Teratogenic and Embryotoxic Effects of the Herbicides Di- and Trichlorophenoxyacetic Acids (2, 4D and 2, 4, 5-T)

Abstract: Commercial solutions of phenoxyacetic acids were tested for teratogenic effects in NMRI-mice. The Swedish product Hormoslyr 500-T contained only 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) while Hormoslyr 64 was a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-T (2:1). Subcutaneous injections were given from day 6 through day 14 of pregnancy and the animals were sacrificed on day 18. The number of resorbed embryos, living embryos with gross malformations, as well as internal and skeletal malformations were recorded. It was found that both preparations at the high dosage (110 mg/kg/day) were teratogenic and embryotoxic. At the low dose level (50 mg/kg/day) the 2,4,5-T solution was more harmful than the mixture of 2,4-D and 2,4,5-T. The risks of teratogenicity in human civilian use and the role of dioxins are discussed.     

Use of the periodic acid schiff stain to grade retarded fetal renal development in mice

In an earlier study, maternal mice were given by gavage 60–120 mg/kg 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on days 6—14 of pregnancy and sacrificed on day 17. The Gomori stain revealed diminished alkaline phosphatase in the renal proximal tubules of fetuses exposed to 2,4,5-T during gestation indicating retarded renal functional and, probably, morphological development. Spare sections of the fetal kidneys from the earlier study were stained by the periodic acid-Schiff (PAS) procedure. This revealed, in exposed fetuses, a reduction of renal tubules with PAS-positive material in the brush borders comparable in incidence and distribution to those with alkaline phosphatase in the earlier study. These findings indicate that PAS can replace the Gomori stain as a screening procedure when retarded fetal renal development by a toxic agent is suspected. Unlike alkaline phosphatase, the PAS procedure is effective even after prolonged fixation in Bouin's solution which is commonly used in fetal studies.     

Teratogenic and toxicological examination of 2,4,5-trichlorphenoxyacetic acid in developing chick embryos

Practical grade 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), dissolved in dimethylsufoxide (DMSO), was injected into the air space of fertilized chicken eggs prior to incubation. Doses of 2,4,5-T administered were 12.5, 25, 50, 75, 100, and 125 mg/kg to determine herbicide toxicity on the first day of incubation. A similar group was studied on day 5 of incubation with doses of 2,4,5-T at 50, 75, 100 and 250 mg/kg. LD₅₀ was estimated to be 62 mg/kg on day zero and 68 mg/kg on day 5. Additional, embryos were exposed to 2,4,5-T at 50 mg/kg on day zero of gestation and sacrificed after 48 h of incubation. Serial sections were examined for teratological and developmental anomalies. None were found.     

Reproduction study of 4-ethoxy-2-methyl-5-morpholino-3(2H)-pyridazinone (M73101) in rabbits. Administration of M73101 during the period of major organogenesis (author's transl)]

M73101 and aspirin were evaluated for the effects on prenatal development of progeny in JW-NIBS strain rabbits. Pregnant females were given orally M73101 (0, 50, 120 and 300mg/kg/day) or aspirin (200mg/kg/day) on days 6 to 18 of gestation. They were sacrificed on days 29 of pregnancy and their fetuses were examined for abnormalities. The results were summarized as follows: 1. During the dosing period, females received 300mg/kg of M73101 showed pronounced body weight depression and decrease in food and water intake. But after the dosing period, these influences were not seen. Females received aspirin did not show such phenomena. 2. There were no adverse effects on number of implants, litter size, fetal mortality or fetal weight, and no malformed fetuses attributable to the drugs were seen in each group.     

Pharmacokinetics of 2,4,5-T in mice as a function of dose and gestational status

A pharmacokinetic study was conducted in CD-1 mice with the herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) as a function of dose (15, 30, 60, and 90 mg/kg, iv) and gestational status (nonpregnant, day 6, 10, 13, and 17 of gestation, and postpartum). Analysis for 2,4,5-T and its metabolites was based on an electron-capture gas-liquid chromatographic method. Pharmacokinetic stimulation of the blood, urine, and feces data from each mouse was performed on an analog-digital hybrid computer system based on a two-compartment model with parallel, first-order elimination kinetics. Data analysis demonstrated dose-independent kinetics for most pharmacokinetic parameters but a gestational status-dependence. There was a tendency, as indicated by an increase in the biologic half-life and AUC and decrease in clearance and total percent recovery, for pregnant animals to eliminate 2,4,5-T more slowly as gestation progressed, resulting in potentially increasing fetal exposure during the later stages of pregnancy.     

