Chemotaxonomic perspectives of the Paracaryum (Cynoglosseae, Boraginaceae) taxa based on fruit fatty acid composition

Paracaryum is a medium sized genus in Cynoglosseae. This study represents the most comprehensive phytochemical investigation of Paracaryum to date. The fatty acid compositions of the fruits of ten Paracaryum taxa belonging to three different subgenera were investigated for chemotaxonomic allocation using gas chromatography. The fatty acid profiles of seven Paracaryum taxa, five of which are endemic to Turkey, were recorded for the first time. Among the twenty-two analysed fatty acids, oleic, linoleic and α-linolenic acids were the major fatty acids represented. The oleic acid content ranged from 22.1% in P. hirsutum to 51.7% in P. lithospermifolium subsp. cariense var. erectum; linolenic acid content ranged from 8.6% in P. lithospermifolium subsp. cariense var. erectum to 20.7% in P. erysimifolium; α-linolenic acid content ranged from 7.5% in P. lithospermifolium subsp. cariense var. erectum to 13.5% in P. cristatum subsp. cristatum; gamma linolenic acid content ranged from 2.8% in P. erysimifolium to 6.0% in P. hirsutum. Additional fatty acids also displayed varying levels in different species; palmitic acid content accounted for 17.7% in P. erysimifolium, erucic acid content was 8.73% in P. strictum, eicosenoic acid content was 6.0% in P. cristatum subsp. cristatum, eicosadienoic acid content was 4.4% in P. hirsutum, and stearic acid content was 4.3% in P. erysimifolium. The classification of the tribe Cynoglosseae remains controversial despite the many intensive morphological and phylogenetic investigations that have been carried out. Our fatty acid data from Paracaryum were analysed together with previously recorded fatty acid data from Cynoglosseae s.l. taxa to examine the chemotaxonomic contribution to the classification among taxa in Cynoglosseae by multivariate methods, including the unweighted pair group method with arithmetic mean and principal component analysis. An assessment of these chemometrics data supported the chemotaxonomic position of the genus Paracaryum in the tribe Cynoglosseae. While the principal component graphic did not depict clear separation of the three subgenera of Paracaryum, the principal component analysis revealed the chemotaxonomic significance of palmitic, linoleic, capric, and oleic acids.