Two unusual conjugated fatty acids, parinaric acid and α-eleostearic acid, are present in several Impatiens species, but not in congener Hydrocera triflora

Parinaric and α-eleostearic acids are unusual conjugated fatty acids. Unusual fatty acids, in general, are known to have roles in defense response; however, the role of parinaric acid in I. balsamina is not known, nor is it known whether it occurs in different species of Impatiens or its closest monotypic relative, Hydrocera triflora (L.) Wight & Arn. The aim of the study was to (a) characterize the fatty acid composition of 21 species of Impatiens and H. triflora and (b) determine whether parinaric and α-eleostearic acids are present in these taxa and, if so, (c) whether there is interspecific and intraspecific variation in parinaric acid content. Fatty acid profiling was done using gas chromatography and mass spectrometry (GC–MS). To uncover taxonomic patterns of variation in fatty acids, principal component analysis and hierarchical cluster analysis were performed. The major fatty acids in Impatiens were found to be palmitic (5.57–20.85%), stearic (2.86–21.61%), oleic (2.79–28.99%), linoleic (C18:2Δ 9,12 , 2.04–26.64%), α-linolenic (C18:3∆ 9,12,15 ; 11.07–53.99%), and four forms of parinaric acid (5.93–70.21%). Genus Impatiens contains two unusual conjugated fatty acids- parinaric and α-eleostearic, however these are absent in closely related H. triflora. This study reports the presence of four different forms of parinaric acid in Impatiens for the first time. Some species ( I. mengtszeana , I. racemulosa and I. oppositifolia ) were found to contain very high levels (> 50%) of parinaric acid and they might be useful for various biomedical and industrial applications. Apparently, the presence of parinaric acid is a characteristic of Impatiens. Significant variations were found in the amount and forms of parinaric acid. We propose the potential application of parinaric acid and α-eleostearic acid as chemotaxonomic markers for Impatiens.