Chromatographic fractionation and analysis of the main components of eggplant ( Solanum melongena L.) leaf cuticular waxes

Abstract

The composition of eggplant ( Solanum melongena L.) leaf cuticular waxes was investigated. Chemical composition was determined as the first step in recognizing the importance to insect pest resistance of eggplant leaf surface chemistry. Waxes were extracted by dipping leaves into dichloromethane for 40 s. Relatively large samples were then fractionated by 'flash chromatography' on silica gel. Compounds were identified on the basis of their mass spectra from GC-MS analysis and retention data from GC-FID analysis, and quantified on the basis of peak areas from GC-FID analysis. Straight-chain alkanes and methyl-branched alkanes were the most abundant wax components. Minor quantities of esters of fatty acids with triterpene and aliphatic alcohols, free triterpene and aliphatic alcohols, sterols, and free fatty acids were also present on the eggplant leaf surface. This method is suitable for analysis of complex mixtures of plant cuticular lipids. It is also applicable to separation of samples for biological tests on insects.