Composition of triacylglycerols containing cyclopropene fatty acids in seed lipids of Munguba (Bombax munguba Mart.)

The seed lipids of Munguba (Bombax munguba Mart., Bombacaceae) were found to contain substantial proportions (ca. 30%) of cyclopropene acyl moieties (sterculoyl and malvaloyl). In a novel approach to the analysis of glycerolipids containing cyclopropene acyl moieties, the triacylglycerols of Munguba seed were first treated with silver nitrate in acetonitrile-acetone (1:1, v/v), in order to convert the cyclopropene groups to the correspondingα,β-unsaturated ketones. The resulting triacylglycerols were fractionated by thin layer chromatography into molecular species containing none, one and two keto (corresponding to none, one and two cyclopropene) acyl moieties per molecule. Each of these molecular species was further fractionated according to carbon numbers by gas chromatography, and the positional distribution of the acyl moieties in each species was determined. Both sterculoyl and malvaloyl moieties were found predominantly at thesn-2 position of the triacylglycerols. The major triacylglycerols of Munguba seed were found to be 1,3-dipalmitoyl-2-oleoylglycerol, 1,3-dipalmitoyl-2-linoleoylglycerol and 1,3-dipalmitoyl-2-sterculoylglycerol.