Current Medicinal Chemistry - Volume 18, Issue 7, 2011

The type I receptor tyrosine kinases (RTKs) are involved in various aspects of cell growth, survival, and differentiation. Among the known RTKs, the epidermal growth factor receptor (EGFR) and ErbB-2 (HER-2) are two widely studied proteins that are prototypic members of the ErbB family which also includes ErbB-3 (Her-3) and ErbB-4 (Her-4). Overexpression of ErbB-2 and EGFR has been associated with aggressive disease and poor patient prognosis in a range of human tumour types (e.g. breast, lung, ovarian, prostate, and squamous carcinoma of head and neck). Disruption of signal transduction of these kinases has been shown to have an antiproliferative effect. Various approaches have been developed to target the ErbB signalling pathways including monoclonal antibodies (trastuzumab/ Herceptin™ and cetuximab/Erbitux™ ) directed against the receptor, and synthetic tyrosine kinase inhibitors (gefitinib/Iressa™ and erlotinib/Tarceva™). Since many tumours overexpress ErbB receptors, simultaneous targeting of multiple ErbB receptors therefore becomes a promising approach to cancer treatment. Lapatinib (Tykerb™), a potent dual EGFR/ErbB-2 inhibitor, was approved for the treatment of ErbB-2-positive breast cancer. Despite years of intensive research on EGFR inhibitors, there is a surprising dearth of chemically distinct small inhibitors with a high degree of selectivity. There is also a need for new scaffolds due to the recent finding of EGFR mutations which render the kinase resistant to gefinitib and erlotinib. The structures under study will be quinazolines with different substituents. The structure-activity relationships and biological evaluation of compounds published during the last four years will be reviewed herein.

Aminopeptidases play essential roles in protein maturation, activation, and stability as well as in the degradation and regulation of hormonal and nonhormonal peptides that can serve as important enzyme targets for drug design. This review will focus on an effective inhibitor of aminopeptidases, bestatin, including work to find better inhibitors in the past three decades that has sought to optimize bestatin and prospective developments in bestatin optimization in the future.

Osteoarthritis (OA) is the leading cause of joint pain and disability in middle-aged and elderly patients, and is characterized by progressive loss of articular cartilage that eventually leads to a complex process involving degradation of various components of the cartilage matrix, chief among them are the cartilage-specific type II collagen (CII) and aggrecan. While the loss of aggrecan is thought to be an early and reversible process, degradation of CII is considered to be irreversible and a key step in the loss of structural and functional integrity of cartilage. Among the various matrix metalloproteinases (MMPs), MMP-13 is specifically expressed in the cartilage of human OA patients and is not present in normal adult cartilage. It is the major collagenase in OA cartilage and has the highest activity against CII. However, the clinical utility of broad-spectrum MMP inhibitors developed for treatment of OA has been restricted by dose- and duration- dependent musculoskeletal side effects in humans. Consequently, selectively inhibiting the MMP-13 would seem to be an attractive therapeutic objective. This review mainly focuses on selective MMP-13 inhibitors development in terms of OA since the late 90s, in terms of synthetic compounds of low molecular mass incorporating specific zinc-binding groups, non-zinc-binding groups. In addition, dual inhibitors of MMP-13 and aggrecanase are also reviewed. Special emphasis is placed on logistic concerns for lead compound search as well as the structure-activity relationship (SAR) in this field. Through these methods, new hope is emerging for the treatment of OA through selective inhibition of MMP-13.

Carbohydrate chemistry and glycobiology have become a “hot” subject. These extensive, complex structures serve essential roles in cell surface phenomena, but we are only beginning to understand what some of these functions are; any advances in the development of synthetic and/or analytical tools for glycobiology are extremely useful for our understanding of the roles of carbohydrates in biology, and as biomarkers of physiological/pathological states. This review provides an outlook of the potential of carbohydrate chemistry/ biology in magnetic resonance imaging (MRI), a major important and prominent technique in diagnostic clinical medicine and biomedical research. During the last 30 years, MRI has developed from an intriguing research project to an essential diagnostic method in the clinic. Although MRI contrast in endogenous tissues provides excellent sensitivity for detecting subtle changes in anatomy and function, MRI still has poor specificity for attributing image contrast to specific biological processes. To overcome this limitation, MRI methods are being developed that induce changes in MR image contrast in response to molecular compositions and functions that serve as early biomarkers of pathologies. Carbohydrates with their intriguing chemistry, not only can provide structures for novel MRI probes for imaging specific biological processes, but can themselves provide novel targets/biomarkers. For example, the glycan structure can simply provide a molecular scaffold for modulating the physicochemical properties of the imaging contrast agent, or can be used for the design of novel MR agents with the ability to disclose relevant physiological or pathological cellular events.

