CYCLOPROPANOIC FATTY-ACIDS OF LITCHI (LITCHI-CHINENSIS) SEED OIL - A REINVESTIGATION

Abstract

Semisynthetic cyclopropanoic fatty acids (CPFA), cis-9,10-methylenehexadecanoic acid, cis-7,8-methylenehexadecanoic acid, and dihydrosterculic acid, were obtained from the corresponding olefinic acids. Their chromatographic equivalent chain lengths on two liquid phases (Carbowax 20M and BDS), together with the mass spectral data of the methoxy derivatives, obtained using 50% boron trifluoride in dry methanol, were compared to the CPFA methoxy derivatives isolated from the lipid content of litchi (Litchi chinensis Sonn.) seeds. The fatty acid composition of the litchi seed lipids included palmitic acid (12%), oleic acid (27%), linoleic acid (11%), and CPFA (42%). The CPFA fraction contained dihydrosterculic acid (37%), cis-7,8-methylenehexadecanoic acid (4%), cis-5,6-methylenetetradecanoic (0.4%), and cis-3,4-methylenedodecanoic acid (0.1%). These results show that CPFA from litchi seed lipids belong to the n-9 series as observed in Euphoria longana.