Occurrence and characterization of oils rich in gamma-linolenic acid Part II: fatty acids and squalene from Macaronesian Echium leaves

Leaves from 25 Macaronesian Echium (Boraginaceae) species have been surveye d for hydrocarbon compounds. These plants were previously reported as the m ajor source of gamma-linolenic acid so far found in nature. In addition, si x European Echium species and the common Borago officinalis have been analy sed for comparative purposes. High squalene amounts were found in all Echiu m plants from the Macaronesia, ranging from 3.73% in E. simplex to 20.11% i n E. fastuosum. Squalene was almost absent from all European Echium species , and the same is true for B. officinalis. The relatively high oil content (2.27%) in leaves of E. fastuosum raises the total squalene amount to about 0.46% within this tissue. The main fatty acid component in the leaf was al pha-linolenic acid (ALA, 18:3 omega 3), ranging in the Macaronesian Echium from 9.32% in E. acanthocarpum to 54.45% in E. simplex. Possible utilisatio n of these plants as a commercial source of squalene and hypotheses about i ts physiological role in the plant are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.