ENZYMATIC AND CHEMICAL LABELING OF PROSTAGLANDIN-E(1) AND 13,14-DIHYDRO-15-KETO-PROSTAGLANDIN-E(1)

Chemical and enzymatic tools were employed to synthesize [1,1-O-18(2)] -prostaglandin (PG) E1, [1,1-O-18(2)]-13,14-dihydro-15-keto-PGE1 and [ 5,6-H-3(2)]-13,14-dihydro-15-keto-PGE1 starting from the corresponding unlabelled compounds and [5,6-H-3(2)]-PGE1, respectively. Reaction pr oducts were purified by high-performance liquid chromatography and the ir isotopic purity was determined by gas chromatography-mass spectrome try (GC-MS). The utility of [1,1-O-18(2)]-PGE1 and [1,1-O-18(2)]-13,14 -dihydro-15-keto-PGE1 as internal standards for GC-MS analysis of the corresponding endogenous compounds in biological fluids is demonstrate d. [5,6-H-3(2)]-13,14-dihydro-15-keto-PGE1 was found to be useful in d eveloping extraction and purification procedures for the quantitation of endogenous 13,14-dihydro-15-keto-PGE1 in human plasma by GC-tandem MS.