Protective effect of ligand-binding proteins against folic acid loss due to photodecomposition

The B group vitamin known as folates is essential for a variety of physiological processes and plays an important role in the prevention of neural tube defects. However, it decomposes when exposed to UV light. In this study, the response of the synthetic form of folates known as folic acid to UV irradiation in the presence of β-lactoglobulin (β-LG), bovine serum albumin (BSA) and α-lactalbumin (α-LA) was investigated using circular dichroism, absorbance and fluorescence spectroscopy. Photodecomposition of folic acid was delayed in the presence of the proteins, which ranked in the order β-LG > BSA > α-LA in terms of effectiveness. Protein unfolding or decomposition occurred at the same time, due to interaction with folic acid photodecomposition products. The results suggest potential uses of ligand-binding proteins as carriers of water-soluble active compounds for nutraceutical applications.