Current Medicinal Chemistry - Volume 25, Issue 14, 2018

Tolfenamic acid is one of the conventional non-steroidal anti-inflammatory drugs (NSAIDs) commonly used for the treatment of inflammation, migraines and pain. There has been a growing body of experimental evidence that tolfenamic acid possesses anti-cancer activity. However, in order to develop a therapeutic strategy using tolfenamic acid for the treatment of cancer, further research is required to highlight reliable cellular and molecular mechanisms of anti-cancer properties. Tolfenamic acid has been shown to alter the expression of several genes that represent cancer hallmarks including apoptosis, growth arrest, angiogenesis and metastasis. Recently, a couple of research groups including ours reported that tolfenamic acid targets multiple oncogenic or tumor suppressive signaling pathways in various types of cancer models. Here, we highlight multiple molecular targets responsible for the anti-cancer mechanism of tolfenamic acid and the benefits of combinational use of this drug with other anti-cancer drugs.

Since its discovery in 1983, followed by gene cloning in 1999, the histamine H3 receptor served as an outstanding target for drug discovery. The wide spectrum of possible therapeutic implications makes H3R's one of the most researched areas in the vast GPCR ligands field - started from imidazole containing ligands, through various successful imidazole replacements, with recent introduction of Wakix® to pharmaceutical market. One such replacement is piperazine moiety, a significant versatile scaffold in rational drug design for most of the GPCR ligands. Therefore, herein, we review ligands built on piperazine, as well as its seven membered analogue azepine, that target H3R's and their potential therapeutical applications, in order to elucidate the current state of the art in this vast field. Due to a high level of structural divergence among compounds described herein, we decided to divide them into groups, where the key division element was the position of nitrogen basicity decreasing moieties in (homo)piperazine ring. Paying attention to a number of published structures and their overall high biological activity, one can realize that the (homo)piperazine scaffold bids a versatile template also for histamine H3 receptor ligands. With two possible substitution sites and therefore a number of possible structural combinations, piperazine derivatives stand as one of the largest group of high importance among H3R ligands.

Mammalian carboxylesterases are key serine hydrolases that catalyze the hydrolysis of a wide variety of ester compounds in the corresponding carboxylic acids and alcohols. In human, two major carboxylesterases, CES1 and CES2, have been identified and well-studied over the past decade. CES1 inhibitors have potential applications in the treatment of hypertriglyceridaemia, obesity and type 2 diabetes, owing to that this enzyme plays prominent role in the metabolism of cholesteryl esters. CES2 plays crucial roles in the metabolic activation of many prodrugs including anticancer agents capecitabine and CPT-11. Co-administration with CES2 inhibitors may ameliorate CPT-11 associated lifethreatening diarrhea or improve the half-lives of CES2-substrate drugs. The important roles of carboxylesterases in both endogenous and xenobiotic metabolism arouse great interest in the discovery and development of potent and selective inhibitors against these enzymes. This review is focused on the application potentials and recent advances in the discovery and development of carboxylesterases inhibitors. The inhibitory capacities and inhibition mechanism of a variety of carboxylesterases inhibitors including synthetic, semi-synthetic and natural compounds are comprehensively summarized. Furthermore, the key structural features and structure-activity relationships (SARs) of different classes of CES1 and CES2 inhibitors are discussed. All information and knowledge summarized in this review will be very helpful for the medicinal chemists to design and develop more potent and highly selective carboxylesterases inhibitors for potential biomedical applications.

Background: Throughout the history of human civilizations, cancer has been a major health problem. Despite the advancements made by modern medical sciences, complete treatment or removal of cancerous cells is still a challenging task. Vinblastine, an alkaloid obtained from Catharanthus roseus (L.) G. Don is one of the prominent antineoplastic agents that is being clinically used. To improve the biological potential and reduce sideeffects of this structurally complex molecule, several related analogues have been reported. The present article reviews recently reported structurally modified vinblastine analogues and its impact on biological activity. Methods: We carried out a comprehensive database search on recently reported vinblastine analogues. Both upper (catharanthine) and lower (vindoline) structural units have been considered. The role of functional group modification on anticancer activities has been discussed. In addition, formulations based on vinblastine being considered by NIH, USA for different types of cancers have also been discussed. Results: Around fifty papers were included in the review, including computational and experimental ones. These papers were analysed to discuss the mechanism of action of the parent vinblastine molecule and their analogues. The importance of each functionalities on its anticancer activity have been discussed. This reviewed identified the potential sites of vinblastine core where modification led to improved anticancer activity. Furthermore, several new formulations have also been discussed which are under different phases of clinical trial. Conclusion: The present article highlights the importance of vinblastine in cancer chemotherapy. Literature survey confirms that it is now possible to synthesize new molecules with activity in picomolar range. Not only the periphery of the molecule, the core structure of this magical molecule can be modified to achieve next generation antineoplastic agents.

The polysaccharides in many plants are attracting worldwide attention because of their biological activities and medical properties, such as anti-viral, anti-oxidative, antichronic inflammation, anti-hypertensive, immunomodulation, and neuron-protective effects, as well as anti-tumor activity. Denodrobium species, a genus of the family orchidaceae, have been used as herbal medicines for hundreds of years in China due to their pharmacological effects. These effects include nourishing the Yin, supplementing the stomach, increasing body fluids, and clearing heat. Recently, numerous researchers have investigated possible active compounds in Denodrobium species, such as lectins, phenanthrenes, alkaloids, trigonopol A, and polysaccharides. Unlike those of other plants, the biological effects of polysaccharides in Dendrobium are a novel research field. In this review, we focus on these novel findings to give readers an overall picture of the intriguing therapeutic potential of polysaccharides in Dendrobium, especially those of the four commonly-used Denodrobium species: D. huoshanense, D. offininale, D. nobile, and D. chrysotoxum.

Combinations of antiretroviral drugs are successfully used to treat HIV-infected patients. However, drug resistance is a major problem that makes discovery of new antiretroviral drugs an ongoing priority. The ribonuclease H (RNase H) activity of the HIV-1 reverse transcriptase catalyzes the selective hydrolysis of the RNA strand of RNA:DNA heteroduplex replication intermediates, and represents an attractive unexploited target for drug development. This review reports on recent progress in the characterization of HIV-1 RNase H inhibitors from 2013 to 2016, describing their chemical structures, structureactivity relationship and binding modes. Focus is given to emerging medicinal chemistry principles and insights into the discovery and development of RNase H inhibitors.