DNA strand breakage by hydroxyphenyl radicals generated from mutagenic diazoquinone compounds.

The mutagenic diazoquinone compounds p-diazoquinone (p-DQ), o-diazoquinone (o-DQ) and 3-diazo-N-nitrosobamethan (D-BM) cleaved the phosphodiester bond of lambda DNA, phi X174 RFI DNA and M13mp8ss DNA. p-DQ also cleaved the phosphodiester bond of bis(p-nitrophenyl)phosphate. The breakage of the phosphodiester bond was inhibited by the antioxidant butyl hydroxyanisole (BHA), ethanol, the spin trapping agent DMPO, cysteine and 2-mercaptoethanol. While incubation of p-DQ and o-DQ alone gave p-hydroquinone and catechol, respectively, incubation of these compounds in the presence of BHA and ethanol gave phenol in large yields. Incubation of p-DQ and o-DQ with the spin trapping agents DMPO and PBN gave spin adducts assignable as p- and o-hydroxyphenyl adducts, respectively. The breakage of the phosphodiester bond of DNA by the diazoquinone compounds is suggested to be due to the hydroxyphenyl radicals generated during incubation.

Possible tumour-initiating and -promoting activities of 3-diazo-N-nitrosobamethan in rat stomach mucosa.

3-Diazo-N-nitrosobamethan (DNB), a mutagen produced by nitrite treatment of bamethan, a cardiovascular drug, induced unscheduled DNA synthesis in the pyloric mucosa of the stomach of male F344 rats 2 h after its administration by gastric tube at doses of 75 to 225 mg/kg body wt. DNB at a dose of 225 mg/kg body wt induced up to a 13-fold increase in replicative DNA synthesis with a maximum at 16 h after its administration. Moreover at doses of 75 to 225 mg/kg body wt, it induced up to a 12-fold increase in ornithine decarboxylase activity with a maximum after 16 h. The present results suggest that DNB has possible tumour-initiating and -promoting activities in the pyloric mucosa of the rat stomach. However, the possible risks to patients posed by clinical use of bamethan cannot be evaluated until further work is completed.

Formation of a highly mutagenic diazo compound from the bamethan-nitrite reaction.

A variety of cardiovascular drugs were treated with 10 equivalent amounts of nitrite in acidic solutions. Among 18 drugs, a preparation of bamethan [1-(4-hydroxyphenyl)-1-hydroxy-2-butylaminoethane] showed strikingly high mutagenicity by this treatment toward Salmonella typhimurium TA98 and TA100 strains. Treatment of bamethan with an equivalent amount of nitrite gave N-nitrosobamethan I which was not mutagenic. However, treatment of bamethan with 4 equivalent amounts of nitrite afforded a highly mutagenic compound II, which was identified as 3-diazo-N-nitrosobamethan by its physicochemical analysis and chemical properties. Specific mutagenic activity of II was 9200 His+ revertants/mu mole toward TA98 and 8060 His+ revertants/mu mole toward TA100. Addition of microsomal system little affected the activity. Bamethan is administrated orally during long period for treatment of cardiovascular diseases. It is noted that this drug can produce the highly mutagenic diazo compound by reaction with nitrite which is present in digestive tracts.

Controlled evaluation of the antitussive activity of viminol p-hydroxybenzoate.

A double-blind cross-over trial was carried out to evaluate the antitussive activity of viminol p-hydroxybenzoate; the comparison was done with three preparations: a placebo and the drug at two doses, 70 and 140 mg respectively. The responses were scored hourly up to 4 hours after the administration of single doses in the morning to subjects with persistent cough. The highest dose of viminol showed a definite antitussive activity, whereas the lowest did not differ from the placebo. The antitussive effect appears clinically useful for the treatment of cough, but further studies are indicated to define optimal dosage schedules.

Adrenergic sulfonanilides. 4. Centrally active beta-adrenergic agonists.

The central nervous system (CNS) activities of a number of soterenol analogs have been investigated, and several of these compounds possessed potent morphine antagonistic and anorexiant properties. The CNS activity of these compounds was enhanced by certain lipophilic [e.g., 1,1-dimethyl-2-phenethyl (43) or cyclopropyl (40 and 44)] nitrogen substituents; however, minor structural changes on either the aromatic or side-chain moieties drastically reduced central activity. Toxicity in this series was related to the inherent alpha-adrenergic stimulating component (direct or indirect).

Conformational effects on the activity of drugs. 5. Pharmacological properties of 2-(p-nitrophenyl)-4-isopropylmorpholine, a cyclic analog of INPEA.

