animals. Additional experiments in rat models of acute acetaminophen-induced and chronic D-galactosamine-induced liver damage indicated that D. adscendens decoction and pure D-pinitol had no curative effect when given in a dose equivalent to 10 mg/kg/day D-pinitol, or up to 20 mg/kg/day as a pure compound daily, respectively.

CONCLUSIONS

The aqueous decoction of D. adscendens showed a protective effect in rats against liver damage induced by D-galactosamine and ethanol, and this effect is at least in part due to the presence of D-pinitol. However, no curative effect of D. adscendens decoction or D-pinitol on liver damage induced by the tested chemicals could be demonstrated.

Cloning, expression and medium optimization of validamycin glycosyltransferase from Streptomyces hygroscopicus var. jinggangensis for the biotransformation of validoxylamine A to produce validamycin A using free resting cells

Validamycin A is widely used to control Basidiomycetes, which causes sheath blight disease in rice, potatoes, vegetables, and other crops as well as dumping-off disease in vegetable seedlings, cotton, sugar beets, and other plants. In order to improve the content of validamycin A in the commercial products, valG from Streptomyces hygroscopicus was successfully cloned into Escherichia coli BL21(DE3) and was directly employed as the biocatalyst in the biotransformation from validoxylamine A to validamycin A with the existence of d-cellobiose using the free resting cells in the present study. The fermentation medium was optimized through single factor experiment and response surface method. With the optimized medium, which contained lactose 4.7g/L, yeast extract 49.5g/L, ammonium chloride 2.7g/L, potassium phosphate buffer solution 110mL/L, Ca(2+) 0.0352g/L, the biomass yield and enzyme activity reached 5.5g/L and 1.49U/mL, respectively, which were nearly twice higher than those with initial medium.

Different sodium salts cause different solute accumulation in the halophyte Prosopis strombulifera

The success of Prosopis strombulifera in growing under high NaCl concentrations involves a carefully controlled balance among different processes, including compartmentation of Cl(-) and Na(+) in leaf vacuoles, exclusion of Na(+) in roots, osmotic adjustment and low transpiration. In contrast, Na(2) SO(4) causes growth inhibition and toxicity. We propose that protection of the cytoplasm can be achieved through production of high endogenous levels of specific compatible solutes. To test our hypothesis, we examined endogenous levels of compatible solutes in roots and leaves of 29-, 40- and 48-day-old P. strombulifera plants grown in media containing various concentrations of NaCl, Na(2) SO(4) or in mixtures of both, with osmotic potentials of -1.0,-1.9 and -2.6 MPa, as correlated with changes in hydric parameters. At 24 h after the last pulse plants grown in high NaCl concentrations had higher relative water content and relatively higher osmotic potential than plants grown in Na(2) SO(4) (at 49 days). These plants also had increased synthesis of proline, pinitol and mannitol in the cytoplasm, accompanied by normal carbon metabolism. When the sulphate anion is present in the medium, the capacities for ion compartmentalisation and osmotic adjustment are reduced, resulting in water imbalance and symptoms of toxicity due to altered carbon metabolism, e.g. synthesis of sorbitol instead of mannitol, reduced sucrose production and protein content. This inhibition was partially mitigated when both anions were present together in the solution, demonstrating a detrimental effect of the sulphate ion on plant growth.

Intestinal alpha-glucosidase inhibitors: abdominal gas cysts

Detailed imaging studies of gas cysts in the intestinal mucosa (pneumatosis cystoides intestinalis) have been reported in around 20 patients taking acarbose, miglitolor voglibose, i.e. intestinal alpha-glucosidase inhibitors used as hypoglycaemic agents. Almost all the patients had nonspecific abdominal symptoms such as abdominal pain, abdominal distension, rectal bleeding or loss of appetite. They underwent multiple diagnostic tests before a role of the drug was raised. The disorders resolved completely when the drugs were withdrawn. In practice, as acarbose and miglitol have no proven impact on morbidity or mortality, and as they have multiple adverse effects, including gas cysts, they should not be used to treat diabetic patients.