Developmental Toxicity of 2,4,5-Trichiorophenoxyacetic Acid (2,4,5-T): II. Multireplicated Dose-Response Studies with Technical and Analytical Grades of 2,4,5-T in Four-Way Outcross Mice

A series of multireplicated developmental toxicity studies wereconducted in four-way outcross mice and CD-1 outbred mice administeredeither analytical or technical grades of 2,4,5-tri-chlorophenoxyaceticacid (2,4,5-T) by gavage on Gestational Days 6 through 14. Theformulations of 2,4,5-T differed by a factor of 10-fold in 2,3,7,8-tetrachlorodibenzo-p-dioxinlevels. Reduced fetal weight and increased incidences of cleftpalate and embryolethality were the most significant prenataleffects of both formulations of 2,4,5-T observed in all strains/stocksof mice. Both the outcross and outbred mice exhibited a dose-responserelationship with each of the above endpoints and the dose-responsecurves were parallel. There were no embryotoxic or fetotoxicdifferences between the technical and analytical grades of 2,4,5-Twith regard to extent of fetal weight reduction, resorptionrate, or cleft palate incidence. There was little differencein the results between the four-way outcross mouse and the CD-1outbred mouse.     

Early pregnancy failure induced by dibutyltin dichloride in mice

In this study, we examined the adverse effects of dibutyltin on initiation and maintenance of pregnancy after maternal administration during early pregnancy in mice. Following successful mating, female ICR mice were given dibutyltin dichloride (DBTCl) at 0, 7.6, 15.2, or 30.4 mg/kg bw/day by gastric intubation on days 0-3 or days 4-7 of pregnancy. Female mice were sacrificed on day 18 of pregnancy, and the pregnancy outcome was determined. After administration of DBTCl on days 0-3, the rate of nonpregnant females and the incidence of preimplantation embryonic loss were significantly increased at 30.4 mg/kg bw/day. The incidences of postimplantation embryonic loss in females given DBTCl on days 0-3 at 15.2 mg/kg and higher and on days 4-7 at 7.6 mg/kg bw/day and higher were increased. No increase in the incidence of fetuses with external malformations was observed after the administration of DBTCl on days 0-3 or days 4-7. A decline in the serum progesterone levels was detected in mice given DBTCl at 30.4 mg/kg bw/day on days 0-3 or days 4-7 of pregnancy. The data show that DBTCl adversely affects the initiation and maintenance of pregnancy when administered during early pregnancy in mice and suggest that the decline in serum progesterone levels is responsible for pregnancy failure.     

The fate of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) following oral administration to rats and dogs

Clearance of ¹⁴C activity from the plasma and its elimination from the body of rats and dogs were determined after single oral doses of [carboxy-¹⁴C]2,4,5-T. The half-life values for the clearance of ¹⁴C activity from the plasma of rats given doses of 5, 50, 100 or 200 mg/kg were 4.7, 4.2, 19.4 and 25.2 hr, respectively; half-lives for elimination from the body were 13.6, 13.1, 19.3 and 28.9 hr, respectively. The apparent volume of distribution also increased with dose. Urinary excretion of unchanged 2,4,5-T accounted for most of the ¹⁴C activity eliminated from the body of rats. A small amount of unidentified metabolite was detected in the urine when rats were given 100 or 200 mg/kg but not 5 or 50 mg/kg. These results show that the distribution, metabolism and excretion of 2,4,5-T are markedly altered when large doses are administered.In dogs given 5 mg/kg, the half-life values for clearance from plasma and elimination from the body were 77.0 and 86.6 hr, respectively, offering a plausible explanation of why 2,4,5-T is more toxic in dogs than in rats. Appreciable excretion in the feces was noted and three unidentified metabolites were detected in urine of dogs, indicating a considerable difference in metabolism of 2,4,5-T by dogs and rats given the same dose.     

In vitro uptake of organic ions by renal cortical tissue of rats treated acutely with 2,4,5-trichlorophenoxyacetic acid.

