Antioxidant activity of reduced menadione in solvent solution and in model membranes.
The antioxidant activity of reduced menadione was investigated and compared with that of alpha-tocopherol both in solvent solution and in large unilamellar vesicles by using azocompounds as free radical generators. The results show that: i) reduced menadione behaves as a chain-breaking antioxidant; ii) its inhibition rate constant is similar to that of alpha-tocopherol in homogeneous solution, whereas it is 4 times larger in egg yolk lecithin vesicles; iii) the stoichiometric factor is found lower than 1 in both systems, since a substantial portion of menadiol is consumed by autoxidation and does not contribute to radical trapping; iv) when both alpha-tocopherol and menadiol are present in vesicles, reduced menadione can spare alpha-tocopherol. Data presented here suggest that the reduced form of vitamin K may protect, when present, cellular membranes from free radical damage.
Fiorentini
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D
Dipartimento di Biochimíca G. Moruzzi, Università di Bologna, Italy.
Cipollone
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M
Galli
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MC
Landi
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L
D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D004357:Drug Synergism; D008081:Liposomes / Q000378:metabolism*; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000037:antagonists & inhibitors / Q000378:metabolism; D011809:Quinones / Q000378:metabolism; D012996:Solutions; D012997:Solvents / Q000378:metabolism*; D014810:Vitamin E / Q000378:metabolism / Q000494:pharmacology; D014812:Vitamin K / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology
D000975:Antioxidants; D008081:Liposomes; D010713:Phosphatidylcholines; D011809:Quinones; D012996:Solutions; D012997:Solvents; D014812:Vitamin K; D014810:Vitamin E; C023885:menadiol