1-Naphthol was metabolized by tyrosinase, polyphenol oxidase, primarily to 1,2-naphthoquinone and to small amounts of 1,4-naphthoquinone as well as to covalently bound products. The inhibition of covalent binding by ethylenediamine, which reacts specifically with 1,2-naphthoquinone but not 1,4-naphthoquinone, suggested that most of the covalent binding was due to 1,2-naphthoquinone or a metabolite of similar structure.
In rat liver microsomal preparations, 1-naphthol is metabolized by the cytochrome p450 mixed function oxidase to 1,4-naphthoquinone and covalently bound species. The major binding species are derived from 1,4-naphthoquinone but not 1,2-naphthoquinone. 1-Naphthol is also metabolized by tyrosinase (monophenol monooxygenase; polyphenol oxidase) primarily to 1,2-naphthoquinone and covalently bound products; most of the covalent binding was derived from a 1,2-naphthoquinone derivative.
The hepatic microsomal metabolism of 1-naphthol, 1,2- and 1,4-naphthoquinone has been shown to generate active oxygen species by using electron spin resonance spin-trapping techniques. 1-Naphthol, in the presence of NADPH, and 1,2- and 1,4-naphthoquinone, with either NADH or NADPH, caused a stimulation in both the rate of microsomal oxygen consumption and the formation of superoxide spin adduct, 5,5-dimethyl-2-hydroxyperoxypyrrolidino-1-oxyl (DMPO-OOH). Superoxide dismutase, but not catalase, prevented the formation of this spin adduct, further supporting the suggestion that the superoxide free radical was the major oxy-radical formed during the microsomal metabolism of 1-naphthol and the naphthoquinones. These results are compatible with the suggestion that 1-naphthol may exert its toxicity to isolated hepatocytes and other cellular systems by metabolism to naphthoquinones followed by their redox cycling with concomittant generation of active oxygen species, in particular superoxide free radicals.
...The toxicity of 1-naphthol may be mediated by the formation of 1,2-naphthoquinone and/or 1,4-naphthoquinone, which may then be metabolized by 1-electron reduction to naphthoquinone radicals. These, in turn, may covalently bind to important cellular macromolecules or enter a redox cycle with molecular oxygen thereby generating active oxygen species. Both of these processes appear to play a role in producing the cytotoxic effects of 1-naphthol.
1,2-Naphthoquinone is a cholinesterase or acetylcholinesterase (AChE) inhibitor. A cholinesterase inhibitor (or 'anticholinesterase') suppresses the action of acetylcholinesterase. Because of its essential function, chemicals that interfere with the action of acetylcholinesterase are potent neurotoxins, causing excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death. Nerve gases and many substances used in insecticides have been shown to act by binding a serine in the active site of acetylcholine esterase, inhibiting the enzyme completely. Acetylcholine esterase breaks down the neurotransmitter acetylcholine, which is released at nerve and muscle junctions, in order to allow the muscle or organ to relax. The result of acetylcholine esterase inhibition is that acetylcholine builds up and continues to act so that any nerve impulses are continually transmitted and muscle contractions do not stop. Among the most common acetylcholinesterase inhibitors are phosphorus-based compounds, which are designed to bind to the active site of the enzyme. The structural requirements are a phosphorus atom bearing two lipophilic groups, a leaving group (such as a halide or thiocyanate), and a terminal oxygen.
来源:Toxin and Toxin Target Database (T3DB)
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).
Acute exposure to cholinesterase inhibitors can cause a cholinergic crisis characterized by severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Accumulation of ACh at motor nerves causes overstimulation of nicotinic expression at the neuromuscular junction. When this occurs symptoms such as muscle weakness, fatigue, muscle cramps, fasciculation, and paralysis can be seen. When there is an accumulation of ACh at autonomic ganglia this causes overstimulation of nicotinic expression in the sympathetic system. Symptoms associated with this are hypertension, and hypoglycemia. Overstimulation of nicotinic acetylcholine receptors in the central nervous system, due to accumulation of ACh, results in anxiety, headache, convulsions, ataxia, depression of respiration and circulation, tremor, general weakness, and potentially coma. When there is expression of muscarinic overstimulation due to excess acetylcholine at muscarinic acetylcholine receptors symptoms of visual disturbances, tightness in chest, wheezing due to bronchoconstriction, increased bronchial secretions, increased salivation, lacrimation, sweating, peristalsis, and urination can occur. Certain reproductive effects in fertility, growth, and development for males and females have been linked specifically to organophosphate pesticide exposure. Most of the research on reproductive effects has been conducted on farmers working with pesticides and insecticdes in rural areas. In females menstrual cycle disturbances, longer pregnancies, spontaneous abortions, stillbirths, and some developmental effects in offspring have been linked to organophosphate pesticide exposure. Prenatal exposure has been linked to impaired fetal growth and development. Neurotoxic effects have also been linked to poisoning with OP pesticides causing four neurotoxic effects in humans: cholinergic syndrome, intermediate syndrome, organophosphate-induced delayed polyneuropathy (OPIDP), and chronic organophosphate-induced neuropsychiatric disorder (COPIND). These syndromes result after acute and chronic exposure to OP pesticides.
