Interconversion of α-tocopherol and its oxidation products

α-Tocopheroxide is not readily reduced polarographically and in mixtures with α-tocopherol does not give a stable electromotive potential; thus α-tocopheroxide is not the electromotively active, bivalent oxidation product detectable polarographically. Various experiments are reported on the conversion of α-tocopheroxide to α-tocopherol and to α-tocopherylquinone; under weakly acidic conditions α-tocopheroxide readily forms α-tocopherylquinone, whereas under similar conditions with ascorbic acid present α-tocopherol is formed. The formation of a common intermediate with a hemi-ketal structure in both reactions is considered as a likely possibility. No intermediate was detected spectrophotometrically during the slow conversion of α-tocopheroxide to α-tocopheryl;quinone near neutral pH. Treatment of α-tocopherylquinone in absolute ethanol with ascorbic and hydrochloric acids converts the quinone principally to α-tocopherol, or a product closely resembling α-tocopherol, by a pathway not involving α-tocopherylhydroquinone; with some preparations considerable amounts of products of unknown structure are formed. Ascorbate and α-tocopherol act synergistically in the prevention of the acceleration by cytochrome c of the oxidation of linoleate near neutral pH. Neither α-tocopheroxide or α-tocopherylquinone are effective with or without ascorbate. The implications of these and other findings are discussed.


The determination of vitamin C in normal human plasma and erythrocytes

The concentration of total vitamin C in plasma is higher than that in erythrocytes, freed as far as possible from leucocytes, when the concentration in plasma is high. When the concentration in plasma is low the reverse relationship holds. In contrast, the concentration of ascorbic acid in plasma tends to be higher than that in erythrocytes at all levels.


BLOOD ASCORBIC ACID LEVEL IN BIOFLAVONOID AND ASCORBIC ACID THERAPY OF COMMON COLD

Great paper that shows the RDA doses of vitamin do not do a damn thing.


Vitamin C and Rheumatoid Arthritis.

The concept of a direct relationship between vitamin C deficiency and rheumatoid arthritis has not been completely abandoned and, in view of the complexity of these relationships, should not be discarded. The idea lingers that somehow a prolonged period of “subclinical” deficiency of the vitamin might lead to irreversible damage to connective tissues. Is there a benefit to be derived from vitamin C more than the mere prevention of obvious disease? The League of Nations Health Organization recommends a daily intake of 30 mg. of vitamin C for the requirement of a normal human adult. This quantity allows a margin of safety over the 10 mg. amount found to prevent or alleviate symptoms of scurvy in the Sheffield experiment in Britain and in Crandon’s experiment in America. The Food and Nutrition Board of the National Research Council, U.S.A., recommends 75 mg. per day. The food habits and economies of the nations, as well as the manner of evaluation, are reflected in these recommendations. It is of interest that those animals which synthesize their own vitamin C maintain their tissues at near saturation levels, a state which would require a daily intake of 7.5 to 100 mg. for the human adult. At the present time, much ado is being made of the presumed larger amounts of vitamin C needed under so-called conditions of stress. Consequently, some physicians advocate the administration of large amounts of the vitamin during the course of severe infections or after injuries and in other circumstances involving particularly active metabolism. No injurious effects of the vitamin have been revealed. Yet others caution against continued administration of large amounts of a substance whose action is such a complete mystery. It is generally presumed that vitamin C affects various enzymes through reactions mediated by its oxidation-reduction potential.


Acerola juice—The richest known source of Vitamin C

Thirty infants ranging in age from 3 to 7 weeks were given acerola juice as the only significant source of ascorbic acid in their diet. All infants showed average or better growth and development for their age and weight. Ascorbic acid levels in the blood plasma of all infants were above average after the acerola juice was introduced into the diet. No reactions occurred from ingestion or from skin and intradermal tests with acerola juice. Acerola juice can be blended with apple juice which is naturally low in vitamin C, and used to satisfy the ascorbic acid requirements in infant feeding. It is particularly valuable in infants who are allergic to orange juice or where the family allergic history deems it advisable to delay giving orange juice until one year of age


West indian cherry—richest known source of natural vitamin C

his fruit yields from 1000 to 4000 milligrams of ascorbic acid per 100 grams of edible matter. It is a potential source of natural Vitamin C which can be exploited to great advantage by canning and other processing industries.


Vitamin C Concentration in Developing and Mature Fruits of Mango (Mangifera indica L.)


VITAMIN C

LESLIE J. HARRIS, Sc.D. D.Sc. Ph.D. F.R.I.C.
British Medical Bulletin, Volume 12, Issue 1, 1 January 1956, Pages 57–60, https://doi.org/10.1093/oxfordjournals.bmb.a069517
Published: 01 January 1956