Current Medicinal Chemistry - Volume 17, Issue 19, 2010

Pigment epithelium-derived factor (PEDF) is a glycoprotein that belongs to the superfamily of serine protease inhibitors with a potent neuronal differentiating activity. Recently, PEDF is found to be a highly effective inhibitor of pathological angiogenesis in both cell culture and animal models. Further, it has also been shown to have neuroprotective, anti-oxidative and anti-inflammatory properties, any of which could potentially be exploited as a therapeutic option for the treatment of cardiometabolic disorders, neurodegenerative disease and cancers. However, as far as we know, there are few comprehensive reviews to deal with the involvement of PEDF in hepatic disease. This article summarizes the pathophysiological role of PEDF for various liver diseases such as hepatic insulin resistance, alcoholic and nonalcoholic liver disease, and hepatocellular carcinoma, and its potential therapeutic implication in these devastating disorders.

A fundamental step in preclinical drug development is the computation of quantitative structure-activity relationship (QSAR) models, i.e. models that link chemical features of compounds with activities towards a target macromolecule associated with the initiation or progression of a disease. QSAR models are computed by combining information on the physicochemical and structural features of a library of congeneric compounds, typically assembled from two or more building blocks, and biological data from one or more in vitro assays. Since the models provide information on features affecting the compounds' biological activity they can be used as guides for further optimization. However, in order for a QSAR model to be relevant to the targeted disease, and drug development in general, the compound library used must contain molecules with balanced variation of the features spanning the chemical space believed to be important for interaction with the biological target. In addition, the assays used must be robust and deliver high quality data that are directly related to the function of the biological target and the associated disease state. In this review, we discuss and exemplify the concept of statistical molecular design (SMD) in the selection of building blocks and final synthetic targets (i.e. compounds to synthesize) to generate information-rich, balanced libraries for biological testing and computation of QSAR models.

Among several types of DNA lesions, the DNA double strand breaks (DSBs) are one of the most deleterious and harmful. Mammalian cells mount a coordinated response to DSBs with the aim of appropriately repair the DNA damage. Indeed, failure of the DNA damage response (DDR) can lead to the development of cancer-prone genetic diseases. The identification and development of drugs targeting proteins involved in the DDR is even more investigated, as it gives the possibility to specifically target cancer cells. Indeed, the administration of DNA repair inhibitors could be combined with chemo- and radiotherapy, thus improving the eradication of tumor cells. Here, we provide an overview about DSBs damage response, focusing on the role of the DSBs repair mechanisms, of chromatin modifications, and of the cancer susceptibility gene BRCA1 which plays a multifunctional role in controlling genome integrity. Moreover, the most investigated DSBs enzyme inhibitors tested as potential therapeutic agents for anti-cancer therapy are reported.

Background: Proprotein Convertases (PCs) or Proprotein Convertase Subtilisin/Kexins (PCSKs) belong to a family of calcium-dependent endoproteases that are structurally related to bacterial subtilisin and yeast kexin. These enzymes play major roles in the processing of inactive precursor proteins producing their bioactive mature forms that are implicated in a wide variety of diseases including cancer, viral and bacterial infections. As a result, PCs are major targets for intervention of these diseases. Objective: Our objective in this study is to find non-peptide inhibitors of PC-enzymes from a potential natural source. Results: Herein we describe several natural flavonoid compounds as inhibitors of PC-enzymes including furin, a key member. These compounds were isolated from the medicinal plant Oroxylum indicum, fully characterized and tested in vitro for their PC-inhibitory property against the fluorogenic peptide substrate, Boc-RVRR-MCA (Boc = tert-butyloxy carbonyl, MCA = 4-Methyl coumarin7-amide). The measured Ki and IC50 were found to be in low μM ranges. A comparative analysis of inhibition against furin, PC4, PC5 and PC7 suggested a partial selectivity towards PC4. These flavonoids also blocked efficiently the PC4-mediated processing of a fluorogenic peptide derived from the processing site of its substrate, pro-Insulin Growth Factor-1 (proIGF-1). This anti-protease activity may provide a rationale for the observed anticancer and anti-HIV properties of some of these flavonoid compounds. This is the first demonstration of anti-PC activity of flavonoid compounds.

