Current Medicinal Chemistry - Volume 18, Issue 28, 2011

The azetidinone core-structure offers a unique approach to the design and synthesis of new derivatives with unique biological properties. During the last two decades researches convincingly demonstrated that the prospect of structural modifications of monocyclic β-lactams with specific substituents is an effective procedure for the detection and improvement of important pharmacological effects different from antibacterial activity. As a matter of fact, new β-lactam compounds demonstrated biological activity as inhibitors of a wide range of enzymes. This review reports the latest developments on monocyclic β-lactam compounds activity as anticancer, antitubercular, HFAAH inhibitors, HDAC inhibitors, anti-inflammatory drugs (tryptase inhibitors), Cathepsin K inhibitors, and vasopressin inhibitors. We attempted to highlight the intertwined relationships between structural features and biological activities, by analysing groups anchored on the three positions of the azetidinone ring as sources of molecular diversity

The development of new treatments for mood disorders, as anxiety and depression, is based on identification of neural substrates and the mechanisms underlying their etiology and pathophysiology. The heterogeneity of mood disorders indicates that its origin may lie in dysfunction of multiple brain regions (amygdala, nucleus accumbens, hippocampus, prefrontal cortex and cingulate cortex). The hippocampus of patients with depression show signs of atrophy and neuronal loss. This suggests the contribute of new neurons to the biology of mood disorders that is still under debate. The production of new neurons, referred to as neurogenesis, occurs throughout life in discrete brain areas such as the dentate gyrus (DG) of the hippocampus and the subventricular zone/olfactory bulb. Findings describing that neurogenesis process in DG is increased by antidepressants, like fluoxetine, and it is required for the behavioral effect of antidepressants, lead to a new strategy and drugs for the treatment of mood disorders. As many patients display poor response to therapy, research on depression and antidepressant drugs is necessary. In this regard, focusing on neurogenesis and neuroplasticity processes in experimental models is particularly interesting for the understanding of the pathophysiology of mood disorders and should define the role of adultborn neurons in hippocampal physiology. Different classes of drugs are currently prescribed for the treatment of mood disorders. Among them selective serotonin reuptake (SSRIs), monoamine oxidase inhibitors (MAOIs), specific norepinephrine reuptake inhibitors (SNRIs) and tricyclic acids (TCA) alleviate symptoms of mood disorders. Here we review different strategies that may be adopted for impairing mood disorders and that may be further developed for innovative therapeutic approaches.

Alzheimer's disease (AD) is a highly complex and rapidly progressive neurodegenerative disorder characterized by the systemic collapse of cognitive function and formation of dense amyloid plaques and neurofibrillary tangles. AD pathology is derived from the cholinergic, amyloid and tau hypotheses, respectively. Current pharmacotherapy with known anti-cholinesterases, such as Aricept® and Exelon®, only offer symptomatic relief without any disease-modifying effects. It is now clear that in order to prevent the rapid progression of AD, new therapeutic treatments should target multiple AD pathways as opposed to the traditional “one drug, one target” approach. This review will focus on the recent advances in medicinal chemistry aimed at the development of small molecule therapies that target various AD pathological routes such as the cholinesterases (AChE and BuChE), amyloidogenic secretases (β/γ- secretase), amyloid-β aggregation, tau phosphorylation and fibrillation and metal-ion redox/reactive oxygen species (ROS). Some notable ring templates will be discussed along with their structure-activity relationship (SAR) data and their multiple modes of action. These emerging trends signal a paradigm shift in anti-AD therapies aimed at the development of multifunctional small molecules as diseasemodifying agents (DMAs).

