Analysis of Interfering Substances in the Measurement of Malondialdehyde Content in Plant Leaves

The Thiobarbituric Acid (TBA) reactive substances assay is an easy and quick assay for the assessment in plants of lipid peroxidation, in which Malondialdehyde (MDA) is derivatized. To analyze the applicability of this method, the MDA concentrations in the leaves of different plants were measured by the TBA method. To further separate the interfering substances, fractional extraction and Gas Chromatography-Mass Spectrometry (GC-MS) were used in this research. The results suggest that lipid peroxidation is accurately measured by the TBA method with trichloroacetic acid as the extraction solution in most plants. However, the method was not suitable for measuring the MDA concentration in golden privet (Ligustrum × vicaryi) leaves. Negative MDA concentrations were obtained in golden privet leaves by this method. The interfering substance in golden privet leaves, which could react with TBA forming a dark green production (the characteristic absorption peak at 615 nm). This substance was highly lipid soluble and was found at the highest level in golden privet leaves. Compared with ether phase extracted from stems, four different compounds in golden privet leaves were found, which were similar to diethyl hydroxybutanedioate (similarity: 94%), 3,4-dimethoxybenzoic acid (72%) and quinuclidine-2-carboxylic acid, 2,3-dehydro-3amino-ethyl ester (63%) and yramine, N-formyl2-(4-Hydroxyphenyl) ethylformamide (82%), respectively.