Abstract:
:Hispidulin (6-methoxy-5,7,4'-trihydroxyflavone) and eupafolin (6-methoxy-5,7,3',4'-tetrahydroxyflavone), are flavonoids found in the leaves of Eupatorium litoralle. They have recognized antioxidant and antineoplastic properties, although their action mechanisms have not been previously described. We now report the effects of hispidulin on the oxidative metabolism of isolated rat liver mitochondria (Mit) and have also investigated the prooxidant and antioxidant capacity of both flavonoids. Hispidulin (0.05-0.2 mM) decreased the respiratory rate in state III and stimulated it in state IV, when glutamate or succinate was used as oxidizable substrate. Hispidulin inhibited enzymatic activities between complexes I and III of the respiratory chain. In broken Mit hispidulin (0.2 mM) slightly inhibited ATPase activity (25%). However, when intact Mit were used, the flavonoid stimulated this activity by 100%. Substrate energized mitochondrial swelling was markedly inhibited by hispidulin. Both hispidulin and eupafolin were able to promote iron release from ferritin, this effect being more accentuated with eupafolin with the suggestion of a possible involvement of H2O2 in the process. Hispidulin was incapable of donating electrons to the stable free radical DPPH, while eupafolin reacted with it in a similar way to ascorbic acid. The results indicate that hispidulin as an uncoupler of oxidative phosphorylation, is able to release iron from ferritin, but has distinct prooxidant and antioxidant properties when compared to eupafolin.
journal_name
Free Radic Resjournal_title
Free radical researchauthors
Dabaghi-Barbosa P,Mariante Rocha A,Franco da Cruz Lima A,Heleno de Oliveira B,Benigna Martinelli de Oliveira M,Gunilla Skare Carnieri E,Cadena SM,Eliane Merlin Rocha Mdoi
10.1080/13561820500177659keywords:
subject
Has Abstractpub_date
2005-12-01 00:00:00pages
1305-15issue
12eissn
1071-5762issn
1029-2470pii
W731GN6G80130467journal_volume
39pub_type
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