Advances in pleural disease

Diabetes Mellitus: New Challenges and Innovative Therapies

Diabetes is a common chronic disease affecting an estimated 285 million adults worldwide. The rising incidence of diabetes, metabolic syndrome, and subsequent vascular diseases is a major public health problem in industrialized countries. This chapter summarizes current pharmacological approaches to treat diabetes mellitus and focuses on novel therapies for diabetes mellitus that are under development.

There is great potential for developing a new generation of therapeutics that offer better control of diabetes, its co-morbidities and its complications. Preclinical results are discussed for new approaches including AMPK activation, the FGF21 target, cell therapy approaches, adiponectin mimetics and novel insulin formulations. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications.

In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality of life in the near future.

Exploring key orientations at protein-protein interfaces with small molecule probes

Small molecule probes that selectively perturb protein-protein interactions (PPIs) are pivotal to biomedical science, but their discovery is challenging. We hypothesized that conformational resemblance of semirigid scaffolds expressing amino acid side-chains to PPI-interface regions could guide this process. Consequently, a data mining algorithm was developed to sample huge numbers of PPIs to find ones that match preferred conformers of a selected semirigid scaffold. Conformations of one such chemotype (1aaa; all methyl side-chains) matched several biomedically significant PPIs, including the dimerization interface of HIV-1 protease. On the basis of these observations, four molecules 1 with side-chains corresponding to the matching HIV-1 dimerization interface regions were prepared; all four inhibited HIV-1 protease via perturbation of dimerization. These data indicate this approach may inspire design of small molecule interface probes to perturb PPIs.

Oxazole phosphonic acids as fructose 1,6-bisphosphatase inhibitors with potent glucose-lowering activity

Phosphonic acid-containing oxazoles were discovered as potent inhibitors of fructose 1,6-bisphosphatase. Several oxazoles demonstrated significant glucose-lowering activity in rats after intravenous dosing.

Discovery of a series of phosphonic acid-containing thiazoles and orally bioavailable diamide prodrugs that lower glucose in diabetic animals through inhibition of fructose-1,6-bisphosphatase

Oral delivery of previously disclosed purine and benzimidazole fructose-1,6-bisphosphatase (FBPase) inhibitors via prodrugs failed, which was likely due to their high molecular weight (>600). Therefore, a smaller scaffold was desired, and a series of phosphonic acid-containing thiazoles, which exhibited high potency against human liver FBPase (IC(50) of 10-30 nM) and high selectivity relative to other 5'-adenosinemonophosphate (AMP)-binding enzymes, were discovered using a structure-guided drug design approach. The initial lead compound (30j) produced profound glucose lowering in rodent models of type 2 diabetes mellitus (T2DM) after parenteral administration. Various phosphonate prodrugs were explored without success, until a novel phosphonic diamide prodrug approach was implemented, which delivered compound 30j with good oral bioavailability (OBAV) (22-47%). Extensive lead optimization of both the thiazole FBPase inhibitors and their prodrugs culminated in the discovery of compound 35n (MB06322) as the first oral FBPase inhibitor advancing to human clinical trials as a potential treatment for T2DM.

A prodrug approach towards the development of tricyclic-based FBPase inhibitors

For the purpose of reducing the strong CYP3A4 inhibitory potency of diamide prodrug 4, cyclic prodrugs of tricyclic-based FBPase inhibitors were synthesized. Extensive SAR studies led to the discovery of pyridine-containing cyclic prodrug 20, which strongly inhibited glucose production in monkey hepatocytes and also showed weak CYP3A4 inhibitory potency.

Diabetes mellitus: new challenges and innovative therapies

Diabetes mellitus is a widespread disease prevalence and incidence of which increases worldwide. The introduction of insulin therapy represented a major breakthrough in type 1 diabetes; however, frequent hyper- and hypoglycemia seriously affects the quality of life of these patients. New therapeutic approaches, such as whole pancreas transplant or pancreatic islet transplant, stem cell, gene therapy and islets encapsulation are discussed in this review. Regarding type 2 diabetes, therapy has been based on drugs that stimulate insulin secretion (sulphonylureas and rapid-acting secretagogues), reduce hepatic glucose production (biguanides), delay digestion and absorption of intestinal carbohydrate (alpha-glucosidase inhibitors) or improve insulin action (thiazolidinediones). This review is also focused on the newer therapeutically approaches such as incretin-based therapies, bariatric surgery, stem cells and other emerging therapies that promise to further extend the options available. Gene-based therapies are among the most promising emerging alternatives to conventional treatments. Some of these therapies rely on genetic modification of non-differentiated cells to express pancreatic endocrine developmental factors, promoting differentiation of non-endocrine cells into β-cells, enabling synthesis and secretion of insulin in a glucose-regulated manner. Alternative therapies based on gene silencing using vector systems to deliver interference RNA to cells (i.e. against VEGF in diabetic retinopathy) are also a promising therapeutic option for the treatment of several diabetic complications. In conclusion, treatment of diabetes faces now a new era that is characterized by a variety of innovative therapeutic approaches that will improve quality-life and allow personalized therapy-planning in the near future.

Fructose-1,6-bisphosphatase Inhibitors. 2. Design, synthesis, and structure-activity relationship of a series of phosphonic acid containing benzimidazoles that function as 5'-adenosinemonophosphate (AMP) mimics

Efforts to enhance the inhibitory potency of the initial purine series of fructose-1,6-bisphosphatase (FBPase) inhibitors led to the discovery of a series of benzimidazole analogues with human FBPase IC(50)s < 100 nM. Inhibitor 4.4 emerged as a lead compound based on its potent inhibition of human liver FBPase (IC(50) = 55 nM) and significant glucose lowering in normal fasted rats. Intravenous administration of 4.4 to Zucker diabetic fatty rats led to rapid and robust glucose lowering, thereby providing the first evidence that FBPase inhibitors could improve glycemia in animal models of type 2 diabetes.

Structure-based drug design of tricyclic 8H-indeno[1,2-d][1,3]thiazoles as potent FBPase inhibitors

With the goal of improving metabolic stability and further enhancing FBPase inhibitory activity, a series of tricyclic 8H-indeno[1,2-d][1,3]thiazoles was designed and synthesized with the aid of structure-based drug design. Extensive SAR studies led to the discovery of 19a with an IC(50) value of 1nM against human FBPase. X-ray crystallographic studies revealed that high affinity of 19a was due to the hydrophobic interaction arising from better shape complementarity and to the hydrogen bonding network involving the side chain on the tricyclic scaffold.

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.