PANTOTHENIC-ACID AND ITS DERIVATIVES PROTECT EHRLICH ASCITES TUMOR-CELLS AGAINST LIPID-PEROXIDATION

Preincubation of Ehrlich ascites tumor cells at 22 or 32 degrees C, bu t not at 0 degrees C, with pantothenic acid, 4'-phosphopantothenic aci d, pantothenol, or pantethine reduced lipid peroxidation (measured by production of thiobarbituric acid-reactive compounds) induced by the F enton reaction (Fe2+ + H2O2) and partly protected the plasma membrane against the leakiness to cytoplasmic proteins produced by the same rea gent. Pantothenic acid and its derivatives did not inhibit (Fe2+ + H2O 2)-induced peroxidation of phospholipid multilamellar vesicles, thus i ndicating that their effect on the cells was not due to the scavenging mechanism. Homopantothenic acid and its 4'-phosphate ester (which are not precursors of CoA) neither protected Ehrlich ascites tumor cells against lipid peroxidation nor prevented plasma membrane leakiness und er the same conditions. Incubation of the cells with pantothenic acid, 4'-phosphopanothenic acid, pantothenol, or pantethine significantly i ncreased the amount of cellular CoA and potentiated incorporation of a dded palmitate into phospholipids and cholesterol esters. It is conclu ded that pantothenic acid and its related compounds protect the plasma membrane of Ehrlich ascites tumor cells against the damage by oxygen free radicals due to increasing cellular level of CoA. The latter comp ound may act by diminishing propagation of lipid peroxidation and prom oting repair mechanisms, mainly the synthesis of phospholipids.