Development of Zeise's Salt Derivatives Bearing Substituted Acetylsalicylic Acid Substructures as Cytotoxic COX Inhibitors.

Zeise's salt derivatives of the potassium trichlorido[η2-((prop-2-en/but-3-en)-1-yl)-2-acetoxybenzoate]platinate(II) type (ASA-Prop-PtCl3/ASA-But-PtCl3 derivatives) were synthesized and characterized regarding their structure, stability, and biological activity. It is proposed that the leads ASA-Prop-PtCl3 and ASA-But-PtCl3 interfere with the arachidonic acid cascade as part of their mode of action to reduce the growth of COX-1/2-expressing tumor cells. With the aim to increase the antiproliferative activity by strengthening the inhibitory potency against COX-2, F, Cl, or CH3 substituents were introduced into the acetylsalicylic acid (ASA) moiety. Each structural modification improved COX-2 inhibition. Especially compounds with F substituents at ASA-But-PtCl3 reached the maximum achievable inhibition of about 70% already at 1 µM. The PGE2 formation in COX-1/2-positive HT-29 cells was suppressed by all F/Cl/CH3 derivatives, indicating COX inhibitory potency in cellular systems. The CH3-bearing complexes showed the highest cytotoxicity in COX-1/2-positive HT-29 cells with IC50 values of 16-27 µM. In COX-negative MCF-7 cells, they were 2-3-fold less active. These data clearly demonstrate that it is possible to increase the cytotoxicity of ASA-Prop-PtCl3 and ASA-But-PtCl3 derivatives by enhancing COX-2 inhibition.

COPD Assessment Test Changes from Baseline Correlate with COPD Exacerbations: A Longitudinal Analysis of the DACCORD Observational Study.

PURPOSE: A number of analyses have shown the immediate impact of COPD exacerbations on health status. However, none evaluated the long-term correlation between health status and the occurrence of exacerbations. METHODS: DACCORD is an observational study in patients with COPD recruited across Germany following initiation or change in COPD maintenance medication. Data collected include COPD Assessment Test (CAT) total score on entry and after 1 and 2 years, and the occurrence of exacerbations. We analysed the correlation between change from baseline in CAT total score and exacerbations, after excluding patients who exacerbated during the quarter immediately prior to the CAT assessment of interest. RESULTS: The initial correlation analysis was performed in 6075 patients, 28% with ≥ 1 exacerbation over the 2-year follow-up, and 58% with a clinically relevant CAT improvement. There was a significant correlation between exacerbations over 2 years and CAT change from baseline at Year 2 (p = 0.0041). The Spearman's correlation coefficient was 0.03711, indicating very weak correlation-potentially driven by the high proportion of non-exacerbating patients. In a subsequent logistic regression, the probability of experiencing frequent (≥ 2 per year) or severe exacerbations was higher in patients with worsening in CAT total score (p < 0.001). However, the probability of a patient exacerbating in Year 1 or Year 2 did not correlate with CAT change. CONCLUSIONS: In this population (initiating or changing maintenance COPD medication), patients with frequent or severe exacerbations had a long-term worsening in health status (beyond the acute effect of an exacerbation) compared with patients who do not exacerbate.

Fluorination as tool to improve bioanalytical sensitivity and COX-2-selective antitumor activity of cobalt alkyne complexes.

The cobalt alkyne complex [(prop-2-ynyl)-2-acetoxybenzoate]dicobalthexacarbonyl (Co-ASS) is an auspicious lead, which exhibits its anticancer activity mainly by inhibition of both cyclooxygenases (COX-1 and COX-2). Since COX-2 participates in carcinogenesis, a selective inhibition of that isoenzyme is aimed. To study if fluorination increases the COX-2/COX-1 inhibition ratio of the lead, substitution was respectively performed in the positions 3, 4, 5, and 6 of the aromatic moiety. The complexes 3/4/5F-Co-ASS and to a much lower extent also 6F-Co-ASS showed cytotoxic, antimetabolic, and apoptotic effects in COX-1/2-positive HT-29 and MDA-MB-231 cells and remarkably less activity in the COX-1/2-negative MCF-7 cell line. The metabolic activity in MCF-7 cells was even unaffected up to a concentration of 40 µM. With exception of 6F-Co-ASS, the complexes strongly reduced the PGE2 synthesis in HT-29 cells and all complexes inhibited COX-2 more effectively than COX-1 in an assay at isolated enzymes. These findings point to an interference in the COX cascade as part of the mode of antitumor action. The limited cellular effects of 6F-Co-ASS are related to its poor uptake as determined by HR CS AAS/MAS. Moreover, the cellular uptake studies confirm fluorination as beneficial tool for bioanalytical labeling. The higher quantification of fluorine by HR CS MAS makes this method about 5-fold more sensitive than HR CS AAS measuring cobalt. As a further positive result, 3/4/5/6-Co-ASS demonstrated high selectivity to tumor cells due to lack of antimetabolic activity against the non-tumorigenic bone marrow stromal cell line HS-5.

Synthesis and Biological Evaluation of Zeise's Salt Derivatives with Acetylsalicylic Acid Substructure.