The effect of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on renal cortical function has been studied in male adult rats. Significant decreases in organic acid and organic base transport were measured when rats were pretreated with 2,4,5-T 24 hr before in vitro analysis of renal function. Experiments in which injections of p-aminohippurate were given showed no effect on organic acid or organic base transport by renal cortical slices. The data are interpreted to mean that pretreatment with 2,4,5-T has a depressive influence on the transport of some organic ions. Adult animals which were treated daily with 2,4,5-T accumulated a large body store of this herbicide during the first 6 days of administration. However, by 9 days the animals excreted essentially the dose of 2,4,5-T administered, and by 16 days the herbicide accumulated during the first 6 days had been almost totally eliminated. This chronic excretion pattern may explain why only moderate toxicity has been reported for this herbicide.     

Toxicity evaluation of a beta-galactosidase preparation produced by Penicillium multicolor

Tilactase is a beta-galactosidase enzyme preparation having lactase activity produced from the fungus Penicillium multicolor. The safety of tilactase was investigated in rats, dogs, and rabbits. Adult and juvenile rats administered 0, 500, 1000, or 4000 mg/kg bw/day of the enzyme preparation by gavage for 35 days, and dogs administered 0, 200, 500, or 1000 mg/kg bw/day in capsules for 30 days, exhibited no significant dose-related changes in body weights, feed consumption, organ weights, urinalysis, hematological profiles, clinical chemistry, or histopathological profiles. Rats receiving the same doses for 6 months also exhibited no dose-related effects, except for a small increase in the weight of the large intestine, an effect considered to be a physiological reaction to passage of a large amount of a non-absorbable substance. The no-observable-adverse-effect level (NOAEL) was 4000 mg/kg bw/day for rats and 1000 mg/kg bw/day for dogs. In three separate studies to examine reproductive and developmental toxicity, rats received 0, 250, 1000 or 4000 mg/kg bw/day by gavage up to the 7th day of pregnancy, during days 7-17 of pregnancy, and from day 17 of pregnancy to 21 days after delivery. There were no treatment-related effects on the dams, gestation period, numbers of implantations, parturition rates, sex ratios, or survival of offspring in any of the studies. No treatment-related external, internal, or skeletal abnormalities were observed in fetuses from any of the three studies. The NOAEL was 4000 mg/kg bw/day. In addition to the three rat studies, rabbits received 0, 250, 500, or 1000 mg/kg bw/day by gavage from the 6th to 18th day of pregnancy. No treatment-related changes were observed in the dams, or fertility indices; nor were there any treatment-related fetal abnormalities. The NOAEL was 1000 mg/kg bw/day. When viable P. multicolor spores were injected into the tail veins of mice, no deaths occured, no fungal cells were observed in various organs, and histopathology showed only focal necrosis in the liver of some of the animals, including the controls. Similar effects were observed when spores were administered to mice in a single dose by gavage. The particular strain of P. multicolor used to prepare tilactase is not pathogenic.     

Antischistosomal effects of 5-(2,4,5-trichlorophenyl)hydantoin and related compounds.

5-(2,4,5-Trichlorophenyl)hydantoin and several analogues effected an 80-90% reduction of live schistosomes in infected mice at doses ranging from 265 to 329 mg/kg per day when administered orally in the diet for 14 days. The sodium salt of 5-(2,4,5-trichlorophenyl)hydantoin, when given by gavage to rhesus monkeys infected with Schistosoma mansoni at 200 mg/kg/day for 5 or 10 days, removed all but a few live worms with no evidence of intolerance.     

NTP toxicology and carcinogensis Studies of 2,4-hexadienal (89% trans,trans isomer, CAS No. 142-83-6; 11% cis,trans isomer) (Gavage Studies)

