Reactivity of ubiquinones and ubiquinols with free radicals.
The reactivity of quinones 1-4 and of the corresponding quinols 5-8 towards carbon- and oxygen-centred radicals were studied. All quinones bearing at least one nuclear position free, readily react with alkyl and phenyl radicals to afford the alkylated quinones 12-24; however, quinones 1 and 3 reacted with 2-cyano-2-propyl radical to yield products (the mono- and di-ethers 9-11) derived from the attack on the carbonylic oxygen. The reactions carried out on quinones with the benzoyloxy radical led to no reaction products and in the case of Q10, the isoprenic chain also remained unchanged. Quinols 5-8 reacted only with oxygen-centred radicals (benzoyloxy and 2-cyano-2-propyl-peroxy radicals) to give the corresponding quinones. The isoprenic chain of Q10 did not undergo attack even with peroxy radicals. Carbon-centred radicals resulted unable to abstract hydrogen from the studied quinols.
Giorgini
E
E
Dipartimento di Scienze dei Materiali e della Terra, via Brecce Bianche, Università, I-60131 Ancona, Italy.
Tommasi
G
G
Stipa
P
P
Tosi
G
G
Littarru
G
G
Greci
L
L
D005609:Free Radicals / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism*
D005609:Free Radicals; D014451:Ubiquinone; C003741:ubiquinol