The development of novel biologically active organometallic compounds bearing an acetylsalicylic acid (ASA) substructure led to the synthesis of analogical Zeise-type salts that accordingly inhibit cyclooxygenase (COX) enzymes. In order to determine the influence of the length of the alkyl chain between the platinum(II) center and the ASA moiety, compounds with varying methylene groups (n = 1⁻4) were synthesized and characterized. For the propene derivative structural elucidation by X-ray crystallography was possible. Prior to evaluation of biological activity, the complexes were investigated regarding their stability in different media, such as water, physiological sodium chloride, and phosphate buffered saline. Therefore, an analytical method based on capillary electrophoresis was established. All of the compounds were tested for their COX inhibitory potential. In general, complexes with longer alkyl chains caused higher inhibition of COX enzymes and the inhibitory potential towards COX enzymes was enhanced when compared to Zeise's salt. The growth inhibitory effects of the synthesized substances were investigated in vitro against colon carcinoma (HT-29) and breast cancer (MCF-7) cells. The IC50 values of the new derivatives ranged from 30 to 50 µM, whereas neither Zeise's salt itself nor ASA showed any antiproliferative activity at the used concentrations.

Chlorinated cobalt alkyne complexes derived from acetylsalicylic acid as new specific antitumor agents.

[(Prop-2-ynyl)-2-acetoxybenzoate]dicobalthexacarbonyl (Co-ASS), an organometallic derivative of the irreversible cyclooxygenase-1/2 (COX-1/2) inhibitor acetylsalicylic acid (ASS), demonstrated high growth-inhibitory potential against various tumor cell lines and inhibition of both COX isoenzymes. With the objective of increasing the selectivity for COX-2, we introduced a chlorine substituent in position 3, 4, 5, or 6 of the ASS moiety, respectively. Increased COX-2 selectivity is desirable as this isoenzyme is predominantly related to the development of cancer and abnormal tissue growth. The new compounds were investigated in comprehensive cellular biological assays to identify the impact of the chlorine substitution at the complex on COX-1/2 inhibition, antiproliferative activity, apoptosis, metabolic activity, cell-based COX inhibition, and cellular uptake. Chlorination distinctly reduced the effects at isolated COX-1 (about 25% inhibition at 10 µM; Co-ASS: 82.7%), while those at COX-2 remained almost unchanged (about 65% inhibition at 10 µM; Co-ASS: 78.5%). In cellular systems, with exception of the 6-Cl derivative, all compounds showed notable antitumor activity in COX-1/2 expressing tumor cells (HT-29 (IC50 = 1.5-2.7 µM), MDA-MB-231 (IC50 = 5.2-8.0 µM)), but were distinctly less active in the COX-1/2-negative MCF-7 breast cancer cell line (IC50 = 15.2-22.9 µM). All complexes possess high selectivity for tumor cells, because they did not influence the growth of the non-tumorigenic, human bone marrow stromal cell line HS-5. These findings clearly demonstrate that the interference with the COX-1/2 cascade contributes to the mode of anticancer action of the cobalt alkyne complexes.

Importance of 5/6-aryl substitution on the pharmacological profile of 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid derived PPARγ agonists.

In this structure-activity relationship study, the influence of aryl substituents at position 5 or 6 on the pharmacological profile of the partial PPARγ agonist 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid was investigated. This lead was previously identified as the essential part of telmisartan to induce PPARγ activation. Para-OCH3-phenyl substitution strongly increased potency and efficacy independent of the position. Both compounds represent full agonists because of strong hydrophobic contacts with the amino acid Phe363 in the ligand binding domain. Partial agonists with higher potency than telmisartan or the lead were obtained with OH or Cl substituents at the phenyl ring. Molecular modeling suggested additional hydrogen or halogen bonds with Phe360 located at helix 7. It is assumed that these interactions fix helix 7, thereby promoting a partial agonist conformation of the receptor. The theoretical considerations correlate very well with the results from the luciferase transactivation assay using hPPARγ-LBD as well as those from a time-resolved fluorescent resonance energy transfer (TR-FRET) assay in which the coactivator (TRAP220, PGC-1α) recruitment and corepressor (NCoR1) release pattern was investigated.

New telmisartan-derived PPARγ agonists: Impact of the 3D-binding mode on the pharmacological profile.

In previous studies, the 4'-((2-propyl-1H-benzo[d]imidazol-1-yl)methyl)-[1,1'-biphenyl]-2-carboxylic acid was identified as pharmacophoric core for PPARγ activation. In this structure-activity relationship study the C2-alkyl chain was elongated and the 2-COOH group was changed to a carbamide/carbonitrile or shifted to the 3- or 4-position. Furthermore, the benzo[d]imidazole was exchanged by 2,3-dihydrobenzo[d]thiazole or 1H-indole. C2-propyl derivatives showed the profile of partial agonists, while elongation of the C2-chain to that of an n-heptyl group or a 4-COOH shift changed the pharmacological profile to that of a potent full agonist. This finding can be explained by binding to the LBD in different ligand conformations. Two anchoring points (Tyr473 and Arg288) exist in the LBD, which have to be contacted to achieve receptor activation. In a crystal violet chemosensitivity assay using COS-7 cells and LNCaP cells expressing PPARγ only the carbamide derivatives influenced the cell growth, independently on the presence of the PPARγ. Therefore, receptor mediated cytotoxicity can be excluded.