Alcoholism is a multifarious and ongoing disease tightly related to the amount of alcohol ingested, the drinking pattern, the history of alcohol drinking and the individual features, such as some genetic traits. Worldwide alcohol is the necessary cause of approximately 60 diseases and causes circa 2.5 million deaths every year. Studies show that alcohol interacts with brain neurotransmission in a complex manner. Dopaminergic, GABAergic, serotonergic, cholinergic and glutamatergic systems are all key participants in the action of ethanol on the brain. Furthermore, several neuropeptides, such as endogenous opioid peptides, substance P, corticotropin-releasing hormone, or the appetite-regulating peptides (eg., neuropeptide Y, ghrelin or orexin) also play a role in alcohol drinking. Treatment of alcohol use disorders (AUD) is based on the application of combined approaches, including pharmacological intervention directed to different molecular targets. Results, however, are variable, not always satisfactory, and not applicable to all stages and pathologies or to all patients. New strategies focused on the control of neuropeptide performance in the brain are being explored and may be an advance in the therapy of alcoholism. The application of treatments ad personam represents a challenge that currently stimulates research in different realms, including epidemiology, psychology, chemistry, biochemistry, cell biology and pharmacology. In this review the potential value and application of ligands that modulate the function of opioid and neurokinin-1 receptors in alcoholism therapy is analyzed.

Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor responsible for cellular and tissue adaption to low oxygen tension. HIF-1, a heterodimer consisting of a constitutively expressed β subunit and an oxygen-regulated α subunit, regulates a series of genes that participate in angiogenesis, iron metabolism, glucose metabolism, and cell proliferation/survival. The activity of HIF-1 is controlled by post-translational modifications on different amino acid residues of its subunits, mainly the alpha subunit. Besides in ischemic stroke (see review [1]), emerging evidence has revealed that HIF-1 activity and expression of its down-stream genes, such as vascular endothelial growth factor and erythropoietin, are altered in a range of neurodegenerative diseases. At the same time, experimental and clinical evidence has demonstrated that regulating HIF-1 might ameliorate the cellular and tissue damage in the neurodegenerative diseases. These new findings suggest HIF-1 as a potential medicinal target for the neurodegenerative diseases. This review focuses on HIF-1α protein modifications and HIF-1's potential neuroprotective roles in Alzheimer's (AD), Parkinson's (PD), Huntington's diseases (HD), and amyotrophic lateral sclerosis (ALS).

Neuropathic pain is a kind of pain related with functional abnormality of neurons. Despite large progress in pharmacotherapy, neuropathic pain is still considered an unmet need. Nowadays, there are few drugs registered for this condition, such as pregabalin, gabapentin, duloxetine, carbamazepine, and lidocaine. Among them, pregabalin, gabapentin and carbamazepine are well known antiepileptic drugs. Among the group of new antiepileptic drugs, which are addressed to 1% of human world population suffering from seizures, it turned out that 30% of the seizures resistant to pharmacotherapy has not enough market to justify the costs of drug development. Therefore, it is already a phenomenon that researchers turn their projects toward a larger market, related with possible similar mechanism. Anticonvulsant mechanism of action is in the first place among primary indications for drugs revealing potential analgesic activity. Therefore, many drug candidates for epilepsy, still in preclinical stage, are being evaluated for activity in neuropathic pain. This review is focusing on antiepileptic drugs, which are evaluated for their analgesic activity in major tests related with neuropathic pain. Relation between structure, mechanism of action and result in tests such as the Chung model (spinal nerve ligation SNL), the Bennett model (chronic constriction injury of sciatic nerve CCI) and other tests are considered. The first examples are carbamazepine, gabapentin, and lacosamide as drugs well established in epilepsy market as well as drug candidates such as valnoctamide, and other valproic acid derivatives, novel biphenyl pyrazole derivatives, etc. Moreover, clinical efficacy related with listed animal models has been discussed.

Major depression is a common mood disorder that affects overall health; currently, almost all of the available antidepressants have the same core mechanisms of action through promotion of serotonin or noradrenaline function in the brain. The major limitation of today's antidepressants is that chronic treatment (3 - 6 weeks) is required before a therapeutic benefit is achieved. More effective and faster treatments for depression are needed. Adult neurogenesis is the birth of new neurons, which continues postnatally and into adulthood in the brains of multiple species, including humans. Recently, a large body of evidence gives rise to the hypothesis that the antidepressant effect and increases in adult hippocampal neurogenesis may be causally related. Multiple classes of antidepressants increase hippocampal neurogenesis in a chronic, but not acute, time course. This effect corresponds to the therapeutic time lag associated with current antidepressants. In addition, antidepressants are not effective in behavioral models of depression when hippocampal neurogenesis is prevented. This review examines the current understanding of adult neurogenesis and the evidence of the causal relationship between antidepressant effects and adult hippocampal neurogenesis. We also present our recent research findings, which support a promising strategy for enhancing adult hippocampal neurogenesis that might be a new approach for the development of novel antidepressants.

