Mini Reviews in Medicinal Chemistry - Volume 13, Issue 14, 2013

Haloperidol (HP) is used for the symptomatic treatment of psychosis, manic phases, hyperactivity, aggressiveness, and acute delirium. Long-term use leads to various adverse side effects, especially to severe impairment of extrapyramidal nerve tracts and in particular, altered QT interval and increased incidence of arrhytmias. It is believed that cytotoxicity of HP and its metabolites is responsible for both neurotoxicity and cardiotoxicity. Extrapyramidal and cardiac adverse side effects may be explained by the HP-induced oxidative stress, as implicated by many studies. HP was reported to induce lipid peroxidation with subsequent membrane changes, responsible for cell death. Vice versa, cells resistant to oxidative stress are also resistant to the toxic effects of HP. Similarly, high percentage of patients suffering from extrapyramidal symptoms treated by vitamin E and other lipid-soluble antioxidants demonstrates diminishing of these adverse side effects. HP’s ability to induce oxidative stress by multi-modal action (increased metabolism of dopamine, decrease of glutathione content, induction of NF-κB transcription factor, and inhibition of complex I of respiratory chain) has been established just recently. This review brings summarizing view on the cytotoxicity of haloperidol and involvement of reactive oxygen species and oxidative stress HP-induced cytotoxicity.

Histone deacetylases (HDACs) regulate the expression and activity of many proteins in both cancer initiation and cancer progression. HDACs are now recognized as promising targets for anticancer agent development. HDAC inhibitors (HDACIs) are emerging as promising anticancer drugs which possess tumor-selective cytotoxicity. HDACIs could promote growth arrest, differentiation, and apoptosis of cancer cells, with minimal effects on normal tissue. Research of HDACIs is now becoming an interesting field. HDACIs comprise structurally diverse anticancer agents and have been widely used in the clinic. This review describes recent progress in the development of HDACIs, especially focusing on the design strategies, novel chemical structures, biological properties and structure-activity relationships (SARs) of HDACIs. We hope it will be helpful for medicinal chemists who are interested in the discovery of anticancer agents.

Polo-like kinases (Plks) are a family of serine/threonine kinases with a highly conserved N-terminal Ser/Thr kinase catalytic domain and a C-terminal region that play crucial roles in cell cycle progression. Plk1, playing a key role in multiple steps of mitotic progression, is the most studied member of the family. It is overexpressed in a wide spectrum of cancer types and is a promising target in oncology. Most of Plk1 inhibitors competitively bind to the ATP-binding site, which is characterized with unique features. Other inhibitors target regions outside the ATP pocket. In this review some pre-clinical or clinical Plk1 inhibitors are reported, focusing on SAR studies and biological activities, including the kinase activity, in vitro and in vivo anti-tumor efficacy. Those studies exhibited the inhibitors’ significant therapeutic effects. Moreover, combination therapies of these Plk1 inhibitors with other anticancer drugs resulted with synergistic effects.

Monoclonal antibodies (mAbs) or their derivatives are often used as the targeted ligands in the ligand targeted liposomes (LTLs). LTLs modified with mAbs or their derivatives are defined as immunoliposomes. Immunoliposomes can be designed to improve the pharmacological properties of conventional drugs. The development of immunoliposomes, which perfectly combines antibody engineering and liposomes, is becoming a possible state-of-the-art in liposome research. This review discusses the recent characterization and therapeutic effects of immunoliposomes in cancer therapy. The recent advances in the field of immunoliposomes for the treatment of cancer are summarized as follows: antibody engineering, current antibody conjugation strategies, characterization and therapeutic effects of immunoliposomes and the future perspective of immunoliposomes. Although antibody targeted immunoliposomes are being developed rapidly, there has been still a number of hot spots in research that require sustained effort for success. It is reasonable to predict that immunoliposomes will be approved for clinic use, and patients will benefit much from this cancer targeted therapy.

This Review deals essentially with the elucidation of structural features of Tachykinin family of neuropeptides, which are known to interact through three distinct GPCR subtypes, namely NK1 (Neurokinin 1), NK2 (Neurokinin 2) and NK3 (Neurokinin 3) receptors. In mammals, Tachykinins have been shown to elicit a wide array of activities such as powerful vasodilatation, hypertensive action and stimulation of extravascular smooth muscle and are known to be involved in a variety of clinical conditions including chronic pain, Parkinson’s disease, Alzheimer’s disease, depression, rheumatoid arthritis, irritable bowel syndrome and asthma. This broad spectrum of action of Tachykinins is attributed to the lack of selectivity of tachykinins to their receptors. All tachykinins interact with all the three-receptor subtypes with SP preferring NK1, NKA preferring NK2 and NKB preferring NK3. This lack of specificity can be accounted for by the conformational flexibility of these short, linear peptides. Hence, identification of structural features of the agonists important for receptor binding and biological activity is of great significance in unraveling the molecular mechanisms involved in tachykinin receptor activation and also in rational design of novel therapeutic agents. Understanding structure of the ligand-receptor complex and analysis of topography of the binding pocket of the tachykinin receptor is also crucial in rational design of drugs.

The phosphoinositide 3-kinases (PI3Ks) are lipid kinases that play a central role in control of cell growth, proliferation, migration, survival and angiogenesis, and drive the progression of tumors by activating phosphoinositidedependent kinase, protein kinase B (Akt) and the mammalian target of rapamycin (mTOR). The PI3K/Akt/mTOR pathway has been shown to play an important role in cancer and has become an important target for anticancer drug development. An interest in targeting two important points along this critical signaling pathway has spurred the development of dual PI3K/mTOR inhibitors that could both prevent cancer cell proliferation and induce programmed cell death (apoptosis) by fully suppressing Akt activation. This review summarizes the developments of a diversity of small molecule dual PI3K/mTOR inhibitors in recent 10 years, with an emphasis on their structural features, the relevant biological activities, and the structure-activity relationships (SARs).

