Determination of Cyclopropenoid Fatty Acids in Ewe Milk Fat by GC-MS after Intravenous Administration of Sterculic Acid.

Veronica Lolli,Pilar Gómez-Cortés,Augusta Caligiani,Pablo G Toral

doi:10.3390/foods9070901

Abstract

Cyclopropenoid fatty acids (CPEFA), found in oilseeds from Malvaceae and Sterculiaceae, have been shown to interfere with the endogenous synthesis of several bioactive lipids of dairy fat, such as cis-9, trans-11 18:2 and cis-9 18:1, by inhibiting Δ9-desaturase. No previous study has reported the presence of sterculic acid in animal fat and its incorporation in tissues after its administration, due to the lack of a proper methodology. In the present research, a GC-MS method based on cold base derivatization to fatty acids methylesters was developed to determine CPEFA in ewe milk triglycerides, after infusing sterculic acid (0.5 g/day) to six lactating ewes. An alternative derivatization based on silanyzation followed by GC-MS analysis was also tested, showing its possible applicability when CPEFA are present in the form of free fatty acids. Sterculic acid was detected in ewe milk triglycerides, demonstrating its incorporation from the bloodstream into milk by the mammary gland. The mean transfer rate represented 8.0 ± 1.0% of the daily dose. This study provides, for the first time, the presence of sterculic acid in milk fat, supporting the importance of understanding its occurrence in vivo and encouraging further research to determine whether it can be present in foods, such as dairy products, obtained under practical farming conditions.

Highlights

Fatty acids containing three-member carbocyclic rings, namely cyclopropane fatty acids (CPFA) and cyclopropene fatty acids (CPEFA), are commonly reported in oilseeds from plants belonging to several families, such as Sterculiaceae, Malvaceae, Bombacaceae, Tiliaceae, and Sapindaceae [1]
Sterculic acid chemically synthesized standard was injected in the GC-MS system both as methyl ester and as silyl ether
To avoid the acid degradation of sterculic acid, an alternative derivatization approach based on sylanization was tested to determine sterculic acid as free fatty acid by GC-MS

Summary

Introduction

Fatty acids containing three-member carbocyclic rings, namely cyclopropane fatty acids (CPFA) and cyclopropene fatty acids (CPEFA), are commonly reported in oilseeds from plants belonging to several families, such as Sterculiaceae, Malvaceae, Bombacaceae, Tiliaceae, and Sapindaceae [1]. Sterculic, and dihydrosterculic (cis-9,10-methyleneoctadecanoic acid) acids have been detected in Baobab seed oil from plants belonging to the Adansonia species (Bombacaceae family) of Madagascar. Carbocyclic fatty acids seemed not to be confined to seeds Both cyclopropane and cyclopropene fatty acids were found in root, leaf, stem, and callus tissue in plants of the Malvaceae [1]. In addition to carbon and energy storage in seeds, the function of CPEFA in plants may involve the resistance against fungal attack [3]

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