Details

Autor(en) / Beteiligte

• Fuentes, Jocelyn
• Atala, Elias
• Speisky, Hernan

Titel

A QUERCETIN OXIDATION PRODUCT WITH EXTREMELY POTENT ANTIOXIDANT AND CYTOPROTECTIVE PROPERTIES

Ist Teil von

• Annals of nutrition and metabolism, 2017-10, Vol.71 (Suppl. 2), p.1231

Ort / Verlag

Basel: S. Karger AG

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Background and objectives: Within the frame of our studies on the redox consequences associated with the oxidation of polyphenols, we recently reported that the oxidation of quercetin leads to the formation of a mixture of metabolites whose ROS-scavenging properties are similar to those displayed by the non-oxidized flavonoid (Food Chem. 234:479-485, 2017). In the present work we established the identity of such metabolites, isolated them and investigated their antioxidant and cytoprotective properties in cultured cells. Methods: The identification and isolation of the metabolites was done chromatographically by means of HPLC-DAD and HPLC-ESI-MS/MS. Each metabolite was added to Hs-68 and Caco2 cells that were exposed to indomethacin or to hydrogen peroxide as ROS-generating agents. The antioxidant and cytoprotective effects of these compounds were evaluated through their dichlorodihydrofluorescin oxidation-inhibiting and LDH leakage-preventing activities, respectively. Results: Under the chromatographic conditions employed by us, twelve major metabolites were evident. Of these, only one, identified as 2,5,7,3',4'-pentahydroxy-3,4-flavandione (FD), was able to account for the antioxidant and cytoprotective effects afforded by the whole oxidized quercetin mixture. Notably, FD exerted such effects at low nanomolar concentrations (1-10 nM), revealing that its antioxidant and cytoprotective potency is threeto-four orders of magnitude greater than that of quercetin (which was effective only at near 10 μM concentrations). Almost identical results were seen in Hs-68 or Caco2 cells. The effects of the flavandione (5 nM) were equally seen regardless of whether this compound was added to the cells 40 min before the ROS-generating agents (namely, pre-incubated and washed-off after) or together with the latter (i.e., co-incubated during 40 min); thus, suggesting that the FD is able to early trigger antioxidant responses intracellularlly. Conclusions: The present results demonstrate for first time that a product of quercetin oxidation is not only active in preventing cells from oxidation and lytic damage, but also reveal that in the case of the FD formed, this metabolite is three-to-four orders of magnitude more potent than quercetin. The present results strongly suggest that when it comes to the antioxidant actions of quercetin, our attention should be increasingly extended towards some of its oxidation products.