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In the search for highly selective and potent cholinesterase inhibitors (AChEI) being able to improve oxidative injury, PMS777, a tetrahydrofuran derivative, was designed as a novel dual PAF and acetylcholinesterase inhibitor. The aim of this study was to investigate the modulatory effects of PMS777 and galanthamine, another AChEI, on the oxidative injury induced in neuronal cells. The SK-N-SH cells stimulated with LPS+IL-(1beta) were selected to investigate the direct inhibitory effect of PMS777 and galanthamine. LPS+IL-(1beta) induced oxidative injury as assessed by ROS production (29%), GSH depletion (11%) and loss of mitochondrial activity (22%). GSH depletion was never decreased by either drug. In contrast, ROS production and mitochondrial activity were totally prevented by addition of PMS777 but not galanthamine. PMS777 also inhibits butylcholinesterase and it shows selectivity for acetylcholinesterase. Thus, this PAF antagonist inaugurates a new type of AChEI, able to fight oxidative injury. Therefore, PMS777 could be of interest on patients with cognitive impairments and inflammatory damage, as in AD.

Starting from 4-tetradecyloxybenzamidine ( PMS815 ), a non-specific inhibitor of GI and GII PLA 2 s, we report in this work the discovery of the specificity through design, synthesis and structure–activity relationships studies of different kinds of PMS815 derivatives. The leading compound, 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4 H -oxadiazol-5-one ( 9b , PMS1062 ) exhibits a micromolar IC 50 towards three group II PLA 2 s, while inactive towards four group I and one group III enzymes in two in vitro enzymatic assay conditions. It is also able to block the PLA 2 -II activities induced by LPS and IL-6 in HepG 2 cell line and no cytotoxicity is observed when PMS1062 is tested up to a concentration of 100 μM in two different cell lines (A549 and LLC-PK 1 ).

3-(4-Tetradecyloxybenzyl)-4H-1,2,4-oxadiazol-5-one (PMS1062 or I) can probably act as a PLA2-II inhibitor on the acute inflammation model, but its highly lipophilic character could prevent it from being biodistributed effectively. In this work, based on a molecular modeling study, we have proposed a model that may provide compounds retaining both anti-PLA2 activity and specificity while becoming active per os. Moreover, molecular dynamics and energy minimization enabled us to characterize the lowest-energy complexes of each derivative. Energy balances taking account of the conformational energy changes of both partners, along with the drug–protein interaction, were performed, and were further completed by single-point computations of the contributions of solvation/desolvation to the binding. The ordering of the resulting energy balances was found to be fully consistent with the experimentally ascertained ordering of affinities inferred from the IC50 values. The essential role of an indole group partaking in cation–π and hydrophobic interactions, together with the CaII-chelating oxadiazolone ring, was highlighted for the best binding compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

1-Benzoyl-2-alkyl piperazines are strong inhibitors of Group I and II secreted PLA2s. An improvement of their activity was obtained by replacing the amide function by a sulfamide and by introduction of electrodonor substituents on the para position of the benzenesulfonyl moiety. Neither the position on one of the carbon of the piperazine ring nor the absolute configuration of this carbon have an effect on the affinity for one or the other group of PLA2, but the lipophilicity remains for these series an essential parameter. In addition structure–activity relationships allow new hypothesis on interaction of these piperazine derivatives with the catalytic site of PLA2s.

The title compound C 11 H 8 O 2 S (I) crystallizes in space group C2/c: a = 11.468(4) A, b = 8.767(1) A, c = 19.249(6) A, β = 107.20(2)°; V = 1848.6(1.4) A 3 ; Z = 8, D x = 1466 kg m -3 ; Cu Kα = 1.542 A, μ = 27 cm −1 ; F(000) = 848; T = 293(1) K; Conventional R = 0.10 = R w for 1594 unique reflections

Galantamine, an acetylcholinesterase inhibitor used to enhance memory in AD patients by acetylcholinesterase inhibition, has been tested for its protective properties on an in vitro model of H 2 O 2 -induced oxidative stress. SK–N–SH cells treated with H 2 O 2 for 2 h showed an increase in ROS production (54%) and in NO production (52%) together with a marked reduction of the mitochondrial membrane potential (19%). These features, typical of the oxidative injury that accompanies AD, were partly recovered by galantamine. Galantamine reduced the release of reactive oxygen species (up to 50%) and prevented loss in mitochondrial activity. When SK–N–SH cells were treated with H 2 O 2 for 24 h, nitrite generation was increased by twice compared with 2 h. Galantamine treatment resulted in a significant inhibition of H 2 O 2 -induced nitrite generation whatever the concentration tested with a return to control values. Galantamine also concentration-dependently inhibited AChE activity (28–88%) in H 2 O 2 –SK–N–SH cells after 24 h. This drug, which facilitates cholinergic neurotransmission, is also neuroprotective by lowering oxidative injury. Our study provides a better understanding of the mechanisms of protection of this acetylcholinesterase inhibitor which also has antioxidative properties.

