Identification of conjugated fatty acids in the seed oil of Acioa edulis (Prance) syn. Couepia edulis (Chrysobalanaceae)

Abstract

The oil ofAcioa edulis has the fatty acid composition: palmitic acid 28.3%, palmitoleic acid 1.3%, stearic acid 6.8%, oleic acid 26.5%, vaccenic acid 1.3%, linoleic acid 8.8%, arachidic acid 0.7%, a-eleostearic acid 7.3% and a-licanic acid 19%. The oil was analyzed and components were identified by ultraviolet (UV), infrared (IR), nuclear magnetic resonance (IH-NMR, 13C-NMR), gas chromatography/mass spectrometry (GC/ MS) and chemical methods. For transesterification the tetramethylguanidine reagent was used and it was shown that the method is very suitable for co~ugated fatty acids. The equivalent chain lengths of aeleostearic acid and ~-licanic acid and their all-trans isomers were determined on DB 23 and OV-1. The electron impact (EI) and chemical ionization (CI) (with isobutane) mass spectra of Hcanic acid, eleostearic acid and the EI mass spectrum of 4-oxo-azelalc acid are presented and discussed. Furthermore, a comparison of literature data of seeds with the same common name is presented. KEY WORDS: Acioa edulis, Chrysobalanaceae, conjugated fatty acids, eleostearic acid, gas chromatography/mass spectrometry (GC/MS), licanic acid, 4-oxo-azelaic acid.Acioa edulis syn. Couepia edulis is a member of the family Chrysobalanaceae found in the basin of the Rio Purus and the central Solimoes of Amazonia, Brazil. The tree is 25 m tall and its stone-fruits are 8-9 cm long and 4.5-cm broad. The kernel is eaten raw by the habitants of the described region or is crushed and added to tapioca cakes. The oil of the seeds is used for cooking and soapmaking (1).The common name "Cotia Chestnut (Castanha de Cotia)" obviously is not unique for this fruit. This curious designation is derived from the name of a tailless animal called "Cotia, "which feeds on these kernels (2). There obtained by argentation thin-layer chromatography was converted to the bis-(methylthio) derivates as described previously (10).

Screening analysis of unknown seed oils

“…However, in some special cases the presence of a keto group can be indicated by its 1 H NMR spectrum as shown, e.g. for 4-keto-α-eleostearic acid [77].…”

“…BPX-70 TM ∆5-unsaturated polymethylene-interrupted fatty acids in Ranunculaceae [120]; γ-linolenic, α-linolenic, and stearidonic acid in Boraginaceae [121]; acetylenic fatty acids in Olacaceae [11] Carbowax 20M TM /DB Wax TM Conjugated triene fatty acids in Cucurbitaceae [90], positional monoene isomers in Sapindaceae [2,122], ∆5-unsaturated polymethylene-interrupted fatty acids in Cupressaceae, Pinaceae, and Taxaceae [123] CP-SIL-88 TM Unusual unsaturated double bond and configuration isomers in Ranunculaceae [124] and Pinaceae [125] CP-WAX 52CB TM Methyl-branched and ∆5-unsaturated polymethylene-interrupted fatty acids in Ginkgo biloba [20] DB-23 TM Cyclopropanoic, cyclopropenoic, and hydroxy fatty acids in Bombacaceae [14], positional monoene isomers in Sapindaceae [2,122], conjugated triene, tetraene, and keto fatty acids in Chrysobalanaceae [21,77,126] and Euphorbiaceae [6], acetylenic acids in Olacaceae [3,128] and Santalaceae [3,128] SILAR 5 CP TM ∆5-unsaturated polymethylene-interrupted fatty acids in Ranunculaceae [129], allenic fatty acids [13] SP2330 TM Polyunsaturated fatty acids in various species [130] Detection of the individual compounds can be made with a flame-ionization detector (FID).…”

“…ref. [2,3,10,14,16,21,23,77,120,122,126,129,180,187,206] for 4,4-dimethyloxazoline derivatives and ref. [20,185,186,196,207] for picolinyl ester derivatives.…”

“…3. IR spectroscopy was employed to prove preliminarily the presence of conjugated olefinic [8,21,77,210] and olefinic-acetylenic [3,10,11] systems in novel seed oils.…”

Analysis of conjugated and trans fatty acids after derivatization (in French)

“…En effet, le spectre de masse est dominé par des ions de faible masse produits par ru p t u re (réarra n gements de Mac Laffe rty) à partir du groupement ester. Les ions qui permettent de diagnostiquer la position des doubles liaisons sont absents par le fait que les doubles liaisons ont été ionisées et ont migré le long de la chaîne aliphatique [25]. Pour remédier à ce problème, il a été nécessaire de stabiliser les doubles liaisons par une modification appropriée de la molécule originale avant de l'analyser par spectrométrie de masse (SM).…”