Abstract
Norethisterone and, to a lesser extent, d-norgestrel are metabolically activated by rat liver microsomal enzymes to intermediates which are capable of irreversibly binding to proteins. This microsomal activation in vitro depends on presence of NADPH and is inhibited by glutathione. Irreversible binding of metabolites of progesterone, nortestosterone acetate and cyproterone acetate is very low, compared to that of norethisterone metabolites. Phenol as a reference compound shows quantitatively a similar binding behaviour as norethisterone. Norethisterone-4β,5β-epoxide, a microsomal metabolite of norethisterone, binds non-enzymatically to albumin, at a rate of 380 pmol/mg albumin per hour (at 37°). The corresponding rate for norgestrel-4β,5β-epoxide, 42 pmol/mg albumin per hour, indicates a considerably lower reactivity of norgestrel-epoxide. The non-SH-proteins concanavalin A and bovine γ-globulin do not react with either norethisterone-epoxide or norgestrel-epoxide. Also, DNA and RNA show no binding reaction. Thus, the requirements for irreversible protein binding of the 19-nortestosterone progestagens norethisterone and norgestrel are similar to those found for oestrogens which, when activated by rat liver microsomes, only bind to proteins with SH-groups, not to DNA or RNA.
Zusammenfassung
Norethisteron und zu einem geringeren Maße d-Norgestrel werden von Rattenlebermikrosomen zu reaktiven Metaboliten aktiviert, die die Fähigkeit haben, an Proteine zu binden. Diese Reaktion erfordert NADPH und wird durch Glutathion gehemmt. Verglichen mit der irreversiblen Proteinbindung der Metaboliten von Norethisteron bzw. d-Norgestrel ist diejenige nach Eingabe von Progesteron, Nortestosteron-Acetat und Cyproteron-Acetat unerheblich. Metaboliten der Referenzsubstanz Phenol binden in etwa dem gleichen Ausmaß irreversibel an mikrosomales Protein wie Metaboliten des Norethisteron. Der Norethisteronmetabolit Norethisteron-4β,5β-epoxid bindet nichtenzymatisch an Albumin (380 pMol/mg Albumin pro Stunde). Der entsprechende Wert für d-Norgestrel-4β,5β-Epoxid (42 pMol/mg Albumin pro Stunde) spricht für eine geringere Reaktivität des Epoxids von d-Norgestrel. Die nicht Thiolgruppen-haltigen Proteine Concanavalin A und Rinder-γ-Globulin reagieren weder mit dem Epoxid von Norgestrel, noch mit dem von Norethisteron. Auch DNS und RNS zeigen keine Bindung dieser Epoxide. Somit zeigen die Ergebnisse, daß die Bedingungen für die irreversible Proteinbindung von Norethisteron und Norgestrel ähnlich sind wie diejenigen für die Bindung von Östrogenen: Die reaktiven Produkte, die durch Lebermikrosomen und NADPH gebildet werden, binden nur an Proteine mit freien SH-Gruppen, jedoch nicht an Nukleinsäuren.
Similar content being viewed by others
References
Briggs, M., Briggs, M.: Effects of some contraceptive steroids on serum proteins of women. Biochem. Pharmacol. 22, 2277–2281 (1973)
Bolt, H. M., Kappus, H.: Irreversible binding of ethynyl-estradiol metabolites to protein and nucleic acids as catalyzed by rat liver microsomes and mushroom tyrosinase. J. Steroid Biochem. 5, 179–184 (1974)
Bolt, H. M., Kappus, H.: Interaction by 2-hydroxyestrogens with enzymes of drug metabolism. J. Steroid Biochem. 7, 311–313 (1976)
Cook, C. E., Dickey, M. C., Christensen, H. D.: Oxygenated norethindrone derivatives from incubation with beagle liver. Drug Metab. Disposition 2, 58–64 (1974)
Edmondson, H. A., Henderson, B., Benton, B.: Liver cell adenomas associated with use of oral contraceptives. New Engl. J. Med. 294, 470–472 (1976)
Gleichmann, W., Bachmann, G. W., Dengler, H. J., Dudeck, J.: Effects of hormonal contraceptives and pregnancy on serum protein patterns. Europ. J. clin. Pharmacol. 5, 218–225 (1973)
Kappus, H., Bolt, H. M.: Irreversible protein binding of norethisterone (norethindrone) epoxide. Steroids 27, 29–45 (1976)
Kappus, H., Remmer, H.: Metabolic activation of norethisterone (norethindrone) to an irreversibly protein-bound derivative by rat liver microsomes. Drug Metab. Disposition 3, 338–344 (1975)
Kappus, H., Bolt, H. M., Remmer, H.: Irreversible protein binding of metabolites of ethynylestradiol in vivo and in vitro. Steroids 22, 203–225 (1973)
Lowry, O. H., Rosebrough, N. J., Farr, A. L., Randal, R. J.: Protein measurement with the folin phenol reagent. J. biol. Chem. 193, 265–275 (1951)
Marks, F., Hecker, E.: Stoffwechsel von 4-14C-2-Hydroxyöstron in Rattenlebermikrosomen. Hoppe-Seylers Z. physiol. Chem. 350, 69–84 (1969a)
Marks, F., Hecker, E.: Metabolism and mechanism of action of oestrogens. Biochim. biophys. Acta (Amst.) 187, 250–265 (1969b)
Redderson, C. L.: Interaction of steroids and serum cholinesterase. Int. J. clin. Pharmacol. 8, 51–57 (1973)
Remmer, H., Greim, H., Schenkman, J. B., Estabrook, R. W.: Methods for the elevation of hepatic microsomal mixed function oxidase levels and cytochrome P-450. Meth. Enzymol. 10, 703–708 (1967)
Schillinger, E., Gerhards, E.: Influence of hormonal contraceptives on carbohydrate and lipid metabolism in the rat. Biochem. Pharmacol. 22, 1835–1844 (1973)
Schuppler, J., Günzel, P.: Cyproterone acetate. Lancet 1976 II, 688
Schwartz, U., Hammerstein, J.: The oestrogenic effect of various contraceptive steroids as determined by their effects on the transcortin binding capacity. Acta endocr. (Kbh.) 76, 159–171 (1974)
Sisenwine, S. F., Kimmel, H. B., Liu, A. L., Ruelius, H. W.: Stereo-selective biotransformation of dl-norgestrel and its enantiomers in the African Green Monkey. Drug Metab. Disposition 2, 65–70 (1974)
Wollenberg, P., Scheuten, M., Bolt, H. M., Kappus, H., Remmer, H.: Wirkung von 2-Hydroxyöstradiol-17β auf den NADPH-abhängigen Elektronentransport in Rattenleber-Mikrosomen in vitro. Hoppe-Seylers Z. physiol. Chem. 357, 351–357 (1976)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bolt, H.M. Structural modifications in contraceptive steroids altering their metabolism and toxicity. Arch. Toxicol. 39, 13–19 (1977). https://doi.org/10.1007/BF00343271
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00343271