Pantothenic acid and pantothenol increase biosynthesis of glutathione by boosting cell energetics.

We have previously observed (summarized in BioFactors 17 (2003) 61) that pantothenic acid, pantothenol and other derivatives that are precursors of CoA protect cells and whole organs against peroxidative damage by increasing the content of cell glutathione. The present investigation was aimed to elucidate the mechanism of this increase in human lymphoblastoic (Jurkat) cells. It showed that incubation of the cells with pantothenic acid or pantothenol increased mainly the content of free glutathione, with little effect on protein-bound glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, prevented this increase. Increase of the content of free glutathione, as produced by pantothenic acid or pantothenol, was largely prevented by respiratory chain inhibitor rotenone, inhibitor of mitochondrial ATP synthesis oligomycin and uncoupler of oxidative phosphorylation of carbonyl cyanide 3-chlorophenylhydrazone. These treatments also decreased the cellular content of ATP. Preincubation with pantothenic acid or pantothenol also increased cell respiration with pyruvate as the exogenous substrate. Although no significant increase of total cell CoA content could be found, it is concluded that the increase of the glutathione level was due to increased production of ATP that was, in turn, a result of the increased content of mitochondrial CoA.

Protective role of L-methionine against free radical damage of rat brain synaptosomes.

Incubation of rat brain synaptosomal/mitochondrial fraction with tert-butylhydroperoxide resulted in accumulation of the lipid peroxidation product, conjugated dienes, damage of the synaptosomal membrane as evidenced by leakage of lactate dehydrogenase, and decrease of the total content of glutathione and of the GSH/GSSG ratio. This treatment also produced a considerable decrease of the ouabain-sensitive ATPase activity and a much smaller diminution of the activities of glutathione reductase and glutathione transferase. Preincubation of the synaptosomal/mitochondrial fraction with 0.5 or 1.0 mM L-methionine significantly protected against lipid peroxidation, membrane damage and changes in the glutathione system produced by low (1 mM) concentrations of tert-butylhydroperoxide and completely prevented inactivation of ouabain-sensitive ATPase, glutathione reductase and glutathione transferase by such treatment. The importance of L-methionine in antioxidant protection is discussed.