The possible role of one-carbon moieties in 2-methoxyethanol and 2-methoxyacetic acid-induced developmental toxicity

The ethylene glycol ether, 2-methoxyethanol (2-ME), is rapidly (less than 1 hr) oxidized to 2-methoxyacetic acid (2-MAA). Both agents are selectively embryotoxic and equipotent in causing digit malformations when given to CD-1 mice on gestation Day 11. Previous observations have shown that simple physiological compounds such as formate, acetate, glycine, and glucose ameliorate the embryotoxicity of 2-ME. A common link for all of the attenuating agents may be oxidation pathways involving tetrahydrofolic acid (THF) as a catalyst for one-carbon transfer into purine and pyrimidine bases. In the present study serine at 16.5 mmol/kg, which reacts directly with THF, was as effective as formate in almost completely eliminating digit malformations resulting from treatment with 2-ME. Unlike formate, serine was equally effective against 2-MAA-induced dysmorphogenesis and the attenuating efficacy remained unchanged when serine administration was delayed for up to 8 hr after 2-ME or 2-MAA exposure. The protective effect of sarcosine, which is an intermediate in a pathway leading from choline to glycine and a structural analog of 2-MAA, was also determined. Both concomitant (43, 16.5, or 3.3 mmol/kg) and delayed (16.5 mmol/kg at 6 hr) sarcosine administration resulted in significantly less 2-ME-induced paw dysmorphogenesis. In addition, acetate administration was delayed for increasing intervals after 2-ME to determine the time at which attenuation would no longer occur, and acetate was effective for as long as 12 hr after 2-ME. These results support our hypothesis that 2-MAA, which has a long biological half-life, may interfere with the availability of one-carbon units for incorporation into purine and pyrimidine bases. Alterations in availability of these precursors might be expected to affect DNA and/or RNA synthesis and thereby influence normal cellular proliferation and differentiation in the developing embryo.

Changes in mitochondrial activity caused by ammonium salts and the protective effect of carnitine

Ammonium salts added to isolated rat liver mitochondria deviate alpha-ketoglutarate to glutamate synthesis, thus decreasing its availability as respiratory substrate. As a consequence a decrease of respiratory rate is observed which is paralleled by progressive mitochondrial swelling. It was demonstrated that L-carnitine may abolish this swelling thus improving structural and metabolic state of mitochondria.

Inhibition of DNA synthesis in mouse whole embryo culture by 2-methoxyacetic acid and attenuation of the effects by simple physiological compounds

Gestation day 11 CD-1 mouse embryos were cultured in serum containing or serum-free media for 6 h in the presence of 2-methoxyacetic acid (2-MAA), the proximate teratogen arising from 2-methoxyethanol. The rate of DNA synthesis was determined following exposure of embryos to [3H]thymidine during the final hour of culture. 2-MAA (25 mM) produced a 50% reduction of [3H]thymidine incorporation into embryos cultured in serum-containing medium, whereas only 5 mM 2-MAA were required for a similar inhibitory effect in embryos cultured in serum-free medium. When embryos were concomitantly exposed to 2-MAA (5 mM) and to formate (1 mM), acetate (5 mM), or sarcosine (2 mM), a significant attenuation of the 2-MAA-induced inhibition of [3H]thymidine incorporation occurred. The findings suggest that these agents, which also attenuated developmental toxicity in vivo, may compete with 2-MAA actions which inhibit DNA synthesis in the embryo.

Effect of oestradiol replacement on swim-induced antinociception in ovariectomized mice

1. A 30 s swim in water at 30 degrees C reduced the number of abdominal constrictions produced in female mice by intraperitoneally administered acetic acid and this antinociceptive effect was antagonized by naloxone. 2. Oophorectomy abolished the development of antinociceptive activity in response to swim. 3. The development of antinociceptive activity and naloxone antagonism were restored in oophorectomized mice maintained on daily oestradiol injection. 4. The present study indicates that the increase in abdominal constriction response to acetic acid in oophorectomized mice was due to the removal of the source of female sex hormone.

