Abstract
Litchi (Litchi sinensis [L. chinensis]) and longan (Euphoria longana [Dimocarpus longan]) seed oils are known for their high cyclopropanoid fatty acid contents (41.5%) and 18.7, respectively). In these 2 oils, the predominant cyclic fatty acids are the cis-7,8-methylenehexadecanoic (Mh) and cis-9,10-methyleneoctadecanoic (Mo) acids. The distribution of these particular fatty acids in the triacylglycerols was studied. After isolation on an open silica column, the triacylglycerols were analysed by HPLC and silver TLC. The triacylglycerols were then submitted to chemical hydrolysis using ethylmagnesium bromide, a reagent without structural specificity and regioselectivity. The results enabled the triacylglycerol composition to be determined, with particular interest in the 2(1,3)-type isomer. The sn-2 position of the majority of the triacylglycerol molecular species was esterified by oleic acid (O), which was present in the internal position in 50% of fatty acids. Litchi seed oil was characterized by one major triacylglycerol O(MoMo); 26.1% content. The longan seed oil contained 2 major triacylglycerols O(PS) and O(MoMo), where P is palmitic acid and S is stearic acid; 14.0% and 11.2% a, respectively.Litchi (Litchi sinensis [L. chinensis]) and longan (Euphoria longana [Dimocarpus longan]) seed oils are known for their high cyclopropanoid fatty acid contents (41.5%) and 18.7, respectively). In these 2 oils, the predominant cyclic fatty acids are the cis-7,8-methylenehexadecanoic (Mh) and cis-9,10-methyleneoctadecanoic (Mo) acids. The distribution of these particular fatty acids in the triacylglycerols was studied. After isolation on an open silica column, the triacylglycerols were analysed by HPLC and silver TLC. The triacylglycerols were then submitted to chemical hydrolysis using ethylmagnesium bromide, a reagent without structural specificity and regioselectivity. The results enabled the triacylglycerol composition to be determined, with particular interest in the 2(1,3)-type isomer. The sn-2 position of the majority of the triacylglycerol molecular species was esterified by oleic acid (O), which was present in the internal position in 50% of fatty acids. Litchi seed oil was characterized by one major triacylglycerol O(MoMo); 26.1% content. The longan seed oil contained 2 major triacylglycerols O(PS) and O(MoMo), where P is palmitic acid and S is stearic acid; 14.0% and 11.2% a, respectively.