Current Medicinal Chemistry (v.19, #26)

Eleven years after the start of a new millennium characterized by amazing scientific development, the cure for cancer remains a major challenge for humanity. In this regard, scientific efforts have focused on the search for new therapeutic targets that involve specific recognition and stop the spread of cancer cells, as well as the development of new therapeutic options that show greater specificity and better therapeutic efficacy. This review includes recent published literature about new anticancer drug design using scaffolds of β-lactams, sulfonamides, quinoline, quinoxaline and natural products, and focuses on the structure-activity relationships of scaffolds that have been reported to potently inhibit cell growth of human tumor cell lines. It describes not only those synthetic or natural compounds aimed at specific molecular targets of cancer cells in vitro, but also compounds currently in clinical trials.

Myeloproliferative neoplasms (MPN) are debilitating stem cell-derived clonal myeloid malignancies. Conventional treatments for the BCR-ABL1-negative MPN including polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofibrosis (PMF) have, so far, been unsatisfactory. Following the discovery of dysregulated JAK-STAT signaling in patients with MPN, many efforts have been directed toward the development of molecularly targeted therapies, including inhibitors of JAK1 and JAK2. Ruxolitinib (previously known as INCB018424; Incyte Corporation, Wilmington, Delaware, USA) is a rationally designed potent oral JAK1 and JAK2 inhibitor that has undergone clinical trials in patients with PV, ET, and PMF. Ruxolitinib was approved on November 16, 2011 by the United States Food and Drug Administration for the treatment of intermediate or high-risk myelofibrosis (MF), including patients with PMF, post-PV MF, and post-ET MF. In randomized phase III studies, ruxolitinib treatment resulted in significant and durable reductions in splenomegaly and improvements in disease-related symptoms in patients with MF compared with placebo or best available therapy. The most common adverse events were anemia and thrombocytopenia, which were manageable and rarely led to discontinuation. This review addresses the cellular and molecular biology, and the clinical management of MPN.

Current Trends in the Chemotherapy of Colorectal Cancer by M. A. Berciano-Guerrero, J. C. Villa-Guzman, R. Acosta-Guerrero, G. Castaneda-Penalvo, J. Rodriguez-Flores (4414-4430).
The increase in the therapeutic arsenal in the last 20 years, has given rise to changes in treating colorectal cancer (CRC) with only pyrimidines to combine several cytotoxic drugs. However, the present question is to determine the optimal sequence of this combination. This review presents an update of data on chemical and clinical features of chemotherapy used for colorectal cancer and the mechanisms of cellular resistance and potential predictive and prognostic biomarkers, which may contribute to a better selection of a therapeutic strategy.

Reactive oxygen and nitrogen species, which are normal products of cell metabolism, may play a dual beneficial/deleterious role, depending on local concentration and mode of generation. As such, they have been identified as key pathogenic factors for many inflammatory and degenerative disorders, carcinogenesis, nociception and ageing. In this perspective, low molecular weight transition metal complexes with organic ligands have been and are still viewed as promising pharmaceutical agents with antioxidant/free radical scavenging properties, owing to their ability to interact and/or react with reactive oxygen or nitrogen species and counterbalance excessive endogenous free radical generation in biological systems. Among these compounds, manganeseII/III complexes have resulted effective as ROS scavengers both in vitro and in vivo. In particular, MnIII complexes with porphyrins and salen derivatives as well as MnII complexes with macrocyclic pentaamines and polyamine-polycarboxylic acids have been recently analyzed as ROS scavengers for therapeutic purposes. In this article, we summarize the chemical and biological properties of manganese complexes with low molecular weight synthetic ligands as scavengers of pro-oxidant species, with particular attention to the mechanisms operating at the metal center in the scavenging process. A proper design of the organic scaffolds may yield manganese complexes capable to catalyze different scavenging reactions, including superoxide and/or hydrogen peroxide dismutation and peroxynitrite decomposition. These manganese complexes can be viewed either as a novel class of drugs helpful to reduce oxidative tissue injury or as useful tools to get further light on the role played by ROS in biological systems.

Biosimilar medicines already on the market may have a primary structure identical to their reference products (e.g., amino acid sequences should be identical). In the case of monoclonal antibodies (mAbs), and due to their more complex structure, a greater level of demand would be in order and identity at other levels (e.g., post-translational modifications within the Fc region of the molecule) should be proved to establish “similarity”. These requirements would lead to a greater development in the process and tighter quality controls during the production of biosimilar mAbs. The following issues should be taken into account in the comparability exercise: - The designs of the studies carried out to obtain approval of the reference product are not always adequate to show that safety and efficacy of the biosimilar mAbs are comparable. A similar efficacy does not necessarily imply a similar safety profile between the innovator and biosimilar products. - The design of clinical tests to demonstrate comparability must be flexible and adaptable throughout the development of the product. - The European Medicines Agency (EMA) will consider suitable goals in the evaluation of biosimilar mAbs for their approval (e.g., to specify whether their goal is to check similarity with the reference product or to show that the treatment is effective at a clinical level).

