After oral administration L-carnitine which is unabsorbed is metabolized in the gastrointestinal tract by bacterial microflora. Major metabolites include trimethylamine N-oxide and [3H]-gamma-butyrobetaine.
In mammals, L-carnitine is synthesized from epsilon-N-trimethyllysine, which is derived from post-translationally methylated lysine residues in proteins, and protein turnover. In normal humans, the rate of synth is est to be ca 1.2 umol/kg/day. The rate of L-carnitine biosynth is regulated by the avail of epsilon-N-trimethyllysine. Thus, conditions that incr protein methylation and/or protein turnover may incr the rate of L-carnitine biosynth.
Synthesis of carnitine begins with methylation of the amino acid L-lysine by S-adenosylmethionine (SAMe). Magnesium, vitamin C, iron, vitamins B3 and B6, and alpha-ketoglutarate - along with the cofactors responsible for creating SAMe (methionine, folic acid, vitamin B12, and betaine) - are all required for endogenous carnitine synthesis.
Unabsorbed L-carnitine is degraded by micro-organisms in the large intestine. Major metabolites identified are trimethylamine oxide in urine and gamma-butyrobetaine in feces.
Carnitine plays an indispensable role in fatty acid oxidation. Previous studies revealed that fetal carnitine is derived from the mother via transplacental transfer. Recent studies demonstrated the presence and importance of an active fatty acid oxidation system in the human placenta and in the human fetus. In view of these findings ... carnitine metabolism /was studied/ in the fetal-placental unit by measuring carnitine metabolites, intermediary metabolites of carnitine biosynthesis, as well as the activity of carnitine biosynthesis enzymes in human term placenta, cord blood and selected embryonic and fetal tissues (5-20 weeks of development). Placenta contained low but detectable activity of gamma-butyrobetaine dioxygenase. This enzyme, which was considered to be expressed only in kidney, liver and brain, catalyzes the last step in the carnitine biosynthesis pathway. In addition, ... human fetal kidney, liver and spinal cord already have the capacity to synthesize carnitine. The ability of the placenta and fetus to synthesize carnitine suggests that in circumstances when maternal carnitine supply is limited, carnitine biosynthesis by the fetal-placental unit may supply sufficient carnitine for placental and fetal metabolism. /Carnitine/
Levocarnitine can be synthesised within the body from the amino acids lysine or methionine. Vitamin C (ascorbic acid) is essential to the synthesis of carnitine. Levocarnitine is a carrier molecule in the transport of long chain fatty acids across the inner mitochondrial membrane. It also exports acyl groups from subcellular organelles and from cells to urine before they accumulate to toxic concentrations. Only the L isomer of carnitine (sometimes called vitamin BT) affects lipid metabolism. Levocarnitine is handled by several proteins in different pathways including carnitine transporters, carnitine translocases, carnitine acetyltransferases and carnitine palmitoyltransferases.
参考文献:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. 美国食品药品监督管理局批准的药物标签用于研究药物诱导的肝损伤,《药物发现今日》,16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank:按人类发展药物诱导肝损伤风险排名的最大参考药物清单。《药物发现今日》2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
References:M Chen, V Vijay, Q Shi, Z Liu, H Fang, W Tong. FDA-Approved Drug Labeling for the Study of Drug-Induced Liver Injury, Drug Discovery Today, 16(15-16):697-703, 2011. PMID:21624500 DOI:10.1016/j.drudis.2011.05.007
M Chen, A Suzuki, S Thakkar, K Yu, C Hu, W Tong. DILIrank: the largest reference drug list ranked by the risk for developing drug-induced liver injury in humans. Drug Discov Today 2016, 21(4): 648-653. PMID:26948801 DOI:10.1016/j.drudis.2016.02.015
Following a single intravenous dose, 73.1 +/- 16% of the dose was excreted in the urine during the 0-24 hour interval. Post administration of oral carnitine supplements, in addition to a high carnitine diet, 58-65% of the administered radioactive dose was recovered from urine and feces in 5-11 days.
The steady state volume of distribution (Vss) of an intravenously administered dose, above endogenous baseline levels, was calculated to be 29.0 +/- 7.1L. However this value is predicted to be an underestimate of the true Vss.
来源:DrugBank
吸收、分配和排泄
清除
总体体清除率平均为4升/小时。
Total body clearance was found to be a mean of 4L/h.