Cognitive dysfunction following surgery is a common complication, which increases the incidence of other co-morbid conditions, hospital and health-care costs. The reported rate of the occurrence of post-operative cognitive decline varies with different studies, depending on population profile, type of surgery, definition of cognitive disorder and detection methods, design of study, etc. It remains unclear whether these psychiatric signs and symptoms are direct results of the effects of surgery or general anesthesia. Nonetheless they are more frequent after cardiac surgery and are likely to be multi-factorial, but the patho-mechanisms are not yet fully characterized. This communication provides a synopsis of proteomics tools and delineates novel SELDI-TOF results to evaluate biomarkers in this regard. Presented for the first time is a classification of the clinically relevant forms of post-operative cognitive decline with the advent of a novel subclass.

The tumor suppressor protein p53 mediates critical cellular functions including regulation of cell cycle, apoptosis, DNA repair, and senescence. This protein has been found to be inactivated or functionally down-regulated in several malignancies such as Li- Fraumeni syndrom, hepatocellular carcinoma, breast cancer, cervical cancer, and acute myeloid leukemia. Thus, p53 represents an attractive target for therapeutic design and development of new anticancer agents. The most clinically used cytotoxic agents target stabilization of wt-p53 through DNA damage and are associated with several unwanted and life threatening side effects. There are a number of recently developed approaches that hold promise for non-genotoxic reactivation of p53. Earlier, we have reported various inhibitors of p53 and their importance to prevent unwanted death of normal cells in a variety of diseases [1]. To extend p53 protein as new target for anticancer agents, in this review we discussed the mechanisms of p53 inactivation. Subsequently, we described some of recently developed non-genotoxic activators of p53 and their significance in various neoplastic disorders. Additionally, we summarized advantages of nongenotoxic p53-activating agents over conventional anticancer therapy and challenges in future of p53 based therapy.

Nowadays, influenza virus is still a big threat to human. Hemagglutinin (HA) and neuraminidase (NA) are the two viral surface proteins, which play important roles in the life cycle of influenza virus. Current influenza vaccines and anti-influenza drugs work mainly by interfering with the functions of the two proteins. In this review, we will display some recent studies about the two proteins. As to HA, this review covers a lot including its fusion function, receptor specificity, antigenic shift hypothesis, novel antibodies and various inhibitors in order to deeply discuss this protein. As to NA, this review mainly focuses on studies about the newly identified 150-cavity of group-1 NAs and shows some untypical NA inhibitors aiming to provide a broader range of lead compounds for anti-influenza drug design.

The discovery of new biologically active compounds that can be exploited therapeutically to treat disease has stalled, with fewer new drugs entering the market every year. The spotlight has now turned onto nanoparticles (NPs) as a versatile and multifaceted platform for the delivery of drugs. NPs offer better pharmacokinetic properties, controlled and sustained release, and targeting of specific cells, tissues or organs. All these features can improve the efficacy of existing drugs. The use of NPs can dramatically impact the treatment of many diseases. Many potential therapeutics that exist for alleviating brain diseases such as epilepsy, Alzheimer's disease and tumours are not feasible due to a lack of means to deliver drugs across the blood brain barrier. NPs offer an alternative solution, since they can be modified to cross the blood brain barrier. Additionally, NPs can also play a part in alternative methods of non-parental administration of drugs e.g. pulmonary and transdermally. Through active targeting and the enhanced permeation and retention effect, NPs reduce the systemic toxicity of chemotherapeutic drugs by ensuring delivery only to the site of the tumour, thus enhancing cancer treatment. We critically review the literature to provide a summary of current synthesis methodologies and applications of NPs in drug delivery.

Non-alcoholic fatty liver disease is regarded as the hepatic manifestation of metabolic syndrome and is an important and common cause of chronic liver disease with a potential to develop end-stage liver disease. While important advances in the pathophysiology have been achieved using genetically modified and diet-induced animal models, in-vitro models have been only recently proposed. These models include primary culture and immortalized cell lines. Here we critically review the characteristics of the in vitro models described, the advantages and limitations of the in vitro approach, and the results derived.

With an inventory of several hundreds secondary metabolites identified, Cannabis sativa L. (hemp) is one of the phytochemically best characterized plant species. The biomedical relevance of hemp undoubtedly underlies the wealth of data on its constituents and their biological activities, and cannabinoids, a class of unique meroterpenoids derived from the alkylation of an olivetollike alkyl resorcinol with a monoterpene unit, are the most typical constituents of Cannabis. In addition to the well-known psychotropic properties of Δ9-THC, cannabinoids have been reported to show potential in various fields of medicine, with the capacity to address unmet needs like the relief of chemotherapy-derived nausea and anorexia, and symptomatic mitigation of multiple sclerosis. Many of the potential therapeutic uses of cannabinoids are related to the interaction with (at least) two cannabinoid G-protein coupled receptors (CB1 and CB2). However, a number of activities, like the antibacterial or the antitumor properties are non totally dependent or fully independent from the interaction with these proteins. These pharmacological activities are particularly interesting since, in principle, they could be easily dissociated by the unwanted psychotropic effects. This review aims at giving readers a survey of the more recent advances in both phytochemistry of C. sativa, the medicinal chemistry of cannabinoids, and their distribution in plants, highlighting the impact that research in these hot fields could have for modern medicinal chemistry and pharmacology.