The acute oral toxicity and primary ocular and dermal irritation of selected N-alkyl-2-pyrrolidones

N-alkyl-2-pyrrolidones are a class of materials that are increasingly used in food, drug, cosmetic and industrial applications; however, toxicological data is only available for a few members of the class. The acute oral toxicity, primary dermal irritation and primary ocular irritation of N-methyl-, N-ethyl-, N-hydroxyethyl-, N-isopropyl-, N-cyclohexyl-, N-octyl-, N-dodecyl-, N-coco- and N-tallow-2-pyrrolidone are reported. Additionally, N-octyl-, N-decyl-, N-dodecyl-, N-tetradecyl-, N-hexadecyl- and N-octadecyl-2-pyrrolidone had the primary ocular and dermal irritation indices measured as a 2% aqueous suspension. These data show a wide range of toxicities dependent upon the alkyl substituent.

Mutagenicity and cytotoxicity of N-methyl-2-pyrrolidinone and 4-(methylamino)butanoic acid in the Salmonella/microsome assay

The industrial solvent N-methyl-2-pyrrolidinone (NMP) and its hydrolysis product, 4-(methylamino)butanoic acid (N-MeGABA), were examined for mutagenicity and cytotoxicity in the Ames Salmonella/microsome assay. In order to detect a broad range of possible mutagenic endpoints, the following strains were used in the assay: base-pair substitution strains TA100, TA102 and TA104; frameshift strains TA97 and TA98; and repair proficient strains TA2638, UTH8413 and UTH8414. In the standard plate incorporation assay, six log-linear doses of each compound were tested; doses ranged from 0.01 to 1000 mumol/plate for NMP, and 0.01 to 316 mumol/plate for N-MeGABA. Neither compound was detectably mutagenic when tested in the presence and absence of metabolic activation by Aroclor-induced rat liver S9. NMP did show significant responses with strains TA102 and TA104 that were less than two-fold over background, but no clear dose-response relationships were evident. A preincubation modification of the assay was also performed, using strains TA98 and TA104. Mutagenic activity was not observed for NMP, while N-MeGABA showed significant responses with TA104 but dose-related mutagenicity was not established. Preincubation testing revealed both NMP and N-MeGABA to be cytotoxic to the test population of Salmonella at the highest treatment doses.

Evaluation of the developmental toxicity of nicotine and cotinine with frog embryo teratogenesis assay: Xenopus

The teratogenic potential of nicotine and a primary metabolite, cotinine, was examined with FETAX (Frog Embryo Teratogenesis Assay: Xenopus). Early embryos of Xenopus laevis were exposed for 96 hr to nicotine or cotinine in two separate static renewal tests of each compound without addition of the metabolic activation system (MAS). Two static renewal tests of nicotine with the MAS were also conducted. Addition of the MAS to nicotine reduced the LC50 from an average of 136 to 20 mg/L. However, the EC50 (malformation) was increased from 0.4 to 5.8 mg/L upon activation. The LC50 and EC50 values for cotinine averaged 4,340 and 720 mg/L, respectively. Based on mortality/malformation index values, growth end points, and the types and severity of the induced malformations, nicotine and cotinine scored as potential teratogens. Metabolism of nicotine to more polar metabolites increased the nicotine concentration required to induce terata. The results are indicative of the versatility of FETAX in developmental toxicity testing.

Pharmacological properties of N-methoxy-3-(3,5-ditert-butyl-4-hydroxybenzylidene)-2-pyrrolidone (E-5110), a novel nonsteroidal antiinflammatory agent

The antiinflammatory activity of a novel pyrrolidone derivative E-5110 was investigated using anti-inflammatory, analgesic and antipyretic animal models in comparison to indomethacin (IND) and piroxicam (PIR). The acute antiinflammatory activity of E-5110 on carrageenin paw edema was similar to IND, and half of PIR. E-5110 inhibited the pleural exudate volume and leucocyte infiltration in a reversed passive Arthus reaction more potent than IND. The chronic inflammatory responses in the established adjuvant- and type II collagen-induced arthritis were suppressed by E-5110 similar to IND and PIR. The analgesic potency of E-5110 was similar to IND and PIR, but the antipyretic activity of E-5110 was more potent than that of IND, and slightly more potent than that of PIR. The ulcerogenic effect of E-5110 on rat gastric mucosa was less than that of the reference drugs.

