Medicinal Chemistry - Volume 2, Issue 6, 2006

Uncontrolled kallikrein activation is involved in diseases such as hereditary angioedema, bacterial septic shock and procedures such as cardiopulmonary bypass. Here we report a series of small molecule compounds that potently inhibit kallikrein activity in vitro. Kinetic studies indicate that some of these compounds are slow binding inhibitors of kallikrein with Ki final less than a nanomolar. The ability of these compounds to inhibit the activity of kallikrein was further confirmed in a plasma model by quantitating the release of bradykinin, an endogenous cleavage product of plasma kallikrein. To understand the inhibitory mechanism of the selected compounds toward kallikrein, the interactions between the selected compounds and kallikrein was explored using molecular modeling based on the information of crystal structures of TF/FVIIa and kallikrein. The information presented in the current study provides an initial approach to develop more selective and therapeutically useful small molecule inhibitors.

Despite the importance of embryonic stem cells in embryology and regenerative medicine, their response to DNA damage is not fully understood. Here we studied the expression profiles of small RNAs approximately 22 nucleotides long called micro RNAs, which play an important role in developmental regulation in plants and animals. We identified a group of micro RNAs with increased expression after exposure to radiation (compared with murine fibroblasts) and characterized putative target genes. These micro RNA sequences are conserved in mice, chickens and humans with similar genomic organizations, suggesting that a common regulatory network is involved in stem cell regulation in response to DNA damage. Micro RNAs might be useful as therapeutic tools to control DNA damage response in pluripotent stem cells.

Physicochemical characteristics of two structurally different cage dimeric 1,4-dihydropyridines HX (1) and CC (2) have been determined and compared to their P-glycoprotein inhibiting properties. While the weakly basic compound (1) showed pH-dependent apparent partition coefficients (log D), the neutral compound (2) proved to have almost identical log D values at varying pH-values. The subsequent determination of partition coefficients (log P) resulted in comparably low log P values revealing a less lipophilic compound character. Determined significantly differing P-glycoprotein (P-gp) inhibitory properties indicated that the lipophilicity of the compounds does not play a decisive role for the P-gp activity.

Recent studies have indicated that minor functional changes on the steroidal part of complex molecules, comprising of an alkylating moiety and a steroidal congener, lead to compounds with enhanced biological activity. The observed induction of the genotoxic, cytotoxic and antileukemic effects suggest a determinative role of the steroidal congener on the mechanism of action. In order to further elucidate the structural requirements responsible for this, we designed and synthesized a new modified steroid, carrying a 17 β-acetamide substituent and a B lactamic ring, and studied the ability of its esters with three potent nitrogen mustards to induce sister chromatid exchange (SCEs) and to inhibit cell proliferation in normal human lymphocytes in vitro. The role of the steroidal skeleton was clearly stated by the results of the in vitro evaluation of the final compounds, as all three derivatives proved better inducers of SCE (58-102 SCE/cell) and cell division delays (1.18-1.25 PRI) than the simple nitrogen mustards (24-38 SCE/cell and 1.51-1.62 PRI). Obviously, the steroidal module enhances the formation of DNA adducts that cannot be repaired by excision repair enzymes probably through the induction of the interaction of these complex compounds with different base sequences or by disabling the repair mechanisms through the blockage of the enzymes responsible for excision repair. On the other hand, it seems that these compounds also act through a parallel site of action responsible for cell death when their primary binding site becomes saturated, as in higher concentrations two of the derivatives tested showed enhanced cytotoxicity while their ability to induce SCE stabilized.

