| Research Abstract |
A rapid ans sensitive high-performance liquid chloromatographic method for the enantiomer resolution of polyunsaturated sn-1,2- and sn-2,3- diacylglycerols as their 3,5-dinitrophenylurethanes was developed with a chiral column (25 cm long) containing (R)-(+)-1-(1-naphthyl)ethylamine. By an isocratic elution with n-hexane-1,2-dichloroethane-ethanol (40 : 30 : 1 by volume), complete enantiomer resolution was obtained within 15 min for monoacid sn-1,2- and sn-2,3-diacylglycerols of linoleic, linolenic, arachidonic, eicosapentaenoic and docosahexaenoic acids.
The methos was applied to the enantiomer resolution of the sn-1,2(2,3)-diacylglycerol moieties of triacylglycerols and phosphatidylcholines from some marine organisms. The sn-1,2(2,3)-diacylglycerols generated by Grignard degradation from the triacylglycerols of tuna fish orbital, pacific pomfret flesh, sardine flesh, mackerel flesh, salmon egg and scallop hepatopancreas were clearly resolved into two groups, which represented sn-1,2- and sn-2,3-diacylglycerol enantiomers. This clear resolution permits the preparative separation of the enatimeric diacylglycerols on the chiral column and the polar capillary GLC of the collected fractions, which would give the detailed enantiomer composition. Satisfactory enantiomer resolution was obtained for the sn-1,2(2,3)-diacylglycerols generated from the triacylglycerols of saury flesh and sea urchin gonard, although some peak overlapings between sn-1,2-enantiomers containing polyunsaturated acids and sn-2,3-enantiomers containing long-chain monounsaturated acids were observed. The diacylglycerols derived from phosphatidylcholines of saury, pacific pomfret and sea urchin by venom phospholipase C were only the sn-1,2-enantiomers. The method presented was also applied to the determination of the stereospecificity of lipases from porcine pancreas, scallop hepatopancreas and some microorganisms.
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