Benzothiazoles are promising candidates for the design of novel antiepileptic drugs. The endocyclic sulphur and nitrogen functions present in this heterocyclic nucleus have been shown to be critical for the anticonvulsant activity. The present review outlines the rational design and anticonvulsant potential of promising benzothiazole lead molecules. Particular focus has been placed on the structure activity relationship of different benzothiazole derivatives giving selected examples of molecules with significant activity being that these molecules may serve as prototypes for the development of more active antiepileptic drugs.

Epilepsy is one of the commonly occurring chronic neurological disorders which involves abnormal electrical impulses in the brain. It is characterized by the sudden loss of consciousness, followed by abnormal shaking of the body. Though there are various types of antiepileptic drugs available clinically, the treatment of epilepsy still remains inadequate because of their toxicity and idiosyncratic side effects. Thus, there is unmet medical need to develop safe drugs for the treatment of epilepsy with lower side effects and improved bioavailability profiles. Considering the structural similarity between phenytoin/lamotrigine, a series of 1,3,4-thiadiazole was designed based on molecular docking study into the active site of the voltage-gated sodium channels. Antiepileptic activity of the synthesized compounds was evaluated in rats by maximal electroshock induced seizures (MES) model at different doses. Among the tested compounds, some exhibited significant anticonvulsant activity as compared to phenytoin in a dose-dependent manner. The neurotoxicity study was carried out using the rotarod test and the results of which suggests that the target compounds are safe and could be further developed as potential lead for antiepileptic drugs.

The p38 Mitogen-Activated Protein (MAP) kinase, a serine/threonine kinase, is one of the best characterized kinases in the inflammatory process. Among the four identified p38 isoforms (p38α, p38β, p38γ, and p38δ), the α-form is the most fully studied and plays a central role in the biosynthesis of the proinflammatory cytokines i.e. IL-1β and TNF-α at the translational and transcriptional levels. Antagonism of these proinflammatory cytokines has been recognized as an effective possibility for the development of new drug candidates. The characterization of the pharmacological profile displayed by the selective p38 inhibitor prototype SB203580, proved its disease-modifying activity in the adjuvantinduced arthritis model. This strongly suggests that adequate modulation of production of these cytokines can bring significant benefits to the therapy of chronic inflammatory diseases. In addition to its important role for the secretion of proinflammatory cytokines, p38 is also involved in the activation of matrix metalloproteinases and the induction of COX- 2 transcription, proteins that are involved in the process of tissue destruction and inflammation. Because of its multiple functions in modulating the inflammatory response, it is expected that p38 inhibiting drugs will treat the underlying cause of chronic inflammatory diseases and stop their progression. The archetypal small molecule p38 inhibitors are the pyridinylimidazoles and these structures formed the basis for much of the early research. More recently a number of nonimidazole based p38 inhibitors such as the ureas, pyrazoles, pyrazoloheteroaryls, pyridazines, indoles, amides, pyridines, triazolopyridines, etc containing a variety of functionality have been reported to inhibit cytokine activity. This article provides a critical account of these different heterocycles reported for p38 MAPK inhibition and covers the recent research in the development of anti inflammatory agents.

From 2005 to 2012, 236 new substances have been officially notified in European Union via the Early Warning System with an increasing trend from year by year. In October 2009, 4-methylamphetamine (4-MA), an amphetamine derivative, was detected in Belgium and on 14 December 2009 this stimulant was notified to the European Monitoring Centre for Drugs and Drug Addiction. Since its appearance within the recreational drug market, some cases of severe intoxication and deaths have been signaled across Europe. In this paper we summarized the chemical, pharmacological and toxicological information about this new potential recreational drug.

Treatment of intoxications caused by nerve agents and organophosphorus pesticides consists of different approaches. The first approach is called prophylaxis or pre-exposure administration of antidotes such as cholinesterase reactivators or bioscavengers. The second, post-exposure treatment consists of anticholinergic drugs, acetylcholinesterase reactivators and anticonvulsants. This article is aimed at both mentioned approaches, especially focused on cholinesterase reactivators, which are a broad group of structurally different compounds that can be used in prophylaxis (separately or in combination with butyrylcholinesterase) and also as post-exposure treatment.

Malaria has been a major cause of morbidity and mortality in developing countries, particularly in Sub-Saharan Africa and South Asia. The global malaria situation is increasingly being challenging owing to lack of credible malaria vaccine and the emergence of drug resistance to most of the available antimalarials. They demand search for novel generation of drugs. Versatility and flexibility for structural modification of natural and synthetic analogues of curcumin and chalcone have been explored extensively for designing new antimalarial agent. Recent advances to our knowledge of parasite biology as well as the availability of the genome sequence, have opened up new vista in the firmament of antimalarial drug designing for identifying novel molecular targets. Curcumin and chalcones has been reported to exert anti-malarial effect by binding directly to numerous signaling molecules, such as histone acetyltransferase, histone deacetylase, sarco (endo) plasmic reticulum Ca2+-ATPase, cysteine proteases etc. This review highlights insights the more recent antimalarial activities of these compounds, their mechanisms of action, molecular targets and relevant structureactivity relationship studies. Natural lead compounds like chalcone and curcumin have shown good and optimal binding to many enzymes present in parasite and can be explored as molecular targets for in silico studies to develop new, affordable and effective antimalarial drugs. With no credible malaria vaccine in sight, there is an imperative need to develop new drugs with different mechanisms of action to help preclude issues of cross-resistance.