A series N-[4-(1H(2H)-benzotriazol-1(2)-yl)phenyl]alkylcarboxamides (8e-k, 9e-i, k, l) and their parent amines (5a-c and 6a-d) were prepared according to Schemes (1 and 2). Compounds were evaluated in vitro for cytotoxicity and antiviral activity against a wide spectrum of RNA (positive- and negative-sense) viruses, like [Bovine Viral Diarrhea Virus (BVDV), Yellow Fever Virus (YFV), Coxsackie Virus B (CVB-2), Polio Virus (Sb-1), Human Immunodeficiency Virus (HIV-1), Respiratory Syncytial Virus (RSV)] or double-stranded (dsRNA) virus, like Reoviridae (Reo-1). The Entero (CVB-2 and Sb-1) were the only viruses inhibited by title compounds. In particular, two of them emerged for their selective, although not very potent, antiviral activity: 8i, which was the most active against CVB-2 (CC50 >100 M; EC50 = 10μ M) and 9l, which was the most active against Sb-1 (CC50 90μM; EC50 = 30μm). Title compounds were evaluated in silico against the Sb-1 helicase, as the crystal structure of this enzyme was not available, the corresponding 3D model was obtained by homology techniques (see Fig. 2).

We have recently presented the synthesis of 2-amino-1,4-benzoquinones by nuclear amination of phydroquinones with primary aromatic amines using fungal laccases as catalysts. In the present report, a series of selected 2-amino-1,4-benzoquinones was tested for biological activities, such as inhibition of human 5-lipoxygenase and antiproliferative/ anti-neoplastic effects. Compound 9 (2-[4'-(iso-propylphenyl)-amino]-5,6-dimethyl-1,4-benzoquinone) was identified as the most potent aminoquinone derivative, suppressing 5-lipoxygenase in intact human polymorphonuclear leukocytes as well as in crude enzyme preparations in the low micromolar range (IC50 = 6 μM). Structure-activity relationships are discussed. Of interest, the 5-lipoxygenase inhibitory properties of 2-amino-1,4-benzoquinones in intact cells correlated to the anti-neoplastic activities of the compounds in breast and urinary bladder cancer cell lines. Based on these features, bioactive 2-amino-1,4-benzoquinones may possess potential for the pharmacological treatment of diseases associated with elevated 5-lipoxygenase activity, in particular certain types of cancer.

We recently identified two compounds of 5-benzylidene-2-phenylimino-1,3-thiazolidin-4-one (BPT) analog, 5- (4-methylbenzylidene)-2-phenylamino-1,3-thiazolidin-4-one (MMPT) and 5-(2,4-dihydroxybenzylidene)-2-phenylimino- 1,3-thiazolidin-4-one (DBPT), that can effectively induce apoptosis in cancer cells but not in normal cells, independently of P-glycoprotein status. To further investigate the antitumor activity of BPT analogs, we obtained 18 commercially available analogs of BPT and synthesized 7 analogs in our lab, and analyzed their antitumor activity in various cancer cells, including paclitaxel- and vinorelbine-sensitive and -resistant human lung cancer cells. Two of the compounds were more potent than MMPT or DBPT in induction of apoptosis in certain cancer cell lines and remained tumor selective. Seven compounds did not induce any cytotoxic effects in any of the cell lines tested at the highest concentration tested (31 μM). The other compounds induced cytotoxic effects in some cancer cells but not in others or were less potent than MMPT and DBPT. Cell uptake studies showed that analogs that effectively induced cell killing in paclitaxel- and vinorelbine-resistant cells could be taken up easily by those cells despite their high levels of P-glycoprotein expression. These data further demonstrate that thiazolidinone analogs are not P-glycoprotein substrates and could be useful for treatment of Pglycoprotein overexpressing refractory cancers.

Purpose: To determine persitent organic pollutants in adipose tissue in a patient with kidney cancer. Methods: Adipose tissue was sampled from the abdominal wall during autopsy of a 75-year old man who had died from a kidney cancer. The concentrations of polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyltrichloroethane (DDE), hexachlorobenzene (HCB), chlordanes and tetrabromodiphenyl ether (TeBDE) were determined on lipid basis. For comparison results from 29 male population based subjects aged 70-80 years were used. Results: All concentrations except for TeBDE were very high in the patient; sum of PCBs 18 808 ng/g fat (median for controls 997), DDE 14 183 (median for controls 751), HCB 424 (median for controls 46), and sum of chlordanes 2 389 (median for controls 62). The patient lost weight from 80 kg to 48 kg when he died, which may have contributed wholly or partly to the very high concentrations of organochlorines. Conclusion: Changes in weight must be recorded in cancer patients and the concentrations of persistent organic pollutants should be normalized to weight. The concentrations in this patient were 10- to almost 40-times higher than in the controls. Such very high concentrations may give clinical symptoms in the final stage of a wasting cancer patient.

