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Photodegradation of cobalamins in aqueous solutions and in human blood

Paper ID Volume ID Publish Year Pages File Format Full-Text
29443 44405 2013 8 PDF Available
Title
Photodegradation of cobalamins in aqueous solutions and in human blood
Abstract

•Adenosylcobalamin- and methylcobalamin are converted to hydroxocobalamin during UVA exposure.•Hydroxocobalamin and cyanocobalamin are the most stable cobalamins.•Cobalamins may photodegrade indirectly due to their antioxidant properties.•Exposure of humans to sun in Norway does not have effect on serum vitamin B12 levels.

Vitamin B12 (cobalamin) is required for proper red blood cell formation, neurologic function, and DNA synthesis. Cobalamins in solutions are light sensitive, but no comprehensive study has been performed to compare the photostability of different cobalamins under UVA exposure. Their indirect photodegradation due to their antioxidant properties and their photostability in vivo have also not been studied so far.The photodegradation of four cobalamins (methylcobalamin (MeCbl), adenosylcobalamin (AdCbl), hydroxocobalamin (OHCbl) and cyanocobalamin (CNCbl)) under UVA exposure in aqueous solutions (pH = 7.4) have been investigated by absorption spectroscopy. The photodegradation of OHCbl in the absence and presence of the endogenous photosensitizer riboflavin was studied. Serum vitamin B12 concentrations before and after summer were measured in four patients with psoriasis.All studied cobalamins are photolabile. The biologically active forms of cobalamin, AdCbl and MeCbl, are converted to OHCbl within seconds during UVA exposure. OHCbl is the most stable cobalamin. However, reactive oxygen species increases the degradation rate of OHCbl. Our pilot study on humans demonstrates that serum vitamin B12 concentrations are not significantly affected during summertime in Norway. Further work is needed to determine vitamin B12 photostability in humans living at lower latitudes or using sunbeds.

Keywords
Vitamin B12; Cobalamin; Adenosylcobalamin; Cyanocobalamin; Methylcobalamin; Hydroxocobalamin
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Photodegradation of cobalamins in aqueous solutions and in human blood
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology B: Biology - Volume 122, 5 May 2013, Pages 7–14
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us