Cardiovascular & Hematological Agents in Medicinal Chemistry - Volume 10, Issue 3, 2012

Cardiovascular complications are the leading cause of death and morbidity in patients with diabetes; accounting for around 7 out of 10 of all causes of death in this population. Returning patients to normoglycaemia alone has been shown to have little effect on cardiovascular end points, therefore new therapies and strategies are required in order to reduce the incidence and improve outcomes of cardiovascular disease in diabetic individuals. The metabolic enzyme AMP-activated protein kinase (AMPK) has emerged in recent years as an attractive potential therapeutic target for diabetic vascular disease, and studies have shown improved endothelial and smooth muscle cell function following AMPK activation. Additionally, improved lipid profiles, reduced hypertrophic cardiomyocyte growth and protection from cardiac ischaemia-reperfusion injury have also been observed as beneficial outcomes of AMPK therapy. In this review we will discuss in detail the potential downstream targets of AMPK activation in the cardiovascular system. We will also provide an overview of long-known and newly discovered direct and indirect AMPK activators, as well as novel synthesised AMPK-activating compounds, which will highlight the potential for further exploiting AMPK in a therapeutic context for cardiovascular disease in diabetes.

The incidence of cardiovascular diseases remains high in diabetic patients despite the optimization of blood glucose control and the therapeutic management of risk factors. One emerging promising pharmacological approach that may help to prevent the development of diabetic cardiovascular complications is to improve endothelial function through the restoration of the bioavailability of epoxyeicosatrienoic acids (EETs). EETs are crucial eicosanoid signaling molecules synthesized by cytochrome P450 epoxygenases in the vascular endothelium and in pancreatic islets. EETs promote vasodilatation and display attractive anti-inflammatory and anti-aggregating actions together with potent effects on insulin release and sensitivity. In animal models of insulin-resistance and diabetes, a decrease in EET availability has been reported, and is a deleterious mechanism that probably contributes to multiple metabolic, cardiovascular and renal disorders in this setting. Moreover, increasing experimental evidence suggest that the use of soluble epoxide hydrolase (sEH) inhibitors, which prevent EET degradation, is a promising pharmacological approach to prevent endothelial dysfunction and to protect against target organ damage in metabolic diseases. This review presents evidence that the EET pathway is disturbed from the early stages of metabolic diseases, and analyzes the potential contribution of EETs impairment to the progression of cardiovascular diseases associated with diabetes. Pathophysiological and therapeutic perspectives are thereafter discussed, including the necessity to demonstrate the role of EET pathway alterations in endothelial dysfunction associated with diabetes in human, and the interest of sEH inhibitors to prevent the development of diabetic cardiovascular complications, with the expected result of improving patients' health.

Mitochondrial oxidative stress is a major etiological factor in the development of cardiovascular disease associated with type 2 diabetes. Hyperglycemia and insulin resistance contribute to the generation of excessive reactive oxygen species (ROS) which have damaging effects on various macromolecules within the mitochondria, leading to mitochondrial dysfunction. Mitochondrial damage within the endothelial cells lining the vasculature causes endothelial dysfunction, a critical event in atherosclerosis. In diabetes, deficiency of the antioxidant defense network prevents the generation of a robust response to counter the damaging effects of ROS. Since oxidative stress is the underlying factor for the damages inflicted by hyperglycemia, a logical therapeutic approach is to use antioxidants to quench ROS produced within the mitochondria. Lipoic acid (LA) is a potent mitochondrial antioxidant and an essential cofactor of α-ketoacid dehydrogenases. Clinical studies testing the effects of LA supplementation in diabetes and its complications have yielded promising results, especially with regard to management of diabetic neuropathy. Endogenously, LA is synthesized within the mitochondria by the enzyme, Lipoic acid synthase (LASY). This review describes a novel therapeutic approach which is aimed at increasing expression of LASY to enhance mitochondrial levels of LA. Such a strategy has the potential of improving mitochondrial function, reducing inflammation and insulin resistance, translating to better metabolic control in diabetes and preventing cardiovascular disease.

