Mini Reviews in Medicinal Chemistry - Volume 13, Issue 9, 2013

An urgent need for the discovery of novel anticancer agents is required for the long term therapy of cancer. Large number of novel bio-active and potential anticancer agents are being used in clinical and pre-clinical trials. Although many heterocyclic compounds are already available commercially as anticancer agents, great efforts have been put to identify novel anticancer targets. This review provides an insight of the novel anticancer targets and molecules of the first and final stage of clinical and pre-clinical trials.

During the last 4 decades, intensive research has focussed on the effect of small organic molecules with antitumour activity that are able to intercalate into DNA and inhibit topoisomerase and telomerase enzymes. In this review, we describe some of the chemical and biological properties of acridine, which is a chemotherapeutic agent that has been used for cancer treatment since 1970. In addition, we summarise the progress that has been made in the development of anticancer agents based on the clinical in vivo/in vitro studies that have been conducted for 13 classes of natural and synthetic acridines.

Protein kinase B (PKB, also known as Akt) plays a critical role in the multiple cellular processes including glucose metabolism, cell growth, survival, apoptosis, transcription, and cell migration. Unregulated activation of protein kinase B is common in a significant fraction of human cancer, making enzyme an exciting new target for cancer therapy. A series of inhibitors with different mechanisms have been found, which is bound to be a positive impact on drug screening and cancer treatment. However, the development of inhibitors targeting PKB has been hampered by lacking of PKB-specific and isoform-specific inhibitors. This article describes the structure and functions of PKB as well as the recent advances in the development and biological evaluation of PKB's inhibitors. It was focused on the developments of selective small-molecule inhibitors with a well-defined, direct molecular interaction with protein kinase B, expecting to give information to design new inhibitors with high selectivity, bioavailability, and potency.

Hypoxia-inducible factor (HIF)-1α is over-expressed in hepatocellular carcinoma (HCC) and degraded by ubiquitin-proteasome pathways under normoxic conditions. Hepatocyte hypoxia enhances proliferation, angiogenesis, metastasis, chemoresistance, and radioresistance of HCC. The importance role of HIF-1α expression in HCC may improve the prognostic and therapeutic technique. This article reviews the HIF-1α expression and its gene during the rat HCC development, the level of HIF-1α expression in HCC patients, and the effect of silencing HIF-1α gene by miRNA on inhibition of HepG2 cell proliferation.

In the research of new bioactive compounds able to regulate the L-arginine metabolism, several substituted amidines were disclosed as potent and selective inhibitors of mainly three enzyme families: the nitric oxide synthase, the dimethylarginine dimethylaminohydrolase and the peptidylarginine deiminase. The present work is focused on the last five years developments in the research for amidine-based inhibitors of the mentioned enzymes and on their potential usefulness in neurodegenerative, inflammatory and autoimmune disorders.

Naturally occurring hydroxamic acid derivatives are biosynthesized by microorganisms (siderophores) and plants (benzoxazinoids). Recent developments in drug discovery have highlighted the numerous biological and pharmacological properties that the hydroxamic acid function may possess, leading to therapeutic applications. These properties may be explained by its ability to chelate metals via the presence of two oxygen atoms. Their pharmacological activities can be divided into three groups. The first concerns the ability of these hydroxamic acid derivatives to scavenge metals (particularly iron), which leads to antioxidant, antimicrobial and metal detoxification activities. The latter is largely used to treat iron overload in patients. The second group of activities is related to their ability to inhibit metallo-enzymes, which gives them a wide range of pharmacological effects: antimicrobial, anti-inflammatory and antitumor. The third group is linked to the capacity of these compounds to generate nitric oxide, which confers hypotensive activity. However, hydroxamates exhibit relatively low stability in vivo, which can be overcome by the synthesis of appropriately designed analogs. For this purpose, many different strategies have been proposed. In this review, we compare and discuss the various synthetic pathways used to obtain the most complex of them, the N-substituted hydroxamic acids. We conclude that among numerous protocols reported so far, the direct N-substitution of hydroxamic acids, the acylation of the appropriate N-O derivative and the direct oxidation of the corresponding amide allow for the synthesis of a wide range of new biologically active compounds.

