Correspondence

The high morbidity, high socioeconomic costs and lack of specific treatments are key factors that define the relevance of brain pathol-ogy for human health and the importance of research on neuronal protective agents. Epidemiological studies have shown beneficial effects of flavonoids on arteriosclerosis-related pathology in gen-eral and neurodegeneration in particular. Flavonoids can protect the brain by their ability to modulate intracellular signals promot-ing cellular survival. Quercetin and structurally related flavonoids (myricetin, fisetin, luteolin) showed a marked cytoprotective ca-pacity in in vitro experimental conditions in models of predomi-nantly apoptotic death such as that induced by medium concentra-tions (200 µM) of H2O2 added to PC12 cells in culture. Neverthe-less, quercetin did not protect substantia nigra neurons in vivo from an oxidative insult (6-hydroxydopamine), probably due to difficulties in crossing the blood-brain barrier. On the other hand, treatment of permanent focal ischemia with a lecithin/quercetin preparation decreased lesion volume, showing that preparations that help to cross the blood-brain barrier may be critical for the expression of the effects of flavonoids on the brain. The hypo-thesis is advanced that a group of quercetin-related flavonoids could become lead molecules for the development of neuroprotec-tive compounds with multitarget anti-ischemic effects