The in vitro mouse hepatic microsomal metabolism of the macrocyclic pyrrolizidine alkaloid senecionine was studied. Senecic acid, senecionine n-oxide and 19-hydroxysenecionine, a new metabolite, were isolated from the microsomal enzyme system of balb/c mice.
The toxic pyrrolizidine alkaloids, such as senecionine, are cyclic arylamines that are dehydrogenated by cytochrome P450 (CYP3A4) to the corresponding pyrroles. Pyrroles themselves are nucleophiles, but electrophiles are generated through the loss of substituents on the pyrrolizidine nucleus... .
In animals, the major metabolic routes of pyrrolizidine alkaloids are: (a) hydrolysis of the ester groups; (b) N-oxidation; and (c) dehydrogenation of the pyrrolizidine nucleus to pyrrolic derivatives. Routes (a) and (b) are believed to be detoxification mechanisms. Route (c) leads to toxic metabolites. Route (a) occurs in liver and blood; routes (b) and (c) are brought about in the liver by the microsomal mixed function oxidase system. /pyrrolizidine alkaloids/
Senecionine is classified as a pyrrolizidine alkaloid (PA). Unsaturated pyrrolizidine alkaloids are hepatotoxic, that is, damaging to the liver. PAs also cause hepatic veno-occlusive disease and liver cancer. PAs are tumorigenic. Disease associated with consumption of PAs is known as pyrrolizidine alkaloidosis. (Wikipedia) The pyrrolizidine alkaloid senecionine has been shown to produce an increase in cytosolic free Ca2+ concentration in isolated hepatocytes that correlated with an increase in cellular toxicity. The cytotoxicity was greater in the absence of extracellular Ca2+ than in its presence, suggesting that alterations in intracellular Ca2+ distribution, and not an influx of extracellular Ca2+, were responsible for the senecionine-induced hepatotoxicity. Senecionine has been shown to be hepatotoxic, genotoxic, and cytotoxic. Senecionine has been shown to produce peroxidation of membrane lipids in a dose-related manner in isolated rat hepatocytes. Alterations in intracellular Ca2+ concentration also were examined as a possible primary mechanism of cellular toxicity. (A15422) Substantial research has revealed that senecionine-induced hepatotoxicity is associated with lipid peroxidation, intracellular Ca2+ alteration, and intercellular glutathione depletion. (A15423)
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).
来源:Toxin and Toxin Target Database (T3DB)
毒理性
副作用
职业性肝毒素 - 第二性肝毒素：在职业环境中的毒性效应潜力是基于人类摄入或动物实验的中毒案例。
Occupational hepatotoxin - Secondary hepatotoxins: the potential for toxic effect in the occupational setting is based on cases of poisoning by human ingestion or animal experimentation.
来源:Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
We have purified three P450s from the liver of the phenobarbital (PB)-treated guinea pig in order to evaluate the role of these enzymes in pyrrolizidine alkaloid (PA) metabolism. PB treatment of guinea pig increased the hepatic microsomal conversion of the PA senecionine (SN) to the pyrrolic metabolite (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP), an activation product, and SN N-oxide, a detoxification product by 224 and 70% respectively. ... . A second purified guinea pig P450, a 2C-type isoform (M(r) = 56,496 by MALDI-TOF mass spectrometry), produced SN N-oxide from SN at the rate of 13.3 min-1 but catalyzed little DHP formation. The third guinea pig P450, an apparent 3A type (M(r) = 54-56,000 by SDS-PAGE), lost its catalytic activity towards SN during the final purification process.
Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poison A and B/
来源:Hazardous Substances Data Bank (HSDB)
吸收、分配和排泄
在动物研究中，最高浓度发现于肝脏、肺、肾脏和脾脏。/吡咯烷生物碱/
In animal studies highest concentrations were found in the liver, lungs, kidneys and spleen. /pyrrolizidine alkaloids/
Blood levels of senecionine in rats given 0.1 LD50 ip were determined. The levels were 0.38, 0.32, and 0.14 mg/litre at 0.5, 1, and 2 h after injection, respectively.
