Mini Reviews in Medicinal Chemistry - Volume 10, Issue 13, 2010

The chemistry of pyrazoloquinolines is well established. This system has proved to be a very attractive scaffold for medicinal chemist in the recent past. Pyrazoloquinolines were extensively studied as bioactive compounds and are known to possess remarkable biological activities such as anti-cancer, anti-anxiety, anti-inflammatory, anti-asthmatic, cerebroprotective and anti-viral among others. For many of the activities the molecular mode of action is known. Recent research efforts have also highlighted the ability of agents based on pyrazoloquinoline skeleton to modulate adenosine A3 receptors and the phosphodiesterase receptors. In this review the developments in the medicinal chemistry of pyrazoloquinolines is discussed.

Inhibitors of thymidylate synthase (TS) play an essential role in the pharmacological management of several tumors. Two antifolates, Raltitrexed and Pemetrexed, are licensed anticancer drugs, with Pemetrexed, unlike Raltitrexed, undergoing further intense clinical development. Other antifolate TS inhibitors, recently/currently tested in clinical studies, that show encouraging anticancer activities are Plevitrexed, GW7904L and Nolatrexed. A new prospect among antifolates, demonstrating a very desirable pattern of pharmacological properties, is BGC 945 that showed promising antitumor activities and has been nominated for clinical development. In this paper, apart from reviewing their biochemical and pharmacological properties, up-to-date characteristics of clinical development of all the mentioned agents are presented. In addition, trends and perspectives for developing improved antifolate inhibitors of TS and future drugs are discussed. Drug resistance is the main barrier to more effective treatment of cancers with antifolates; therefore, mechanisms of antifolate resistance and currently applied approaches to overcome it are also pointed out in the review.

Chromatography technology has been widely applied in various aspects of the pharmacy research on traditional Chinese medicine (TCM). This paper reviews literatures, published in the past decades, on the separation of active component from TCM using chromatography technology. Ultra-performance liquid chromatography (UPLC), high-speed counter-current chromatography (HSCCC), rapid resolution liquid chromatography (RRLC), supercritical fluid chromatography (SFC), affinity chromatography (AC), and bio-chromatography (BC) are introduced in detail. Compared to high performance of high-performance liquid chromatography (HPLC), analysis time and solvent loss are significantly reduced by UPLC with increase in resolution and sensitivity. Some ingredients from nature derived drugs can be separated more completely by HSCCC, which has remarkable characteristics such as low cost, simple operation and no pollution. Trace components from complex systems can be selectively and efficiently separated and purified by AC, This feature makes it effective in isolation and identification of active components of Chinese herbs. Interference of some impurities could be excluded by BC. Active ingredients that are difficult to be separated by normal method can be acquired by SFC. Currently, application of novel chromatography techniques in TCM is still in the exploratory stage and many problems, such as preparation of stationary phase and detection, need to be solved.

Alkaloids are a group of natural products with unmatched chemical diversity and biological relevance forming potential quality pools in drug screening. The molecular aspects of their interaction with many cellular macromolecules like DNA, RNA and proteins are being currently investigated in order to evolve the structure activity relationship. Isoquinolines constitute an important group of alkaloids. They have extensive utility in cancer therapy and a large volume of data is now emerging in the literature on their mode, mechanism and specificity of binding to DNA. Thermodynamic characterization of the binding of these alkaloids to DNA may offer key insights into the molecular aspects that drive complex formation and these data can provide valuable information about the balance of driving forces. Various thermal techniques have been conveniently used for this purpose and modern calorimetric instrumentation provides direct and quick estimation of thermodynamic parameters. Thermal melting studies and calorimetric techniques like isothermal titration calorimetry and differential scanning calorimetry have further advanced the field by providing authentic, reliable and sensitive data on various aspects of temperature dependent structural analysis of the interaction. In this review we present the application of various thermal techniques, viz. isothermal titration calorimetry, differential scanning calorimetry and optical melting studies in the characterization of drug-DNA interactions with particular emphasis on isoquinoline alkaloid- DNA interaction.

This review discusses the most active natural and synthetic curarelike compounds demonstrating myorelaxants activity. The data are grouped according to chemical structures, namely, quinoline and isoquinoline myorelaxants, myorelaxants with saturated heterocyclic or alkylamine fragments, myorelaxants with a steroid framework, natural and synthetic alkaloid myorelaxants.

Histone Deacetylases (HDACs) enzymes are critical in regulating gene expression and transcription. They also play a fundamental role in regulating cellular activities such as cell proliferation, survival and differentiation. Inhibition of HDACs has generated many fascinating results including a new strategy in human cancer therapy. HDAC Inhibitors (HDACIs) like SAHA, TSA are emerging as new promising drugs for various anti-inflammatory and CNS-disorders. This review, along with chemical classification, emphasizes on the therapeutic potential of various HDACIs against different diseases.

CCR5 (C-C chemokine receptor type 5) is a chemokine receptor that has been identified as a major HIV coreceptor in viral entry and therefore is a highly validated target for the development of new anti-HIV drugs. Here, we discuss the insights gained so far relevant to the development of small-molecule CCR5 inhibitors for the treatment of HIV, and highlight small-molecule CCR5 inhibitors that are currently under preclinical and clinical trials.