Antioxidant activity and stability of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

Abstract

Abstract6‐Hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid in thin layer tests in vegetable oils and animal fats has two‐four times the antioxidant activity of butylated hydroxytoluene and butylated hydroxyanisole and is more active than propyl gallate, nordihydroquaiaretic acid, ascorbyl palmitate, and α‐ and γ‐tocopherols. It is also more active than tertiary butylhydroquinone in chicken and pork fats and corn, peanut, sunflower, and safflower oils in thin layer tests. Tertiary butylhydroquinone is slightly more active in corn, soybean, cottonseed, and peanut oils in the active oxygen method, probably due to decomposition of the chroman at 98 C. This decomposition is inhibited by ascorbic acid. The chroman is synergized by ascorbyl palmitate‐thiodipropionate and ascorbic acids. Active oxygen method values of 190 hr are obtained in combination with the latter. A spectrofluorometric assay for 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid has been developed. The compound is 95–100% stable for 2 months at room temperature and 45 C, and a low level of toxicity is found. The copper and iron breakdown products of the chroman have been determined. A possible relationship between these products, protection of the chroman by ascorbic acid and ethylene diaminetetraacetic acid, and a mechanism of action is presented.