Vitamin E Nicotinate

Abstract

Vitamin E refers to a family of compounds that function as lipid-soluble antioxidants capable of preventing lipid peroxidation. Naturally occurring forms of vitamin E include tocopherols and tocotrienols. Vitamin E in dietary supplements and fortified foods is often an esterified form of α-tocopherol, the most common esters being acetate and succinate. The vitamin E esters are hydrolyzed and converted into free α-tocopherol prior to absorption in the intestinal tract. Because its functions are relevant to many chronic diseases, vitamin E has been extensively studied in respect to a variety of diseases as well as cosmetic applications. The forms of vitamin E most studied are natural α-tocopherol and the esters α-tocopheryl acetate and α-tocopheryl succinate. A small number of studies include or focus on another ester form, α-tocopheryl nicotinate, an ester of vitamin E and niacin. Some of these studies raise the possibility of differences in metabolism and in efficacy between vitamin E nicotinate and other forms of vitamin E. Recently, through metabolomics studies, we identified that α-tocopheryl nicotinate occurs endogenously in the heart and that its level is dramatically decreased in heart failure, indicating the possible biological importance of this vitamin E ester. Since knowledge about vitamin E nicotinate is not readily available in the literature, the purpose of this review is to summarize and evaluate published reports, specifically with respect to α-tocopheryl nicotinate with an emphasis on the differences from natural α-tocopherol or α-tocopheryl acetate.

Keywords: tocopherol nicotinate; tocopheryl nicotinate; vitamin E nicotinate.

Figure 1

Chemical structures of niacin (nicotinic acid), α-tocopherol, and α-tocopheryl nicotinate.

Figure 2

Levels of α-tocopheryl nicotinate in the heart of healthy control rats and rats with heart failure. Pulmonary arterial hypertension-induced right-sided heart failure was generated by administering ovalbumin and SU5416 to Sprague-Dawley rats [16]. Homogenates of right-heart ventricular tissues were injected into a reverse-phase column of an Acquity ultra-performance liquid chromatography (UPLC) system. Mass spectrometry (MS) was performed using a quadrupole-time-of-flight mass spectrometer. The box-and-whisker plot represents the levels of the metabolite corresponding to α-tocopheryl nicotinate (m/z 536.4077) in arbitrary units (a.u.). * denotes significant difference between each other at p < 0.05.

Figure 3

Confirmation of the α-tocopheryl nicotinate peak. Results of metabolomics experiments using UPLC/MS were confirmed by time-of-flight/time-of-flight (TOF/TOF) tandem mass spectrometry. Both healthy control rat right-ventricle homogenate samples and α-tocopherol nicotinate (purchased from Sigma-Aldrich, St. Louis, MO, USA) used as a standard exhibited the m/z peak at 536.410.