Current Drug Discovery Technologies - Volume 12, Issue 2, 2015

Human Immunodeficiency Virus (HIV) is the viral agent of Acquired Immunodeficiency Syndrome (AIDS), and at present, there is no effective vaccine against HIV. Reverse Transcriptase (RT) is an essential enzyme for retroviral replication, such as HIV as well as for other RNA infectious viruses like Human T lymphocyte virus. Polymerases act in DNA metabolism, modulating different processes like mitosis, damage repair, transcription and replication. It has been widely documented that DNA Polymerases and Reverse Transcriptases serve as molecular targets for antiviral and antitumoral chemotherapy. Coumarins are oxygen heterocycles that are widely distributed throughout the plant kingdom. Natural coumarins have attraction due to their bioactive properties such as tumor promotion inhibitory effects, and anti-HIV activity. Coumarins and derivates exhibit potent inhibitory effects on HIV-1 replication in lymphocytes and compounds isolated from Calophyllum inophyllum or DCK derivates showed inhibitory activity against human RT. Furthermore, natural isocoumarins isolated from cultures of fungi or hydroxycoumarins were able to inhibit human DNA polymerase. In view of their importance as drugs and biologically active natural products, and their medicinally useful properties, extensive studies have been carried out on the synthesis of coumarin compounds in recent years. Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs), a class of antiretroviral chemotherapeutic agents, act by binding to an allosteric pocket showing, generally, low toxicity. This work tries to summarize the investigation about natural and synthetic coumarins with the ability to inhibit key enzymes that play a crucial role in DNA metabolism and their possible application as antiretroviral and antitumoral agents.

Medicinal plants are known for their many advantages, including the ability to treat diseases such as cancer. Nigella sativa and its active constituent thymoquinone (TQ) have long been used in traditional medicine for treating various conditions related to the respiratory and gastrointestinal systems as well as breast, colorectal, gastric, hepatic, pancreatic cancers and leukemia. TQ has been documented to possess chemo-preventive and chemotherapeutic antitumor effects. Studies reported that TQ inhibits the growth of cancer cells in animal models and culture tumors. This review summarizes the in vitro and in vivo possible mechanisms of TQ anticancer effect.

Introduction: Dyslipidemia is increased fasting level of total cholesterol (TC), LDL cholesterol (LDL-C), and triglycerides (TG), along with decreased levels of HDL cholesterol (HDL-C). Owing to effect on the cardiovascular system and increased chances of metabolic diseases, it is needed to review novel under development drugs and new approaches in drug discovery for dyslipidemia. Areas Covered: This article reviews all phases I to IV clinical trials and preclinical trials with results associated with novel treatment of dyslipidemia. Drug discovery for dyslipidemia, toward newer targets has been addressed. Findings: Statins are, currently available, best choice of drugs for treating dyslipidemia and coronary diseases. In addition to this, lipid lowering drugs support treatment to a great extent, either as monotherapy or in combinations with other groups. Pravastatin used in combination with cholesteryl ester, transfers protein inhibitors (CETP) to produce efficient results. Peroxisome proliferator-activated receptor agonists (PPAR) like muraglitazar, aleglitazar and tesaglitazar are PPAR α/γ receptor agonist, dual in action performs better in phase 3 clinical study and reduces renal and cardiovascular events. By targeting both receptors, a better treatment for cardiovascular and diabetic problems can be achieved. Proprotein convertase subtilisin/kexin type 9 (PCSK-9) inhibitors like humanized monoclonal antibodies, are newly discovered inhibitors that reduce the risk of cardiovascular diseases. During the past few years, nucleic acid–based therapies targeting lipid and lipoprotein metabolism, such as microsomal TG transfer protein (MTP) may be a promising therapeutic approach to treat vascular diseases. Gene regulating transcription factors involved in bile acids and cholesterol metabolism can be controlled by FXR agonists in dyslipidemia. To overcome these drawbacks, many thyroid hormone analogues have been developed to lower down cholesterol level by targeting specifically thyroid hormone β receptors abundantly present in the liver without severe side effects. Virtual screening, an important tool in screening databases of the lead compounds, provides a good platform to access new compounds. In this review, examples of novel FXR modulators, thyromimetic agents, cholesterol absorption inhibitors and other new anti hyperlipidemia scaffolds have been addressed.

Identification of active ligands using computational methods is a challenging task. For example, molecular docking, pharmacophore modeling, and three dimensional quantitative structure-activity relationship models (3D-QSAR) are widely used methods to identify novel small molecules. However, all these methods have, in addition to advantages, also significant pitfalls. The aim of this study was to compare some commonly used computational methods to estimate their ability to separate highly active PDE4B-inhibitors from less active and inactive ones. Here, 152 molecules with pIC50-range of 3.4-10.5, originating from six original studies were used. High correlation coefficients by using docking, docking with postprocessing with molecular mechanics-generalized Born-surface area -method (MMGBSA), pharmacophore modeling, and 3D-QSAR were obtained. These results are well in line with earlier studies done with similar methods, and suggest that computational methods could be successfully used to identify novel PDE4B-inhibitors, especially if using multiple methods together.