Claudia Cusan

Mitochondria Are Direct Targets of the Lipoxygenase Inhibitor MK886 A STRATEGY FOR CELL KILLING BY COMBINED TREATMENT WITH MK886 AND CYCLOOXYGENASE INHIBITORS

We have investigated the mitochondrial and cellular effects of the lipoxygenase inhibitor MK886. Low concentrations (1 μm) of MK886 selectively sensitized the permeability transition pore (PTP) to opening, whereas higher concentrations of MK886 (10 μm) caused depolarization through combination of an ionophoretic effect with inhibition of respiration. MK886 killed prostate cancer PC3 cells only at the higher, toxic concentration (10 μm), whereas the lower concentration (1 μm) had no major effect on cell survival. However, 1 μm MK886 alone demonstrably induced PTP-dependent mitochondrial dysfunction; and it caused cell death through the mitochondrial pathway when it was used in combination with the cyclooxygenase inhibitor, indomethacin, which had no effectsper se. Treatment with 1 μm MK886 plus indomethacin sensitized cells to killing by exogenous arachidonic acid, which induces PTP opening and cytochrome c release (Scorrano, L., Penzo, D., Petronilli, V., Pagano, F., and Bernardi, P. (2001) J. Biol. Chem. 276, 12035–12040). Combination of MK886 and cyclooxygenase inhibitors may represent a viable therapeutic strategy to force cell death through the mitochondrial pathway. This approach should be specifically useful to kill cells possessing a high flux of arachidonic acid and its metabolites like prostate and colon cancer cells.

A new Multi-charged C60 Derivative: Synthesis and Biological Properties

A new water-soluble multi-charged monoadduct fullero[60]pyrrolidine derivative with three ethylene glycol chains and three ammonium groups has been synthesized by means of two alternative synthetic pathways. Increasing the concentration of this C60 derivative did not show a significant modification of concentration of superoxide anion radical O2·−, generated by the xanthine/xanthine oxidase system. Moreover, this C60 derivative was ineffective for neuroprotection in quantitative assessment of a neuronal injury considered to occur via radicals. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

Enzymatic synthesis of C-terminal arylamides of amino acids and peptides.

A mild and cost-efficient chemo-enzymatic method for the synthesis of C-terminal arylamides of amino acid and peptides is described. Using the industrial serine protease Alcalase under near-anhydrous conditions, C-terminal arylamides of N-Cbz-protected amino acids and peptides could be obtained from the corresponding C-terminal carboxylic acids, methyl (Me) or benzyl (Bn) esters, in high chemical and enantio- and diastereomeric purities. Yields ranged between 50% and 95% depending on the size of the aryl substituents and the presence of electron-withdrawing substituents. Complete alpha-C-terminal selectivity could be obtained even in the presence of various unprotected side-chain functionalities such as beta/gamma-carboxyl, hydroxyl, and guanidino groups. In addition, the use of the cysteine protease papain and the lipase Cal-B gave anilides in high yields. The chemo-enzymatic synthesis of arylamides proved to be completely free of racemization, in contrast to the state-of-the-art chemical methods.

Pyrazolo-triazolo-pyrimidines as adenosine receptor antagonists: Effect of the N-5 bond type on the affinity and selectivity at the four adenosine receptor subtypes

In the last few years, many efforts have been made to search for potent and selective human A3 adenosine antagonists. In particular, one of the most promising human A3 adenosine receptor antagonists is represented by the pyrazolo-triazolo-pyrimidine family. This class of compounds has been strongly investigated from the point of view of structure-activity relationships. In particular, it has been observed that fundamental requisites for having both potency and selectivity at the human A3 adenosine receptors are the presence of a small substituent at the N8 position and an unsubstitued phenyl carbamoyl moiety at the N5 position. In this study, we report the role of the N5-bond type on the affinity and selectivity at the four adenosine receptor subtypes. The observed structure-activity relationships of this class of antagonists are also exhaustively rationalized using the recently published ligand-based homology modeling approach.

Anti-inflammatory and anti-oxidant activity of a new class of phenyl-pyrazolone derivatives.

The anti-inflammatory activity of a new class of phenyl-pyrazolone derivatives, structurally related to phenidone, has been evaluated using the Croton oil ear test in mice as model of acute inflammation. Derivative 5h reduces the percentage of oedema similarly to indomethacin and more efficiently than phenylbutazone. The anti-inflammatory activity of these two reference drugs depends on their COX inhibition, but for the synthesized derivatives it has not been demonstrated a significant COX or LOX inhibition, as previously reported. While the anti-inflammatory activity of phenidone is correlated to its anti-oxidant properties, the redox potential of these compounds appears not decisive in the inflammatory process inhibition. In order to investigate the mechanism of action for these compounds, we quantified their anti-oxidant activity and the lipophilicity, and a relationship between the calculated logP and the percentage of oedema reduction was found. We hypothesize that the anti-inflammatory activity, recorded in vivo, could be related to lipophilic parameter of these compounds.