(1) H NMR analysis of O-methyl-inositol isomers: a joint experimental and theoretical study

Density functional theory (DFT) calculations of (1) H NMR chemical shifts for l-quebrachitol isomers were performed using the B3LYP functional employing the 6-31G(d,p) and 6-311 + G(2d,p) basis sets. The effect of the solvent on the B3LYP-calculated NMR spectrum was accounted for using the polarizable continuum model. Comparison is made with experimental (1) H NMR spectroscopic data, which shed light on the average uncertainty present in DFT calculations of chemical shifts and showed that the best match between experimental and theoretical B3LYP (1) H NMR profiles is a good strategy to assign the molecular structure present in the sample handled in the experimental measurements. Among four plausible O-methyl-inositol isomers, the l-quebrachitol 2a structure was unambiguously assigned based only on the comparative analysis of experimental and theoretical (1) H NMR chemical shift data. The B3LYP infrared (IR) spectrum was also calculated for the four isomers and compared with the experimental data, with analysis of the theoretical IR profiles corroborating assignment of the 2a structure. Therefore, it is confirmed in this study that a combined experimental/DFT spectroscopic investigation is a powerful tool in structural/conformational analysis studies.

Alpha-glucosidase inhibitors 2012 - cardiovascular considerations and trial evaluation

Alpha-glucosidase inhibitors have been available for clinical use for about 20 years. They have shown reasonably good efficacy comparable to other oral blood glucose lowering drugs and in some parts of the world are the most commonly prescribed oral diabetes medication, especially in Asian countries. Unlike as has been observed with some other blood glucose lowering agents, however, no adverse signals of potential cardiovascular harm have emerged in relation to their use. On the contrary, significant beneficial cardiovascular outcome results have been observed in the post-hoc analyses of randomised placebo-controlled trials with the alpha-glucosidase inhibitor acarbose. Targeting mainly postprandial hyperglycaemia, alpha-glucosidase inhibitors favourably affect several cardiovascular risk factors, such as obesity, hypertension and high glycaemic variability with little to no risk for hypoglycaemia. Furthermore, acarbose favourably affects endothelial dysfunction and carotid intima media thickening in humans and, in animal models, improves cardiac interstitial fibrosis and hypertrophy of cardiomyocytes. The ultimate determination of the cardiovascular effects of alpha-glucosidase inhibitors in terms of clinical outcomes awaits the results of ongoing long-term, randomised, placebo-controlled trials.

Differential effects of α-glucosidase inhibitors on postprandial plasma glucose and lipid profile in patients with type 2 diabetes under control with insulin lispro mix 50/50

BACKGROUND

The additive effect of α-glucosidase inhibitors (α-GIs) was investigated in patients with type 2 diabetes (T2D) under control with rapid-acting insulin analog.

SUBJECTS AND METHODS

Thirty-six poorly controlled T2D patients were recruited, and plasma glucose (PG) was controlled by three times daily injection of insulin lispro mix 50/50 (Mix50) to maintain fasting PG <130 mg/dL and 2-h postprandial PG (PPG) <180 mg/dL. Another group of 20 patients was randomly assigned to either 0.3 mg of voglibose or 50 mg of miglitol, which was administered at breakfast every other day. Another group of 16 patients was assigned to a crossover study, in which each α-GI was switched every day during the 6-day study. PPG, C-peptide, and lipid profile were analyzed.

RESULTS

The addition of voglibose had no effect on PPG, but miglitol blunted the PPG rise and significantly decreased 1-h and 2-h postprandial C-peptide levels compared with Mix50 alone. In addition, miglitol significantly decreased the 1-h postprandial triglyceride rise and the remnant-like particle-cholesterol rise, while it increased the 1-h postprandial high-density lipoprotein-cholesterol and apolipoprotein A-I levels in the crossover study.

CONCLUSIONS

Miglitol appears to have rapid action, which appears earlier than that of lispro. The combination of miglitol and Mix50 seems effective for the control of PPG and lipid profile in T2D.