2-(p-Nitrophenyl)-4-isopropylmorphine (V), an analog of 1-(p-nitrophenyl)-2-isopropylaminoethanol (INPEA, I) in which the OCHCHN chain of I is locked in a morpholine ring, loses the beta-receptor blocking activity of I on various isolated preparations. The same ineffectiveness is observed in the O-methyl (II), N-methyl (III), and N,O-dimethyl analog (IV) of I. However, some other properties which are present in I, such as inhibitory effect on acetylcholine or on 5-HT, intrinsic alpha-sympathomimetic activity, and potentiation of catecholamines, are maintained; this demonstrates a complete dissociation of these effects from beta-receptor blockade. The interactions with the alpha-adrenoceptors and with the uptake mechanism are discussed on the basis of the structure-activity relationship between I and its analogs II-V.

Influence of changes in amine substitution on the beta-adrenoceptor stimulant activity of soterenol and related compounds in the anaesthetized cat.

1. Three 3-methanesulphonamido, 4-hydroxy ring substituted phenylethanolamines with N-isopropyl (soterenol), N-t-butyl (MJ7999-1) and N-(1-phenyl-t-butyl)(MJ9184-1) amine substituents have been compared with ()-isoprenaline for their ability to produce beta-receptor mediated reductions in serotonin-induced increases in pulmonary resistance, decreases in soleus muscle contractility, and increases in heart rate in anaesthetized cats. For each parameter, the dose of a compound required to produce 50% of its maximal response (ED50) was calculated. 2. For all three parameters ()-isoprenaline was the most potent of the compounds studied, and the rank order of potency of the methanesulphonanilides was MJ9184-1 (N-(1-phenyl-t-butyl))congruent to MJ7999-1 (N-t-butyl) greater than soterenol (N-isopropyl). 3. For each individual drug, molar dose-ratios [drug:()-isoprenaline] were calculated. Ratios for the effects of the compounds on the soleus muscle and in the bronchi were similar. With each compound higher dose-ratios were found in the heart. The rank order for relative beta2-selectivity was soterenol (N-isopropyl) greater than MJ7999-1 (N-t-butyl) congruent to MJ9184-1 (N-(1-phenyl-t-butyl)).

Regulation of phospholipid biosynthesis in isolated rat hepatocytes. Effect of different substrates.

The effects of choline, ethanolamine and its N-methyl analogs, different fatty acids, and L-methionine on phospholipid biosynthesis via the CDP-ester pathways and the methylation pathway were studied in rat hepatocytes. Phosphatidylethanolamine synthesis was stimulated severalfold by 0.02 to 0.1 mM ethanolamine, especially in the presence of long chain unsaturated fatty acids. At higher concentrations of ethanolamine, phosphorylethanolamine accumulated but the level of CDP-ethanolamine and the rate of phosphatidylethanolamine synthesis did not increase further. The rate of phosphatidylcholine synthesis via the CDP-ester pathway responded in a way analogous to that of phosphatidylethanolamine synthesis upon the addition of choline and fatty acid, except that a 10- to 20-fold higher concentration of choline was required for maximal stimulation, probably due to the rapid oxidation of choline to betaine. Phospholipids containing N-monomethyl- or N,N-dimethylethanolamine were efficiently formed from the corresponding free bases in the absence of ethanolamine and choline. Ethanolamine, but not other bases, inhibited completely phospholipid formation from N-monomethylethanolamine, probably as a result of competition at the level of CDP-ester formation. The data indicate that the cytidylytransferase reactions are rate-limiting steps in the synthesis of phosphatidylethanolamine and probably also phosphatidylcholine. In addition, the availability of diacylglycerol and its fatty acid composition may significantly affect the rate of phospholipid synthesis. The rate of phosphatidylcholine formation via phospholipid N-methylation approximately doubled when L-methionine was added at concentrations similar to that in rat plasma. Under these conditions the rate of phosphatidylcholine synthesis via this pathway was 20 to 40 percent of that via diacylglycerols and CDP-choline. The methylation of phosphatidylethanolamine to phosphatidylcholine remained essentially constant when the rate of phosphatidylethanolamine synthesis was varied 8-fold, but was significantly reduced when the formation of N-monomethyl- or N,N-dimethylphospholipid was stimulated by addition of the corresponding base. These phospholipids not only replaced phosphatidylethanolamine as the substrate for methylation but also increased the rate of phosphatidylcholine formation via this pathway. A method for the determination of nanomole amounts of different ethanolamine compounds is described.