Flavonoids and health: end or beginning of an era?

C. G. FRAGA; M. GALLEANO

Siena

Conferencia; II International Conference on Environmental Stressors in Biology & Medicine; 2011

Universidad de Siena

Polyphenols include several groups of naturally occurring plant compounds, which biological effects could explain some of the health benefits linked to the consumption of fruit and vegetables. Polyphenols molecular actions depend on the active chemical species (parent compound or metabolite), and on the amount available to interact with the target entity. Presence of flavonoids, a special type of plant polyphenols, ranges from sub-nanomolar to high micromolar concentrations, and are mainly dependent on the tissue and the conditions of polyphenol administration. Within the interest of the free radical field, flavonoids have and are being extensively studied as antioxidants. However, when compared with other molecules with antioxidant actions, polyphenols can only be efficient in scavenging radicals in a limited number of cell and tissues. Under these considerations, the study of the flavonoid effects on vascular health and hypertension has advanced steadily in the last years, providing evidence on the mechanisms relating flavanol consumption/presence and the regulation of vascular function,  involving the modulation of the oxidant/antioxidant balance. Among the events explaining the effects of flavanols on the vasculature, the following are relevant: i) NADPH oxidase regulation and superoxide production; ii) eNOS regulation and NO production; iii) regulation of NF-êB and other redox-sensitive signaling molecules involved in inflammation. Many of these actions seem to be interrelated, e.g. superoxide and NO regulation; and/or mediated by membrane related events, i.e. TNFá-mediated effects. Applying these results to vascular health, as paradigm of flavonoids effects on health, it can be concluded that: i) the era of reducing flavonoids effects on biological systems to generic antioxidant effects is ended; and ii) we are at the beginning of an era that considers specific flavonoid interactions with target molecules operating at significantly lower concentrations of flavonoids and that are compatible with their actual presence in most cells and tissues. Supported by UBACyT (01-1111). CGF is member of CIC, CONICET, Argentina.