...Senecionine... /was/ studied regarding the distribution, excretion, transfer into milk, and covalent binding to hepatic macromolecules in BALB/c mice. After injection, radioactivity was rapidly excreted in the urine and feces (84% or greater) within 16 hr. The liver contained over 1.5% of the dose at 16 hr. A small amount, 0.04%, of the dose was transferred into the milk in 16 hr; the majority of radioactivity was found in the skim-milk fraction, suggesting that the PA's were transferred to the milk as water-soluble metabolites. ...The binding to calf thymus DNA and microsomal macromolecules was measured in vitro. The binding was diminished in the absence of O2 or a NADPH-generating system or by boiling the microsomes.
...Following intravenous administration of [14C]SEN (60 mg/kg, 10 microCi/kg), bile, urine and blood were collected over a 7-hr period. Of the total administered radioactivity, 44% and 43% were excreted in the bile and urine, respectively. Using mass spectroscopy, senecionine N-oxide (SENNOX) was identified as the major metabolite in bile (52% of 44%) and urine (30% of 43%). For the total 7 hr, <5% in bile and 18% in urine was excreted as parent alkaloid.
NEW USE FOR A COMPOUND AS A MATRIX IN THE SPECIFIC DETECTION, IDENTIFICATION AND/OR QUANTIFICATION OF ALKALOIDS BY MALDI-TOF MASS SPECTROMETRY
申请人：Dias Marylène
公开号：US20140319331A1
公开（公告）日：2014-10-30
There is provided (i) a method of analysing small molecules that may have a mass of <800 Da, in particular alkaloids, said method being generally referred to as MALDI-TOF-MS (or MALDI time-of-flight mass spectrometry), which is an acronym for a method of analysis by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. Also provided is (ii) a molecule according to formula (I) and the use of the molecule as a matrix in the analysis method.
Method And Assay Kit For Detection Of Toxicity Induced By Pyrrolizidine Alkaloids
申请人：Lin Ge
公开号：US20130189710A1
公开（公告）日：2013-07-25
An antibody, which specifically recognizes adducts between pyrrole and cellular macromolecules. Such adducts are likely to occur in mammals suffering an incident of pyrrolizidine alkaloid poisoning. The antibody can be produced using a synthetic immunogen conjugated with a pyrrole as a hapten and it can be used, for example in an assay kit and/or by itself, as a novel means for detecting or diagnosing pyrrolizidine alkaloid poisoning both clinics and research laboratories.
Species differences in the hepatic microsomal enzyme metabolism of the pyrrolizidine alkaloids
作者：Jian-Ya Huan、Cristobal L Miranda、Donald R Buhler、Peter R Cheeke
DOI：10.1016/s0378-4274(98)00152-0
日期：1998.10
cytochrome P450s and flavin-containing monooxygenases (FMO) in bioactivation and detoxification of pyrrolizidine alkaloids (PA) were studied in vitro using sheep and hamster hepatic microsomes. Chemical and immunochemical inhibition data suggested that the conversion of SN to DHP is catalyzed mainly by cytochrome P450s (68-82%), whereas the formation of SN N-oxide is carried out largely by FMO (55-71%)
在体外测量了八种动物（绵羊、牛、沙鼠、兔子、仓鼠、日本鹌鹑、鸡、大鼠）的吡咯代谢物和 senecionine (SN) N-氧化物形成的物种差异，这些动物对吡咯里西啶生物碱 (PA) 中毒的易感性不同通过肝微粒体孵化。结果表明，吡咯代谢物的产生与动物对 PA 毒性的易感性之间没有很强的相关性。通过 (+/-)6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) 的形成测量，仓鼠（一种抗性物种）中 PA 的活化速率远远超过 SN N-氧化物的速率形成（解毒）（DHP/N-氧化物 = 2.29）。相比之下，SN N-氧化物是绵羊的主要代谢物，绵羊是另一种抗性物种，DHP 的产量要低得多（DHP/N-氧化物 = 0.26）。使用绵羊和仓鼠肝微粒体在体外研究了细胞色素 P450 和含黄素的单加氧酶 (FMO) 在吡咯里西啶生物碱 (PA)
Identification of the UDP-Glucuronosyltransferase Isozyme Involved in Senecionine Glucuronidation in Human Liver Microsomes