Peptides As Therapeutics with Enhanced Bioactivity by D. Goodwin, P. Simerska, I. Toth (4451-4461).
The development of techniques for efficient peptide production renewed interest in peptides as therapeutics. Numerous modifications for improving stability, transport and affinity profiles now exist. Several new adjuvant and carrier systems have also been developed, enhancing the immunogenicity of peptides thus allowing their development as vaccines. This review describes the established and experimental approaches for manufacturing peptide drugs and highlights the techniques currently used for improving their drug like properties.

Mitochondria As Potential Targets of Flavonoids: Focus on Adipocytes and Endothelial Cells by L. Duluc, R. Soleti, N. Clere, R. Andriantsitohaina, G. Simard (4462-4474).
Obesity is a major public health problem, resulting from an excess of energy storage and/or a default of energy expenditure leading to the increased occurrence of cardiovascular risk factors that favour the development of vascular complications. As a consequence, many studies are interested to find novel therapeutic chemical including flavonoids that appear to be promising natural compounds to treat obesity and its complications. Several in vitro studies addressed the mechanisms involved that might explain their beneficial effects, on adipocytes and endothelial cells, two cell types that play major role in obesity and its vascular complications. Besides the well-described antioxidant properties of flavonoids, at least a part of their beneficial effects on these cell types might be explained by their action on the regulation of mitochondrial function. In this review, we will therefore focus on the pathophysiological role of mitochondria in regulating endothelial and adipocyte functions. In addition, we will present some of the more promising flavonoids, important in human diet, including flavanols, flavonols, isoflavones, anthocyanins, flavanones and flavones; and their potential effects to improve endothelial or adipocyte functions via the mitochondria.

Novel Approaches in the Synthesis of Batracylin and Its Analogs: Rebirth of an Old Player? by K. Dzierzbicka, W. Januchta, A. Skladanowski (4475-4487).
Batracylin (8-aminoisoindol[1,2-b]-quinasolin-12(10H)-one, BAT), a heterocyclic amine, was isolated in 1978 (NCI, Bethesda, USA) in the course of search for the new anticancer drugs. It showed high in vitro and in vivo anticancer activities against murine leukemia P338 and colon adenocarcinoma 38. Mechanism of action of BAT is still not completely clear. It was reported, that BAT is a topoisomerase II inhibitor and induces unscheduled DNA synthesis (UDS) in non-proliferating cells. Low solubility of BAT in water, high toxicity and necessity of high drug dosing are major limitations of its use as a chemotherapeutic drug. As a result, new BAT analogs were synthesized to improve its pharmacological properties. The modifications of BAT chemical structure include various substituents introduced to isoindoloquinazoline moiety (Cl, Br, NO2, CH2, NH2, Me, CO2Me, OMe). It has been shown that the desamino derivative and the 8-aza analog of BAT retained the ability to inhibit topoisomerase II but did not induce unscheduled DNA synthesis. While less active than BAT, these analogs were cytotoxic toward CCRF-CEM leukemia cells. The isoindolo [2,1-a]benzimidazole derivatives were inactive as topoisomerase II inhibitors and, in general, failed to exhibit comparable antitumor activity or to induce unscheduled DNA synthesis. Batracylin was acylated with aminoacids, dipeptides, tripeptides to increase its solubility in water. Other modifications include introduction of nitrogen atom to ring A or D, extension of polycyclic ring 4, reduction of ring B from six- to five-membered one, and obtaining of benzimidazole, indole or derivatives containing a fucose ring. A series of novel BAT analogs bearing sugar residues and thiocarbonyl aminoacids, which provided better solubility in water and high cytostatic activity have been designed. Also, new azabatracylines, where aniline ring was replaced by pyridine or other substituted quinazolines, have been obtained. This paper reviews the most important approaches in batracylin synthesis and its analogs and presents structure-reactivity relationships for these compounds.

