Antioxidant and prooxidant role of beta-carotene in murine normal and tumor thymocytes: effects of oxygen partial pressure

Gabriella Calviello, Paola Palozza, C Luberto, P Ricci, Bartoli Gm

Risultato della ricerca: Contributo in rivistaArticolo in rivistapeer review

Abstract

The effects of the partial pressure of oxygen (pO2) on antioxidant efficiency of beta-carotene in inhibiting radical-initiated lipid peroxidation were studied in murine normal and tumor thymocytes. At 150 mm Hg pO2 (the pressure of oxygen in normal air), beta-carotene acted as an antioxidant, inhibiting radical-induced lipid peroxidation in both normal and tumor thymocytes. At 760 mm Hg p02, beta-carotene lost its antioxidant activity in normal thymocytes and exhibited a dose-dependent prooxidant effect in tumor thymocytes. In these cells, the prooxidant effect of beta-carotene was also accompanied by an increase of endogenous alpha-tocopherol loss. beta-Carotene radical-trapping and autooxidation reactions were faster at 760 mm Hg pO2 than at 150 mm Hg pO2 in both normal and tumor thymocytes and the carotenoid was more rapidly consumed in tumor cells. These data point out a key role of the oxygen tension on the antioxidant effectiveness of beta-carotene. They also show a selective prooxidant effect of beta-carotene under 100% oxygen in tumor cells.
Lingua originaleEnglish
pagine (da-a)1065-1073
Numero di pagine9
RivistaFREE RADICAL BIOLOGY & MEDICINE
Stato di pubblicazionePubblicato - 1997

Keywords

  • beta-carotene
  • prooxidant

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