Influence of Human Serum Albumin on Photodegradation of Folic Acid in Solution

Abstract

It has been proposed that photodegradation of folates may be the reason for the pigmentation of races living under high fluence rates of ultraviolet radiation. The photodegradation of folic acid (FA) induced by ultraviolet-A (UV-A) radiation, in solution and in the presence of human serum albumin (HSA), was studied with absorption and fluorescence spectroscopy. FA photodegradation, with formation of p-aminobenzoyl-l-glutamic acid, 6-formylpterin and pterin-6-carboxylic acid, was found to follow an exponential trend. A scheme of FA photodegradation, which involves photosensitization of FA degradation by its photoproducts, was proposed. The rate of FA photodegradation decreased drastically in the presence of HSA, whereas the spectral characteristics of the photoproducts remained constant. The reduction of the FA photodegradation rate by HSA was accompanied by degradation of tryptophan in HSA. Tryptophan, when added to solutions of FA, had a similar effect as HSA. In solutions of FA and HSA the FA photoproducts cause photodamage mainly to HSA rather than to FA itself. The oxygen dependence of FA photodegradation and the inhibition of this process by sodium azide indicate that singlet oxygen may participate in the photosensitizing activity of FA photoproducts.

Effects of UVA Irradiation on the Concentration of Folate in Human Blood

“…Some investigators 6,7,19) have already shown that PGA was degraded by UVA exposure, however, these experiments just showed the detection of the degraded compounds. No quantitative experiment had been reported.…”

“…The main folate supplement that is available on the market is PGA, which is a synthetic form of folate, and is the oxidized and most stable form of folates. However, the demerit of PGA is that it is destroyed by UVA exposure 6) which partly penetrates into the blood stream. Therefore, there is the possibility of a reduction of the blood folate level with sunlight exposure.…”

“…However, there is a deficit in masking vitamin B 12 deficiency by PGA supplementation which is a more severe deficiency than folate deficiency. 5) Vorobey et al 6) have reported that PGA in an aqueous solution was degraded by UVA. Furthermore, Der-Petrossian et al 7) have reported that extracorporeal exposure of plasma to UVA during extracorporeal photophoresis led to photodegradation of folate.…”

Study of the Interaction of Ciprofloxacin and Sparfloxacin with Biomolecules by Spectral, Electrochemical and Molecular Docking Methods

“…Because of its pharmacological activity, the investigation of the interactions between this compound and biomolecules are very important [13]. Furthermore, binding of drugs to albumin alters the pattern and volume of distribution, lowers the rate of clearance, and increases the plasma half-life of the drug [12][13][14][15].…”

“…It is a globular, multifunctional protein composed of three structurally similar domains each containing two subdomains and having molecular weight of 67 kD stabilized by 17 disulfide bonds [13]. Apart from ligands binding and transport, it involves in maintaining pH and osmotic pressure, preventing photodegradation of folic acid, and is also a marker of inflammatory state [14,15].…”