Physico-Chemical Properties Mediating Reproductive and Developmental Toxicity of Engineered Nanomaterials by Luisa Campagnolo, Micol Massimiani, Andrea Magrini, Antonella Camaioni, Antonio Pietroiusti (4488-4494).
With the increasing production of engineered nanomaterials (ENMs) exploited in many consumer products, a wider number of people is expected to be exposed to such materials in the near future, both in occupational and environmental settings. This has raised concerns about the possible implications on public health. In particular, very recently the scientific community has focused on the effect that ENMs might exert on the reproductive apparatus and on embryonic development. Indications that ENMs might have adverse effects on cells of the germ line and on the developing embryos have been reported. In the present minireview we will perform a critical analysis of the published work on reproductive and developmental toxicity of the most commonly used nanoparticles with a major focus on mammalian models. We will place emphasis on the main physico-chemical characteristics that can affect NP behaviour in biological systems, i.e. presence of contaminants and nanoparticle destabilization, size, dosage, presence of functional groups, influence of the solvent used for their suspension in biological media, aggregation/agglomeration, intrinsic chemical composition and protein corona/opsonisation. The importance of this specific field of nanotoxicology is documented by the rapidly increasing number of published papers registered in the last three years, which might be a consequence of the growing concerns on the possible interference of ENMs with reproductive ability and pregnancy outcome, in a time in which reproductive age has increased and the possibility to bear children appears reduced.

The hydrophobic character of most drug molecules and their potential for degradation under the hostile environment of the gastrointestinal tract (GIT) constitutes the main obstacle in the development of a successful oral drug delivery system, since these are related to limitations of bioavailability and absorption processes. However, according to the advantages of the oral route, alternative ways of drug administration in the oral cavity should be considered. In this context, it is essential to have a systematic knowledge of the GIT and the oral cavity components, for a better understanding of the processes taking place during the oral administration of drugs. This review gives an overview of those anatomical and physiological features and elucidates about the current approaches employed to enhance the bioavailability of oral poorly water-soluble drugs. Strategies including the uses of lipid-based nanocarriers, such as nanoemulsions, liposomes and lipid nanoparticles are discussed, considering their ability to improve solubility, dissolution kinetics, absorption and, consequently, biopharmaceutical properties. Some toxicological concerns are also highlighted.

Tandem Mass Spectrometry Newborn Screening for Inborn Errors of Intermediary Metabolism: Abnormal Profile Interpretation by C. Fernandez-Lainez, JJ. Aguilar-Lemus, M. Vela-Amieva, I. Ibarra-Gonzalez (4511-4522).
Expanded newborn screening for inherited metabolic disorders using tandem mass spectrometry was introduced in 1990's and is widely used around the world. In contrast to conventional screening methods, tandem mass spectrometry does not measure single analytes but identifies and quantifies metabolite profiles; one single blood spot analyzed provides information of about 60 metabolites including amino acids, acylcarnitines and related ratios that enable the diagnosis of approximately 50 different diseases. However, the interpretation of these profiles can become quite complex. The aim of this work is to present in an easy and practical manner a comprehensive compilation of information needed for tandem mass neonatal screening profile interpretation, and basic actions for immediate follow up of abnormal results, including the tests that are required for confirmatory purposes. Other conditions not attributable to metabolic disorders which can lead to an abnormal profile of these markers are also described as well as a series of general recommendations which would be useful for health professionals who are beginning newborn screening for inborn errors of intermediary metabolism using tandem mass spectrometry.

A Liver-Derived Rat Epithelial Cell Line from Biliary Origin Acquires Hepatic Functions Upon Sequential Exposure to Hepatogenic Growth Factors and Cytokines by J. De Kock, S. Snykers, S. Branson, S. Jagtap, J. A. Gaspar, A. Sachinidis, T. Vanhaecke, V. Rogiers (4523-4533).
Withdrawal of promising drug candidates is often due to the detection of liver toxicity. In particular the parenchymal liver cells or hepatocytes are targeted since they are the major sites of drug transport and of metabolite formation and thus also the place where not only detoxification, but also activation of new chemical (NCE) and biological (NBE) entities may occur. Therefore, primary hepatocyte- based cultures are currently the preferred in vitro model to screen for liver toxicity. However, within a few days, they undergo dedifferentiation with loss of liver-specific functionality, including xenobiotic biotransformation capacity, making them only suitable for short-term applications. A plausible alternative to primary hepatocyte cultures that can be maintained for longer periods of time could be the use of liver-derived epithelial cell lines and their optimized derivatives. Therefore, in the present study, we evaluated the stability and the hepatic differentiation potential of a neonatal liver-derived rat epithelial cell line from biliary origin (rLEC). Undifferentiated rLEC stably express the hepatic progenitor markers CEBPA, FOXA2, GJA1, ONECUT1, KRT18 and KRT19 for at least 15 consecutive passages after cryopreservation. Upon sequential exposure to hepatogenic growth factors and cytokines, rLEC generate functional hepatic progeny, expressing mature hepatic markers including Alb, Ahr, Car, C/ebpα, Cx32, Foxa2, Hnf1α, Hnf1β and Onecut1. Furthermore, an active polarization is observed for the hepatic drug transporters Oatp4 and Ntcp. rLEC-derived hepatic cells also acquire the ability to store glycogen, express genes encoding for key hepatic enzymes as shown by Affymetrix microarray data, and display stable CYP1A1/2- and CYP2B1/2-dependent activities for several weeks at levels comparable to those observed in cultured primary rat hepatocytes. The acquisition of such a stable and active biotransformation capacity is key for the applicability of liver-based in vitro models for long-term toxicity testing.