2,4-Hexadienal, a colorless to yellow liquid with a pungent "green" or citrus odor, is used as a food additive for flavor enhancement, as a fragrance agent, as a starting material or intermediate in synthetic reactions in the chemical and pharmaceutical industries, as a fumigant, and as a corrosion inhibitor for steel. 2,4-Hexadienal was nominated for study by the National Cancer Institute because of the potential for carcinogenicity based on its alpha,beta-unsaturated aldehyde structure and the potential link between exposure to lipid peroxidation products in the diet and human malignancies. The commercial product is a mixture containing chiefly trans,trans-2,4-hexadienal in equilibrium with cis,trans-2,4-hexadienal. Male and female F344/N rats and B6C3F1 mice received 2,4-hexadienal (89% trans,trans; 11% cis,trans) in corn oil by gavage for 16 days, 14 weeks, or 2 years. Tissues and plasma from dosed rats were examined for malondialdehyde and glutathione concentrations, and DNA adducts were characterized in liver and forestomach samples from dosed rats and mice. Genetic toxicology studies were conducted in Salmonella typhimurium, rat and mouse bone marrow cells, and mouse peripheral blood erythrocytes. 16-DAY STUDY IN RATS: Groups of five male and five female rats were administered 0, 3, 9, 27, 80, or 240 mg 2,4-hexadienal/kg body weight in corn oil by gavage, 5 days per week, for 16 days. Three male and three female 240 mg/kg rats died before the end of the study. Mean body weight gains of 240 mg/kg rats were significantly less than those of the vehicle controls. Clinical findings included diarrhea, ataxia, lethargy, and nasal/eye discharge in males, and lethargy, paleness, and abnormal breathing in females in the 240 mg/kg groups. Liver weights of 240 mg/kg females were significantly greater than those of the vehicle controls. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were present in most 240 mg/kg rats, and forestomach epithelial hyperplasia was microscopically evident in most 80 mg/kg rats. 16-DAY STUDY IN MICE: Groups of five male and five female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 3, 9, 27, 80, or 240 mg/kg, 5 days per week, for 16 days. Chemical-related deaths occurred in one male and one female in the 240 mg/kg groups. Female mice in the 240 mg/kg group lost weight during the study. Gross and microscopic lesions indicative of forestomach necrosis and ulceration were present in all 240 mg/kg mice, and forestomach epithelial hyperplasia and hyperkeratosis were microscopically evident in 80 mg/kg mice. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 7.5, 15, 30, 60, or 120 mg/kg, 5 days per week, for 14 weeks. All rats survived to the end of the study. Mean body weights of 30, 60, and 120 mg/kg males were significantly less than those of the vehicle controls. The only clinical finding attributed to 2,4-hexadienal administration was hypersalivation in 30 and 120 mg/kg males and females. The incidences of forestomach hyperplasia and nasal olfactory atrophy or necrosis were significantly increased in 120 mg/kg rats. Nasal lesions occurred in most 120 mg/kg male rats. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 7.5, 15, 30, 60, or 120 mg/kg, 5 days per week, for 14 weeks. No deaths were attributed to administration of 2,4-hexadienal. Mean body weights of males and females were similar to those of the vehicle controls throughout the study. Clinical findings included salivation and anal wetness in males and females. Kidney weights of 60 and 120 mg/kg males and liver weights of 60 mg/kg males and females were significantly greater than those of the vehicle controls. The incidences of forestomach hyperplasia and/or nasal olfactory atrophy or necrosis were significantly increased in 120 mg/kg mice. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were administered 2,4-hexministered 2,4-hexadienal in corn oil by gavage at doses of 0, 22.5, 45, or 90 mg/kg, 5 days per week, for up to 105 weeks. Survival of all dosed groups of rats was similar to that of the vehicle control groups. The mean body weights of 90 mg/kg males were generally less than those of the vehicle controls throughout the study. The incidences of squamous cell papilloma of the forestomach occurred with positive trends in male and female rats. This neoplasm was found in 58% of males and 34% of females in the 90 mg/kg groups. In the forestomach of male rats, papilloma multiplicity was increased in the 90 mg/kg group, and squamous cell carcinomas were found in one 45 mg/kg male and two 90 mg/kg males. Epithelial hyperplasia of the forestomach occurred in most 45 and 90 mg/kg rats. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were administered 2,4-hexadienal in corn oil by gavage at doses of 0, 30, 60, or 120 mg/kg, 5 days per week, for up to 105 weeks. Survival of dosed mice was similar to that of the vehicle controls. The mean body weights of all dosed groups were generally similar to those of the vehicle controls throughout the study. The incidences of squamous cell papilloma of the forestomach occurred with positive trends in male and female mice; squamous cell carcinomas were present in 120 mg/kg males and females. Epithelial hyperplasia of the forestomach occurred in many 120 mg/kg mice. Two 120 mg/kg males had uncommon squamous cell carcinoma of the oral cavity (tongue). GENETIC TOXICOLOGY: 2,4-Hexadienal was mutagenic in S. typhimurium strain TA100 with and without induced hamster or rat liver enzymes; no mutagenic activity was detected with strains TA1535 or TA98, with or without S9. Results of bone marrow tests in male rats and male mice given intraperitoneal injections of 2,4-hexadienal showed a small increase in the induction of micronucleated erythrocytes. However, neither test was repeated, and the test results were judged to be inconclusive. Results of peripheral blood micronucleus tests in male and female mice treated with 2,4-hexadienal by gavage for 14 weeks were negative. CONCLUSIONS: Under the conditions of these 2-year gavage studies, there was clear evidence of carcinogenic activity* of 2,4-hexadienal in male and female F344/N rats and male and female B6C3F1 mice based on increased incidences of squamous cell neoplasms of the forestomach. The occurrence of squamous cell carcinoma of the oral cavity (tongue) in male B6C3F1 mice may have been related to the administration of 2,4-hexadienal. Hyperplasia of the forestomach in male and female rats and mice was associated with administration of 2,4-hexadienal. Synonyms: Hexa-2,4-dienal; 2,4-hexadienal; 2,4-hexadien-1-al; 2,4-Hx; 1,3-pentadiene-1-carboxaldehyde; 2-propylene acrolein; sorbaldehyde; sorbic aldehyde     