Cardiovascular disease represents the major cause of morbidity and mortality in patients with diabetes mellitus. Studies by us and others have implicated increased flux via aldose reductase (AR) as a key player in mediating diabetic complications, including cardiovascular complications. Data suggest that increased flux via AR in diabetics perpetuates increased injury after myocardial infarction, accelerates atherosclerotic lesion formation, and promotes restenosis via multiple mechanisms. Most importantly, studies have shown that increased generation of reactive oxygen species due to flux via AR has been a common feature in animal models of diabetic cardiovascular disease. Taken together, these considerations place AR in the center of biochemical and molecular stresses that characterize the cardiovascular complications of diabetes. Stopping AR-dependent signaling may hold the key to interrupting cycles of cellular perturbation and tissue damage in diabetic cardiovascular complications.

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity among diabetics. Vitamin D deficiency is very common all over the world. Over last few years, vitamin D has been considered as an important regulating factor for cardiovascular health. Metabolic syndrome and obesity are highly prevalent in vitamin D deficient people. In fact all components of metabolic syndrome are affected by vitamin D. Vitamin D regulates insulin secretion and its action. It has also some controlling effect on Renin-Angiotensin system, which influences cardiomyocytes positively. Vitamin D plays a role in vascular system too. This vitamin reduces vascular calcification and inflammatory processes. Given the important role of Vitamin D in cardiovascular health, this review focuses on the impacts of vitamin D on the various CVD risk factors.

Naturally occurring plant alkaloids, in particular those identified from herbal medicines, are finding therapeutic use. Heart diseases can be well managed with specific formulations of herbal medicines. The combined action of multiple constituents of herbal medicines works with therapeutic benefits in humans. The established formulations of Traditional Chinese medicines show efficacy in treatment of diseases. However, individual herbal principles seldom show pharmacological activity. Nevertheless, some of the active alkaloids and terpenoids from medicinal herbs have been identified. The pharmacological activities of these herbal compounds have been studied. These active constituents of herbal medicine are also used in nutrient supplements, but the modes of action of the active component remain sketchy. The present review describes the recent development of those active principles from herbal medicines as cardiovascular agents. The study will provide insights into herbal medicines for drug development for the treatment of cardiovascular disease.

The no-reflow phenomenon (NRP) is defined as the lack of adequate myocardial tissue perfusion despite a patent epicardial coronary artery. The incidence of NRP varies between 2-5% of elective percutaneous coronary interventions (PCI) and 30% in primary PCI. Clinically, it is an independent predictor of myocardial infarction, in-hospital mortality, and long-term mortality. It may be categorized in interventional (after PCI, especially in saphenous venous grafts) or reperfusion NRP (after re-opening of a totally occluded coronary artery, usually during primary PCI or thrombolysis). There are many physiopathological factors implicated: distal microembolization, interstitial and intracellular edema, coronary spasm and capillary plugging. Although reperfusion and no reflow is a field of intense research, no single mechanical or pharmacological therapy has demonstrated a clear efficacy against NRP, probably due to its multifactorial nature. Once established, the treatment of NRP is based on vasodilators like adenosine, verapamil, nitroprusside or nicorandil. However, the efficacy of these measures is poor, so every effort should be made to prevent the apparition of NRP. The objective of this report is to provide an update of the pharmacological armamentarium available for the prevention and treatment of NRP, and suggest a systematic approach of the management of NRP according to the different possible clinical scenarios.

In endothelium, calcium (Ca2+) influx through plasma membrane Ca2+-permeable channels plays a fundamental role in several physiological functions and in the pathogenesis of cardiovascular disease. Current knowledge on the influence of Ca2+ influx in signaling events associated to endothelial dysfunction has grown significantly over recent years, particularly after identification of members of the Transient Receptor Potential Canonical (TRPC) family of channel forming proteins as prominent mediators of Ca2+ entry in endothelial cells. Among TRPC members TRPC3 has been at the center of many of these physiopathological processes. Progress in elucidating the mechanism/s underlying regulation of endothelial TRPC3 and characterization of signaling events downstream TRPC3 activation are of most importance to fully appreciate the role of this peculiar cation channel in cardiovascular disease and its potential use as a therapeutic target. In this updated review we focus on TRPC3 channels, revising and discussing current knowledge on channel expression and regulation in endothelium and the roles of TRPC3 in cardiovascular disease in relation to endothelial dysfunction.