Fructose-1,6-bisphosphatase inhibitors. 1. Purine phosphonic acids as novel AMP mimics

Inhibition of FBPase is considered a promising way to reduce hepatic gluconeogenesis and therefore could be a potential approach to treat type 2 diabetes. Herein we report the discovery of a series of purine phosphonic acids as AMP mimics targeting the AMP site of FBPase, which was achieved using a structure-guided drug design approach. These non-nucleotide purine analogues inhibit FBPase in a similar manner and with similar potency as AMP. More importantly, several purine analogues exhibited potent cellular and in vivo glucose-lowering activities, thus achieving proof-of-concept for inhibiting FBPase as a drug discovery target. For example, compounds 4.11 and 4.13 are as equipotent as AMP with regard to FBPase inhibition. Furthermore, compound 4.11 inhibited glucose production in primary rat hepatocytes and significantly lowered blood glucose levels in fasted rats.

Effect of sowing date and N fertilisation on the yield and yield stability of maize ( Zea mays L.) hybrids in a long-term experiment

The effect of sowing date, N fertilisation and genotype on the grain yield and yield stability of maize was studied between 1991 and 2006 in a long-term N fertilisation experiment set up on chernozem soil in Martonvásár, Hungary. The N treatments (0, 60, 120, 180 and 240 kg ha−1) represented the main plot of the three-factor, split-split-plot experiment, with the sowing date (early, optimum, late, very late) in the sub-plots and hybrids from different maturity groups in the sub-sub-plots. The highest yields were obtained for the early and optimum sowing dates (8.712 and 8.706 t ha−1). Compared with the optimum sowing date, a delay of ten or twenty days led to yield losses of 5% and 12.5%, respectively. In the late and very late sowings and in years with unfavourable weather conditions, yield increments were only observed up to an N rate of 60 kg ha−1, while in the early and optimum sowings and in favourable years yield increments were significant up to 120 kg ha−1N. Yield stability was smallest in the early and very late sowings, in the control and for high N rates, and in the early and late maturity hybrids. It can be concluded that high yields and yield stability are not mutually exclusive.

A cascade reaction with iminium ion isomerization as the key step leading to tetrahydropyrimido[4,5-d]pyrimidines

A novel cascade reaction of aminopyrimidines 1 with N-alkyl amino acids or analogues was investigated. The keys to this cascade are the isomerization of an iminium ion formed between the aldehyde group in pyrimidine and the secondary amine of an amino acid, and subsequent cyclization to the neighboring amino group. This sequence could be useful in the synthesis of novel tetrahydropyrimido[4,5-d]pyrimidine libraries.

Structure-guided design of AMP mimics that inhibit fructose-1,6-bisphosphatase with high affinity and specificity

AMP binding sites are commonly used by nature for allosteric regulation of enzymes controlling the production and metabolism of carbohydrates and lipids. Since many of these enzymes represent potential drug targets for metabolic diseases, efforts were initiated to discover AMP mimics that bind to AMP-binding sites with high affinity and high enzyme specificity. Herein we report the structure-guided design of potent fructose 1,6-bisphosphatase (FBPase) inhibitors that interact with the AMP binding site on FBPase despite their structural dissimilarity to AMP. Molecular modeling, free-energy perturbation calculations, X-ray crystallography, and enzyme kinetic data guided our redesign of AMP, which began by replacing the 5'-phosphate with a phosphonic acid attached to C8 of the adenine base via a 3-atom spacer. Additional binding affinity was gained by replacing the ribose with an alkyl group that formed van der Waals interactions with a hydrophobic region within the AMP binding site and by replacing the purine nitrogens N1 and N3 with carbons to minimize desolvation energy expenditures. The resulting benzimidazole phosphonic acid, 16, inhibited human FBPase (IC50 = 90 nM) 11-fold more potently than AMP and exhibited high specificity for the AMP binding site on FBPase. 16 also inhibited FBPase in primary rat hepatocytes and correspondingly resulted in concentration-dependent inhibition of the gluconeogenesis pathway. Accordingly, these results suggest that the AMP site of FBPase may represent a potential drug target for reducing the excessive glucose produced by the gluconeogenesis pathway in patients with type 2 diabetes.