Symptoms of low dose exposure include excessive salivation and eye-watering. Acute dose symptoms include severe nausea/vomiting, salivation, sweating, bradycardia, hypotension, collapse, and convulsions. Increasing muscle weakness is a possibility and may result in death if respiratory muscles are involved. Hypertension, hypoglycemia, anxiety, headache, tremor and ataxia may also result.
If the compound has been ingested, rapid gastric lavage should be performed using 5% sodium bicarbonate. For skin contact, the skin should be washed with soap and water. If the compound has entered the eyes, they should be washed with large quantities of isotonic saline or water. In serious cases, atropine and/or pralidoxime should be administered. Anti-cholinergic drugs work to counteract the effects of excess acetylcholine and reactivate AChE. Atropine can be used as an antidote in conjunction with pralidoxime or other pyridinium oximes (such as trimedoxime or obidoxime), though the use of '-oximes' has been found to be of no benefit, or possibly harmful, in at least two meta-analyses. Atropine is a muscarinic antagonist, and thus blocks the action of acetylcholine peripherally.
Dirhodium-Catalyzed Phenol and Aniline Oxidations with T-HYDRO. Substrate Scope and Mechanism of Oxidation
作者:Maxim O. Ratnikov、Linda E. Farkas、Emily C. McLaughlin、Grace Chiou、Hojae Choi、Sahar H. El-Khalafy、Michael P. Doyle
DOI:10.1021/jo1024865
日期:2011.4.15
and CuI are provided, and mechanistic comparisons are made between these catalysts that are based on diastereoselectivity (reactions with estrone), regioselectivity (reactions with p-tert-butylphenol), and chemoselectivity in the formation of 4-(tert-butyldioxy)cyclohexadienones. The data obtained are consistent with hydrogen atom abstraction by the tert-butylperoxy radical followed by radical combination
The formation of orthoquinones in the dimethyldioxirane oxidation of phenols
作者:Jack K. Crandall、Martine Zucco、R.Scott Kirsch、David M. Coppert
DOI:10.1016/0040-4039(91)80053-9
日期:1991.9
The dimethyldioxiraneoxidation of selected phenols provides the corresponding orthoquinones. This conversion proceeds via the related arenediols, which are cleanly oxidized to the quinones by this oxidant.
Chemistry of L-ascorbic acid. Part 3. Photoreduction of quinones with 5,6-O-isopropylidene-L-ascorbic acid†
作者:Mukund G. Kulkarni、Sandesh D. Kate
DOI:10.1039/b005120i
日期:——
Upon irradiation with UV light, instead of undergoing the Paternò–Büchi reaction, 5,6-O-isopropylidene-L-ascorbic acid reduced quinones quite efficiently and rapidly to the corresponding hydroquinones.
compared to conventional phenyliodine(III) diacetate and bis(trifluoroacetate), as a result of the rapid oxidation of both phenols and naphthols 2. Furthermore, the oxidation reactions proceeded even in water using water-soluble μ-oxo oxidant 1, which has promise for μ-oxo-bridged reagent 1 to become the favored reagent over hydrophobic phenyliodine(III) diacetate and bis(trifluoroacetate).
Novel lapachone compounds and methods of use thereof
申请人:Ashwell Mark A.
公开号:US20090105166A1
公开(公告)日:2009-04-23
The present invention provides novel tricyclic spiro-oxathiine naphthoquinone derivatives, a synthetic method for making the derivatives, and the use of the derivatives to induce cell death and/or to inhibit proliferation of cancer or precancerous cells. The naphthoquinone derivatives of the present invention are related to the compound known as β-lapachone (3,4-dihydro-2,2-dimethyl-2H-naphtho(1,2-b)pyran-5,6-dione).