Toxicity of N-methyl-2-pyrrolidone (NMP): teratogenic, subchronic, and two-year inhalation studies

Pregnant rats were exposed to N-methyl-2-pyrrolidone (NMP) at atmospheric concentrations of 0.1 and 0.36 mg/liter for 6 hr/day on Days 6 through 15 of gestation. Except for sporadic lethargy and irregular respiration in several rats the first 3 days of exposure, there were neither abnormal clinical signs nor pathological lesions in the maternal rats. Exposure did not affect either the outcome of pregnancy or embryonal growth rate. No abnormal development was detected in the vital organs and skeletons of the fetuses. Rats were exposed to an aerosol-vapor mixture of NMP at concentrations of 0, 0.1, 0.5, and 1.0 mg/liter for 6 hr/day, 5 days/week for 4 weeks. At 0.1 and 0.5 mg/liter exposure levels, rats did not show any significant clinical signs or pathological lesions. However, lethargy, respiratory difficulty, and excessive mortality were found in rats exposed to 1.0 mg/liter. These rats had focal pneumonia, bone marrow hypoplasia, and atrophy of lymphoid tissue in the spleen and thymus. These lesions were reversible in surviving rats following 2 weeks of recovery. Increases in the relative and absolute numbers of neutrophils were observed during exposure at 1.0 mg/liter, but returned to normal limits after 2 weeks of recovery. Rats were exposed to vapor of NMP at concentrations of 0, 0.04, or 0.4 mg/liter for 6 hr/day, 5 days/week for 2 years. Male rats at 0.4 mg/liter showed slightly reduced mean body weight. No life-shortening toxic or carcinogenic effects were observed in rats exposed for 2 years to 0.04 or 0.4 mg/liter of NMP.

Muscarinic actions of an N-methyl-N-2-bromoethylamino analog of oxotremorine (BR 401) in the mouse

The pharmacological effects of N-[4-(2-bromoethylmethylamino)-2-butynyl]-2-pyrrolidone (BR 401) were compared in the mouse with those of N-[4-(2-chloroethylmethylamino)-2-butynl]-2-pyrrolidone (BM 123) and oxotremorine. BR 401 was more toxic than oxotremorine and BM 123 when administered i.v. (LD50, 0.7 mumol kg-1), but less toxic than oxotremorine when given i.p. (LD50, 39 mumol kg-1). Atropine and methylatropine (10 mumol kg-1 i.p.) increased the LD50 value of BR 401, given i.v., 75- to 100-fold. Upon i.v. administration, BR 401 was 2- to 3-fold more potent than oxotremorine and 10 to 20 times more potent than BM 123 in producing central (tremor and analgesia) and peripheral (salivation) muscarinic effects. However, after i.p. administration BR 401 was 3-fold less potent than oxotremorine in eliciting tremor and analgesia. The aziridinium ion (BR 401A), formed by cyclization of BR 401, produced salivation but no tremor. These observations suggest that BR 401 when given i.v. penetrates effectively into the central nervous system where it cyclizes rapidly to the pharmacologically active aziridinium ion. In contrast, after i.p. administration a large proportion of BR 401 will cyclize before it can reach the central nervous system. BM 123, because of its slower cyclization, enters the central nervous system effectively also by the i.p. route. Thus, central potency of 2-haloethylamines such as BR 401 and BM 123 is critically dependent not only on the rate of cyclization, but also on the route of administration. The duration of tremor induced by BR 401 and BM 123 was considerably shorter than that induced by oxotremorine.(ABSTRACT TRUNCATED AT 250 WORDS)

Anticancer activity of new 3-amino-pyrrolidinedione-nitrogen mustard derivatives on murine sarcoma 180

A 2,5-pyrrolidinedione linked nitrogen mustard derivative, (R,S)3-[N,N-bis(2-chloroethyl)]-amino-1-(2'-methoxyphenyl)pyrrolidine- 2,5-dione hydrochloride (I) showed a marked antiproliferative effect on mouse Sarcoma 180. Since (I) is also active against L1210 and P388 leukaemias, its toxicity in mice was evaluated. A study of acute toxicity revealed focal liver cell necrosis. Another derivative, (R,S)3-[N,N-bis-(2-chloroethyl)]amino-1-(4'-n-butoxyphenyl)pyrrolidine- 2,5-dione dihydrate (II), which also possessed significant anticancer effect on P388 and L1210 leukaemias, was inactive against Sarcoma 180.

