title: Co-oxidation of all-trans retinol acetate by human term placental lipoxygenase and soybean lipoxygenase.
abstract: The oxidation of all-trans retinol acetate (t-RAc) mediated by soybean lipoxygenase (SLO) and affinity purified human term placental lipoxygenase (HTPLO) was investigated. Under optimum assay conditions, SLO, which is used as a model enzyme, exhibited a specific activity of 850 nmol of t-RAc depleted/min/nmol of enzyme. For HTPLO, incubation of 100 microM t-RAc, 2 mM linoleic acid, and 50 micrograms of enzyme protein in Tris buffer at pH 9.0 was essential to observe the optimum rate of t-RAc cooxidation (370 nmol of t-RAc depleted/min/mg protein). The linoleate dependent cooxidation of t-RAc by both SLO and HTPLO was significantly inhibited by micromolar concentrations of nordihydroguaiaretic acid, butylated hydroxytoluene, butylated hydroxyanisole, gossypol, and 5,8,11-eicosatriynoic acid. These results suggest that t-RAc is metabolized via the lipoxygenase pathway. Significant rate of t-RAc oxidation by HTPLO observed in this study suggests that it may constitute an important part of the puzzle worthy of consideration in the understanding of retinoid teratogenicity in humans.
authors.affiliation: Department of Environmental and Occupational Health, University of South Florida, Tampa, USA.
authors.forename: K
authors.initials: K
authors.lastname: Datta
authors.forename: A P
authors.initials: AP
authors.lastname: Kulkarni
mesh_terms: D004224:Diterpenes; D005260:Female; D006801:Humans; D008084:Lipoxygenase / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D010920:Placenta / Q000201:enzymology*; D011247:Pregnancy; D000084562:Retinyl Esters; D013025:Glycine max / Q000201:enzymology*; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D004224:Diterpenes; D000084562:Retinyl Esters; D014801:Vitamin A; C009166:retinol acetate; D008084:Lipoxygenase