Lipids and lipophilic components from seeds of three Boraginaceae species

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In continuation of the search for lipid-bearers containing -3 and -6 acids, we studied lipids from seeds of Lindelofia macrostyla, Trichodesma incanum, and Anchusa italica (Boraginaceae) collected in Tashkent Oblast. These plants have attracted interest because many of their seed oils contain very active essential -3 and -6 fatty acids. Total neutral lipids were isolated by extraction with benzine (bp 72–85°C) in a Soxhlet apparatus. Bound lipids were extracted from the remaining pulp according to Folch [1]. Because a part of the NL was found in the bound fraction, they were separated from the latter by column chromatography with elution by CHCl3; GL, by acetone; PL, by MeOH. The NL obtained from the bound fraction were combined with those previously extracted. The yield of NL from oil of L. macrostyla was 13.9%; from T. incanum, 10.8; from A. italica, 22.6. The maximum content of NL was found in seed oil of A. italica. GL and PL dominated oil from T. incanum seeds. NL from the three studied species contained hydrocarbons, triacylglycerides, esters of cyclic alcohols with fatty acids, free fatty acids, sterols, and diacylglycerides according to TLC on silica gel using hexane:Et2O (4:1 and 1:1). GL were analyzed by TLC on silica gel using CHCl3:(CH3)2CO:MeOH:HOAc:H2O (65:20:10:10:3). It was found that GL from L. macrostyla seed oil consisted of sterolglycosides, esters of sterolglycosides, cerebrosides, esters of cerebrosides, digalactosyldiglycerides, and monogalactosyldiglycerides. GL from seed oil of T. incanum and A. italica had the same composition as that from L. macrostyla but did not contain cerebrosides and their esters. Two-dimensional chromatography was used to separate PL. The first direction used CHCl3:MeOH:NH4OH (25%) (65:25:5); the second, CHCl3:MeOH:HOAc:H2O (14:5:1:1). Phhosphatidylcholines (PC), phosphatidylinositols (PI), phosphatidylethanolamines (PE), phosphatidic acids (PA), and N-acyl-lyso-phosphatidylethanolamines were observed in PL of L. macrostyla seed oil. PL from T. incanum and A. italica had the same composition with the exception of N-acyl-lyso-phosphatidylethanolamines. The emulsions obtained after alkaline hydrolysis of NL, GL, and PL were decomposed by H2SO4 (10%). The released fatty acids were extracted with Et2O, methylated by diazomethane, and analyzed by GC on a Chrom-2 instrument [2]. Table 1 lists the composition of the fatty acids. It can be seen that the qualitative fatty-acid compositions of L. macrostyla and T. incanum seed oils were identical and consisted of 13 components whereas fatty acids from A. italica seed oil numbered 9 components. The principal saturated acid was 16:0; unsaturated, 18:1 and 18:2. Furthermore, seed oil of T. incanum and A. italica also contained significant quantities of -6 and -3-octadecatrienoic acids.