Protection against acute hyperammonemia: the role of quaternary amines

The quaternary amine L-carnitine is able to protect Swiss Albino mice from hyperammonemia when administered in high doses before ammonium acetate. This has been explained by its specific ability to shuttle fatty acids into mitochondria. The structure of L-carnitine resembles the chemical structure of other substances that have been described as being able to protect living cells against osmotic stress. We subjected Swiss Albino mice to hyperammonemia after pretreatment with L-carnitine or "osmoprotectants" such as the quaternary amines choline and betaine, and trimethylamine N-oxide. L-Carnitine proved to be the drug of choice to protect against acute hyperammonemia. Nevertheless, the other tested compounds appeared also to be effective, suggesting that osmoregulation plays a major role in protection against hyperammonemia.

Failure of L-carnitine to protect mice against ammonia toxicity

Recent reports indicate that intraperitoneal administration of L-carnitine protects mice from ammonia toxicity. We found that mice injected with L-carnitine and subsequently challenged with ammonium acetate succumb as readily as mice injected with saline and the ammonium acetate. Mice pretreated with L-carnitine exhibited higher levels of liver ammonia than the saline-pretreated control mice. The ammonia and urea levels in serum and brains were similar in two groups. Our findings are in contrast to those reported previously and therefore warrants further investigation before L-carnitine can be considered as a drug to alleviate hyperammonemia in humans.

General pharmacology of 1-(2-ethoxyethyl)-2-(4-methyl-1-homopiperazinyl)benzimidazole difumarate. 1st communication: effects on the central nervous system

Effects of 1-(2-ethoxyethyl)-2-(4-methyl-1-homopiperazinyl)benzimidazole difumarate (KB-2413) on the central nervous system were compared with those of ketotifen and chlorpheniramine. Among the various activities related to the central nervous system, KB-2413 showed inhibitory effects on locomotor activity, acetic acid-induced writhing in mice and reserpine-induced hypothermia in rats at a high dose such as 100 mg/kg p.o. However, in mice, it (10-100 mg/kg p.o.) exerted no significant influence on muscle tone, various experimental convulsions, oxotremorine-induced tremor, physostigmine-induced mortality or hexobarbital-induced sleep, and in rats, it had no effect on rectal temperature or conditioned avoidance. It also did not affect spontaneous electroencephalogram (EEG), EEG arousal responses or photic driving response in rabbits at 5 mg/kg i.v. On the other hand, ketotifen and chlorpheniramine affected more widely and strongly the central nervous system than KB-2413. In conclusion, KB-2413 showed a less potent effect on the central nervous system than ketotifen and chlorpheniramine, and no results suggested serious side effects of KB-2413.

Aneuploidy induced by nocodazole or ethyl acetate is suppressed by dimethyl sulfoxide

Nocodazole and ethyl acetate have previously been shown to be potent inducers of aneuploidy in Saccharomyces cerevisiae. The elevation in aneuploidy frequency induced by high doses of these compounds was reduced in a dose-response manner in the presence of increasing concentrations of dimethyl sulfoxide. These results imply that compounds dissolved in dimethyl sulfoxide which either are weak inducers of aneuploidy or are of unknown potency may register as false negatives in routine screening procedures.

Prevention of ammonia-induced brain edema in dogs infused with a branched-chain amino acid solution

Infusion of an ammonium acetate solution into dogs during mannitol-induced reversible opening of the blood-brain barrier resulted in a marked rise in intracranial pressure (ICP). The preventive effect of a branched-chain amino acid (BCAA) solution on ammonia-induced brain edema was tested by measuring ICP and brain water content. The BCAA solution apparently prevented ammonia-induced brain edema, indicating that BCAA accelerated ammonia detoxification in the brain.

Analgesic and anti-inflammatory activities in rats of alpha-(3,5-di-t-butyl-4-hydroxybenzylidene)-gamma-butyrolactone (KME-4), and its intestinal damage

alpha-(3,5-Di-t-butyl-4-hydroxybenzylidene)-gamma-butyrolactone (KME-4), an anti-inflammatory drug, possesses analgesic activity in rat models. In the acetic acid-induced writhing test, the oral ED50 values for KME-4, indomethacin, naproxen and ibuprofen were 5.2, 3.8, 7.0 and 18.6 mg kg-1, respectively, and the relative order of potency of these drugs correlated with their inhibitory effect on acetic acid-induced vascular permeability in rats. KME-4 also had analgesic activity in the tests of Randall-Selitto and adjuvant arthritic flexion, but the dose required was greater than that needed in the writhing test. KME-4 (10 mg kg-1 day-1 orally) has a preventive effect against adjuvant-induced arthritis in rats, and its efficacy was more potent than indomethacin (2 mg kg-1 day-1) as judged from various parameters determined. When administered orally to rats once daily for 12 days, KME-4 caused perforating ulceration of the small intestine but this action was less potent than the effect of indomethacin, naproxen and ibuprofen.

