VitVitamin-C imported from the intestine is present in plasma, almost exclusively in the reduced form as AFR (Ascorbate Free Radical) and DHA (Dehydroascorbate) and is also transported to tissues to play a variety of roles. Ascorbate donates either one or two electrons in redox reactions. At physiological pH, more than 99 percent of Ascorbate is in the monoanion form. Loss of the first electron results in the formation of AFR. The AFR, although a stronger reducing agent than Ascorbate, is stabilized by resonance on the three-ring oxygens and is not very reactive. Mild oxidants such as Fe3+(CN)6 (Ferricyanide) remove a second electron and convert the AFR to DHA and itself gets reduced to Fe2+(CN)6 (Ferrocyanide). Ferricyanide reduction is associated with increased intracellular ATP generation. PMOR (Plasma Membrane Oxidoreductases), a multienzyme complex that includes NADPH- Ferricyanide Reductase and NADPH Oxidase along with Cytochrome-B5 Reductases play a vital role in the conversion of AFR to DHA. Despite the term ‘acid’ in its common name, DHA is uncharged at physiological pH. This lack of charge increases its ability to diffuse across the plasma membrane and it also gets transported to the cytoplasm through GLUTs (Glucose Transporters). GLUTs do not transport Ascorbate in vivo (Ref.3). DHA is unstable at physiological pH and unless reduced back to Ascorbate, it undergoes irreversible ring opening to form 2,3-Diketo-1-Gulonic Acid. Once inside cells, DHA is very rapidly reduced to Ascorbate, either directly by Glutathione or in reactions catalyzed by TxnRd (Thioredoxin Reductase) or Glrx (Glutaredoxin). NADH-dependent mechanisms may also contribute to this mechanism. Inside the cells Vitamin-C activates cytoplasmic P4H enzymes in order to facilitate strengthening of tissues (Ref.4).