Design of group IIA secreted/synovial phospholipase A(2) inhibitors: an oxadiazolone derivative suppresses chondrocyte prostaglandin E(2) secretion.

Group IIA secreted/synovial phospholipase A(2) (GIIAPLA(2)) is an enzyme involved in the synthesis of eicosanoids such as prostaglandin E(2) (PGE(2)), the main eicosanoid contributing to pain and inflammation in rheumatic diseases. We designed, by molecular modeling, 7 novel analogs of 3-{4-[5(indol-1-yl)pentoxy]benzyl}-4H-1,2,4-oxadiazol-5-one, denoted C1, an inhibitor of the GIIAPLA(2) enzyme. We report the results of molecular dynamics studies of the complexes between these derivatives and GIIAPLA(2), along with their chemical synthesis and results from PLA(2) inhibition tests. Modeling predicted some derivatives to display greater GIIAPLA(2) affinities than did C1, and such predictions were confirmed by in vitro PLA(2) enzymatic tests. Compound C8, endowed with the most favorable energy balance, was shown experimentally to be the strongest GIIAPLA(2) inhibitor. Moreover, it displayed an anti-inflammatory activity on rabbit articular chondrocytes, as shown by its capacity to inhibit IL-1beta-stimulated PGE(2) secretion in these cells. Interestingly, it did not modify the COX-1 to COX-2 ratio. C8 is therefore a potential candidate for anti-inflammatory therapy in joints.

Antioxidative properties of galantamine on neuronal damage induced by hydrogen peroxide in SK-N-SH cells.

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 2h 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 24h, nitrite generation was increased by twice compared with 2h. 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 24h. 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.

Inhibition of secretory phospholipase A2. 1-design, synthesis and structure-activity relationship studies starting from 4-tetradecyloxybenzamidine to obtain specific inhibitors of group II sPLA2s.

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).

Differential effect of PMS777, a new type of acetylcholinesterase inhibitor, and galanthamine on oxidative injury induced in human neuroblastoma SK-N-SH cells.

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.

Inhibition of secretory phospholipase A2. 2-Synthesis and structure-activity relationship studies of 4,5-dihydro-3-(4-tetradecyloxybenzyl)-1,2,4-4H-oxadiazol-5-one (PMS1062) derivatives specific for group II enzyme.

We have recently reported the discovery of a series of specific inhibitors of human group IIA phospholipase A(2) (hGIIA PLA(2)) 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 PLA(2) versus porcine group IB PLA(2). The SAR results, as well as the logP and pK(a) values of oxadiazolone determined in this work, provide important information towards the comprehension of the mode of action of this kind of compounds.