title: Effect of xenobiotics on quinone reductase activity in first trimester explants.
abstract: The placental protective enzyme quinone reductase (QR) has recently been reported to be induced by exposure to mercury, which is a toxic metal in vitro at term. In the present study we have examined the effect of three groups of xenobiotics-carcinogens, chemoprotectors and a natural antioxidant, ascorbic acid (vitamin C) on this enzyme activity in the first trimester placenta in vitro. Incubations with the carcinogen benzo[a]pyrene (BP) at 10-50 microM doses increased the enzyme activity at 6 h. At 24 h the effect of 10 microM BP was significant while that of 50 microM BP was not consistent. On the other hand the effect of 50 microM 3-methylcholanthrene at both time points was not significant. Ascorbic acid (5-25 microM) added for 24 h caused a 2- and 4-fold increase in the enzyme activity, respectively (P < 0.005). Exposure to a 25 microM concentration of different classes of chemoprotectors 2(3)-tert-butyl-4-hydroxyl-anisole (BHA), dicoumarol and Sudan I caused a 2.5- to 3.6-fold significant increase in the enzyme activity after 24 h (P < 0.01). Present data suggest that QR activity in the early placenta is responsive to a wide variety of xenobiotics in vitro. Vitamin C in concentrations usually consumed, exerted a potent effect on local QR activity in vitro which may protect pregnant women and their conceptus in an adverse environment.
authors.affiliation: University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School at Camden.
authors.forename: E R
authors.initials: ER
authors.lastname: Barnea
authors.forename: S
authors.initials: S
authors.lastname: Avigdor
authors.forename: W Y
authors.initials: WY
authors.lastname: Boadi
authors.forename: J H
authors.initials: JH
authors.lastname: Check
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology*; D046508:Culture Techniques; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D006801:Humans; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000096:biosynthesis / Q000187:drug effects*; D010920:Placenta / Q000187:drug effects* / Q000201:enzymology; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000187:drug effects / Q000378:metabolism; D015262:Xenobiotics / Q000494:pharmacology*
chemical_list: D002273:Carcinogens; D015262:Xenobiotics; D016660:NAD(P)H Dehydrogenase (Quinone); D001205:Ascorbic Acid