Phytol and Phytyl Fatty Acid Esters: Occurrence, Concentrations, and Relevance

Abstract

Phytyl fatty acid esters (PFAE) are long chain isoprenoid esters consisting of phytol esterified to fatty acids. Phytol, which is mainly known as side chain of the plant pigment chlorophyll, is released during chlorophyll breakdown. PFAE mainly function as storage forms for free phytol to protect plant cells as phytol shows membrane toxic properties. Surprisingly, only scattered data on PFAE can be found in the literature. For instance, PFAE are known to occur in mosses, selected leaves of higher plants, and also in some fruits and vegetables. As PFAE seem to be fissile in the human body, their phytol moiety is bioavailable and can be converted into phytanic acid. Patients with Refsum's disease cannot metabolize phytanic acid and accumulate it in blood and organs with severe consequences. For treatment, patients must keep a special diet avoiding foods with high amounts of phytanic acid or free phytol with the tolerable daily intake being ≤10 mg. In addition, PFAE in fruits and vegetables directly add to the intake of phytol or rather phytanic acid. Therefore, their contents must be taken into account regarding dietary recommendations. This review summarizes the literature data on occurrence, concentrations, and analytical methods for the determination of PFAE.Practical application: The data provided give an overview of matrices containing PFAE which also include edible plant parts. This information can help improving the life quality of patients suffering from Refsum's disease. Additionally, a summary of different analytical methods for the determination of PFAE is presented which will hopefully encourage further research on this class of esters.Phytyl fatty acid esters (PFAE) are long chain isoprenoid esters consisting of trans‐phytol esterified with fatty acids. They are reported to occur in several mosses and algae, in leaves of some higher plants as well as in selected fruits and vegetables. In contrast to chlorophyll, PFAE are found to be a potential source for bioavailable trans‐phytol. Free trans‐phytol is known as a precursor for phytanic acid which cannot be metabolized by patients with Refum's disease. Hence, edible plant parts with elevated PFAE levels add to the daily tolerable intake of phytanic acid for these patients. This review gives an overview of occurrence, variability, and contents of PFAE and summarizes various analytical methods for their determination.