The influence of deleterious UV radiation on collagen molecules in the absence and presence of ascorbic acid using UV-vis and FT-IR spectroscopy has been studied. Intensity of UV-vis absorption spectrum of collagen with a maximum at 275 m due to the aromatic residues (tyrosine and phenylalanine) increases with the increasing dose of UV radiation. This effect is significantly hindered in the presence of antioxidant ascorbic acid. Intensities of FT-IR bands (amide A, B, I and II) of collagen decrease with the increase of the UV radiation dosage. Intensities of bands are also decreased in the presence of ascorbic acid. Results suggest that increasing the concentration of ascorbic acid increases the photo-stability of collagen, and the collagen becomes less sensitive to UV radiation. It is possible that hydrogen bonds form between the groups N-H of collagen and C=O of ascorbic acid. It is believed that under UV radiation free radicals appear in acid soluble collagen and resulting in photodegradation of the macromolecule restore due to the ability of ascorbic acid donating one or two electrons. Increasing the dose of radiation causes more molecules of ascorbic acid to slow down, and their antioxidant effect is diminished accordingly.
(c) 2009. Published by Elsevier Inc.