Riboflavin‐photosensitized singlet oxygen oxidation product of vitamin D₂

Abstract

The riboflavin-photosensitized singlet oxygen oxidation of vitamin D 2 in a model system of 12% water and 88% acetone was studied to understand the possible oxidation of fortified vitamin D in milk. Only the samples containing vitamin D 2 and riboflavin under light storage showed two new peaks in the HPLC chromatogram, indicating that singlet oxygen oxidation of vitamin D 2 had occurred. UV analysis indicated that a new compound was formed from the reaction of the triene of vitamin D 2 with oxygen. The mass spectrum showed that one of the two compounds had a molecular ion at m/z = 412, which was an increase of the mass of vitamin D 2 by the mass of exactly one oxygen. The IR spectrum suggested the presence of a hydroxyl group and no carbonyl group in the product. The combined information from UV, MS, and FTIR spectra and the chemical mechanisms of singlet oxygen oxidation of vitamin D 2 indicated that a 5,6-epoxide of vitamin D 2 was formed from vitamin D 2 in the presence of riboflavin under light.

Voltammetric Studies on Vitamins D2 and D3 in Organic Solvents

“…It was proposed in previous studies that vitamin D 3 and D 2 were likely undergoing reactions at the triene moiety [16][17][18][19][20][21]. Similar peak potential values were also obtained for SWV measurements performed in CH 2 Cl 2 solutions (Fig.…”

“…Chemical oxidation experiments on vitamin D 2 and D 3 have been performed using various methods such as permanganate in ethanol [16], selenium dioxide and hydrogen peroxide in dioxane [17], ozone [18], biomimetic oxidation with a combination of ironsulfur protein model cluster and oxygen [19], electrolysis using a metal salt-hematoporphyrin-O 2 -cathodic reduction system [20] and riboflavin-photosensitized singlet oxygen [21]. While the proposed structures of the oxidized products vary, the products showed a common oxidation site at the triene.…”

Chemical Reactions and Stability of Riboflavin in Foods

“…Riboflavin accelerated the oxidation of vitamin D under light via singlet oxygen pathway (Li and Min 1998;Li and others 2000), and major oxidation product was 5, 6-epoxide of vitamin D (King and Min 2002). Riboflavin had no effect on the vitamin D oxidation in the dark (King and Min 1998).…”

Kinetic Study of the Quenching Reaction of Singlet Oxygen by Common Synthetic Antioxidants (tert‐Butylhydroxyanisol, tert‐di‐Butylhydroxytoluene, and tert‐Butylhydroquinone) as Compared with α‐Tocopherol

“…Oxidation in foods induces the loss of important nutrients, color degradation, off‐flavor, and toxic compound formation, and quality deterioration of the foods. Polyunsaturated lipids, amino acids, proteins, vitamins (ascorbic acid, riboflavins, retinyl palmitate, ergosterol, carotenoids, tocopherols), cholesterol, limonene, isoflavone, and conjugated terpenes in various types of foods are extremely susceptible to photooxidation, especially in the presence of photosensitizers (Jung and others 1998a, 1998b; King and Min 1998, 2002; Kim and others 2001, 2003a, 2003b; Yang and others 2007; Lee and Choe 2008; Liu and Yang 2008). Photooxidation occurs through Type I or II reaction pathway.…”