In mice, rats, rabbits, or dogs methylparaben is excreted in the urine as unchanged benzoate, p-hydroxybenzoic acid, p-hydroxyhippuric acid (p-hydroxybenzoylglycine), ester glucuronides, ether glucuronides, or ether sulfates.
By the oral route, parabens are rapidly absorbed, metabolized, and excreted. The metabolic reactions and conversions in mammals vary with the chain length of the ester, the animal species, route of administration, and quantity tested. The metabolism of parabens in humans appears to be most closely related to that of dogs. The rate of metabolite excretion appears to decrease with increasing molecular weight of the ester. /4-Hydroxybenzoates (Parabens)/
/This study examined/ the metabolic fate of methylparaben in rabbits. The compound was given by gastric intubation, and urine was analyzed by paper chromatography. Three major metabolites, p-hydroxybenzoic acid, p-hydroxyhippuric acid, and p-carboxyphenyl glucuronide, as well as two minor metabolites, p-hydroxybenzoyl glucuronide and p-carboxyphenyl sulfate, were identified. Rabbits given orally 0.4 or 0.8 g/kg methylparaben, ethylparaben, propylparaben, or butylparaben excreted only 0.2 to 0.9% of the unchanged ester by 24 hr. Urinary excretion of p-hydroxybenzoic acid was slower with increasing carbon chain length of the paraben alkyl group. Excretion of the conjugated acid was approximately that of the free acid. At 24 hr following paraben administration, 25 to 39% was recovered as p-hydroxybenzoic acid, 15 to 29% as the glycine conjugate, 5 to 8% as the ester glucuronide, 10 to 18% as the ether glucuronide, and 7 to 12% as the sulfate.
The metabolism of methylparaben, ethylparaben, and propylparaben was studied in rats. Animals were given orally 100 mg of ester. Blood and urine were collected regularly and analyzed by paper chromatography. Paraben metabolites were identified in the urine 30 minutes after dosing. No unchanged paraben was detected. Ninety minutes after dosing, excretion of metabolites was maximum; thereafter, excretion decreased. p-Hydroxyhippuric acid appeared in the urine after 30 minutes; its concentration then increased evenly during the next 4 hr. The glucuronide and ethereal sulfate metabolites appeared only between 30 and 75 minutes postingestion. After 90 minutes, 67 to 75% of the total paraben dose was excreted as p-hydroxybenzoic acid, 10 to 12.5% as p-hydroxyhippuric acid, and 8 to 10% as glucuronyl derivatives. The concentration of free p-hydroxybenzoic acid in the blood remained extremely low. A continuous rise occurred within the first hour, but the concentration thereafter decreased and leveled off 1 to 2 hr after ingestion. The authors concluded that there were two stages of paraben detoxification: (1) absorption of paraben and excretion in urine of p-hydroxybenzoic acid, and (2) metabolic detoxification by glucuronic-, sulfo-, and glycino-conjugation.
IDENTIFICATION AND USE: Methylparaben is a methyl ester of p-hydroxybenzoic acid. It is a stable, non-volatile compound used as an antimicrobial preservative in foods, drugs and cosmetics. HUMAN EXPOSURE AND TOXICITY: Parabens are reported to cause contact dermatitis reactions in some individuals on cutaneous exposure. Parabens have been implicated in numerous cases of contact sensitivity associated with cutaneous exposure; however, the mechanism of this sensitivity is unknown. Sensitization has occurred when medications containing parabens have been applied to damaged or broken skin. Allergic reactions to ingested parabens have been reported, although rigorous evidence of the allergenicity of ingested paraben is lacking. ANIMAL STUDIES: Acute toxicity studies in animals indicate that methylparaben is practically non-toxic by both oral and parenteral routes. In a population with normal skin, methylparaben is practically non-irritating and non-sensitizing. In chronic administration studies, no-observed-effect levels (NOEL) as high as 1050 mg/kg have been reported and a no-observed-adverse-effect level (NOAEL) in the rat of 5700 mg/kg is posited. Methylparaben did increase chromosomal aberrations in a Chinese Hamster ovary cell assay. Methylparaben was noncarcinogenic when injected subcutaneously in mice or rats, or when administered intravaginally in rats. Methylparaben was nonteratogenic in rabbits, rats, mice, and hamsters. It is not embryotoxic. Methylparaben failed to produce any effect in uterotrophic assays in two laboratories, but did produce an effect in other studies from another laboratory. In one in vitro study, sperm were not viable at concentrations as low as 6 mg/mL methylparaben, but an in vivo study of 0.1% or 1.0% methylparaben in the diet of mice reported no spermatotoxic effects. Methylparaben was studied using rats at levels in the diet up to an estimated mean dose of 1141.1 mg/kg per day with no adverse testicular effects. ECOTOXICITY STUDIES: Medaka vitellogenin assays and DNA microarray analysis were carried out for methylparaben and found induction of significant vitellogenin in male medaka at 630 ug/L of methylparaben, while the expression levels of genes encoding proteins such as choriogenin and vitellogenin increased for concentrations at 10ug/L of methylparaben.