Alkyl Hydroxybenzoic Acid Derivatives that Inhibit HIV-1 Protease Dimerization by O. A. Flausino, L. Dufau, L. O. Regasini, M. S. Petronio, D. H.S. Silva, T. Rose, V. S. Bolzani, M. Reboud-Ravaux (4534-4540).
The therapeutic potential of gallic acid and its derivatives as anti-cancer, antimicrobial and antiviral agents is well known. We have examined the mechanism by which natural gallic acid and newly synthesized gallic acid alkyl esters and related protocatechuic acid alkyl esters inhibit HIV-1 protease to compare the influence of the aromatic ring substitutions on inhibition. We used Zhang-Poorman's kinetic analysis and fluorescent probe binding to demonstrate that several gallic and protecatechuic acid alkyl esters inhibited HIV-1 protease by preventing the dimerization of this obligate homodimeric aspartic protease rather than targeting the active site. The tri-hydroxy substituted benzoic moiety in gallates was more favorable than the di-substituted one in protocatechuates. In both series, the type of inhibition, its mechanism and the inhibitory efficiency dramatically depended on the length of the alkyl chain: no inhibition with alkyl chains less than 8 carbon atoms long. Molecular dynamics simulations corroborated the kinetic data and propose that gallic esters are intercalated between the two N- and C-monomer ends. They complete the β-sheet and disrupt the dimeric enzyme. The best gallic ester (14 carbon atoms, Kid of 320 nM) also inhibited the multi-mutated protease MDR-HM. These results will aid the rational design of future generations of non-peptide inhibitors of HIV-1 protease dimerization that inhibit multi-mutated proteases. Finally, our work suggests the wide use of gallic and protocatechuic alkyl esters to dissociate intermolecular β-sheets involved in protein-protein interactions.

Immunomodulatory and Anti-inflammatory Properties of Artesunate in Experimental Colitis by Z. Yang, J. Ding, C. Yang, Y. Gao, X. Li, X. Chen, Y. Peng, J. Fang, S. Xiao (4541-4551).
Background: Inflammatory bowel disease is a chronic and idiopathic gastrointestinal inflammation mediated by disregulated immune responses. Artemisinin (a chemical from a traditional Chinese herbal medicine Artemisia annua L.) and its derivatives have been proven to exhibit anti-inflammatory and immunomodulatory effects in the treatment of systemic lupus erythematosus and rheumatoid arthritis with low side-effects. This study is aimed to evaluate the potential therapeutic value of artesunate for inflammatory bowel disease. Methods: Murine colitis was induced by either oral administration of dextran sulfate sodium salt (DSS) or intrarectal delivery of 2,4,6- trinitrobenzene sulfonic acid (TNBS) or oxazolone. Mice were treated with artesunate (150mg/kg/day). Peritoneal macrophages were stimulated with lipopolysaccharide (LPS) in the presence or absence of artesunate. Changes in cytokines or proteins of interests were analyzed by enzyme-linked immunosorbent assay (ELISA) or SDS-PAGE/Western blot. Results: Artesunate significantly ameliorated DSS colitis and TNBS colitis (but not oxazolone colitis), including reduced weight loss and disease activity, as well as macroscopic and microscopic colonic injury. The expression of NF-κBp65 and p-IκB-α were reduced in artesunate treated TNBS colitis compared with untreated. The levels of IFN-γ, IL-17, and TNF-α were significantly decreased in artesunate treated TNBS colitis or DSS colitis. Furthermore, in vitro artesunate treatment significantly inhibited TNF-α production by LPS-activated macrophages. Conclusions: Artesunate suppresses TNF-α expression in vitro and in vivo as well as T-helper (Th)1/Th17 responses in TNBS colitis model. Our data suggest a novel clinical application of artesunate as a potential therapy for Crohn's disease.