D-chiro-inositol negatively regulates the formation of multinucleated osteoclasts by down-regulating NFATc1

PURPOSE

Osteoclasts (OCs) are multinucleated giant cells that resorb bone matrix. Accelerated bone destruction by OCs might cause several metabolic bone-related diseases, such as osteoporosis and inflammatory bone loss. D-pinitol (3-O-methyl-D-chiro-inositol) is a prominent component of dietary legumes and is actively converted to D-chiro-inositol, which is a putative insulin-like mediator. In this study, we analyzed the effect of D-chiro-inositol on OC differentiation.

METHODS

To analyze the role of D-chiro-inositol on OC differentiation, we examined OC differentiation by the three types of osteoclastogenesis cultures with tartrate-resistant acid phosphatase (TRAP) staining and solution assay. Then, we carried out cell fusion assay with purified TRAP(+) mononuclear OC precursors. Finally, we analyzed the effect of D-chiro-inositol on OC maker expression in response to the regulation of nuclear factor of activated T cells c1 (NFATc1).

RESULTS

We demonstrated that D-chiro-inositol acts as an inhibitor of receptor activator of NF-κB ligand-induced OC differentiation. The formation of multinucleated OCs by cell-cell fusion is reduced by treatment with D-chiro-inositol in a dose-dependent manner. In addition, we demonstrated that D-chiro-inositol inhibits the expression of several osteoclastogenic genes by down-regulating NFATc1.

CONCLUSIONS

We have shown that D-chiro-inositol is negatively involved in osteoclastogenesis through the inhibition of multinucleated OC formation by cell-cell fusion. The expression of NFATc1 was significantly down-regulated by D-chiro-inositol in OCs and consequently, the expression of OC marker genes was significantly reduced. Hence, these results show that D-chiro-inositol might be a good candidate to treat inflammatory bone-related diseases or secondary osteoporosis in diabetes mellitus.

Enhancement of validamycin A production by addition of ethanol in fermentation of Streptomyces hygroscopicus 5008

The effect of ethanol on the production of the important agro-antibiotic validamycin A (Val-A) in medium containing agricultural by-products was investigated. Under the optimal condition of ethanol addition, the maximal Val-A production titer reached 18 g/L, which increased by 60% compared to the control. To provide an insight into cell response to ethanol, the intracellular reactive oxygen species (ROS), gene transcription and enzyme activity were determined. Intracellular ROS as the molecular signal was increased in the ethanol condition. Global regulators afsR and glnR were involved in regulation of Val-A biosynthesis, and the transcription of eight Val-A structural genes was enhanced. The activity of glucose-6-phosphate dehydrogenase (G6PD) was enhanced while glyceraldehyde 3-phosphate dehydrogenase (GAPDH) was inhibited. A signal transduction cascade from cell signal response to activated transcription of Val-A biosynthetic genes and enhanced antibiotic production is proposed. The information can be helpful for the improvement of large-scale fermentation.

Herbal constituent sequoyitol improves hyperglycemia and glucose intolerance by targeting hepatocytes, adipocytes, and β-cells

The prevalence of insulin resistance and type 2 diabetes increases rapidly; however, treatments are limited. Various herbal extracts have been reported to reduce blood glucose in animals with either genetic or dietary type 2 diabetes; however, plant extracts are extremely complex, and leading compounds remain largely unknown. Here we show that 5-O-methyl-myo-inositol (also called sequoyitol), a herbal constituent, exerts antidiabetic effects in mice. Sequoyitol was chronically administrated into ob/ob mice either orally or subcutaneously. Both oral and subcutaneous administrations of sequoyitol decreased blood glucose, improved glucose intolerance, and enhanced insulin signaling in ob/ob mice. Sequoyitol directly enhanced insulin signaling, including phosphorylation of insulin receptor substrate-1 and Akt, in both HepG2 cells (derived from human hepatocytes) and 3T3-L1 adipocytes. In agreement, sequoyitol increased the ability of insulin to suppress glucose production in primary hepatocytes and to stimulate glucose uptake into primary adipocytes. Furthermore, sequoyitol improved insulin signaling in INS-1 cells (a rat β-cell line) and protected INS-1 cells from streptozotocin- or H₂O₂-induced injury. In mice with streptozotocin-induced β-cell deficiency, sequoyitol treatments increased plasma insulin levels and decreased hyperglycemia and glucose intolerance. These results indicate that sequoyitol, a natural, water-soluble small molecule, ameliorates hyperglycemia and glucose intolerance by increasing both insulin sensitivity and insulin secretion. Sequoyitol appears to directly target hepatocytes, adipocytes, and β-cells. Therefore, sequoyitol may serve as a new oral diabetes medication.