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌物分类
对人类不具有致癌性(未被国际癌症研究机构IARC列名)。
No indication of carcinogenicity to humans (not listed by IARC).
来源:Toxin and Toxin Target Database (T3DB)
毒理性
副作用
神经毒素 - 其他中枢神经系统神经毒素
Neurotoxin - Other CNS neurotoxin
来源:Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
... Using human intestinal (Caco-2) cells, it was observed that hydrolysis of parabens to p-hydroxybenzoic acid is reduced markedly by ethanol concentrations that can occur in the human intestine, 0.25-0.5% (v/v). Ethanol concentrations of 1.0-2.5% (v/v) were optimal for transesterification to ethylparaben in Caco-2 cell homogenates. The kinetics of the transesterification reaction with regard to ethanol concentration (0-20%), time, pH (3-9), protein concentration (1-5 mg/mL) and substrate concentration (6.25-200 uM) as well as the effects of different alcohols were studied. The Km and Vmax values for transesterification with ethanol for methyl, propyl, butyl, heptyl and octyl parabens were 449.7, 165.7, 86.1, 24.2 and 45.9 uM and 114.4, 37.5, 19.5, 7.5 and 7.6 umol/hr/mg Caco-2 cell protein, respectively. The Vmax values for transesterification of methylparaben with ethanol, propan-1-ol, butan-1-ol were 114.4, 5.1 and 4.9 umol/hr/mg, respectively. ... The clinical or toxicological implication is that, following co-ingestion of ester compounds with ethanol, transesterification could provide the basis for a previously unrecognized drug-alcohol interaction.
... /The authors/ investigated the effects of ultraviolet-B (UVB) exposure on methylbaraben (MP)-treated human skin keratinocytes. HaCaT keratinocyte was cultured in MP-containing medium for 24 hr, exposed to UVB (15 or 30 mJ/cm2) and further cultured for another 24 hr. Subsequent cellular viability was quantified by MTT-based assay and cell death was qualified by fluorescent microscopy and flow cytometry. ... Practical concentrations of MP (0.003%) had a little or no effect on cellular viability, oxidative stress, nitric oxide (NO) production, lipid peroxidation and activation of nuclear transcription factors in HaCaT keratinocytes. Low-dose UVB also had little or no effect on these parameters in HaCaT keratinocytes. However, UVB exposure significantly increased cell death, oxidative stress, NO production, lipid peroxidation and activation of transcription factors in MP-treated HaCaT keratinocytes. These results indicate that MP, which has been considered a safe preservative in cosmetics, may have harmful effects on human skin when exposed to sunlight.
By the oral route, parabens are rapidly absorbed, metabolized, and excreted. The metabolic reactions and conversions in mammals vary with the chain length of the ester, the animal species, route of administration, and quantity tested. The metabolism of parabens in humans appears to be most closely related to that of dogs. The rate of metabolite excretion appears to decrease with increasing molecular weight of the ester. /4-Hydroxybenzoates (Parabens)/
After methyl paraben is intravenously infused into the dog, nonhydrolyzed methyl paraben is found in brain, spleen, and pancreas. In liver, kidney, and muscle, it is immediately hydrolyzed to p-hydroxybenzoic acid ... Six hours after oral administration of 1.0 g/kg to dogs, the peak plasma concentration of free and total methyl paraben (630 and 867 ug/cu cm) is reached. After 48 hr, the vast majority was eliminated.
The excretion and metabolism of methylparaben were monitored in 6 preterm infants after they had received multiple doses of a gentamicin formulation containing paraben preservatives. The recovery of the paraben from urine averaged 82.6%. The urinary excretion ranged from 13.2 to 88.1%.