Senecionine (SEN) is a representative of the hepatotoxic pyrrolizidine alkaloids. Although phase I metabolism for cytochrome P450-mediated metabolic activation of SEN was investigated extensively, phase II metabolism for glucuronidation of this compound has not been investigated until now. In our present study, one unique glucuronidation product of SEN in human liver microsomes (HLMs) was identified as SEN N -glucuronide using an authentically synthesized product for which the structure was identified via 1H and 13C NMR analysis. Subsequently, kinetics indicated that SEN N -glucuronidation followed the typical Michaelis-Menten model and only one major isozyme participated in it. Finally, this isozyme was demonstrated to be UDP-glucuronosyltransferase (UGT) 1A4, with the direct evidence that recombinant UGT1A4 exhibited predominant and exclusive activity on SEN N -glucuronidation. This result was confirmed by other experiments including chemical inhibition by selective inhibitors and a correlation study between activities of SEN N -glucuronidation and various UGT isozymes. The exclusive role of UGT1A4 on SEN N -glucuronidation was strengthened additionally by its inhibitory kinetic study in which the selective inhibitor of UGT1A4 showed a similar inhibition pattern and K i values in both HLM and recombinant UGT1A4 systems. Because UGT2B10 activity failed to correlate with SEN N -glucuronidation in HLMs from 10 individuals, it was impossible for UGT2B10 to play an important role in this metabolism.
METHOD FOR PREDICTING ACTIVATION ENERGY USING AN ATOMIC FINGERPRINT DESCRIPTOR OR AN ATOMIC DESCRIPTOR
申请人：Bioinformatics&Molecular Design Research Center
公开号：EP2354987A2
公开（公告）日：2011-08-10
The present invention provides a method for constructing a database of atomic fingerprint descriptors. The invention provides a method for predicting activation energy using an atomic fingerprint descriptor and an atomic descriptor, the method comprising the steps of: (i) calculating the atomic fingerprint descriptor of a substrate; (ii) comparing the calculated atomic fingerprint descriptor with the constructed atomic fingerprint descriptor database to select an atomic position where cytochrome P450-mediated metabolism occurs; and (iii) predicting activation energy for the selected atomic position using an atomic descriptor. Also, the invention provides a method of predicting the activation energy of CYP450-mediated phase I metabolism using effective atomic descriptors. Specifically, the invention provides a method of predicting the activation energy either for cytochrome P450-mediated hydrogen abstraction or for tetrahedral intermediate formation in cytochrome P450-aromatic hydroxylation using equations including effective atomic descriptors. The method of the invention can rapidly predict activation energy for phase I metabolites at a practical level without having to perform a docking experiment between any additional CYP450 and the substrate, or a quantum mechanical calculation, thereby making it easier to develop new drugs using a computer. Also, the present invention may propose a strategy for increasing the bioavailability of drugs through the avoidance of metabolites based on the possibility of drug metabolism. Furthermore, the method of the present invention proposes new empirical approaches which can also be easily applied to activation energies for various chemical reactions, and makes it possible to explain physical and chemical factors that determine activation energy. In addition, through the prediction of activation energy according to the present invention, it is possible to predict i) metabolic products, ii) the relative rate of metabolism, iii) metabolic regioselectivity, iv) metabolic inhibition, v) drug-drug interactions, and vi) the toxicity of a metabolite.