A new strategy toward fused-pyridine heterocyclic scaffolds: Bischler-Napieralski-type cyclization, followed by sulfoxide extrusion reaction

Method development was completed for a new strategy to obtain fused-pyridine heterocyclic scaffolds. The synthetic route entails a Bischler-Napieralski-type reaction as the key step, followed by a sulfoxide extrusion reaction. The reactions of 3-amino-2-arylthiopyridines or 3-amino-4-arylthiopyridines and carboxylic acids promoted by a Lewis acid such as SnCl4 yielded novel tricyclic pyridobenzothiazepines, which could be readily converted to their corresponding oxidized products via a sequence of sulfur oxidations and eventually to benzonaphthyridines via a sulfoxide extrusion. The synthetic strategy provides an efficient way to access libraries of novel structurally diversified heterocyclic compounds with potential pharmaceutical or biological activities.

Discovery of fructose-1,6-bisphosphatase inhibitors for the treatment of type 2 diabetes

Overproduction of glucose via gluconeogenesis is a principal cause of the high blood glucose levels found in patients with type 2 diabetes, and is inadequately controlled by currently available medications. The enzyme fructose-1,6-bisphosphatase (FBPase), a major control point in the pathway of gluconeogenesis, is recognized as an attractive target for pharmacological intervention. This review describes recent progress in the discovery and optimization of inhibitors of FBPase, with emphasis on non-competitive inhibitors that interact with the adenosine monophosphate site of the enzyme. The biological characterization of the most advanced of these drugs, CS-917, is also summarized.

Bis[(para-methoxy)benzyl] phosphonate prodrugs with improved stability and enhanced cell penetration

A series of substituted bis[(para-methoxy)benzyl] (bisPMB) esters of 1-naphthalenemethylphosphonate (NMPA) were synthesized and evaluated as phosphonate prodrugs. BisPMB NMPA esters (4b and 4c) with significantly improved aqueous stability were identified that also resulted in increased intracellular levels of NMPA following prodrug incubation with primary rat hepatocytes.

A Cascade Reaction Consisting of Pictet−Spengler-Type Cyclization and Smiles Rearrangement: Application to the Synthesis of Novel Pyrrole-Fused Dihydropteridines

[reaction: see text] Tandem Pictet-Spengler-type cyclization and Smiles rearrangement have been discovered in the synthesis of pyrimidine-fused heterocycles. The reaction of 4-chloro-5-pyrrol-1-ylpyrimidine amino aldehyde with an amine under an acidic condition yielded the Pictet-Spengler-type cyclization product diazepine, which readily underwent Smiles rearrangement to give a novel pyrrolo[1,2-f]pteridine derivative.

Rapid Access to Pyrimido[5,4-c]isoquinolines via a Sulfur Monoxide Extrusion Reaction

The scope of a sulfur monoxide extrusion reaction of pyrimido[4,5-b][1,4]benzothiazepines leading to pyrimido[5,4-c]isoquinolines was investigated. Thus, selective oxidation followed by nucleophilic displacement of the oxidized side chain sulfur group and subsequent extrusion reaction of sulfur monoxide in the ring, which can be conducted in a two-step sequence or in a one-pot procedure, produced novel pyrimido[5,4-c]isoquinolines, a class of compounds with potential biological and pharmaceutical applications. [reaction: see text].

[Retrospective analysis of drug treatment on inpatients with chronic heart failure]

OBJECTIVE

To investigate drug treatment of inpatients with chronic heart failure(CHF) during the past 30 years in some areas and to provide more information on the treatment strategy of CHF.

METHODS

In two centers a retrospective study was conducted. All data were taken from the hospitalized cases with chronic heart failure. The medication distributions in different decade, gender, age heart function grade and etiology were analyzed.

RESULTS

5189 cases were enrolled with the ratio of male to female as 1:1.02. The mean age was (62.93 +/- 13.49) years old. The general causes of chronic heart failure were as follows: coronary heart disease (44.2%), rheumatic heart disease (24.1% ) , pulmonary heart disease (19.0%) and cardiomyopathy (4.8%). The admission cardiac function was mostly seen as grade NYHA IlI and IV, and their proportions were 40.6% and 44.5%. Major medication would include nitride (80.0%), diuretics (71.8% ), digitalis (68.1% ), angiotensin conversion enzyme inhibitors (ACEI) (52.2% ) and beta-blockers (19.5% ) etc. Moreover the frequency of above used medication was essentially increasing decade by decade. The major drug treatment of pulmonary heart disease also included diuretics, nitride, digitalis. ACEI was more commonly used in male than in female cases. The frequency of ACEI and ARB were more commonly used in the group > or = 60 years old than that in the group < 60 years old. The administration frequency of beta- blockers had no significant difference among different age and sexes.