Coronary vasoactivity of acetate in dog and guinea-pig

This study compares the coronary vasoactivity of acetate in the blood-perfused heart of the open-chest dog and in the buffer-perfused guinea-pig heart. In the dog acetate is a weak but probably fully efficacious coronary agonist. Direct intracoronary infusions of isosmolar Na acetate caused dose-dependent coronary vasodilation and decreased transcoronary O2 extraction, resulting in an increase in cardiac O2 usage of up to 40%. Acetate raised coronary flow to at least 50% above control in 63 of 67 dogs but caused maximum coronary vasodilation (400% of control) in only 39 of the 67. The frequency distribution of the acetate EC-20 decreased monotonically from a mode at less than 1 mM over a range extending to greater than 6 mM, suggesting a single population of animals characterized by a rather wide range of sensitivity to acetate. Theophylline antagonized acetate vasodilation, in support of the idea that adenosine mediates the coronary effects of acetate. In the guinea-pig heart, acetate in concentrations up to 10 mM caused minimal increases in coronary flow that were completely accounted for by the small change in O2 usage that resulted from switching from glucose to acetate the main energy source. Acetate (10 mM) elicited a small release of adenosine and its degradation products.

Protective effects of zinc acetate toward the toxicity of nickelous acetate in rats

Zinc pretreatment is known to ameliorate the acute and chronic effects of the toxic heavy metal, cadmium. However, the ability of zinc to decrease the toxicity of other metals has not been widely investigated. Therefore, this study was designed to determine the effects of zinc pretreatment on the acute toxicity of nickel. Male Fischer rats received either nickel alone (i.p.), zinc alone (s.c.), zinc plus nickel, or saline (i.p. and s.c.; controls). In the lethality studies, the dose of nickel was 115 mumol nickel/kg (as nickel acetate) while for all other studies the dose was 95 mumol nickel/kg. Zinc was given in multiple doses of 300 mumol zinc/kg (as zinc acetate) at -24, 0 and +24 h relative to nickel (total zinc dose 900 mumol/kg) for lethality studies or -24 and 0 h for studies 24 h and under in duration (total dose 600 mumol/kg). Zinc pretreatment significantly increased the 14-day survival of nickel-related rats. Zinc did not, however, prevent the reduction in weight gain over 2 weeks seen with nickel treatment. Histopathologically, at 120 h following nickel exposure, kidneys in the group receiving nickel alone generally showed moderate nephropathy (multifocal proximal tubule degeneration with necrosis) while in the zinc plus nickel group the nephropathy was generally mild. Zinc pretreatment had no apparent effect on the pharmacokinetics of nickel over 24 h as assessed by urinary excretion, blood levels or organ distribution. Zinc pretreatment also did not alter the subcellular distribution of renal nickel 6 h after nickel exposure. Enhanced synthesis of metallothionein did not appear to play a critical role in the reduction of nickel toxicity, since renal concentrations of this metal-binding protein, although elevated compared to control, were not different in rats receiving zinc and nickel or zinc alone. Zinc pretreatment did, however, have marked effect on nickel-induced hyperglycemia, reducing both the duration and severity of elevated blood glucose levels. Results of this study show that zinc can prevent some of the toxic effects of nickel and that the mechanism of this action does not appear to involve either metallothionein or alterations in the pharmacokinetics of nickel.

Inhibition of acetate incorporation into lipids by adriamycin

Adriamycin (ADM) inhibits 14C-acetate incorporation into cardiomyocytes, with the ID50 being 0.9 microM. Incorporation into neutral lipids were inhibited except for cholesterol ester. Cholesterol and phospholipids demonstrated the strongest inhibition at 5 microM ADM.

