11-OCTADECENOIC ACID AND OTHER FATTY ACIDS OF ASCLEPIAS SYRIACA SEED OIL

Abstract

The seed oil of A. syriaca, family Asclepidaceae, was examined by gas chromatography and distillation of the methyl esters. The fatty acids were found to include a considerable proportion of cis-11-octadecenoic acid, which has not been observed previously in seed oils. It was obtained as a concentrate (80%) by low-temperature crystallization of the C18 acids and identified as 11,12-dihydroxystearic acid. The amount of 11-octadecenoic acid in the oil was determined by oxidative splitting of the total fatty acids and estimation of the resulting azelaic and undecanedioic acids by gas chromatography. The C16 acids included 9,12-hexadecadienoic acid, which is rare in seed oils, and an unusually large proportion of 9-hexadecenoic acid. The percentage composition of the fatty acids was estimated from the data as follows: palmitic 4,9-hexadecenoic 10, 9,12-hexadecadienoic 2, stearic < 1, oleic 15, 11-octadecenoic 15, linoleic 53, linolenic < 1. The unsaturated acids have the cis configuration.