INTERNAL AND EXTERNAL DISTRIBUTION OF FAT TY-ACIDS IN THE TRIACYLGLYCEROLS OF 2 CYCLOPROPANIC OILS - LETCHI AND LONGANI

Triacylglycerols in litchi, Litchi sinensis Sonn, and longan, Euphoria longana lam., seed oils are characterised by cyclopropanoic fatty aci ds : cis-9,10-methyleneoctadecanoic acid or dihydrosterculic acid cons titutes 38.0 % of total fatty acids in litchi and 17.4 % in longan whe reas cis-7,8-methylenehexadecanoic acid only constitutes 5.5 % and 1.0 % respectively. Triacylglycerols of these two particular oils underwe nt enzymatic hydrolysis with porcine pancreatic lipase and chemical de gradation with ethylmagnesium bromide, reactive with no chain specifit y or regioselectivity. We have outlined an unequal distribution of cis -7,8-methylenehexadecanoic and cis-9,10-methyleneoctadecanoic acids. T he first is found in the sn-2 position at 84 % in the litchi triacylgl ycerols and at 100 % in the longan triacylglycerols, while the second is located in external positions at 88 % and 92 % respectively. Compar ison of results confirmed the impossibility of using those obtained fr om the enzymatic hydrolysis in order to determine the internal and ext ernal distribution of fatty acids in triacylglycerols containing cyclo propanoic fatty acids.