Protection of resveratrol against the photodecomposition of folic acid and photodecomposition-induced structural change of beta-lactoglobulin

Folic acid is a synthetic form of the B-group vitamin known as folate and essential for a variety of physiological processes. However, it decomposes under UV irradiation, causing indirect oxidation and structural change of protein. In this study, the protective effect of resveratrol against the photodecomposition of folic acid and its caused protein structural change was investigated by using fluorescence and absorbance spectroscopy, high performance liquid chromatography and ABTS assay. It was found that resveratrol could inhibit the folic acid decomposition and control the decomposition process, depending on the polyphenol concentration and addition time. Transformation of resveratrol was accelerated by photodecomposition of folic acid. Antioxidant activity of resveratrol was important for the protective effect. Moreover, resveratrol could also inhibit the unfolding of beta-lactoglobulin caused by the folic acid decomposition by using circular dichroism.