CONCLUSION

The conventional drugs such as nitride, diuretics, digitalis were still dominated the treatment of CHF. Although the administration frequency of ACEI and beta-blockers increased quickly, there had been a great gap between the optimal medical strategy and clinical practice in the management of CHF. Data showed the treatment strategy was changing.

A novel, fully implantable, multichannel biotelemetry system for measurement of blood flow, pressure, ECG, and temperature

Biotelemetry provides high-quality data in awake, free-ranging animals without the effects of anesthesia and surgery. Although many biological parameters can be measured using biotelemetry, simultaneous telemetric measurements of pressure and flow have not been available. The objective of this study was to evaluate simultaneous measurements of blood flow, pressure, ECG, and temperature in a fully implantable system. This novel system allows the measurement of up to four channels of blood flow, up to three channels of pressure, and a single channel each of ECG and temperature. The system includes a bidirectional radio-frequency link that allows the implant to send data and accept commands to perform various tasks. The system is controlled by a base station decoder/controller that decodes the data stream sent by the implant into analog signals. The system also converts the data into a digital data stream that can be sent via ethernet to a remote computer for storage and/or analysis. The system was chronically implanted in swine and alligators for up to 5 wk. Both bench and in vivo animal tests were performed to evaluate system performance. Results show that this biotelemetry system is capable of long-term accurate monitoring of simultaneous blood flow and pressure. The system allows, within the room, recordings, since the implant transmission range is between 6 and 10 m, and, with a relay, backpack transmission distance of up to 500 m can be achieved. This system will have significant utility in chronic models of cardiovascular physiology and pathology.

Inhibition of fructose 1,6-bisphosphatase reduces excessive endogenous glucose production and attenuates hyperglycemia in Zucker diabetic fatty rats

Gluconeogenesis is increased in type 2 diabetes and contributes significantly to fasting and postprandial hyperglycemia. We recently reported the discovery of the first potent and selective inhibitors of fructose 1,6-bisphosphatase (FBPase), a rate-controlling enzyme of gluconeogenesis. Herein we describe acute and chronic effects of the lead inhibitor, MB06322 (CS-917), in rodent models of type 2 diabetes. In fasting male ZDF rats with overt diabetes, a single dose of MB06322 inhibited gluconeogenesis by 70% and overall endogenous glucose production by 46%, leading to a reduction in blood glucose of >200 mg/dl. Chronic treatment of freely feeding 6-week-old male Zucker diabetic fatty (ZDF) rats delayed the development of hyperglycemia and preserved pancreatic function. Elevation of lactate ( approximately 1.5-fold) occurred after 4 weeks of treatment, as did the apparent shunting of precursors into triglycerides. Profound glucose lowering ( approximately 44%) and similar metabolic ramifications were associated with 2-week intervention therapy of 10-week-old male ZDF rats. In high-fat diet-fed female ZDF rats, MB06322 treatment for 2 weeks fully attenuated hyperglycemia without evidence of metabolic perturbation other than a modest reduction in glycogen stores ( approximately 20%). The studies confirm that excessive gluconeogenesis plays an integral role in the pathophysiology of type 2 diabetes and suggest that FBPase inhibitors may provide a future treatment option.

An Efficient and Regiospecific Strategy to N7-Substituted Purines and Its Application to a Library of Trisubstituted Purines

A regiospecific strategy for the preparation of N(7)-substituted purines in an efficient manner was devised. This approach to 6,7,8-trisubstituted purines relies on the cyclization reactions of suitably substituted pyrimidines (1) with either a carboxylic acid or an aldehyde. The method development for the five-step synthetic strategy outlined here was completed using 5-amino-4,6-dichloropyrimidine (4) as the starting material. The utility of this methodology was demonstrated through the preparation of a 40-membered library of 6,7,8-trisubstituted purines (3) in good yields and high purity.

Design and Synthesis of a Tetracyclic Pyrimidine-Fused Benzodiazepine Library

Method development for a heterocyclic library which entails novel scaffolds of benzodiazepines fused with various heterocycles, such as pyrimidines, indolines, and tetrahydroquinolines, was accomplished. The new synthetic strategy is based on an electrophilic cyclization reaction involving an iminium intermediate formed by the corresponding aminopyrimidine with a carbonyl compound to give the desired heterocycles in high yields. Subsequent replacement of the chloro group in the resulted structures with a nucleophile, such as boronic acids, amines, alcohols and thiols, led to a library of privileged compounds with up to eight accessible diversity points.