CONVERSION OF VITAMIN-K-1 TO 2',3'-DIHYDROVITAMIN-K-1 DURING THE HYDROGENATION OF VEGETABLE-OILS

When vitamin K-1 (phylloquinone) was measured by HPLC in foods contain ing partially hydrogenated vegetable oils, a peak corresponding to the retention time of 2',3'-dihydrovitamin K-1 was observed. Dihydrovitam in K-1 has a molecular mass 2 Da greater than that of vitamin K-1 due to saturation of the 2',3' double bond of the side chain. For confirma tion of this putative compound, samples of a commercial shortening, so ybean oil, and soybean oil subjected to light and heavy hydrogenation were purified by preparative HPLC and analyzed by GC/MS. Authentic dih ydrovitamin K-1 and the oil samples produced molecular ions at m/z 452 and fragment ions at m/z 186. Although absolute levels of both vitami n K-1 and dihydrovitamin K-1 decreased with an increase in hydrogenati on, there was an overall increase in the ratio of dihydrovitamin K-1 t o vitamin K-1. The biological activity of dihydrovitamin K-1 remains t o be determined; however, if biologically active, it could have a sign ificant role in vitamin K nutriture.