Letters in Drug Design & Discovery - Volume 3, Issue 10, 2006

There is a hope that inhibitors of the purinoreceptor P2X7, a ligand-gated ion channel, would have a beneficial role in the therapy of inflammatory processes. Therefore, the P2X7 channel is a putative drug target but neither X-ray nor NMR analyses have been made. It was attempted to predict the conformations of P2X receptor subunits using homology-based comparative modelling and threading. The modelling could not be carried out because of missing template proteins. The paper reviews a new method to predict the conformation of proteins. The method is exemplified on the human P2X7 (h-P2X7) receptor. The coordinates of the spatial structure of the h-P2X7 protein were determined by a profile-based neural network prediction. The conformation was geometry optimised using the quantum chemistry RHF/3-21G minimal basic set and allatom molecular mechanics AMBER force field. A dielectric constant of ε = 3.5 was used to simulate the lipophilic environment of the membrane-bound glycoprotein. The h-P2X7 protein has a number of interacting peptide modules. The discovery of peptide module raises the possibility of exploiting structure-based strategies to design h-P2X7 inhibitors.

Chemokines represent a family of over 40 small proteins that, for the most part, are secreted into the environment and function by binding to G protein-coupled receptors (GPCRs) that are expressed on many different cell types. Chemokines play an important role in many biological processes including maintenance of the organizational integrity of secondary lymphoid tissue, participation in various aspects of immune responses following infection or injury, and induction of directional migration of targeted immune cell populations to sites of inflammation. Importantly, chemokines are associated with numerous inflammatory diseases in humans including multiple sclerosis (MS) and spinal cord injury (SCI). MS is a demyelinating disease characterized by an exacerbated inflammatory response leading to immune-mediated myelin destruction. The immune system also plays a critical role in SCI; primary trauma to the adult mammalian spinal cord is immediately followed by secondary degeneration in which the inflammatory response is thought to play a detrimental role. In the central nervous system (CNS), the inflammatory response is mediated in part by T lymphocytes that are recruited by chemotactic molecules such as chemokines. We have used wellaccepted animal models of MS and SCI to provide insight into the functional role of chemokines in neuroinflammation and disease. This review summarizes studies which indicate that ablation of the T cell chemotactic CXC chemokine ligand 10 (CXCL10) results in diminished neuropathology associated with decreased immune cell infiltration into the CNS. Importantly, these findings reveal that targeting chemokines such as CXCL10 may offer a powerful therapeutic approach for the treatment of neuroinflammatory diseases.

CCR1 antagonists were prepared by coupling bridged piperazines and bridged piperidines with 2- acetylamino-4-chloro-5-methoxy cinnamic acid. Compound 2 of the series showed the desired equal potency against human, mouse and rat CCR1 (IC50= 20; 22; 28nM), exhibited a superior pharmacokinetic profile and inhibited the clinical grades in rat acute experimental autoimmune encephalomyelitis and knee swelling in rat antigen induced arthritis at doses of 2 x 30 and 2 x 15 mg/kg p.o.

During the last decade, resulting from expanded knowledge in tumor biology, several new and target-specific approaches have been presented. With some exceptions, however, most early clinical trials with these compounds are discouraging, suggesting that the expanding knowledge might not easily translate into new substantially better anti-cancer drugs. One of the classical chemotherapeutic agents is melphalan, first synthesized over fifty years ago. The anti-tumor effect has been attributed to alkylation of cellular nucleophiles, among them DNA. Intravenous melphalan has single-agent activity in a variety of solid tumors and has good activity alone or combined with other drugs or radiation in high-dose bone marrow transplant regimens for breast cancer, ovarian cancer, testicular cancer and multiple myeloma. Recent studies suggest a continuous role for melphalan as part of high dose combination therapy in advanced solid tumor malignancies. Immediately after the first publication on melphalan (p-L-bis(2-chloroethyl)aminophenylalanine), investigators began attempting to improve the therapeutic index and thus provide a greater margin of clinical safety during treatment with the drug. The amino-acid based chemical structure of melphalan invites to modification of both the N- and C-termini as well as incorporation into peptides. In this review we discuss the past and present history of melphalan in the perspective of modern cancer chemotherapy, from the medicinal chemist's point of view, and with special emphasis on how target-directed approaches have been applied to the molecule.

