γ-linolenic acid purification from seed oil sources by argentated silica gel chromatography column

The polyunsaturated fatty acid gamma -linolenic acid (GLA,18:3 omega6), which has several pharmaceutical properties, has been purified from the seed oil of three plant species, Anchusa azurea, Scrophularia sciophila and Echium fastuosum. The process consists of four main steps, (i) simultaneous extraction and saponification of the seeds; (ii) urea fractionation method; (iii) urea-concentrate methylation; (iv) argentated silica gel column chromatography of the urea-concentrate methylated. Argentated silica gel chromatography yields high purity GLA in the process in A. azurea and S. sciophila, with yields in the combined process of 73 and 64%, respectively. With E. fastuosum, the recovery for the combined process was 60%, with a final purity 86%, due to the presence of the alpha -linolenic acid (ALA, 18.3 omega3), which elutes with GLA in the chromatography column. The suitability of a process without urea concentration is also compared and discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.