Inflammatory injury and induction of oxidative stress have been implicated as causative factors in neurodegenerative diseases such as Alzheimer's disease (AD). Using LPS-stimulated RAW 264.7 macrophages as a model of inflammatory injury, LPS was found to stimulate ROS production (159%), GSH depletion (15%) and loss of mitochondrial activity (32%) as well as TNFalpha release (40%), and NO production (13.7 times), all parameters involved in AD. PMS777, a tetrahydrofuran derivative, designed as a dual PAF and acetylcholinesterase inhibitor, was found to decrease ROS (up to 32%) and NO production (up to 5 times), TNFalpha release (33%). PMS777 also prevents loss of mitochondrial activity, and GSH depletion. In contrast, tacrine was found to decrease ROS production (57% up to 102%) and TNFalpha level (up to 30%). It decreases NO release only at the highest concentrations without preventing loss of mitochondrial activity and GSH depletion. In this study, we show that PMS777 is strongly anti-inflammatory against LPS-induced responses in RAW 264.7. Differential effects between PMS777 and tacrine could be attributed to the anti-PAF activity of PMS777 which was able to fight inflammatory events and oxidative injury whereas tacrine only minimizes them. PMS777 could open a new approach in the treatment of AD.

Acetylcholinesterase inhibitors are commonly used as cognitive enhancers for dementia in aged people. Among them, tacrine (THA) but not galanthamine, was shown to exhibit hepatotoxicity which reduces its clinical use. PMS777, both a PAF antagonist and a new potent acetylcholinesterase inhibitor was recently demonstrated to reverse scopolamine-induced amnesia in mice without toxicity. In the present study, the effects of THA, galanthamine and PMS777 were compared in HepG2 cells on the oxidative parameters involved in the reported hepatotoxicity of THA. THA (or = 10 microM) induced an oxidative stress as shown by elevated ROS and MDA production and by a decrease in GSH level. Moreover, mitochondrial membrane potential and redox status were decreased. At low concentrations (or =10 microM), there was no significant disturbance. None of the oxidative stress markers was affected by PMS777 up to the maximum concentration tested and it is suggested that PMS777 is not cytotoxic for HepG2 cells. Galanthamine was also without cytotoxicity. Our results suggest that the toxic effect of THA above 10 microM may be caused by drug-induced mitochondrial energization impairment and destabilisation of membrane phospholipids associated with an oxidative stress. In contrast by preventing these dysfunctions, PMS777 could be safer than THA.

We have recently reported the discovery of a series of specific inhibitors of human group IIA phospholipase A2 (hGIIA PLA2) to display promising in vitro and in vivo properties. Here we describe the influence of different structural modifications on the specificity and potency against hGIIA PLA2 versus porcine group IB PLA2. The SAR results, as well as the log P and pKa values of oxadiazolone determined in this work, provide important information towards the comprehension of the mode of action of this kind of compounds.

Starting from 4-tetradecyloxybenzamidine (PMS815), a non-specific inhibitor of GI and GII PLA2s, we report in this work the discovery of the specificity through design, synthesis and structure-activity relationships studies of different kinds of PMS815 derivatives. The leading compound, 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one (9b, PMS1062) exhibits a micromolar IC50 towards three group II PLA2s, while inactive towards four group I and one group III enzymes in two in vitro enzymatic assay conditions. It is also able to block the PLA2-II activities induced by LPS and IL-6 in HepG2 cell line and no cytotoxicity is observed when PMS1062 is tested up to a concentration of 100 microM in two different cell lines (A549 and LLC-PK1).

1-Benzoyl-2-alkyl piperazines are strong inhibitors of Group I and II secreted PLA2s. An improvement of their activity was obtained by replacing the amide function by a sulfamide and by introduction of electrodonor substituents on the para position of the benzenesulfonyl moiety. Neither the position on one of the carbon of the piperazine ring nor the absolute configuration of this carbon have an effect on the affinity for one or the other group of PLA2, but the lipophilicity remains for these series an essential parameter. In addition structure–activity relationships allow new hypothesis on interaction of these piperazine derivatives with the catalytic site of PLA2s.

The serotonin reuptake process is observed in the central nervous system and in cells derived from the neural crest. It would therefore be of great interest to visualize this reuptake for brain exploration and to visualize the tumors derived from these cells (Apudome). Fluvoxamine has been described as a specific uptake inhibitor for serotonin uptake and we therefore supposed that an iodinated derivative of this compound would be a suitable tracer for this purpose. We had shown by computer-assisted investigation that the trifluoromethyl group of fluvoxamine can be replaced by iodine without changing the steric hindrance of the structure. We therefore expected that this result would allow the development of a new iodinated ligand for human exploration by SPECT which would inhibit for the serotoninergic transporter. This new ligand is 4′-iodo-5-methoxyvalerophenone O-(-2-aminoethyl)oxime in its E configuration. In vitro binding studies demonstrated that this iodinated ligand has a weaker affinity for the serotonin uptake sites than fluvoxamine. Steric hindrance is not sufficient to predict affinity, other structural factors such as electronic density and dipole moment must be considered to explain the biological difference between fluvoxamine and its iodinated analog.