Non-narcotic orally effective, centrally acting analgesic from an Ayurvedic drug

Embelin, a p-quinone, is derived from Embelia ribes Burm. The analgesic effect of potassium embelate has been studied in rats and mice. The test drug was found to be effective by oral, i.m. and i.c.v. routes and the results compared well with morphine. Although potassium embelate acts centrally to produce analgesia, its effect is not antagonized by naloxone indicating a different central site of action. There is no precipitation of abstinence syndrome as observed with morphine. Peripheral site of action of the drug is ruled out as it lacks any demonstrable anti-inflammatory action. It can be concluded that high oral efficacy and non-narcotic properties of the test drug make it more acceptable than morphine. In addition, lack of any adverse effects, high therapeutic index and absence of abstinence syndrome confers a long term safety on potassium embelate for use as an analgesic.

Studies on the combination of Glycyrrhizae Radix in Shakuyakukanzo-To

The pharmacological properties of the five samples of glycyrrhizic acid, paeoniflorin, the extracts of Glycyrrhizae Radix, the extracts of Paeoniae Radix and a preparation of Chinese drug Shakuyakukanzo-To were compared by investigating their actions in the carrageenan-induced paw edema, the cotton pellet granuloma formation and acetic acid-induced writhing syndrome tests, using ddY-strain mice. The concentrations of glycyrrhizic acid and paeniflorin, the main components of Glycyrrhizae Radix and Paeoniae Radix respectively, were determined in the preparations by high performance liquid chromatography. Anti-inflammatory activity was observed with the doses of glycyrrhizic acid, 3.0 and 30.0 mg/kg p.o., which are almost equivalent to the quantities contained in the extracts of Glycyrrhizae Radix, 18.0 (normal human dose per day) and 180.0 mg/kg, or in Shakuyakukanzo-To, 32.0 (normal human dose per day) and 320.0 mg/kg, respectively and with the doses of the extracts of Glycyrrhizae Radix, 18.0 and 180.0 mg/kg p.o., but not with the doses of Shakuyakukanzo-To, 32.0 and 320.0 mg/kg p.o., in carrageenan-induced edema and cotton pellet method. Doses of paeoniflorin (2.0, 20.0 and 200.0 mg/kg p.o.) and the extracts of Paeoniae Radix, 21.0 (normal human dose per day) and 210.0 mg/kg p.o., which contain almost equivalent quantities of paeoniflorin, 2.0 and 20.0 mg/kg, respectively, showed significant inhibitory effects in the writhing syndrome test. Furthermore, Shakuyakukanzo-To, 32.0 and 320.0 mg/kg p.o., which contain almost equivalent quantities of paeoniflorin, 2.0 and 20.0 mg/kg, showed strong effects in this test.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthesis, biological data and correlation analysis in a set of analgesic drugs

A set of ortho-disubstituted benzene derivatives (2-X--C6H4NH--Y) designed as analgesics has been studied. Some physicochemical properties which are potentially correlated with the considered pharmacological activities are determined. Quantitative structure-activity relationships (QSAR) show that the analgesic potency (writhing test) is a function of the hydrophobic-lipophilic parameters associated with the structures under study. Since the derivatives are inactive or very poor inhibitors of prostaglandin biosynthesis, the appropriate modulation of substituents may maximize the differentiation between anti-nociceptive and analgesic activity.

Antinociceptive action of sodium valproate in the mouse

The antinociceptive action of sodium valproate (VPA) was examined using male NMRI mice. Using the hot-plate assay at 60 degrees C, orally-administered VPA (50-400 mg/kg) produced antinociceptive effects; the ED50 was about 160 mg/kg. Oral doses of VPA (6.3-400 mg/kg) decreased the writhing response elicited by intraperitoneally-injected acetic acid. The antinociceptive effect of VPA, as determined with the writhing test, exhibited complex characteristics, the most pronounced effect occurring at doses of 12.5-50 mg/kg. The antinociceptive effect of VPA in the writhing test was not antagonized by bicuculline or by naloxone. VPA, like other agents which enhance central GABA-ergic mechanisms, might possess analgesic activity.

Synthesis of some 5-phenylhexahydroazepino[4,5-b]indoles as potential neuroleptic agents

5-Phenyl-1,2,3,4,5,6-hexahydroazepino[4,5-b]indole (3a) and five derivatives have been prepared and screened for neuroleptic activity. None of the compounds antagonized methamphetamine aggregate toxicity in mice. A number of compounds, including 3a and its 3-methyl derivative 3d, showed activity in the antidepressant screens.