Protein C is a vitamin K-dependent anticoagulant serine protease zymogen in plasma which upon activation by the thrombin-thrombomodulin complex down-regulates the coagulation cascade by degrading cofactors Va and VIIIa by limited proteolysis. In addition to its anticoagulant function, activated protein C (APC) also binds to endothelial protein C receptor (EPCR) in lipid-rafts/caveolar compartments to activate protease- activated receptor 1 (PAR-1) thereby eliciting antiinflammatory and cytoprotective signaling responses in endothelial cells. These properties have led to FDA approval of recombinant APC as a therapeutic drug for severe sepsis. The mechanism by which APC selects its substrates in the anticoagulant and antiinflammatory pathways is not well understood. Recent structural and mutagenesis data have indicated that basic residues of three exposed surface loops known as 39-loop (Lys-37, Lys-38, and Lys-39), 60-loop (Lys-62, Lys- 63, and Arg-67), and 70-80-loop (Arg-74, Arg-75, and Lys-78) (chymotrypsin numbering) constitute an anion binding exosite in APC that interacts with the procoagulant cofactors Va and VIIIa in the anticoagulant pathway. Furthermore, two negatively charged residues on the opposite side of the active-site of APC on a helical structure have been demonstrated to determine the specificity of the PAR-1 recognition in the cytoprotective pathway. This article will review the mechanism by which APC exerts its proteolytic function in two physiologically inter-related pathways and how the structure- function insights into determinants of the specificity of APC interaction with its substrates in two pathways can be utilized to tinker with the structure of the molecule to obtain APC derivatives with potentially improved therapeutic profiles.

During the last 20 years, numerous clinical trials have examined the therapeutic usefulness of melatonin in different fields of medicine. The objective of this article is to review, in depth, the science regarding clinical trials performed to date. The efficacy of melatonin has been assessed as a treatment of ocular diseases, blood diseases, gastrointestinal tract diseases, cardiovascular diseases, diabetes, rheumatoid arthritis, fibromyalgia, chronic fatigue syndrome, infectious diseases, neurological diseases, sleep disturbances, aging and depression. Melatonin has been also used as a complementary treatment in anaesthesia, hemodialysis, in vitro fertilization and neonatal care. The conclusion of the current review is that the use of melatonin as an adjuvant therapy seems to be well founded for macular degeneration, glaucoma, protection of the gastric mucosa, irritable bowel syndrome, arterial hypertension, diabetes, side effects of chemotherapy and radiation in cancer patients or hemodialysis in patients with renal insufficiency and, especially, for sleep disorders of circadian etiology (jet lag, delayed sleep phase syndrome, sleep deterioration associated with aging, etc.) as well as in those related with neurological degenerative diseases (Alzheimer, etc.,) or Smith-Magenis syndrome. The utility of melatonin in anesthetic procedures has been also confirmed. More clinical studies are required to clarify whether, as the preliminary data suggest, melatonin is useful for treatment of fibromyalgia, chronic fatigue syndrome, infectious diseases, neoplasias or neonatal care. Preliminary data regarding the utility of melatonin in the treatment of ulcerative colitis, Crohn's disease, rheumatoid arthritis are either ambiguous or negative. Although in a few cases melatonin seems to aggravate some conditions, the vast majority of studies document the very low toxicity of melatonin over a wide range of doses.

Objectives: Our aim was to evaluate the diagnostic value of pleural fluid TNF-α and IL-10 levels in tuberculous pleural effusion (TPE) and compare with that of ADA. Material and Methods: 70 patients were enrolled in the study. Fourteen patients had TPE, 19 patients malignant pleural effusion (MPE), 18 patients complicated parapneumonic effusion (PPE) and 19 patients had transudative pleural effusion. Results: The pleural fluid TNF-α levels were significantly higher in TPE than MPE and transudates. There was no significant difference in pleural fluid IL-10 levels between groups. Among exudative effusions, TNF-α was significantly higher in tuberculous group, while there was no difference in IL-10 levels between tuberculous and nontuberculous group. The pleural fluid ADA levels were significantly higher in TPE than other groups. ROC analysis was performed and the optimal cut-off points of TNF-α and ADA were 13.3 pg/mL and 41.5 U/L, respectively. The sensitivity of TNF-α was 71% and specificity was 66% in the diagnosis of TPE. In contrast, the sensitivity and specifity of ADA was 78% and 86% respectively. Conclusion: TNF-α is a useful marker in the diagnosis of TPE and IL-10 has no diagnostic value. However, the sensitivity and specifity of TNF-α is lower than that of ADA.