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NEUROPHARMACOLOGY
Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche e Farmacologiche, University of Piemonte Orientale "Amedeo Avogadro", Novara, Italy
The endolipid N-palmitoylethanolamine (PEA) shows a pleiotropic pattern of bioactivities, whose mechanistic characterization is still unclear and whose pharmacological potential is substantially limited by rapid metabolization by the amido hydrolyzing enzymes fatty acid amide hydrolases and N-acylethanolamine-hydrolyzing acid amidase. To overcome this problem, we have synthesized a new series of PEA homologs and characterized their activity on two in vitro models of neurodegeneration (oxidative stress, excitotoxicity). PEA partially prevented tert-butylhydroperoxide (t-BOOH; 100 µM; 3 h)-induced cell death (maximal effect, 26.3 ± 7.5% in comparison with t-BOOH-untreated cells at 30 µM), whereas it was ineffective against the L-glutamate (1 mM; 24 h)-induced excitotoxicity at all concentrations tested (0.0130 µM). Oxyhomologation of the amide bond, although leading to an increased enzymatic stability, also potentiated neuroprotective activity, especially for N-palmitoyl-N-(2-hydroxyethyl)hydroxylamine (EC50 = 2.1 µM). These effects were not mediated by cannabinoid/vanilloid-dependent mechanisms but rather linked to a decreased t-BOOH-induced lipoperoxidation and reactive oxygen species formation and L-glutamate-induced intracellular Ca2+ overload. The presence of the hydroxamic group and the absence of either redox active or radical scavenger moieties suggest that the improved neuroprotection is the result of increased metal-chelating properties that boost the antioxidant activity of these compounds.
Address correspondence to: Grazia Lombardi, Dipartimento di Scienze Chimiche, Alimentari, Farmaceutiche, e Farmacologiche, University of Piemonte Orientale "Amedeo Avogadro", Via Bovio, 6, 28100 Novara, Italy. E-mail: lombardi{at}pharm.unipmn.it