Analgesic narcotic antagonists. 1. 8 beta-Alkyl-, 8 beta-acyl-, and 8 beta-(tertiary alcohol)dihydrocodeinones and -dihydromorphinones

Conjugate addition of lithium dialkyl cuprates to codeinone (3) gave as the major product a series of 8 beta-alkyldihydrocodeinones 4a-m. A low yield of the 8 alpha-isomer 6 was isolated in several cases. 8 beta-Acyldihydrocodeinones 10 were prepared by the addition of acyl carbanion equivalents (protected cyanohydrin method or lithium bis(alpha-ethoxyvinyl)cuprate) to 3 followed by hydrolysis. 8 beta-Acetyldihydrocodeine (12) was reacted with MeLi or n-BuLi to give tertiary alcohols 13, which were oxidized to target dihydrocodeinones 14. The 8 beta-substituted compounds with unsaturated (4c,f,m), branched (4d,g,i-k), or large straight-chain (4h,l) alkyl groups, as well as the acyl (10a-d) and tertiary alcohol (14a,b) derivatives, were less active than dihydrocodeinone (4n) in the mouse writhing and rat tail-flick analgesic assays. The analgesically active 8 beta-methyl (4a) and 8 beta-ethyl (4b) compounds were converted to N-(cyclopropylmethyl)- and N-(cyclobutylmethyl)dihydronorcodeinones (17 and 18) and -dihydronormorphinones (19 and 20). Some of these compounds had mixed agonist-antagonist profiles of action. One of these compounds, N-(cyclopropylmethyl)-8 beta-ethyldihydronorcodeinone (17b), has been selected for further study in man.

Analgesic narcotic antagonists. 2. 8-Alkymorphinan-6-ones

A series of 8-alkyl-3-methoxy-17-methylmorphinan-6-ones (3C) and -isomorphinan-6-ones (3T) were prepared by conjugate addition of lithium dialkylcuprates to the corresponding 7,8-didehydro-6-ones 2C and 2T. These 17-methyl compounds were potent analgesics and were converted to mixed narcotic agonists-antagonists 7-10, by replacement of the 17-methyl groups with cycloalkylmethyl moieties. The 8 substituent modified the type of activity observed. One of these compounds, 17-(cyclobutylmethyl)-3-hydroxy-8 beta-methylmorphinan-6-one (10Ca), had an agonist-antagonist ratio of 0.1. Compound 10Ca did not support or cause dependence in rats. This compound, however, appeared to be a typical narcotic agent in morphine-dependent monkeys.

Synthesis and analgesic activities of some (4-substituted phenyl-1-piperazinyl)alkyl 2-aminobenzoates and 2-aminonicotinates

A series of (4-substituted phenyl-1-piperazinyl)alkyl 2-aminobenzoates and 2-aminonicotinates has been prepared and screened for analgesic and antiinflammatory properties in mice and rats. The tabulated results reveal several 2-(4-substituted phenyl-1-piperazinyl)ethyl 2-(7- or 8-substituted 4-quinolinylamino)benzoates to be six to nine times more potent analgesics than the reference compounds (glafenine and aminopyrine) and to possess minor antinflammatory activity. Compound 45, 2-[4-[3-(trifluoromethyl)phenyl]-1-piperazinyl]ethyl 2-[[7-(trifluoromethyl)-4-quinolinyl]amino]benzoate (antrafenine), showed marked analgesic activity, long duration of action, and excellent tolerance in pharmacological and toxicological studies, as well as in clinical trials.

A new nonsteroidal analgesic-antiinflammatory agent. Synthesis and activity of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone and related compounds

In order to examine analgesic and antinflammatory activities, various 2-alkyl- or 2-alkenyl-4-alkoxy-5-(substituted amino)-3(2H)-pyridazinones were prepared. Among the compounds prepared, 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (8) was evaluated to be the most attractive compound as an analgesic-antiinflammatory agent. Compound 8 was shown to be more potent in analgesic and antiinflammatory activities and less potent in toxicity than aminopyrine and phenylbutazone. Some pyridazinone derivatives in which possible active sites of 8 are eliminated and altered were prepared, and their activities were evaluated by means of analogous assays. On the basis of available data, the structure-activity relationship in a series of 4-alkoxy-2-substituted-5-(substituted amino)-3(2H)-pyridazinones was also discussed.