Temperature shift-induced reactive oxygen species enhanced validamycin A production in fermentation of Streptomyces hygroscopicus 5008

In order to enhance the production of validamycin A (VAL-A), a widely used agricultural antibiotic, a temperature shift strategy was developed in the fermentation of Streptomyces hygroscopicus 5008. VAL-A production and the transcriptional levels of its structural genes were enhanced in the optimal temperature shift condition. The addition of diphenyleneiodonium [DPI, reactive oxygen species (ROS) inhibitor] inhibited intracellular ROS level and VAL-A production, which indicated that ROS signal might contribute to the enhancement of VAL-A production in the temperature shift process. The transcriptional levels of stress response sigma factors SigmaB and SigmaH as well as global regulator PhoRP were enhanced, which suggested that these regulators might participate in the signal pathway. This study developed a useful strategy for VAL-A production. It will help to further understand the regulation mechanism of ROS on VAL-A synthesis. The involvement of ROS in this process will encourage researchers to develop new ROS induction strategies to enhance VAL-A production.

Linagliptin monotherapy provides superior glycaemic control versus placebo or voglibose with comparable safety in Japanese patients with type 2 diabetes: a randomized, placebo and active comparator-controlled, double-blind study

AIMS

To evaluate the efficacy and safety of linagliptin 5 and 10 mg vs. placebo and voglibose in Japanese patients with type 2 diabetes mellitus (T2DM).

METHODS

This study enrolled patients with inadequately controlled T2DM who were previously treated with one or two oral antidiabetics or were drug naÏve. After a 2 to 4-week washout and placebo run-in, 561 patients were randomized (2 : 2 : 2 : 1) to double-blind treatment with linagliptin 5 or 10 mg qd, voglibose 0.2 mg tid or placebo. The primary endpoint was the change from baseline in haemoglobin A1c (HbA1c) with linagliptin vs. placebo after 12 weeks and vs. voglibose after 26 weeks.

RESULTS

Baseline characteristics were well balanced across treatment groups (overall mean HbA1c was 8.01%). The adjusted mean (95% confidence interval) treatment differences at week 12 were -0.87% (-1.04, -0.70; p < 0.0001) and -0.88% (-1.05, -0.71; p < 0.0001) for linagliptin 5 and 10 mg vs. placebo and at week 26 were -0.32% (-0.49, -0.15; p = 0.0003) and -0.39% (-0.56, -0.21; p < 0.0001) for linagliptin 5 and 10 mg vs. voglibose. At week 12, mean HbA1c was 7.58, 7.48 and 8.34% in patients receiving linagliptin 5 mg, linagliptin 10 mg and placebo, respectively. At week 26, mean HbA1c was 7.63% with linagliptin 5 mg, 7.50% with linagliptin 10 mg and 7.91% with voglibose. Drug-related adverse event rates were comparable across treatment groups over 12 weeks (9.4% linagliptin 5 mg, 8.8% linagliptin 10 mg and 10.0% placebo) and 26 weeks (11.3% linagliptin 5 mg, 10.6% linagliptin 10 mg and 18.5% voglibose). There were no documented cases of hypoglycaemia.

CONCLUSIONS

Linagliptin showed superior glucose-lowering efficacy and comparable safety and tolerability to both placebo and voglibose in Japanese patients with T2DM.