Evaluation of the effects of cotinine and nicotine-N'-oxides on the development of tumors in rats initiated with N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide

The effects of cotinine and nicotine-N'-oxides on tumor development in F344 rats initiated with N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide [(FANFT) CAS: 24554-26-5] were evaluated. When rats were 6 weeks old, FANFT in an agar diet was administered for a 6-week period. Subsequently, cotinine, trans-nicotine-N'-oxide, and a mixture of cis-nicotine-N'-oxide and trans-nicotine-N'-oxide in drinking water were given as promoters in concentrations of 0.1, 0.02, and 0.02%, respectively. These nicotine metabolites were offered ad libitum for 78 weeks. Control groups consisted of rats that received tap water with or without prior administration of FANFT. Cotinine, trans-nicotine-N'-oxide, and the mixture of cis- and trans-nicotine-N'-oxides were neither carcinogens nor promoters of urinary bladder tumors in rats initiated with FANFT. A reduced incidence of urinary bladder tumors was observed in FANFT-pretreated animals that also received a mixture of cis- and trans-nicotine-N'-oxides. FANFT administration increased the incidences of mesothelioma of the peritoneum and thyroid tumors. Tumor formation in the tongue and palate observed in FANFT-treated rats was not affected by administration of these nicotine metabolites. There was, however, a significant increase in the incidence of forestomach tumors in rats that were initiated with FANFT and subsequently received either trans-nicotine-N'-oxide or a mixture of cis- and trans-nicotine-N'-oxides.

Stereoselectivity of muscarinic receptors in vivo and in vitro for oxotremorine analogues. N-[4-(tertiary amino)-2-butynyl]-5-methyl-2-pyrrolidones

The enantiomers of three 5-methyl-2-pyrrolidone analogues of the muscarinic agent oxotremorine (1) were synthesized. The pyrrolidine derivative (R)-13 was an antagonist to carbachol in the guinea pig ileum and also showed central and peripheral antimuscarinic activity in vivo. It was more potent and more selective than atropine in antagonizing the central effects of 1. The dimethylamino analogue (R)-14 and the trimethylammonium salt (R)-15 were potent agonists in the guinea pig ileum. (R)-14 showed both central muscarinic (hypothermia) and central antimuscarinic activity (antagonism of oxotremorine-induced tremor) in vivo. The R enantiomers of 13-15 were considerably more potent than the S enantiomers in vivo and in vitro irrespective of whether agonist or antagonist activity was measured. From a comparison of the contribution of the methyl group at the chiral center to the overall affinities, it is suggested that agonists and antagonists in this series bind in an essentially identical manner to the muscarinic receptor.

Neurotoxic effects of endogenous materials: quinolinic acid, L-pyroglutamic acid, and thyroid releasing hormone (TRH)

The previously reported, dose-related, and selective neurotoxic action of 100 to 200 nmol quinolinic acid on intrastriatal injection was confirmed. A slight neurotoxicity was obtained with 250 nmol thyroid releasing hormone but not with a similar dose of L-pyroglutamic acid.

L-pyroglutamate: an alternate neurotoxin for a rodent model of Huntington's disease

Intrastriatal injections of L-Pyroglutamate (L-PGA) in mice produced behavioral and neuropathological effects that resemble in part the kainate-injected rat striatal model of Huntington's Disease (HD). The behavioral responses induced after unilateral injections of L-PGA included circling, postural asymmetry of head and trunk and possible dyskinesias. The neuropil in the injected striatum contained dilated profiles, degenerating neurons and oligodendroglia, and numerous phagocytic microglial-like cells. A dose response relation existed. The size of the lesion (expressed as a percent volume of the striatum destroyed) ranged from 1 +/- 0.18% at 0.02 mumoles to 20.2 +/- 3.97% at 200 mumoles L-PGA (pH = 7.3). L-PGA is a weak neurotoxin when compared to kainic acid. Several factors raise interest in the possible role of L-PGA in HD, including the recently reported elevated plasma levels of L-PGA in some HD patients, and these considered in the discussion.

