2,5-Di-tert-pentylhydrochinon

2,5-di-t-pentylhydroquino (CAS # 79-74-3) was evaluated for dermal sensitization. The Shelanski and Shelanski Repeated Insult Patch Test was used, the test substance was administered to more than 50 adults. The induction phase included 10 occluded applications of 0.2 ml of a 50% dispersion of test substance to the intact skin on the left side of the back. No adverse responses occurred in 21 subjects. In another 21 subjects, responses not greater than a Grade 1 occurred. In 5 subjects, responses not greater than a Grade 2 occurred. Indurated erythematous (Grade 4) occurred once in 6 subjects and twice in 1 subject. Five weeks after the induction phase, the challenge phase included application of the test substance to naive sites at the same concentration as the induction phase. No adverse responses occurred in 37 subjects. In 9 subjects, responses not greater than a Grade 1 occurred. In 4 subjects, responses not greater than a Grade 2 occurred. In 3 subjects, a Grade 4 was obtained after the second application of the challenge phase. The test substance was determined to have a weak to moderate skin-irritating propensity.

2,5-di-t-pentylhydroquino (CAS # 79-74-3) was evaluated for teratogenic toxicity. The test substance was administered orally in a corn oil vehicle to pregnant Sprague-Dawley rats (25/group) at dosage levels of 0, 20, 70, or 175 mg/kg/day on gestation days 6-15. All doses were administered at a constant volume of 5 mg/kg. Clinical signs at 70 mg/kg/day were slight maternal toxicity and substantial maternal toxicity at 175 mg/kg/day. Signs of toxicity included post-dosing salivation, increased incidence of reddish colored vaginal discharge at the 70 mg/kg/day level, and more frequent and severe toxicity, body weight loss and reduced food consumption at the 175 mg/kg/day level. Fetal toxicity at 175 mg/kg/day, included statistically significant body weight loss and litters with ossification variations, such as an increased incidence of skull anomalies, 7th cervical ribs, and #5 and/or #6 sternebrae were unossified. The no observable effect level (NOEL) for maternal toxicity was 20 mg/kg/day, and the NOEL for developmental toxicity was 70 mg/kg/day.

2,5-di-t-pentylhydroquino (CAS # 79-74-3) was evaluated for the potential to induce structural chromosomal aberrations in the hemopoietic cells of the rat bone marrow when administered by oral gavage. The test substance was administered in single oral doses to three groups of fasted young albino Sprague-Dawley rats (number and sex of rats was not reported) at a dosage of 1000 mg/kg of body weight. Treated rats were evaluated at intervals of 6, 18, and 30 hours. Approximately 2 hours before each sacrifice time, rats were administered colchicine at 4 mg/kg of body weight to arrest cells in metaphase. Both femurs were removed from sacrificed animals and metaphase slides were prepared for scoring of chromosome aberrations. All rats exhibited mild to severe toxic signs, including diarrhea, abnormal gait, and stance. In the 18 hour group, toxic signs included decreased body tone and inactivity. In the 30 hour group, toxic signs included yellow to brown wet pellage in the anal-genital region and decreased body tone. From the 18 hour harvest group 2 females died. From each animal, 50 metaphase cells were analyzed. There were no statistically significant increase in the incidence of aberrations or number of aberrant metaphases observed at any of the three sampling times, therefore, the test substance was classified as not clastogenic.

2,5-di-t-pentylhydroquino (CAS # 79-74-3) was evaluated for mutagenicity in the rat liver homogenate metabolic activation system (S9). The test substance was tested in an insoluble concentration in aqueous media (greater than 100 ug/ml). Increases in cytotoxicity were observed as the S9 levels increased from 2% to 10%. Maximum concentrations tested in mutagenicity assays were 150 ug/ml in the absence of S9 and 100 ug/ml in the presence of 1%, 2%, 5%, and 10% S9. The test substance was determined not to be a mutagen.

For more TSCA Test Submissions (Complete) data for 2,5-DI-T-PENTYLHYDROQUINONE (6 total), please visit the HSDB record page.

2,5-DITERTIARY AMYL HYDROQUINONE WAS NON-HEMOLYTIC IN NORMAL RAT ERYTHROCYTES.

AFTER POS MATING OF WALTER REED-CARWORTH FARMS RATS IN THEIR 1ST GESTATION, FEMALES WERE RANDOMLY DISTRIBUTED INTO EXPTL & CONTROL GROUPS, FORMER GIVEN 2,5-DI-TERT-AMYLHYDROQUINONE BY MOUTH OR INTO DIET & KILLED 21 DAYS AFTER MATING. DATA SUGGEST BENEFICIAL EFFECT ON RESORPTION RATE.

Acute neurotoxic effects reported in animals include convulsions; medullary paralysis. /From table; Quinones/

The effects of diethyl maleate on the cytotoxicity of phenyl-hydroquinone and other hydroquinones were studied in freshly isolated rat hepatocytes. Addition of phenyl hydroquinone (O.5 or 0.75 mM) to hepatocytes resulted in dose-dependent cell death accompanied by the abrupt depletion of both glutathione and protein thiols and the accumulation of phenyl-benzoquinone. Pretreatment with diethyl maleate (1.25 mM) which causes an abrupt depletion of cellular glutathione in hepatocytes delayed the onset of phenyl hydroquinone-induced cytotoxicity. The delay correlated with inhibition of phenyl benzoquinone formation. Among other hydroquinones (0.5 mM), tert-butyl-hydroquinone-induced cytotoxicity was decreased by diethyl maleate (1.25 mM), but diethyl maleate did not affect the cytotoxicity of 2,5-di(tert-butyl)-1,4-benzohydroquinone. Phenyl-hydroquinone -induced cytotoxicity correlated with the accumulation of phenyl-benzoquinone in the cell.