- In vivo and in vitro formation of morphinone from morphine in rat
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1. Morphinone, a toxic metabolite, and its glutathione adduct (MO-GSH) were identified in the bile of rat after subcutaneous injection of morphine (25 mg/kg) by hplc procedures. The amounts of morphinone and MO-GSH excreted in the 12-h bile were 0.8 ± 0 3 and 8.4 ± 4.3% respectively. 2. The 9000 g supernatants of rat, guinea pig, rabbit, mouse, hamster and bovine livers produced morphinone from morphine in the presence of either NAD+ or NADP+. NAD+ was a more efficient cofactor than NADP+ except in the guinea pig which equally utilized both cofactors. With NAD+ as cofactor, the amounts of morphinone formed in rat and guinea pig were 5.70 and 5.82 μmol/g liver/30 min respectively and were three-to-four times those in other species. 3. The enzyme activity responsible for formation of morphinone from morphine in the rat was almost exclusively distributed in the microsomal fraction, whereas guinea pig, hamster and bovine expressed the enzyme activity mainly in the cytosolic fraction. Rabbit and mouse gave higher activity in the cytosolic and microsomal fractions respectively, but other fractions of both species contained considerable activity. 4. The enzyme activities in male and female rat microsomes were characterized with respect to developmental pattern, kinetic parameters, pH dependency and susceptibility to inhibitors. 5. In conclusion the metabolism of morphine to morphinone in rat was confirmed by in vivo and in vitro experiments. It is also suggested that this pathway is a common route in morphine metabolism in several mammalian species.
- Yamano,Takahashi,Todaka,Toki
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- Thiol-Reactive Analogues of Galanthamine, Codeine, and Morphine as Potential Probes to Interrogate Allosteric Binding within Nicotinic Acetylcholine Receptors
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Alkaloids including galanthamine (1) and codeine (2) are reported to be positive allosteric modulators of nicotinic acetylcholine receptors (nAChRs), but the binding sites responsible for this activity are not known with certainty. Analogues of galanthamine (1), codeine (2), and morphine (3) with reactivity towards cysteine thiols were synthesized including conjugated enone derivatives of the three alkaloids 4-6 and two chloro-alkane derivatives of codeine 7 and 8. The stability of the enones was deemed sufficient for use in buffered aqueous solutions, and their reactivity towards thiols was assessed by determining the kinetics of reaction with a cysteine derivative. All three enone derivatives were of sufficient reactivity and stability to be used in covalent trapping, an extension of the substituted cysteine accessibility method, to elucidate the allosteric binding sites of galanthamine and codeine at nAChRs.
- Gallagher, Ryan,Chebib, Mary,Balle, Thomas,McLeod, Malcolm D.
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p. 1834 - 1841
(2015/12/26)
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- Activities of morphinone and N-(cyclopropylmethyl)normorphinone at opioid receptors
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Morphinone (3) and N-(cyclopropylmethyl)normorphinone (4) were synthesized and tested on electrically stimulated smooth muscle preparations (guinea pig ileum and mouse vas deferens) and in mice. Compound 3 behaved as an agonist and 4 as an antagonist in vitro and in vivo. No pronounced nonequilibrium agonist or antagonist activity was observed with either compound.
- Fang,Takemori,Portoghese
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p. 1361 - 1363
(2007/10/02)
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