Mortality in mice infected with an amyocarditic coxsackievirus and given a subacute dose of mercuric chloride

An amyocarditic strain of coxsackievirus B3 (CVB3/0) induces heart damage when inoculated into selenium (Se)-deficient mice. Mercury (Hg), an Se antagonist, is known to aggravate viral infections. The experiments reported here assessed the effect of prior Hg treatment in mice subsequently inoculated with an amyocarditic strain of coxsackievirus. A pilot study showed that under our conditions the maximum tolerated dose of HgCl2 in uninfected mice was 6 mg HgCl2/kg body weight. In the main study, doses of 0, 3 or 6 mg HgCl2/kg body weight were administered intraperitoneally (ip) to 7-wk-old male mice fed a standard chow diet. Two hours later, half the mice were inoculated ip with CVB3/0. Ten days postinoculation, no mortality was observed in mice given only virus. In mice not given virus, 10% injected with 6 mg HgCl2/kg body weight died. On the other hand, 64% of the mice given both virus and 6 mg HgCl2/kg body weight died. Fifteen percent of the hearts from virus-infected mice given 3 mg HgCl2/kg body weight and 33% of the hearts from virus-infected mice given 6 mg HgCl2/kg body weight exhibited a higher incidence of lesions than hearts from mice-given virus alone. Moreover, viral heart titers were elevated in infected mice injected with 6 mg HgCl2/kg body weight compared to infected mice receiving no Hg. Thus, an amyocarditic coxsackievirus given to mice after a nonlethal subacute dose of Hg results in mortality, increased incidence of heart lesions, and elevated viral heart titers. These results demonstrate the important role of toxic elements in determining the severity of viral infections.     

Subchronic toxicity of all-trans-retinoic acid and retinylidene dimedone in Sprague-Dawley rats

Sprague-Dawley rats received daily oral gavage doses of either 2-retinylidene-5,5-dimethyl-1,3-cyclohexanedione (retinylidene dimedone; 14, 50, 150, or 330 mg/kg) or all-trans-retinoic acid (1, 4, 14, or 50 mg/kg) for 13 weeks. Rats given 50 mg/kg of all-trans-retinoic acid developed numerous long-bone fractures and became moribund during the third week of the study. Those receiving lower dosages survived until scheduled termination, but the 14 mg/kg group showed clear signs of retinoid intoxication including growth depression, anemia, serum alkaline phosphatase elevation, bone fracture, and testicular degeneration. Exposure to retinylidene dimedone did not result in any treatment-related deaths, growth depression, or histopathologic lesions, even at the highest dose, 300 mg/kg. Animals given this dosage exhibited mild anemia, equivocal evidence of bone fracture, but no increase in alkaline phosphatase activity. Retinylidene dimedone appears to be considerably less toxic than all-trans-retinoic acid.     

