Microwave-assisted synthesis of hydroxyphenyl nitrones with protective action against oxidative stress.

Oxidative stress plays an important role in neuronal death in neurodegenerative disorders such as Parkinson's disease (PD). Hydroxyphenyl nitrones, derivatives of the nitrone spin trap alpha-phenyl-N-tert-butylnitrone (PBN), were synthesized and their antioxidant, anti-inflammatory and neuroprotective activity in neural cells evaluated. These hydroxyphenyl nitrones 5-7 were synthesized by reaction of the corresponding hydroxybenzaldehyde with N-tert-butyl hydroxylamine under microwave irradiation. They showed good peroxyl free radical scavenger capacities, analyzed by oxygen radical absorbance capacity (ORAC). Also inhibited peroxynitrite-mediated tyrosine nitration of alpha-synuclein in vitro and protected human neuroblastoma (SH-SY5Y) cells against SIN-1 and 6-OHDA toxicity when micromolar concentrations were used. Besides, the hydroxyphenyl nitrones evaluated showed anti-inflammatory activity modulating nitrite production in primary neural cell cultures of astrocytes and microglia treated with lipopolysaccharide (LPS), a potent inflammatory agent. These experimental data suggest a potential therapeutic use of these hydroxyphenyl nitrones against oxygen and nitrogen reactive species involved in neurodegenerative pathology.