L-Carnitine is a naturally occurring compound that facilitates the transport of fatty acids into mitochondria for beta-oxidation. ... In humans, the endogenous carnitine pool, which comprises free L-carnitine and a range of short-, medium- and long-chain esters, is maintained by absorption of L-carnitine from dietary sources, biosynthesis within the body and extensive renal tubular reabsorption from glomerular filtrate. In addition, carrier-mediated transport ensures high tissue-to-plasma concentration ratios in tissues that depend critically on fatty acid oxidation. The absorption of L-carnitine after oral administration occurs partly via carrier-mediated transport and partly by passive diffusion. After oral doses of 1-6 g, the absolute bioavailability is 5-18%. In contrast, the bioavailability of dietary L-carnitine may be as high as 75%. Therefore, pharmacological or supplemental doses of L-carnitine are absorbed less efficiently than the relatively smaller amounts present within a normal diet. L-Carnitine and its short-chain esters do not bind to plasma proteins and, although blood cells contain L-carnitine, the rate of distribution between erythrocytes and plasma is extremely slow in whole blood. After iv administration, the initial distribution volume of L-carnitine is typically about 0.2-0.3 L/kg, which corresponds to extracellular fluid volume. There are at least three distinct pharmacokinetic compartments for L-carnitine, with the slowest equilibrating pool comprising skeletal and cardiac muscle. L-Carnitine is eliminated from the body mainly via urinary excretion. Under baseline conditions, the renal clearance of L-carnitine (1-3 mL/min) is substantially less than glomerular filtration rate (GFR), indicating extensive (98-99%) tubular reabsorption. The threshold concentration for tubular reabsorption (above which the fractional reabsorption begins to decline) is about 40-60 umol/L, which is similar to the endogenous plasma L-carnitine level. Therefore, the renal clearance of L-carnitine increases after exogenous administration, approaching GFR after high iv doses. ...
New methods and intermediates are discussed for the stereospecific synthesis of oxazinone compounds.
讨论了用于氧杂环酮化合物立体特异合成的新方法和中间体。
[EN] 4-PHENOXY-NICOTINAMIDE OR 4-PHENOXY-PYRIMIDINE-5-CARBOXAMIDE COMPOUNDS<br/>[FR] COMPOSÉS DE 4-PHÉNOXYNICOTINAMIDE OU DE 4-PHÉNOXY-PYRIMIDINE-5-CARBOXAMIDE
申请人:HOFFMANN LA ROCHE
公开号:WO2011089099A1
公开(公告)日:2011-07-28
This invention relates to novel phenyl amide or pyridyl amide derivatives of the formula (I), wherein A1, A2, B1, B2 and R1 to R11 are as defined in the description and in the claims, as well as pharmaceutically acceptable salts thereof. These compounds are GPBAR1 agonists and can be used as medicaments for the treatment of diseases such as type II diabetes.
This invention provides, but is not limited to, novel oleanolic acid derivatives having the formula (I) wherein the variables are defined herein. Also provided are pharmaceutical compositions, kits and articles of manufacture comprising such compounds, methods and intermediates useful for making the compounds, and methods of using the compounds and compositions.
Stereoselective Cobalt-Catalyzed Cross-Coupling Reactions of Arylzinc Chlorides with α-Bromolactones and Related Derivatives
作者:Maximilian S. Hofmayer、Alisa Sunagatullina、Daniel Brösamlen、Philipp Mauker、Paul Knochel
DOI:10.1021/acs.orglett.9b04564
日期:2020.2.21
α-Bromolactones bearing a substituent in the β-position undergo a highly trans-diastereoselective arylation with arylzincchlorides in the presence of 10-20% CoCl2 and 10-20% PPh3 in THF under mild conditions (25 °C, 16 h) leading to optically enriched α-arylated lactones and protected aldol products (99% ee) in 52-96% yield. The synthetic utility of this arylation was demonstrated by the stereoselective
[EN] HETEROCYCLIC COMPOUNDS AND METHODS FOR THEIR USE<br/>[FR] COMPOSÉS HÉTÉROCYCLIQUES ET PROCÉDÉS POUR LEUR UTILISATION
申请人:SPINIFEX PHARM PTY LTD
公开号:WO2013102242A1
公开(公告)日:2013-07-11
The present invention relates to heterocyclic compounds useful for antagonising angiotensin II Type 2 (AT2) receptor. More particularly the invention relates to pyrrolidine and azetidine compounds, compositions containing them and their use in methods of treating or preventing disorders or diseases associated with AT2 receptor function including neuropathic pain, inflammatory pain, conditions associated with neuronal hypersensitivity, impaired nerve conduction velocity, cell proliferation disorders, disorders associated with an imbalance between bone resorption and bone formation and disorders associated with aberrant nerve regeneration.