The redox couple between glutathione and ascorbic acid: A chemical and physiological perspective

Intracellular ascorbic acid enhances the DNA single-strand breakage and toxicity induced by peroxynitrite in U937 cells

“…One of these systems is represented by facilitated diffusion by the glucose transporter that efficiently takes up DHA, the two-electronoxidized form of AA, whereas AA itself is a poor ligand for this transporter [26,27]. Once within the cell, DHA is rapidly converted into AA via GSH-dependent mechanisms that can be both chemical [28][29][30] and enzymic [30][31][32], as well as by GSHindependent mechanisms [22] that are more frequently involved in the reduction of low levels of DHA [33]. Exposure to micromolar concentrations of DHA therefore seems to be an ideal strategy for increasing the intracellular AA content in the absence of the undesirable parallel effects encountered with AA.…”

Hybridization kinetics is different inside cells

“…For example, the concentration calibration can be misguided through intracellular fluorescence quenching by reducing agents (32) or bleaching. However, control measurements with glutathione and ascorbic acid at typical intracellular concentrations (33,34) showed only an effect of a few percent on the determined concentration (Fig. S7B).…”

Dehydroascorbic acid uptake in a human keratinocyte cell line (HaCaT) is glutathione-independent

“…Transport studies have revealed that there are at least two different systems involved in the cellular uptake of vitamin C in mammalian cells ; a Na + -dependent co-transporter for AA [6], and a facilitative glucose transporter for DHA [7]. Following its uptake, DHA can be reduced to ascorbate in an enzymic or non-enzymic manner through a direct chemical reaction with reduced glutathione [8]. The exact nature of the systems involved in DHA reduction in human cells is still under debate, though a tissue-specific difference appears to be implicated.…”