Objective: To study the effects of interleukin-10 on the expression of fas and fasL in hepatic stellate cells in experimental rat hepatic fibrosis. Methods: Sixty clean SD rats were divided into control group (8 in group N), the model group (28 in group C) and the IL- 10 treated group (24 in group I) randomly. The rats were administered CCl4 with or without IL-10 treatment. Hepatic stellate cells (HSCs) were isolated from these rats at the beginning of the seventh and eleventh weeks during the course of liver fibrosis, respectively. Semi-quantitative RT-PCR and Western-blot were used to analyze mRNA and protein expressions of Fas and FasL from freshly isolated HSC. The liver tissues were harvested from three groups. Results: The CCl4- induced experimental rat hepatic fibrosis model was established successfully. The IL-10 could decrease the fibrotic degree of rat liver. The Fas and FasL mRNA can be measured in HSC of 3 groups. The mRNA of Fas and FasL in group C were significantly increased time-dependently compared to those of control group. In the 7th week, the expression level of Fas and FasL in group C was 0.66±0.02 and 0.45±0.33 respectively, and in the group I, the level was 0.74±0.02 and 0.52±0.05 respectively. In the 11th week, the level in group C was 0.72±0.02 and 0.62±0.04 respectively, and in the group I, the level was 0.73±0.04 and 0.83±0.04 respectively. The western-blot analysis showed that there was no FasL expression in group N, the expression of Fas and FasL in group C was significantly increased timedependently compared to those of control group. After being treated with IL-10, the expression level of Fas and FasL was higher than those of group C. In group C, the expression level of Fas and in the 11th week was 0.92±0.02and 0.99±0.02 respectively, and in group I, the level was 0.96±0.16 and 1.22±0.03 respectively. In group C, the level of FasL in the 7th week and in the 11th week was 1.24±0.03 and 1.33±0.03 respectively, and in group I, the level was 1.36±0.16 and 1.39±0.19 respectively. Conclusions: The expression of Fas and FasL increased in the course of the liver fibrosis, and would be furthered by IL- 10. The IL-10 could cause the apoptosis of activated HSC, and making antifibrogenic come into effect in these ways.

Two new series of N4-(2, 5-disubstitutedphenyl) semicarbazones were synthesized and evaluated for the anticonvulsant activity in various animal models of seizures. Quantum mechanical modeling was carried out on these compounds to understand the structural features essential for activity. The higher the difference in HOMO and LUMO energy levels the greater was the activity profile. Substitution with fluoro group on the ortho position of the aryl ring was found to decrease the reactivity and hence the activity profile of aryl semicarbazones, which has been justified with the molecular orbital surface analysis of the synthesized compounds.

Preventative medicine in the form of vaccination had a huge impact on human health in the 20th Century. Vaccines are now recognized as the most effective line of defence against infectious agents that cause disease and death, and in some cases vaccines have enabled complete eradication of disease from the globe (e.g. smallpox). Nevertheless there are still many human diseases (e.g. viral and parasitic infections, cancers) for which there are no effective vaccines. Current vaccines are mainly live and attenuated viruses or viral, bacterial or recombinant proteins and polypeptides. By virtue of their natural aminoacid composition, polypeptides and proteins are relatively safe materials for vaccination, but they are expensive to manufacture making them inaccessible to the most vulnerable and needy human populations that cannot afford such medicines. This review will focus on shorter synthetic peptides that are cheaper to manufacture, conceivably even safer for human use because of increased specificity, but they also suffer from problems that have presumably resulted in their lack of progress in clinical trials. Since 1990, over 100 chemically synthesized short peptide vaccines have entered Phase I clinical trials, less than 20 have progressed into Phase II, but none have entered Phase III clinical trials. In this review we discuss reasons why vaccines based on short peptides may not have succeeded in the clinic, identify problems such as insufficient immunogenicity, structural/conformational instability, chemical instability due to degradation, and describe possible solutions to some of these problems that have been investigated in recent years.