Toxicological aspects of feprazone,a new nonsteroidal anti-inflammatory drug

The subacute and chronic toxicities of oral feprazone were studied in rats and beagle dogs. Administration of more than 150 mg/kg/day of feprazone to rats for 1 month induced retardation of growth and liver enlargement. In addition, treatment with 600 mg/kg/day of feprazone caused death, gastrointestinal ulcers, decreased hemoglobin concentration, and leucocytosis. Treatment of rats with 540 mg/kg/day of feprazone for 6 months had similar effects to those described above except that it did not cause death or gastrointestinal ulcers. Toxic nephropathy, nontoxic goiter, hepatomegaly, and increase of ovarian weight were observed in rats given more than 60 or 180 mg/kg/day of feprazone for 6 months. Injection of 1080 mg/kg/day of feprazone into dogs, caused one of six animals to become moribund on Day 18 and one to die on Day 7. The dogs surviving after administration of 360 and 1080 mg/kg/day of feprazone for 1 month showed anemia, leucocytosis, and elevations of phenolsulfonphthalein retention and serum alkaline phosphatase (ALP) activity. Similar effects were observed in dogs surviving after treatment with 150 or 375 mg/kg/day of feprazone for 12 months; in addition, increased ALP activity was observed even at a dose of 60 mg/kg/day. Liver enlargement was observed in dogs treated with all doses of feprazone for 1 or 12 months, and cytoplasmic inclusion bodies were observed in liver cells of dogs given more than 120 mg/kg/day of feprazone for 1 month.     

Toxicity of CI-949, a Novel Anti-allergy Agent

The toxicity of CI-949, an effective inhibitor of allergic mediatorrelease in pharmacology models, was evaluated in rodents anddogs. Median lethal doses at 24-hr postdose ranged from 343to 453 mg/kg in mice and 806 to 2058 mg/kg in rats. Delayedtoxicity was observed at 300 mg/kg and greater in mice and at500 mg/kg and greater in rats. Mortality and clinical intoleranceoccurred in rats at 200 and 400 mg/kg in the subacute studies,and at 100 and 150 mg/kg in the 13-week study. In rats, dose-dependentlymphoid tissue atrophy and depletion or necrosis of lymphocytesin lymphoid tissues were seen in deaths and moribund terminations.Although doses up to 60 mg/kg administered for 2 weeks to dogswere well tolerated, 60 and 120 mg/kg in the 13-week dog studywere poorly tolerated. Cutaneous sores, mucocutaneous purulentdischarge, emesis, diarrhea, and weight loss were identifiedat these lethal doses. Histopathologic changes in dogs includedmyocardial, vascular and soft tissue inflammation, and gastriculceration at 60 and 120 mg/kg, and thymic atrophy at 20 mg/kgand greater. Doses of 10 and 50 mg/kg were no-effect doses in13-week repeated dose studies in dogs and rats, respectively.These results were used to support initial human clinical trialsof CI-949.     

Toxic responses to acute, subchronic, and chronic oral administrations of monochlorobenzene to rodents

Acute (single exposure), 14-d repeated exposure, 91-d subchronic, and 103-wk chronic toxicity studies of orally administered (gavage, in corn oil) monochlorobenzene were conducted in male and female Fischer-344 rats and B6C3F1 hybrid mice. A single exposure to 4000 mg/kg was lethal to male and female rats, while a single exposure to a dose as low as 1000 mg/kg was lethal to mice. Fourteen daily exposures to 1000 mg/kg caused death in rats of both sexes, but neither survival nor clinical health were compromised at 500 mg/kg in rats or mice. In the 91-d studies, wherein monochlorobenzene was administered once daily, 5 d/wk, survival was reduced by doses of 500 mg/kg and higher in rats, and by doses of 250 mg/kg and higher in mice. Dose-dependent necrosis of the liver (hepatocytes), degeneration or focal necrosis of the renal proximal tubules, and lymphoid or myeloid depletion of the spleen, bone marrow, and thymus (mild to severe) were produced by doses of 250 mg/kg or greater of monochlorobenzene in both sexes of rats and mice, although the incidences of these lesions varied considerably by sex and species. Consistent changes in the circulating blood components were not observed, but a mild porphyrinuria was detected at the higher doses. No toxic effects were observed at doses of 125 mg/kg or less. In the 2-yr studies, wherein monochlorobenzene was administered once daily, 5 d/wk, doses of 30 or 60 mg/kg in male mice and 60 or 120 mg/kg in female mice and male and female rats did not produce any evidence of toxicity. Doses of 60 or 120 mg/kg caused slight (statistically significant at 120 mg/kg; p less than 0.05) increases in the frequencies of male rats with neoplastic nodules of the liver. Increased tumor frequencies were not observed in female rats or in male or female mice receiving monochlorobenzene.     

