Application of Gas Chromatography – Flame Ionization Detection to Study Cellular Incorporation of Dietary Trans Fatty Acids of Medical Importance

Anna Somogyi,Farkas Sarnyai,Judit Mátyási,Miklós Csala,Zsófia Gór-Nagy,Blanka Tóth

doi:10.3311/ppch.16646

Abstract

Putative health effects of dietary trans fatty acids (TFAs) receive a growing attention; while very little is known about the metabolism of these special food components. In vitro studies carried out in cultured cells provide an efficient and standardizable approach to follow the metabolic fate of TFAs, but it requires suitable techniques for the quantitative measurement of FAs in cell samples. Here, the development and validation of a simple and reliable method for the quantification of a group of relevant FAs by gas chromatography and flame ionization detection is presented. Sample preparation used a fast one-step and chloroform-free process for simultaneous extraction and esterification, and chromatographic separation was achieved in 25 min using a Zebron ZB-88 capillary column. A linear calibration (of R2 >0.99) was obtained in the concentration range of 1-200 µg/mL for each FA. Recovery rate was 82 % for samples of non-esterified FAs and >95 % for complex lipids, such as ceramides, diglycerides and triglycerides. The LOD and LOQ were below 0.5 µg/mL, and a robust method precision was achieved (RSD % was below 6 % for each lipid classes). The present method was also tested on a cultured cell line with or without FA treatment at close to physiological concentration, and the observed changes in the metabolite concentration levels revealed characteristic differences between the metabolism of cis and trans unsaturated FAs.

Highlights

Increasing attention has been focused on the health effects of dietary trans fatty acids (TFAs) with special emphasis on the role of these food components in the development of cardiovascular diseases, cancer and diabetes
We aimed to develop and validate a sensitive, reproducible and precise GC-flame ionization detector (FID) method with a simple and fast combined extraction and derivatization process followed by an evaporation step, which is suitable for the determination of saturated and cis- or trans-unsaturated FAs, including those incorporated into complex lipids, from cultured cells
Pathologies associated to high-fat diet and obesity provide overwhelming evidence that extensive FA supply can severely disturb cellular metabolism and signaling, which leads to dysfunction or even cell death

Summary

Introduction

Increasing attention has been focused on the health effects of dietary trans fatty acids (TFAs) with special emphasis on the role of these food components in the development of cardiovascular diseases, cancer and diabetes. Living organisms incorporate FAs into a wide variety of complex lipids, including phosphoglycerolipids and sphingolipids forming the bilayers in the cellular membranes, and triglycerides for a fuel storage [1]. The depot fat is stored in the adipocytes in form of lipid droplets and its triglyceride molecules contain endogenously synthetized FAs as well as FAs ingested with natural or hydrogenated plant oils [2, 3] or animal fat [4]. The optimal physical properties of biological membranes and fat depots requires a balanced utilization of both saturated and unsaturated FAs [5]. TFAs, mostly elaidate (C18:1, trans-Δ9) can be formed as by-products of industrial food processing, primarily during hydrogenation of plant oils [7]

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