Comparisons of the effects of 12-week administration of miglitol and voglibose on the responses of plasma incretins after a mixed meal in Japanese type 2 diabetic patients

To compare the effects of miglitol [an alpha-glucosidase inhibitor (AGI) absorbed in the intestine] and voglibose (an AGI not absorbed) on plasma glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) levels, 26 and 24 Japanese type 2 diabetic patients were randomly assigned to receive miglitol or voglibose, respectively. After 12-week administration of both drugs, during 2-h meal tolerance test, plasma glucose, serum insulin and total GIP were significantly decreased and active GLP-1 was significantly increased. Miglitol group showed a significantly lower total GIP level than voglibose group. Miglitol, but not voglibose, significantly reduced body weight (BW). In all participants, the relative change in BW was positively correlated with that of insulin significantly and of GIP with a weak tendency, but not of GLP-1. In conclusion, both drugs can enhance postprandial GLP-1 responses and reduce GIP responses. The significant BW reduction by miglitol might be attributable to its strong GIP-reducing efficacy.

Structural and functional analysis of validoxylamine A 7'-phosphate synthase ValL involved in validamycin A biosynthesis

Validamycin A (Val-A) is an effective antifungal agent widely used in Asian countries as crop protectant. Validoxylamine A, the core structure and intermediate of Val-A, consists of two C₇-cyclitol units connected by a rare C-N bond. In the Val-A biosynthetic gene cluster in Streptomyces hygroscopicus 5008, the ORF valL was initially annotated as a validoxylamine A 7′-phosphate(V7P) synthase, whose encoded 497-aa protein shows high similarity with trehalose 6-phosphate(T6P) synthase. Gene inactivation of valL abolished both validoxylamine A and validamycin A productivity, and complementation with a cloned valL recovered 10% production of the wild-type in the mutant, indicating the involvement of ValL in validoxylamine A biosynthesis. Also we determined the structures of ValL and ValL/trehalose complex. The structural data indicates that ValL adopts the typical fold of GT-B protein family, featuring two Rossmann-fold domains and an active site at domain junction. The residues in the active site are arranged in a manner homologous to that of Escherichia coli (E.coli) T6P synthase OtsA. However, a significant discrepancy is found in the active-site loop region. Also noticeable structural variance is found around the active site entrance in the apo ValL structure while the region takes an ordered configuration upon binding of product analog trehalose. Furthermore, the modeling of V7P in the active site of ValL suggests that ValL might have a similar SNi-like mechanism as OtsA.

A new inositol derivative from Prenanthes macrophylla

A new chiro-inositol ester, 4-hydroxyphenylacetyl-3-d-chiro-inositol ester (1), was isolated from the whole plants of Prenanthes macrophylla Franch., along with 10 known compounds, 4-hydroxyphenylacetic acid (2), trans-ethyl caffeate (3), cis-ethyl caffeate (4), protocatechualdehyde (5), luteolin (6), luteolin-7-O-β-d-glucoside (7), 15-hydroxy-2-oxo-guai-3-en-1α,5α,6β,7α,10α,11βH-12,6-olide (8), 15-glucopyranosyloxy-2-oxo-guaia-3,11(13)-dien-1α,5α,6β,7α,10αH-12,6-olide (9), ursolic acid (10), and oleanolic acid (11). Their structures were elucidated on the basis of spectroscopic analyses including HR-ESI-MS, ESI-MS, (1)H and (13)C NMR, HSQC, HMBC, and ROESY, and chemical evidences.

D-Pinitol attenuates 7, 12 dimethylbenz [a] anthracene induced hazards through modulating protein bound carbohydrates, adenosine triphosphatases and lysosomal enzymes during experimental mammary carcinogenesis

We have reported here that the ameliorative potentials of D-Pinitol during 7, 12-Dimethylbenz [a] anthracene induced experimental breast carcinogenesis. DMBA is a potent organ specific carcinogen which is widely employed to induce mammary carcinoma in rats. D-Pinitol a natural inositol has been reported to found in soybean with many biological functions. The female sprague dawley rats were subjected to carcinogen 7, 12-DMBA and the ameliorative potentials of dietary compound D-Pinitol was investigated with reference to cell surface glycoproteins, lysosomal enzymes and adenosine triphosphatases. Interestingly, administration of D-Pinitol was found to be significantly down regulated the breast tissue glycoproteins and lysosomal enzymes and in contrast the levels of adenosine triphosphatases were remarkably up regulated. Further, the biochemical changes were well reflected and evidenced in the histology of breast and liver tissues. Thus, it can be concluded from the present study that D-Pinitol efficiently attenuates the hazardous consequences of the environmental carcinogen 7,12-DMBA through modulating cell surface glycoproteins, membrane protective role both in lysosomal and ATPase compartment via its antioxidant nature which ultimately results in the findings of future innovative remedies for genotoxin mediated hazards.

