Current Medicinal Chemistry - Volume 18, Issue 21, 2011

Cancer remains one of the major causes of death worldwide. The switch to pathological angiogenesis is a key process in the promotion of cancer and consequently provides several new and promising targets to anticancer therapy. Thus, antagonizing angiogenesis cuts off the tumor's oxygen and nutrition supply. This review focuses on angiogenesis inhibitors as option for cancer treatment. Modes of action, adverse effects, mechanisms of resistance as well as new developments are highlighted. One approach in angiogenesis inhibition is intermitting the VEGF (vascular endothelial growth factor) signal pathway with monoclonal antibodies. Bevacizumab is a highly specific recombinant humanized monoclonal IgG antibody targeting VEGF-A. An efficient antitumor therapy demands more specific antibodies that affect other signal molecules besides VEGF-A, which is in the focus of current research. In addition to antagonizing VEGF, there are also small molecules that inhibit receptor tyrosine kinases (RTKs). Many RTK inhibitors have been described, which exhibit different specificity profiles. The question, whether highly specific antagonists are necessary remains open, because other affected RTKs may also represent growth factor receptors that are essential for tumor growth. Therefore their inhibition may also contribute to anticancer activity. Secondary plant metabolites represent templates for the development of new small molecules. The identification of new drugs from plants has a long and successful history. There is convincing evidence for the beneficial effect of phytochemicals on cancer-related pathways, particularly with regard to anti-angiogenesis. Plant phenolics are the most important category of phytochemicals, including flavanoids. Prominent phytochemicals affecting different pathways of angiogenesis are green tea polyphenols (epigallocatechin gallate) and soy bean isoflavones (genistein).

Since Warburg proposed in 1956 that cancer cells exhibit increased glycolysis due to mitochondrial damage, numerous researchers have assumed that glycolysis is the predominant ATP supplier for cancer cell energy-dependent processes. However, chemotherapeutic strategies using glycolytic inhibitors have been unsuccessful in arresting tumor proliferation indicating that the Warburg hypothesis may not be applicable to all existing neoplasias. This review analyzes recent information on mitochondrial metabolism in several malignant neoplasias emphasizing that, although tumor cells maintain a high glycolytic rate, the principal ATP production may derive from active oxidative phosphorylation. Thus, anti-mitochondrial drug therapy may be an adequate adjuvant strategy to arrest proliferation of oxidative phosphorylation-dependent neoplasias.

The discovery of hypoxia-inducible factor-1 has led to a rapidly increasing understanding of the molecular mechanism of tumor hypoxia in the past two decades. Today it is generally accepted that HIF-1 plays a pivotal role in the cellular response to tumor hypoxia which represents a major obstacle to the success of radiotherapy and chemotherapy. Meanwhile, many details involved in the expression, accumulation and transactivation of HIF-1 have been well elucidated. Targeting HIF-1 has become a novel and efficient strategy for cancer therapy and a number of agents have been developed aiming to suppress HIF-1. This review will concisely introduce the general knowledge on the molecular biology of HIF-1 and possible targets along the HIF-1 pathway. Moreover, a number of compounds reported with anti-HIF-1 activity are included and mainly classified as direct and indirect inhibitors based on their different modes of action. While direct HIF-1 inhibitors prevent HIF-1 from transactivation, DNA binding and subsequently initiating transcriptional activity, indirect HIF-1 inhibitors generally block the transcription or translation of HIF-1α or promote the degradation of HIF-1α protein. According to different structural features, direct HIF-1 inhibitors are divided into several groups: polyamides, quinols and naphthoquinone spiroketal analogues, shikonin derivatives, epidithiodiketopiperazines, and two representative drugs: echinomycin and bortezomib. In the same way, indirect inhibitors comprise the following classes: polyphenols, benzoazaheterocycles, rapamycins, camptothecins, geldanamycins, (aryloxyacetylamino)benzoic acid analogues, 2-methoxyestradiol and analogues, hydroxamic acid compounds and others. The rest with mechanism still not so clear would also be listed and introduced, with an emphasis on the marinederived natural products. The in vitro and/or in vivo activities of these compounds and their mechanisms of HIF-1 inhibition would be discussed and the SARs of unique structural types of HIF-1 inhibitors will be briefly concluded.

A number of herbal medicines are increasingly used by cancer patients worldwide, despite the fact that the clinical evidence that supports their use to fight cancer is weak or lacking. Pharmacokinetic studies have been integrated into modern drug development, but they are generally not needed for herbal remedies. To update our knowledge in this field, this paper highlights the pharmacokinetic properties of anticancer herbal medicines and the clinical relevance. To retrieve relevant data, the authors have searched through computer-based literatures by full text search in Medline (via Pubmed), ScienceDirect, Current Contents Connect (ISI), Cochrance Library, CINAHL (EBSCO), CrossRef Search and Embase ((all from inception to May 2011). An extensive literature search indicates that there are limited data on the pharmacokinetic properties of anticancer herbal medicines in humans. There are increasing pharmacokinetic studies of anticancer herbal remedies, but these studies are mainly focused on a small number of herbal medicines including curcumin, ginseng, ginkgo, ginger and milk thistle. For an anticancer herbal medicine, the pharmacological activity is gained when the active agents or the active metabolites reach and sustain proper levels at their sites of action. Both the dose levels and pharmacokinetic processes of active herbal components in the body determine their target-site concentrations and thus the anticancer effect. In this regard, a safe and optimal use of anticancer herbal medicines requires a full understanding of their pharmacokinetic profiles. To optimize the use of anticancer herbal remedies, further studies to explore their pharmacokinetic properties and the relavance to pharmacodynamics and toxicity in humans are certainly warranted.