Teratogenesis study of N-cyclohexyl-2-pyrrolidone in rats and rabbits

Teratogenesis studies were performed in rats and rabbits given N-cyclohexyl-2-pyrrolidone, an aprotic solvent used in chemical processing. Dosages of 0, 15, 50, 150, or 500 mg N-cyclohexyl-2-pyrrolidone/kg body wt/day were administered by gavage to groups of 25 pregnant Sprague-Dawley rats on Days 6 through 15 of gestation. Dosages of 0, 10, 30, 100, or 300 mg/kg/day were administered by gavage to groups of at least 15 pregnant Dutch-Belted rabbits on Days 6 through 18 of gestation. Animals were killed and subjected to uterine examination on Day 20 of gestation for rats and on Day 29 for rabbits. There were no significant differences between the vehicle control and N-cyclohexyl-2-pyrrolidone-treated groups for implantation numbers or live or dead fetuses, resorptions, and fetal body weight in rats and rabbits. Dam body weight gain during gestation was comparable among groups. External gross visual examination of the fetus as well as examination of skeletal and soft tissues revealed no effects related to treatment with N-cyclohexyl-2-pyrrolidone.

Hypolipidemic activity of 4-phenyl-5,5-dicarbethoxy-2-pyrrolidinone in rodents

A series of pyrrolidinones have been reported to possess hypolipidemic activity in mice. The most active agent, 4-phenyl-5-5-dicarbethoxy-2-pyrrolidinone, effectively lowered both serum cholesterol and triglyceride levels at 20-30 mg/kg/d. The agent suppressed liver mitochondrial citrate exchange, phosphatidate phosphohydrolase, and sn-glycerol-3-phosphate acyl transferase activities. Lipid content of the liver, small intestine, and serum lipoprotein fractions was reduced by drug treatment, but lipid levels increased in the bile and fecal samples, suggesting the drug accelerated lipid excretion. The mode of action of the pyrrolidinone appears similar to that of the cyclic imides.

Pyroglutamate kinetics and neurotoxicity studies in mice

Plasma and brain kinetics of L-glutamic (GA) and L-pyroglutamic (PY) acids were studied after oral administration of monosodium glutamate (MSG) or pyroglutamate to adult mice. Oral MSG (0.5 g/kg) increased plasma GA and PY levels 4.5 and 1.8 times, respectively. A small increase in brain PY (1.3 times the basal level) but not in brain GA, was observed. Oral administration of pyroglutamate (0.5 g/kg) increased plasma PY levels 56 times in adult mice and 69 times in infant mice. No lesions in the arcuate nucleus of the hypothalamus were observed when pyroglutamate was administered orally to infant mice at doses of 2 and 4 g/kg.

Subchronic feeding study in beagle dogs of N-methylpyrrolidone

The potential toxicity of N-methylpyrrolidone was evaluated following dietary administration for 13 weeks to male and female beagle dogs at dosage levels of 25, 79 and 250 mg per kg body weight per day. Body weight gain and food consumption, hematological and clinical chemical data, and ophthalmic, gross and histopathological examinations were used to study possible toxicological or pathological effects. No statistically significant treatment-related effects that were judged to be biologically meaningful were seen in any parameters of either male or female animals exposed to N-methylpyrrolidone at any dose level. However, a dose-dependent decrease in body weight and increase in platelet count that correlated with increased megakaryocytes was observed. Serum cholesterol in males decreased with increasing doses.

Teratogenicity study of N-methylpyrrolidone after dermal application to Sprague-Dawley rats

Teratogenicity studies were performed in rats given N-methylpyrrolidone, a solvent used in chemical processing. Dosages of 75,237 and 750 mg of N-methylpyrrolidone/kg body weight/day were administered dermally to groups of 25 pregnant Sprague-Dawley rats on days 6 through 15 of gestation. Additionally, the study used a positive dermal control. Hexafluoroacetone, was chosen based on its dermal teratogenic activity. An oral positive control, aspirin, was included in order to add significance to the data generated in the experimental positive dermal control group. All animals were killed and subjected to uterine examination on day 20 of gestation. Maternal toxicity was indicated at 750 mg of N-methylpyrrolidone/kg by reduced body weight gain during gestation. Treatment with N-methylpyrrolidone resulted in dose-dependent brightly colored yellow urine and dry skin. Treatment at the high dosage level resulted in fewer live fetuses per dam, an increase in the percentage of resorption sites and skeletal abnormalities. These effects could be the result of maternal toxicity. There was no evidence of teratogenic effects nor effects on the dams at 75 and 237 mg/kg of body weight.

Synthesis and pharmacological properties of 1,3 and 5-substituted 2-pyrrolidinones

We described synthesis of 1-aryl-3 and 5-substituted 2-pyrrolidinones (2a--5a and 3b--4b). Pharmacological studies revealed that compounds 3b, 4a and 4b have analgetic and antiinflammatory properties. None of the compounds posesses neuroleptic or anticonvulsant properties.