Tocochromanols encompass a group of compounds with vitamin E activity essential for human nutrition. Structurally, natural vitamin E includes eight chemically distinct molecules: alpha-, beta-, gamma- and delta-tocopherol; and alpha-, beta-, gamma- and delta-tocotrienol. Symptoms caused by alpha-tocopherol deficiency can be alleviated by tocotrienols. Thus, tocotrienols may be viewed as being members of the natural vitamin E family not only structurally but also functionally. Palm oil and rice bran oil represent two major nutritional sources of natural tocotrienol. Taken orally, tocotrienols are bioavailable to all vital organs. The tocotrienol forms of natural vitamin E possesses powerful hypocholesterolemic, anti-cancer and neuroprotective properties that are often not exhibited by tocopherols. Oral tocotrienol protects against stroke-associated brain damage in vivo. Disappointments with outcomes-based clinical studies testing the efficacy of alpha-tocopherol need to be handled with caution and prudence recognizing the untapped opportunities offered by the other forms of natural vitamin E. Although tocotrienols represent half of the natural vitamin E family, work on tocotrienols account for roughly 1% of the total literature on vitamin E. The current state of knowledge warrants strategic investment into investigating the lesser known forms of vitamin E.
This study reports the effect of physical refining on palm vitamin E including α−tocopherol, α−, γ− and δ−tocotrienols as well as α−tocomonoenol. A method using HPLC with fluorescence detector using normal phase silica column is described. An isocratic elution with n-hexane/THF/2-propanol (1000:60:4, by vol.) as mobile phase was used. The structure of the α−tocomonoenol was determined using gas chromatography coupled with mass spectrometry. The composition of the vitamers were α−tocopherol (14–17%), α−tocotrienol (22–24%), γ−tocotrienol (49–53%), δ−tocotrienol (6–7%) and α−tocomonoenol (3%) throughout the physical refining. The concentration of all vitamers in crude palm oil was 1273±18 ppm. The concentrations of all vitamers in degummed palm oil, bleached palm oil and deodorized palm oil were 1134±20 ppm, 1095±18 ppm and 1029±18 ppm, respectively. This method provides fast and valuable information with minimal analysis time and no sample pre-treatment.