TY - CHAP
T1 - Vitamin C
AU - Levine, Mark
AU - Katz, Arie
AU - Padayatty, Sebastian J.
AU - Wang, Yaohui
AU - Eck, Peter
AU - Kwon, Oran
AU - Chen, Shenglin
AU - Lee, Jee Hyuk
N1 - Publisher Copyright:
© 2005 by Marcel Dekker. All rights reserved.
PY - 2004/1/1
Y1 - 2004/1/1
N2 - Vitamin C is an electron donor, and this property accounts for its known and postulated functions. As an antioxidant, or reducing agent, the vitamin sequentially donates two electrons from the C2-C3 double bond. The first intermediate, formed by the loss of one electron, is the unstable free radical semidehydroascorbic acid. This intermediate is relatively unreactive and does not interact with other compounds to form potentially harmful free radicals, and can be reversibly reduced to ascorbate. Semidehydroascorbic acid undergoes further oxidation to form the more stable product dehydroascorbic acid (DHA) (Fig. 1), which can be reduced back to ascorbate by glutathione or by three distinct enzymatic reduction reactions.[2,3] If not reduced, DHA undergoes ring rupture and is irreversibly hydrolyzed to 2,3-diketogulonic acid. The latter is metabolized to xylose, xylonate, lyxonate, and oxalate, which is a clinically significant end product of vitamin C metabolism.
AB - Vitamin C is an electron donor, and this property accounts for its known and postulated functions. As an antioxidant, or reducing agent, the vitamin sequentially donates two electrons from the C2-C3 double bond. The first intermediate, formed by the loss of one electron, is the unstable free radical semidehydroascorbic acid. This intermediate is relatively unreactive and does not interact with other compounds to form potentially harmful free radicals, and can be reversibly reduced to ascorbate. Semidehydroascorbic acid undergoes further oxidation to form the more stable product dehydroascorbic acid (DHA) (Fig. 1), which can be reduced back to ascorbate by glutathione or by three distinct enzymatic reduction reactions.[2,3] If not reduced, DHA undergoes ring rupture and is irreversibly hydrolyzed to 2,3-diketogulonic acid. The latter is metabolized to xylose, xylonate, lyxonate, and oxalate, which is a clinically significant end product of vitamin C metabolism.
UR - http://www.scopus.com/inward/record.url?scp=85059710863&partnerID=8YFLogxK
U2 - 10.1081/E-EDS-120022052
DO - 10.1081/E-EDS-120022052
M3 - Chapter
AN - SCOPUS:85059710863
SN - 0824755049
SN - 9780824755041
SP - 745
EP - 755
BT - Encyclopedia of Dietary Supplements
PB - CRC Press
ER -