Phytyl fatty acid esters in vegetables pose a risk for patients suffering from Refsum's disease.

Stephanie Krauß,Lea Michaelis,Walter Vetter,Yang Cai

doi:10.1371/journal.pone.0188035

Abstract

Patients suffering from Refsum’s disease show mutations in the enzyme necessary for the degradation of phytanic acid. Accumulation of this tetramethyl-branched fatty acid in inner organs leads to severe neurological and cardiac dysfunctions which can even result in death. Thus, patients with Refsum’s disease have to follow a specific diet resigning foods with high levels of phytanic acid and trans-phytol like products from ruminant animals with a tolerable daily intake (TDI) of ≤ 10 mg/d. We recently reported the occurrence of phytyl fatty acid esters (PFAE, trans-phytol esterified with a fatty acid) in bell pepper with trans-phytol amounts of up to 5.4 mg/100 g fresh weight (FW). In this study we carried out in vitro-digestion experiments of PFAE with artificial digestion fluids. Our results demonstrate that PFAE actually are a source for bioavailable trans-phytol and thus add to the TDI. Eating only one portion of bell pepper (∼150 g) could therefore lead to exploitation of the TDI of up to 81%. Analysis of additional vegetable matrices showed that also rocket salad with up to 4.2 mg/100 g FW trans-phytol bound in PFAE represents a risk-relevant food for patients with Refsum’s disease and should therefore be taken into account.

Highlights

Refsum’s disease–short for heredopathia atactica polyneuritiformis–is an inherited disorder of the lipid metabolism which affects the degradation of phytanic acid (3R/S,7R,11R,15-tetramethylhexadecanoic acid)–a tetramethyl-branched chain fatty acid (Fig 1A) [1,2,3]
Identification of trans-phytol in form of its trimethylsilyl ether (TMS) was possible by its characteristic Gas chromatography coupled to mass spectrometry (GC/MS) spectrum which is dominated by the ions with m/z 143.1 and m/z 123.1 [29] and by comparing its retention time to a standard solution
Their origin was ascribed to the enzymes that were used in the experiment

Summary

Introduction

Refsum’s disease–short for heredopathia atactica polyneuritiformis–is an inherited disorder of the lipid metabolism which affects the degradation of phytanic acid (3R/S,7R,11R,15-tetramethylhexadecanoic acid)–a tetramethyl-branched chain fatty acid (Fig 1A) [1,2,3]. Phytanic acid has initially to be converted into pristanic acid (Fig 1B) through α-oxidation which moves the first methyl branch to C-2. Patients with Refsum’s disease show mutations in the enzyme phytanoyl-CoA-hydroxylase which results in the first step of α-oxidation of phytanic acid being blocked [6,7,8]. This leads to the accumulation of phytanic acid in blood plasma and inner organs like kidneys, liver or in the heart muscle [6,9,10]. Due to the high levels of phytanic acid

Methods

Results

Conclusion