Humanized monoclonal antibodies specific for two ErbB family members, an anti-EGFR (HER1) antibody (cetuximab) and an anti-HER2 antibody (trastuzumab), are proved to be therapeutically important. In this report, we have attempted to design long circulating liposome carriers that have covalently attached, therapeutically active monoclonal antibodies (mAb) specific for EGFR or HER2. Two issues that were resolved here concerned: 1) the use of whole mAb in preparing liposomal conjugates exhibiting extended circulation lifetime and improved mAb delivery to tumors, and 2) the selection of a coupling strategy that did not influence the anti-cancer activity of the conjugated therapeutic antibody. Unlike previous studies contemplating the use of antibodies to target liposomes, the rationale for the studies described in this report was based on the potential that such liposomes could be developed as a versatile approach to deliver the associated antibody/drug combinations to sites of tumor growth. We have demonstrated that strategies which minimized the accessibility of Fc region of the conjugated mAb were useful in reducing plasma elimination of the mAb-liposome conjugates. In particular, Fc exposure could be reduced by conjugating mAb via carbohydrate moieties, which resulted in improved circulation longevity and a five-fold increase in tumor liposomal lipid levels compared to those observed for liposomes prepared with mAb conjugated through amine thiolation. Alternatively, amine conjugation of mAb to the poly(ethylene glycol) terminus resulted in circulation kinetics comparable to those of non-targeted liposomes. Using the later approach, conjugation of the therapeutically active mAb, trastuzumab, did not substantially compromise the anti-tumor activity of the mAb as measured in a human MDA-MB-435/LCC6HER2 (LCC6HER2) breast cancer xenograft model. These results indicate the potential of such liposomal formulations for use in combination with encapsulated anticancer drugs that would act synergistically with mAb against ErbB family members.

In this study, we investigated whether oxidant/antioxidant imbalance in bleomycin (BLM)-instilled lungs would be prevented by curcumin. A single intratracheal injection of bleomycin (5 mg/kg body weight) to rats induced acute lung injury accompanied by significant increases in biochemical markers and inflammatory cell accumulation in bronchoalveolar lavage fluid and increased lung levels of myeloperoxidase (MPO) and intercellular adhesion molecule-1 (ICAM-1) 7 days after bleomycin administration. Also, bleomycin instillation led to leukocytes accumulation and fibrotic changes in the lung interstitium. Lung levels of thiobarbituric acid reactive substances (TBARS), conjugated dienes and protein carbonyls were increased at 7 and 14 days after bleomycin administration. In addition, increases in lung antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, glutathione reductase and glutamate cysteine ligase were noticed 7 and 14 days after BLM administration. Curcumin (300 mg/kg body weight, one week before and daily thereafter for 14 days) treatment significantly inhibited bleomycin-induced increases in lung lavage fluid biomarkers, histopathological changes, lung lipid peroxidation products and restored the levels of antioxidant enzymes to normal values. These findings indicate that curcumin is capable of inhibiting bleomycin-induced lung injury through inhibition of oxidative stress and perturbations in pulmonary antioxidant defense mechanisms.

Relaxation behavior and crystallization kinetics of amorphous acetaminophen are studied by dielectric spectroscopy and standard DSC. Isothermal crystallization experiments at temperatures from 2K below to 35K above the thermal glass transition of amorphous acetaminophen (Tg = 24°C) have been performed. We demonstrate that dielectric on-line measurements provide detailed information about the crystallization kinetics. Dielectric and calorimetric results consistently show that the crystallization slows rapidly down if the crystallization temperature Tc approaches Tg since the mobility is significantly reduced. Polarization microscopy images show that a few large spherulites grow in ultra-viscous acetaminophen. It is discussed why solid-like acetaminophen can also crystallize on time scales of days and weeks in the glassy state below Tg.

