Yasumasa Kido

Protective effect of sulfhydryl compounds on acute toxicity of morphinone.

The ability of sulfhydryl compounds to provide protection against the acute toxicity of morphinone was investigated in mice. Subcutaneous administration of morphinone produced a reduction of hepatic non-protein sulfhydryl concentration. Pretreatments of mice with glutathione or cysteine significantly increased the survival rate of mice given a lethal dose of morphinone, whereas morphinone lethality was markedly potentiated by diethyl maleate. On the other hand, the administration of morphine produce a dose dependent reduction of hepatic non-protein sulfhydryl contents. However, neither glutathione nor cysteine protected mice from the acute toxicity of morphine. A possible explanation for these observations was proposed as follows: morphine is oxidized by morphine 6-dehydrogenase to morphinone, and the morphinone thus produced decreases the sulfhydryl contents in the liver. This mechanism is supported by the fact that morphinone reacts easily with glutathione and cysteine in vitro.

Effect of morphinone on opiate receptor binding and morphine-elicited analgesia

Specific binding of 3H-naloxone to opiate receptors was found to be irreversibly inactivated by morphine. This inactivation exhibited pseudo-first-order kinetics. The presence of sulfhydryl compounds or morphine during incubation with morphinone proved good protection. Morphinone-pretreated mice blocked the analgesic effect of morphine. The possible mechanism for these observations is proposed as follows: morphinone binds covalently to sulfhydryl group of opiate receptors, and inactivates irreversibly opiate binding sites, thus blocking the analgesic effect of morphine.

Metabolic fate of 2,5-dimethoxy-4-methylamphetamine in the guinea pig and rabbit.

Metabolic fate of 2, 5-dimethoxy-4-methylamphetamine (DOM) was investigated in the guinea pig and rabbit. DOM concentration in serum decreased rapidly after a subcutaneous injection and DOM was scarcely obtained at 3 to 4 hours later by radioimmunoassay and thin-layer chromatography. As the metabolites of DOM, 2, 5-dimethoxy-4-hydroxymethylphenyl-2-aminopropane and 2, 5-dimethoxy-4-carboxyphenyl-2-aminopropane were confirmed in the urine of guinea pig and rabbit. 2, 5-Dimethoxy-4-methylphenyl-2-propanol and 2, 5-dimethoxy-4-methylphenyl-2-propanone, which had not been detected in rat urine but in the incubation mixture of DOM with rabbit liver microsome, were identified in guinea pig and rabbit urines. 2, 5-Dimethoxy-4-methylbenzoic acid was firstly detected as a minor metabolic product of DOM in the urine of both species of animals. Principal metabolic pathway of DOM in guinea pig was not regarded as the side-chain oxidation but as the oxidation of methyl group on benzene ring as well as in rabbit.

Mechanism of the Millon reaction

The mechanism of the Millon reaction with p-cresol was investigated using the Hopkins-Cole reagent. As shown in Fig.1, typical coloration was obtained with higher concentration of mercuric sulfate. 2-Chloromercuri-4-methylphenol(I), an assumed intermediate, colored blood red immediately on the treatment with sodium nitrite in sulfuric acid, and from the reaction mixture, brownish prisms(Pig. I, d. p. 172°C) were obtained.From the color reaction mixture of p-cresol, besides Pig. I, dark reddish violet prisms (Pig. II) and brownish red powders(Pig. III) were isolated. The constitutions of Pig. I were confirmed to be I and 2-nitroso-4-methylphenol(II) and those of Pig. II were II and mercuric ion. The structure of Pig. I was determined as formula III by X-ray diffraction studies, consequently, Pig. II was assumed as formula IV.These results indicate that the Millon reaction proceeds through the mercuration at the o-position of phenolic hydroxyl group, which is followed by the substitution of the mercury atom by attacking NO+, and the coordination of resulted nitrosophenol to either organic or inorganic mercury gives colored substances.Among 70 kinds of phenols tested, not only 2, 6 and 3, 5- but also 2, 5-disubstituted phenols, poly phenols, aminophenols and nitrophenols were found inactive or scarcely reactive. In the case of m-xylenol, such inactivity was proved to be caused by the steric hindrance of its methyl groups.