Positional‐Species Composition of Triacylglycerols from the Arils of Mature Euonymus Fruits

Abstract

Positional‐species composition (PSC) of 1,2,3‐triacyl‐sn‐glycerols (TAG) from the arils of mature fruits of 13 species of Euonymus L. genus was established. The residues of six major fatty acids (FA), palmitic, stearic, hexadecenoic (H), octadecenoic (O), linoleic (L), and linolenic, were present in the TAG. PSC of TAG was determined by their partial lipase hydrolysis. By using hierarchical cluster and principal component analyses, it was definitely demonstrated that separate taxonomic units forming this genus were significantly distinguished as regards PSC of TAG. In particular, the Euonymus subgenus greatly exceeded the Kalonymus subgenus in both total content of L in TAG and in the rate of its incorporation into their mid‐position, while TAG of Kalonymus were marked by a prevalence of O‐TAG and sn‐2‐O isomers. Thus, these subgenera were significantly distinct in the rate of incorporation of O and L residues in the sn‐2 position of TAG molecules. Meanwhile, the TAG from the Euonymus section species were marked by an enhanced concentration of H and the incorporation of H in UUU TAG was much more active than in other TAG types. As for positional‐type composition of TAG, saturated FA were always virtually absent in the sn‐2 position of Euonymus aril TAG.

Positional‐Species Composition of Diacylglycerol Acetates from Mature Euonymus Seeds

“…. It can be seen that, as in our previous study , all the species studied are grouped into two large clusters. Cluster 2 is formed solely by species belonging to the Euonymus section of Euonymus subgenus, while cluster 1 includes two subclusters: one (1a) consists of species belonging to the Kalonymus subgenus, and the other (1b) is formed by Melanocarya ( E. alatus and E. sacrosanctus ) and Pseudovyenomus ( E. verrucosus and E. pauciflorus ) sections of the subgenus Euonymus .…”

“…Previously, while performing a similar study on TAGs of Euonymus arils, it was established that the theoretical calculations made from lipolysis data are completely applicable for the determination of PSC of TAGs . Such a conclusion was also reached during the recent study of several sunflower oils using GC separation of TAGs along with these calculations.…”

“…, E. sachalinensis Maxim ., E. pauciflorus Maxim . , E. alatus , E. verrucosus , and E. sacrosanctus Koidz ., belonging to several sections of both subgenera of this genus . We have found that the separate taxonomic units of this genus differ from each other at the concentration of major FAs.…”

“…We have found that the separate taxonomic units of this genus differ from each other at the concentration of major FAs. Using statistical analysis, we have demonstrated that the aril TAGs of the Euonymus subgenus species were characterized by the increased content of linoleate, while those of the Kalonymus subgenus, by the predominance of octadecenoate . In this connection, it would be worthwhile to compare the PSC of aril TAGs and the PSC of the quite unusual AcDAGs predominating in the seed oils of the same Euonymus fruits .…”

Defining the extreme substrate specificity of Euonymus alatus diacylglycerol acetyltransferase, an unusual membrane-bound O-acyltransferase

“…Acetyl-TAG are unusually structured triacylglycerols (TAG) found in the seeds of various plant species, including E. alatus [2–4] and possess different properties than typical TAG due to the presence of the sn -3 acetate group. For example, acetyl-TAG possess a lower kinematic viscosity and improved cold temperature properties, making them potentially useful for a variety of applications [1,5].…”