Sepsis remains a common cause of death in the intensive care units worldwide. However, in the last decade a significant development could be noticed in sepsis research regarding diagnostic markers that can help the physicians to recognize the disease in the early phase, which is the clue of the successful treatment of sepsis. This development provided the identification of new molecules and structures (i.e. cytokins, cell surface markers, receptors) that are potential biomarkers of sepsis in the clinical settings. Besides, the advance in the understanding of the pathophysiologic, immunologic and biochemical pathway of sepsis has made the way for assignment of new drug targets in the therapy of sepsis. This review aims to provide a summary about these novelties regarding our knowledge about sepsis published in the medical literature recently. We will describe the presumed pathophysiological role and diagnostic value of sepsis markers that are used even more widely in the clinical practice (i.e. procalcitonin, IL-6), summarize the data regarding the sepsis marker candidates that are investigated in some initial study (i.e. matrix metalloproteinases, microRNA fingerprints), and we will discuss substances that may be specific markers for certain organ failures related to sepsis (i.e. neutrophil gelatinase-derived lipocalin in acute renal failure). Furthermore, we will review the mediators of the immuno-inflammatory cascade in sepsis concerning their potential applicability as therapeutic targets in the treatment of this often lethal disease. In addition, we present some insights into the identification of genetic markers of sepsis.

Inflammation plays a crucial pathophysiological role in the entire continuum of the atherosclerotic process, from its initiation, progression, and plaque destabilization leading ultimately to an acute coronary event. Furthermore, once the clinical event has occurred, inflammation also influences the left ventricular remodelling process. Under the same paradigm, there is evidence that lymphocytes play an important role in the modulation of the inflammatory response at every level of the atherosclerotic process. Low lymphocyte count (LLC) is a common finding during the systemic inflammatory response, and clinical and animal studies suggest that LCC plays a putative role in accelerated atherosclerosis. For instance, there is recent evidence that LLC is associated with worse outcomes in patients with heart failure, chronic ischemic heart disease and acute coronary syndromes. Further indirect evidence supports the pathologic role of LLC related to the fact that 1) lymphopenia - due to a decreased count of lymphocyte T cells - normally occurs as a part of the human ageing process, and 2) increased incidence of cardiovascular events has been reported in conditions where lymphopenia is common, such as renal transplant recipients, human immunodeficiency virus infection, survivors of nuclear disasters and autoimmune diseases. The aim of the present article is to review: a) the pathophysiological mechanisms that have been proposed for the observed association between LLC and cardiovascular diseases (CVD), b) the available evidence regarding the diagnostic and prognostic role attributable to LLC in patients with CVD, and; c) the potential therapeutic implications of these findings

Natural products are regarded as vital key source of lead compounds for drug discovery due to their structural diversity and broad array of biological activities. Phenylpropanoid sucrose esters are naturally occurring compounds isolated from various plants and are structurally characterized by a sucrose core connected to one or more Ph-CH=CH-CO- moieties through an ester linkage. These compounds were extensively used in folk medicine and are found to possess many biological activities such as antitumor, antibacterial, antioxidant, antiviral, anti-inflammatory, neuro-protective and glycosidase inhibitory activities. This extensive review, which is the first of its kind on phenylpropanoid sucrose esters, aims to provide an up-to-date account of naturally occurring known phenylpropanoid sucrose esters with special focus on their sources, structures, biological and pharmacological activities.

The pharmacological action of salicylates has been historically related to their ability to inhibit cyclooxygenases, thereby blocking the synthesis of prostaglandins and thromboxane A2. On the other hand, several studies have suggested that salicylates have a multitude of cyclooxygenase-independent actions specially related with their antioxidant properties, which might contribute to the overall salutary effects of these compounds. Although salicylates are well-known antioxidants through their ability to scavenge hydroxyl radical, their antioxidant mechanisms of action have not been fully compiled and characterized. In this context, several mechanisms of action have been suggested, namely i) scavenging of hydroxyl radical and chelation of transition metals; ii) upregulation of nitric oxide; iii) increased synthesis of lipoxins; iv) inhibition of neutrophil oxidative burst; v) inhibition of NF-κB and AP-1 protein kinases; and vii) inhibiton of lectin-like oxidized LDL receptor-1. The newly discovered acetyl salicylic acid-triggered lipoxins probably play a key role in the maintenance of the oxidative stress balance. Furthermore, salicylates have shown to protect low-density lipoprotein from oxidation and elicit an inhibitory effect on the expression of lectin-like receptors on endothelial cells. This review aims to provide an overview of the various proposed antioxidant mechanisms of salicylates.

Research and development for novel substances possessing anti-infective activity have attracted considerable attention due to the escalating resistance towards conventional antibiotics. Therefore, the discovery and development of effective antimicrobial drugs with novel mechanism of action have become an insistent task for infectious diseases research programs. Triazole scaffold has been consistently rewarded as a promising versatile lead molecule with a pivotal position in modern medicinal chemistry. The literature reveals that this heterocyclic moiety has drawn attention of the chemists, pharmacologists, microbiologists and other researchers owing to its indomitable biological potential as anti-infective agents. The present communication is a cogent attempt to review the chemistry and antimicrobial activities of triazole derivatives reported in recent scientific literature. The biological profiles of these new triazole derivatives represent a fruitful matrix for further development as promising and superior anti-infective medicinal agents.