Polar compounds isolated from the leaves of Albertisia delagoensis (Menispermaceae)

Aqueous infusions of the leaves of the shrub Albertisia delagoensis (Menispermaceae) are used in South Africa in traditional Zulu medicine to alleviate a variety of symptoms, including fever, and intestinal problems. We report the analysis of such an aqueous extract using the HPLC-NMR technique. A number of polar compounds were identified, including proto-quercitol, nicotinic acid, allantoic acid, 3,4-dihydroxy-benzoic acid, phthalic acid and the aporphine alkaloid derivative roemrefidine. Allantoic acid and roemrefidine have been fully characterised by (1)H- and (13)C-NMR and mass spectrometry. Earlier reports of antiplasmodial activity of roemrefidine and of A. delagoensis extracts are correlated with this study and with the antipyretic properties of neutral aqueous extracts.

Alogliptin plus voglibose in Japanese patients with type 2 diabetes: a randomized, double-blind, placebo-controlled trial with an open-label, long-term extension

OBJECTIVE

To compare the efficacy and safety of alogliptin and placebo as add-on therapy in Japanese patients with type 2 diabetes who experienced inadequate glycemic control on voglibose plus diet/exercise therapy.

RESEARCH DESIGN AND METHODS

During an 8 week screening phase, patients aged ≥ 20 years were stabilized on voglibose 0.2 mg three times daily plus diet/exercise therapy. Those with HbA1c between ≥ 6.9% and <10.4% were randomly assigned to 12 weeks' double-blind treatment with once daily alogliptin 12.5 or 25 mg, or placebo. The primary endpoint was the change in HbA1c at 12 weeks from baseline. Patients then entered an open-label, 40 week extension trial (patients in the placebo group were randomly allocated to alogliptin 12.5 or 25 mg).

CLINICAL TRIALS REGISTRATION

www.clinicaltrials.gov ; pivotal trial NCT01263483; Long term trial NCT01263509.

RESULTS

Least square mean change in HbA1c after 12 weeks' therapy from baseline (primary endpoint) was significantly greater in the alogliptin 12.5 mg (-0.96%; P < 0.0001) and 25 mg (-0.93%; P < 0.0001) groups compared with placebo (+0.06%). This was associated with statistically significant improvements in other measures of glycemic control, in particular sustained reductions in fasting plasma glucose and postprandial plasma glucose. These benefits were maintained for the duration of the 1 year study and, importantly, they were achieved without detrimental effects on tolerability/safety. In particular, there was no increase in the rate of hypoglycemia and almost no changes in mean body weight.

CONCLUSIONS

Addition of once daily alogliptin to voglibose monotherapy in Japanese patients with uncontrolled type 2 diabetes produced clinically significant improvements in glycemic control, and was well tolerated.

Temperature stress effects in Quercus suber leaf metabolism

Based on projections that climate changes are will intensify in the near future, it is important to understand how plants respond to climate. Consequently, we have been studying the effect of contrasting temperatures on leaf metabolism of Quercus suber, an important Mediterranean oak. Potted plants were grown under controlled conditions for 53 days at 28°C or 10°C. The accumulation of major soluble metabolites was analyzed by NMR. The relative levels of transcripts of genes encoding key enzymes of the shikimate and phenylpropanoid pathway (CS, PAL, CAD and ChS) were examined by means of quantitative, real-time RT-PCR. At 10°C, in the pre-existing leaves, the concentrations of sucrose, quercitol and catechin were higher, as were PAL and ChS transcripts. At 28°C, however, it was the concentration of quinic acid that was higher, as were the concentrations of CS and CAD transcripts. We conclude that contrasting temperatures greatly influence Q. suber metabolism and that a deeper analysis of the effects of more extreme temperatures is needed to understand the possible effects of temperature changes on Q. suber metabolism and physiology.