Checkpoint kinase 2 is a serine/threonine protein which functions as an important transducer in apoptosis or DNA repair following activation by DNA damage. Inhibition of checkpoint kinase 2 is thought to sensitize p53-mutated or p53-deficient cancerous cells but protect normal tissue following DNA-damage caused by ionizing radiation or chemotherapeutic agents. The development of checkpoint kinase inhibitors for the treatment of cancer has therefore been a major objective in drug discovery over the past decade. Several inhibitors have been co-crystallized in the active site of checkpoint kinase 2 revealing important features of effective inhibitors. Some of these inhibitors have entered clinical trials in the last decade. This review describes and discusses the most recent inhibitors of checkpoint kinase 2 as reported in the literature, including an evaluation of biological activity.

Hepatocellular carcinoma (HCC) is a major cause of cancer mortality worldwide. Unresectable or metastatic HCC has a poor prognosis, and systemic cytotoxic chemotherapy has failed to show a substantial benefit for patients with HCC. However, there has been increasing interest in developing novel molecularly targeted agents in HCC due to the accumulation of knowledge of cell signaling and molecular carcinogenesis. Furthermore, some of these agents have proven to be efficacious in other traditionally challenging carcinomas, such as renal cell carcinoma. Recently, a phase III, randomized, placebo-controlled trial demonstrated that sorafenib, an oral multikinase inhibitor of the vascular endothelial growth factor receptor and Ras kinase, improves overall survival (OS) in patients with advanced HCC. This seminal study described the first agent to improve OS in HCC and began a new era of molecule-targeted cancer therapies. Currently, many novel molecularly targeted agents are under evaluation in clinical trials. In this review, we comprehensively summarize the molecular pathogenesis, targets, and signal transduction pathways involved in HCC. We also detail the current status of molecularly targeted agents that are under clinical development in advanced HCC, including the mechanisms of action of these agents.

Topoisomerase I (Top1) represents an important target of active interest in developing novel anticancer agents. Camptothecin derivatives are the only class of clinically approved Top1 inhibitors and show potent efficacy in anticancer therapy. However, there are also several major limitations for them, such as poor chemical stability, drug resistance, long infusions and side effects. To overcome the drawbacks of the camptothecins, the discovery of non-camptothecin Top1 inhibitors has recently emerged as a promising field to find better antitumor agents. Non-camptothecin Top1 inhibitors are expected to possess better chemical stability, different therapeutic activities and antitumor spectrum, improved pharmacokinetics and lower toxicity. This review focuses on various strategies that were used in the discovery of non-camptothecin Top1 inhibitors. In particular, the chemical scaffolds, structure-activity relationships and binding modes of the newly identified non-camptothecin Top1 inhibitors are discussed in detail.

Ribosome inactivating proteins (RIPs) are toxic RNA N-glycosidases that cleave an adenine-ribose glycosidic bond at position adenine4324 with the conserved ricin/α-sarcin loop in the eukaryotic 28S ribosomal RNA. RIPs have captured the attention of botanists, biochemists, and drug discoverers, due to their diverse potent defensive activities, and inter alia, their antitumor and anti-HIV activities. Out of the 145 families of plants, Trichosanthes ranks among the top 5 genera with a good potential of use for discovery of anticancer drugs. Trichosanthin (TCS) is a famous type I RIP purified from T. kirilowii that has been known for around 30 years. Based on the results of voluminous in vitro and in vivo investigations, TCS is considered a good candidate for the treatment of HIV/AIDS and neoplasms. Here we integrate recent progress of the research on the different medicinal activities of TCS. In addition to TCS, other promising RIPs from the same species (such as TAP29 and trichoanguin), and from the same genus Trichosanthes are included. This review presents a brief panorama of the studies on Trichosanthes RIPs. Regarding the debilitating nature of AIDS and different tumors, further understanding of these multifunctional proteins is worthwhile since it may help to open a novel therapeutic window for these stubborn diseases.