Self-assembled nanocarriers attract increasing attention due to their wide application in various practical fields; among them, one of the most focused fields is drug delivery. Appropriate selection of surfactant is the basis for preparing a successful nanocarrier. Until now, from phospholipid to synthetic surfactants, many surfactants have been used to explore a suitable drug delivery vehicle for the complex in-vivo environment. Among all, bio surfactants are found to be more suitable due to their bio-origin, less-toxicity, biodegradability, cheaper rate and above all, their versatile molecular structures. This molecular property enables them to self assemble into fascinating structures. Moreover, binding DNA, enhancing pH sensitivity and stability allows novelty over their synthetic counterparts and phospholipid. This review paper focuses on the properties and applications of bio-nano-carriers for drug delivery. Micelle, microemulsion, and vesicle are the three nanocarriers which are discussed herein.

Plasmodium falciparum has a specific metabolism of particular interest because several of its features, with respect to the host human ones, are potential pharmacological targets. Such features have been more intensely investigated since 2002, thanks to the full sequencing of the genome of P. falciparum. In this review, we are interested in the potential metabolic targets of therapeutic interest identified and investigated over the past decade in terms of lead-to-drug development.

Many plants are used in traditional medicine as active agents against various effects of snake bites. Phospholipase A2 enzymes are commonly found in venoms of snakes of the Viperidae and Elaphidae families, which are their main components. This article presents an overview of inhibitors isolated from plants, which show antiophidian properties.

Naphthoflavones are synthetic flavonoids containing a conjugated phenyl group attached to A-ring of flavones. Most of their synthetic studies involved the Baker–Venkataraman rearrangement and subsequent cyclization catalyzed by acid. Based on their special structural features, these synthetic flavones exert pronounced influences on the metabolism of various endogenous and exogenous substances as well as the bioactivation of certain procarcinogens. Several mechanisms of these effects have been established, including the potent inhibition on CYP1 and aromatase, allosteric activation of CYP3A4 and/or activation of AhR. Furthermore, they have also been identified as CFTR activators, BCRP inhibitors and/or anticancer agents. All of the findings suggest that these synthetic ones are a series of promising lead compounds in cystic fibrosis therapeutic and anticancer drug discovery. This review primarily focuses on the structure, chemistry and pharmacology of naphthoflavones, while benzothioflavones, benzoflavanones, benzoflavans and benzochalcones as their analogues are also included.

Stimuli-responsive polymers could respond to external stimuli, such as temperature, pH, photo-irradiation, electric field, biomolecules in solution, etc., which further induce reversible transformations in the structures and conformations of polymers, providing an excellent platform for controllable drug release, while the accuracy of drug delivery could obtain obvious improvement in this system. In this review, recent progresses in the drug release systems based on stimuli-responsive polymers are summarized, in which drugs can be released in an intelligent mode with high accuracy and efficiency, while potential damages to normal cells and tissues can also be effectively prevented owing to the unique characteristics of materials. Moreover, we introduce some smart nanoparticles-polymers conjugates and drug release devices, which are especially suitable for the long-term sustained drug release.

3-N-substituted-estrogen derivatives were synthesized and characterized. Their antiproliferative activities against human ER (+) MCF-7 (Breast), ER (-) MDA-MB-231 (breast) and Ishikawa (endometrial) cancer cell lines were determined after 72 hours drug exposure employing CellTiter-Glo assay at concentrations ranging from (0.01-100,000 nM). The antiproliferative activities of these compounds were compared to tamoxifen (TAM), 4-hydroxytamoxifen (4-OHT, active metabolite of tamoxifen) and raloxifene (RAL). In vitro results indicated that compound 5 (IC50 = 12µM) displayed comparable antiproliferative activity against MDA-MB 231 cell line; while compounds 6, 7 and 13 (IC50 = 12µM) displayed higher activity against MCF-7 and Ishikawa cell lines, in comparison to TAM activity (19-33µM).