... a study /was conducted/ using human volunteers in which the levels of methylparaben in the stratum corneum were measured. Cosmetic emulsions containing 0.15, 0.25, and 0.5% (w/v) methylparaben were applied one time to the forearm (42 sq cm) of one male and one female subject. At 1, 2, 5, and 12 hr after application, a small area was cleaned of emulsion using wet cotton and methylparaben was extracted by application of a glass cylinder (3.1 sq cm) with 0.5 mL ethanol for 25 min. Methylparaben concentrations were determined in the ethanol solvent using HPLC (for the 1, 2, and 5 hr durations) and GC/MS for other treatments. ... For the single application, methylparaben reached its peak 1 - 2 hr after application (peak was slightly higher for each higher use concentration) and returned to baseline after 12 hr. /In another study,/ healthy Japanese adults (one male, eleven female) applied a lotion only (6 subjects) or a lotion and an emulsion (6 subjects) containing Methylparaben (concentration not stated) twice a day for 1 month. Concentrations of methylparaben in the stratum corneum were determined as above using GC/MS before the first application, at 1, 2, 3, and 4 weeks, and 2 days after stopping. ... Repeated applications resulted in an increase in methylparaben concentration in the stratum corneum over time for both the lotion application and the lotion plus emulsion application. After 2 days, methylparaben had returned to pretreatment levels.
1.周国泰,化学危险品安全技术全书,化学工业出版社,1997 2.国家环保局有毒化学品管理办公室、北京化工研究院合编,化学品毒性法规环境数据手册,中国环境科学出版社.1992 3.Canadian Centre for Occupational Health and Safety,CHEMINFO Database.1998 4.Canadian Centre for Occupational Health and Safety, RTECS Database, 1989
[EN] BENZAMIDE OR BENZAMINE COMPOUNDS USEFUL AS ANTICANCER AGENTS FOR THE TREATMENT OF HUMAN CANCERS<br/>[FR] COMPOSÉS BENZAMIDE OU BENZAMINE À UTILISER EN TANT QU'ANTICANCÉREUX POUR LE TRAITEMENT DE CANCERS HUMAINS
申请人:UNIV TEXAS
公开号:WO2017007634A1
公开(公告)日:2017-01-12
The described invention provides small molecule anti-cancer compounds for treating tumors that respond to cholesterol biosynthesis inhibition. The compounds selectively inhibit the cholesterol biosynthetic pathway in tumor-derived cancer cells, but do not affect normally dividing cells.
PYRAZOLO[1,5a]PYRIMIDINE DERIVATIVES AS IRAK4 MODULATORS
申请人:Arora Nidhi
公开号:US20120015962A1
公开(公告)日:2012-01-19
Compounds of the formula I or II:
wherein X, m, Ar, R
1
and R
2
are as defined herein. The subject compounds are useful for treatment of IRAK-mediated conditions.
[EN] S-NITROSOMERCAPTO COMPOUNDS AND RELATED DERIVATIVES<br/>[FR] COMPOSÉS DE S-NITROSOMERCAPTO ET DÉRIVÉS APPARENTÉS
申请人:GALLEON PHARMACEUTICALS INC
公开号:WO2009151744A1
公开(公告)日:2009-12-17
The present invention is directed to mercapto-based and S- nitrosomercapto-based SNO compounds and their derivatives, and their use in treating a lack of normal breathing control, including the treatment of apnea and hypoventilation associated with sleep, obesity, certain medicines and other medical conditions.
Cell adhesion-inhibiting antiinflammatory and immune-suppressive compounds
申请人:Abbott Laboratories
公开号:US20040116518A1
公开(公告)日:2004-06-17
The present invention relates to novel cinnamide compounds that are useful for treating inflammatory and immune diseases and cerebral vasospasm, to pharmaceutical compositions containing these compounds, and to methods of inhibiting inflammation or suppressing immune response in a mammal.
Compositions for Treatment of Cystic Fibrosis and Other Chronic Diseases
申请人:Vertex Pharmaceuticals Incorporated
公开号:US20150231142A1
公开(公告)日:2015-08-20
The present invention relates to pharmaceutical compositions comprising an inhibitor of epithelial sodium channel activity in combination with at least one ABC Transporter modulator compound of Formula A, Formula B, Formula C, or Formula D. The invention also relates to pharmaceutical formulations thereof, and to methods of using such compositions in the treatment of CFTR mediated diseases, particularly cystic fibrosis using the pharmaceutical combination compositions.