Plumbagin,A Plant Naphthoquinone with Antitumor and Radiomodifying Properties

The tumor inhibitory and radiomodifying effects of plumbagin (Pl), a naphthoquinone isolated from Plumbago rosea, on mouse Ehrlich ascites carcinoma was studied. Tumor response was assessed by increase in life span (% ILS) and animal survival at 120 days. The acute LD 50 of plumbagin in normal mice was 9.4 mg/kg body weight. Single doses from 2 to 6 mg/kg Pl, given intraperitoneally (i.p.), produced inhibition of exponentially growing tumors. However, increases in dose above 3 mg/kg did not increase 120 day survival significantly over that produced by 3 mg/kg. Multiple dose treatment, starting from 24 h after tumor cell inoculation, showed that a total dose of 9 mg/kg, administered in three fractions of 3 mg/kg, once daily, gave the maximum %ILS and tumor free survival. Combination of radiation (RT, 7.5 Gy to the abdomen) after the first Pl dose (1-3mg/kg/fraction) synergistically increased mouse survival at 120 days. The tumor inhibitory effect was less pronounced when treatment was started at more advanced tumor stages, but combination of low dose fractions (2.5 or 3 mg/kg/fraction) with RT enhanced the %ILS and animal survival. Higher dose fractions in combination with radiation were not tolerated by the mice. DNA appears to be the likely target of Pl cytotoxicity; the mechanism of interaction of Pl + RT in enhancing tumor response is not clear.     

Toxicological studies on pepleomycin sulfate (NK 631). I. Acute toxicity of pepleomycin in mice, rats and dogs (author's transl)]

Studies on acute toxicities of pepleomycin sulfate were carried out in both sexes of mice and rats, comparing with bleomycin, and male dogs. Pepleomycin was administered subcutaneously, intravenously and intraperitoneally in both sexes of mice and rats, and intravenously in male dogs respectively. Mice and rats, and intravenously in male dogs respectively. Mice and rats were observed respectively for 10 and 14 days after the administration. LD50 values were calculated by the method of Litchifield & Wilcoxon. LD50 values of pepleomycin were 4 approximately 6 times smaller than those of bleomycin in all routes of mice, but difference between them was not significant in all routes of rats. Additionally sex-difference of LD50 values was scacely recognized in all routes of both species. Toxicological findings observed in common to all routes of both species were ataxia, depression, tremor and epiphora, and only in all routes of mice, head-twitch, running-round and rolling were especially recognized as toxic behavior, which were not observed in bleomycin. Hepatic and renal lesions were recognized in biochemically and histopathologically in the survived rats. The dogs treated with pepleomycin 50 and 30 mg/kg had the decrease in food intake and the loss of body weight. They became moribund in 9 approximately 36 days after administration. In these dogs the lesions of liver and kidney were severely recognized in biochemical and histopathological findings. One of them which received 50 mg/kg recovered biochemically and histopathologically in 209 days after administration by the supplemental nutrition in early stage.     

A study on the effect of (2"R)-4'-O-tetrahydropyranyladriamycin, a new antitumor antibiotic, on reproduction. I. Its effect on the fertility of rats

The effect of a new antitumor antibiotic on the fertility was studied using SD rats. (2"R)-4'-O-Tetrahydropyranyladriamycin (THP) was administered to each rat at 0.01, 0.03 or 0.1 mg/kg daily. Males were given the drug intravenously for 63 days prior to mating and during the mating period; females were given the drug intravenously from 14 days prior to mating until day 7 of pregnancy. All the pregnant rats were sacrificed on day 20 of pregnancy, followed by external, visceral and skeletal observations of their fetuses. Results were summarized as follows. THP, at 0.1 mg/kg, suppressed body weight gain in females during the late period of pregnancy but did not affect body weight gain in males. THP, at 0.1 mg/kg, increased the numbers of dead fetuses and of resorptions. It caused no external, visceral or skeletal anomalies at any dose levels. The results suggest that, in rats, the maximum "no effect" dose of THP is 0.03 mg/kg/day intravenously regarding fertility and fetal development.