Over-expression of UDP-glucose pyrophosphorylase increases validamycin A but decreases validoxylamine A production in Streptomyces hygroscopicus var. jinggangensis 5008

During the fermentation of Streptomyces hygroscopicus TL01 to produce validamycin A (18 g/L), a considerable amount of an intermediate validoxylamine A (4.0 g/L) is accumulated. Chemical or enzymatic hydrolysis of validamycin A was not observed during the fermentation process. Over-expression of glucosyltransferase ValG in TL01 did not increase the efficiency of glycosylation. However, increased validamycin A and decreased validoxylamine A production were observed in both the cell-free extract and fermentation broth of TL01 supplemented with a high concentration of UDP-glucose. The enzymatic activity of UDP-glucose pyrophosphorylase (Ugp) in TL01, which catalyzes UDP-glucose formation, was found to be much lower than the activities of other enzymes involved in the biosynthesis of UDP-glucose and the glucosyltransferase ValG. An ugp gene was cloned from S. hygroscopicus 5008 and verified to code for Ugp. In TL01 with an extra copy of ugp, the transcription of ugp was increased for 1.5 times, and Ugp activity was increased by 100%. Moreover, 22 g/L validamycin A and 2.5 g/L validoxylamine A were produced, and the validamycin A/validoxylamine A ratio was increased from 3.15 in TL01 to 5.75. These data prove that validamycin A biosynthesis is limited by the supply of UDP-glucose, which can be relieved by Ugp over-expression.

Genetic and physiological analysis of the relationship between partial resistance to clubroot and tolerance to trehalose in Arabidopsis thaliana

In Arabidopsis thaliana the induction of plant trehalase during clubroot disease was proposed to act as a defense mechanism in the susceptible accession Col-0, which could thereby cope with the accumulation of pathogen-synthesized trehalose. In the present study, we assessed trehalose activity and tolerance to trehalose in the clubroot partially resistant accession Bur-0. We compared both accessions for several trehalose-related physiological traits during clubroot infection. A quantitative trait loci (QTLs) analysis of tolerance to exogenous trehalose was also conducted on a Bur-0xCol-0 RIL progeny. Trehalase activity was not induced by clubroot in Bur-0 and the inhibition of trehalase by validamycin treatments resulted in the enhancement of clubroot symptoms only in Col-0. In pathogen-free cultures, Bur-0 showed less trehalose-induced toxicity symptoms than Col-0. A QTL analysis identified one locus involved in tolerance to trehalose overlapping the confidence interval of a QTL for resistance to Plasmodiophora brassicae. This colocalization was confirmed using heterogeneous inbred family (HIF) lines. Although not based on trehalose catabolism capacity, partial resistance to clubroot is to some extent related to the tolerance to trehalose accumulation in Bur-0. These findings support an original model where contrasting primary metabolism-related regulations could contribute to the partial resistance to a plant pathogen.

Alpha-synuclein interacts with Glucocerebrosidase providing a molecular link between Parkinson and Gaucher diseases

The presynaptic protein α-synuclein (α-syn), particularly in its amyloid form, is widely recognized for its involvement in Parkinson disease (PD). Recent genetic studies reveal that mutations in the gene GBA are the most widespread genetic risk factor for parkinsonism identified to date. GBA encodes for glucocerebrosidase (GCase), the enzyme deficient in the lysosomal storage disorder, Gaucher disease (GD). In this work, we investigated the possibility of a physical linkage between α-syn and GCase, examining both wild type and the GD-related N370S mutant enzyme. Using fluorescence and nuclear magnetic resonance spectroscopy, we determined that α-syn and GCase interact selectively under lysosomal solution conditions (pH 5.5) and mapped the interaction site to the α-syn C-terminal residues, 118-137. This α-syn-GCase complex does not form at pH 7.4 and is stabilized by electrostatics, with dissociation constants ranging from 1.2 to 22 μm in the presence of 25 to 100 mm NaCl. Intriguingly, the N370S mutant form of GCase has a reduced affinity for α-syn, as does the inhibitor conduritol-β-epoxide-bound enzyme. Immunoprecipitation and immunofluorescence studies verified this interaction in human tissue and neuronal cell culture, respectively. Although our data do not preclude protein-protein interactions in other cellular milieux, we suggest that the α-syn-GCase association is favored in the lysosome, and that this noncovalent interaction provides the groundwork to explore molecular mechanisms linking PD with mutant GBA alleles.