To establish the extent to which participants in maintenance treatment programmes (methadone and sublingual buprenorphine) used opioids, benzodiazepines, ethanol, cocaine and amphetamines, and to define the pattern of such use over time. Design: A retrospective analysis of data of 42,610 analyses from urinalysis screening. Setting: Outpatient drug treatment centre, Department of Psychiatry at Innsbruck Medical University, offering maintenance treatment and detoxification programmes in Tyrol, Austria. Measurements: Enzyme-multiplied immunoassay and gas chromatography-mass spectrometry. Results: Urine samples from 23.4% (N = 4998) of those in the methadone treatment group and 16.5% (N = 1110) in the sublingual buprenorphine group tested positive for consumption of additional drugs (p < 0.001). The most frequently detected drugs were benzodiazepines (63% of all methadone, and 40% of all sublingual buprenorphine positive samples; (p < 0.001)) and opioids (26% of all methadone, and 21% of all sublingual buprenorphine positive samples; (p < 0.001)). In both of the treatment programmes morphine abuse (63%) was higher than heroin (7%). There was a significant decrease of benzodiazepine abuse in the study period (2000- 2003) both among clients receiving methadone (p < 0.001) and those receiving sublingual buprenorphine (p = 0.006). Benzodiazepine (Spearman rank correlation coefficient r = 0.281, p < 0.001), cocaine (r = 0.057, p = 0.007), ethanol (r = 0.073, p= 0.028) and morphine (r = -0.179, p < 0.001) abuse were associated with age in sublingual buprenorphine treated patients. Methadone clients showed a lifetime relation for cocaine (r = -0.032, p =0.007), ethanol (Spearman corr. coeff. r = 0.118, p < 0.001), morphine (r = -0.107, p < 0.001) and dihydrocodeine abuse (r = 0.093, p < 0.001). Discussion: The present data indicate that nonprescribed drug use remains a persistent problem for patients in maintenance treatment. Substances misused are mainly opioids and benzodiazepines. Non-prescribed morphine has replaced heroin.

Oleoylethanolamide is an endogenous lipid mediator that reduces food intake and decreases body weight gain in rodents. As in leptin, oleoylethanolamide has a central and peripheral anorexic effect. In this article, we describe common potential targets, suggesting a molecular cross-talk between leptin and oleoylethanolamide which may regulate feeding behaviour.

The synthesis and “in vitro” chemical and enzymatic stability of Dopa/Benserazide conjugates (2 and 3) as dual acting codrugs are described. These codrugs possess a good lipophilicity (log P = -0.10) when compared to the parent drug LD and benserazide. Furthermore carbonyl and oxalyl spacers provide adequate stability in aqueous buffer solutions (pH 1.3 and 7.4). In 80% rat plasma at 37 °C, catechol esters and amide bonds of the studied derivatives were cleaved, and LD and benserazide were formed in one step. Our findings indicate that synthesized codrugs show good stability toward g.i. hydrolysis releasing LD and benserazide in rat plasma after enzymatic hydrolysis.

The isolation, structural characterization and cytotoxic properties of three new (1-3) and three known (4-6) gracilins, obtained from the sponge Spongionella pulchella is described. Gracilin B (4) exhibited selective, broad spectrum inhibition of integrin-mediated cell adhesion to a variety of physiological substrates.

We report the synthesis and evaluation of a range of triazole-based inhibitors of the two components of 17α-hydroxylase/17,20-lyase (P45017α). The results show that the compounds were poor inhibitors of 17α- OHase in comparison to lyase; they are therefore good lead compounds in the search for selective inhibitors of P45017α.