FLUOROMETRIC-DETERMINATION OF A 1,3-DIETHYL-2-THIOBARBITURIC ACID-MALONDIALDEHYDE ADDUCT AS AN INDEX OF LIPID-PEROXIDATION IN PLANT MATERIALS

A fluorometric method has been developed to measure a 1,3-diethyl-2-thiobarbituric acid (DETBA)-malondialdehyde (MDA) adduct as an index of lipid peroxidation in plant materials. Plant tissue samples were prepared under nitrogen gas and then added to an assay system containing butylated hydroxytoluene. Following the reaction between DETBA and the plant tissue samples, the DETBA-MDA adduct was extracted with ethyl acetate and measured by spectrofluorometry or high-performance liquid chromatography (HPLC) with a fluorescence detector. The species of influencing substances with spectrofluorometry were fewer and their interfering concentration was higher than that by traditional colorimetry. When this method was applied to plant materials, the detection limits for the DETBA-MDA adduct were 2.5 nmol/g of fresh weight and 0.0625 nmol/g of fresh weight by spectrofluorometry and HPLC with a fluorescence detector, respectively. Using this sensitive, specific and simple fluorometric method, DETBA-MDA adducts ranging from 0.8 to 18.0 pmol/g of fresh weight could easily be detected from vegetables, fruits, and potatoes.