Inhibition of trehalose breakdown increases new carbon partitioning into cellulosic biomass in Nicotiana tabacum

Validamycin A was used to inhibit in vivo trehalase activity in tobacco enabling the study of subsequent changes in new C partitioning into cellulosic biomass and lignin precursors. After 12-h exposure to treatment, plants were pulse labeled using radioactive (11)CO(2), and the partitioning of isotope was traced into [(11)C]cellulose and [(11)C]hemicellulose, as well as into [(11)C]phenylalanine, the precursor for lignin. Over this time course of treatment, new carbon partitioning into hemicellulose and cellulose was increased, while new carbon partitioning into phenylalanine was decreased. This trend was accompanied by a decrease in phenylalanine ammonia-lyase activity. After 4d of exposure to validamycin A, we also measured leaf protein content and key C and N metabolite pools. Extended treatment increased foliar cellulose and starch content, decreased sucrose, and total amino acid and nitrate content, and had no effect on total protein.

Accumulation and distribution of α-synuclein and ubiquitin in the CNS of Gaucher disease mouse models

Gaucher disease, a prevalent lysosomal storage disease, is caused by insufficient activity of acid β-glucosidase (GCase) and resultant glucosylceramide accumulation. Recently in Parkinson disease (PD) patients, heterozygous mutations in GCase have been associated with earlier onset and more progressive PD. To understand the pathogenic relationships between GCase variants and Parkinsonism, α-synuclein and ubiquitin distributions and levels in the brains of several mouse models containing GCase variants were evaluated by immunohistochemistry. Progressive α-synuclein and ubiquitin aggregate accumulations were observed in the cortex, hippocampus, basal ganglia, brainstem, and some cerebellar regions between 4 and 24 weeks in mice that were homozygous for GCase [D409H (9H) or V394L (4L)] variants and also had a prosaposin hypomorphic (PS-NA) transgene. In 4L/PS-NA and 9H/PS-NA mice, this was coincident with progressive neurological manifestations and brain glucosylceramide accumulation. Ultrastructural studies showed electron dense inclusion bodies in neurons and axons of 9H/PS-NA brains. α-synuclein aggregates were also observed in ventricular, brainstem, and cerebellar regions of older mice (>42-weeks) with the GCase variant (D409H/D409H) without overt neurological disease. In a chemically induced GCase deficiency, α-synuclein aggregates and glucosylceramide accumulation also occurred. These studies demonstrate a relationship between glucosylceramide accumulation and α-synuclein aggregates, and implicate glucosylceramide accumulation as risk factor for the α-synucleinopathies.

D-chiro-inositol affects accumulation of raffinose family oligosaccharides in developing embryos of Pisum sativum

Developing garden pea embryos are able to take up exogenously applied cyclitols: myo-inositol, which naturally occurs in pea, and two cyclitols absent in pea plants: d-chiro-inositol and d-pinitol. The competition in the uptake of cyclitols by pea embryo, insensitivity to glucose and sucrose, and susceptibility to inhibitor(s) of H(+)-symporters (e.g. CCCP and antimycin A) suggest that a common cyclitol transporter is involved. Both d-chiro-inositol and d-pinitol can be translocated through the pea plant to developing embryos. During seed maturation drying, they are used for synthesis of mainly mono-galactosides, such as fagopyritol B1 and galactosyl pinitol A. Accumulation of d-chiro-inositol (and formation of fagopyritols), but not d-pinitol, strongly reduces accumulation of verbascose, the main raffinose oligosaccharide in pea seeds. The reasons for the observed changes are discussed.