Metabolism of tetramethrin isomers in rat: IV. Tissues responsible for formation of reduced and hydrated metabolites

1. To identify the sites of formation of the reduced metabolites, 3-hydroxy-cyclohexane-1,2-dicarboximide (3-OH-HPI-1 and -2), 1,2-cyclohexanedicarboxylic acid (TCDA) and 1-hydroxy-1,2-cyclohexanedicarboxylic acid (1-OH-HPA), in rat treated with 14C-labelled (1RS, trans)-tetramethrin, [3,4,5,6-tetrahydrophthalimidomethyl (1RS, trans)-chrysanthemate], bile-duct cannulated animals were orally or intravenously administered 14C-labelled 3,4,5,6-tetrahydrophthalimide (TPI) or 3,4,5,6-tetrahydrophthalic acid (THPA), precursors of these metabolites, and bile, urine and faeces were collected for analysis. 2. 3-OH-HPI-1 and 3-OH-HPI-2, which are cis-form reduced metabolites, and 1-OH-HPA were detected in bile and urine samples of the bile-cannulated rat treated intravenously and orally with 14C-labelled TPI, indicating their formation in tissues or blood. TCDA, a trans-form reduced metabolite, was not detected in bile, urine or faeces of the bile-cannulated rat treated intravenously with 14C-THPA, but was found in the faeces after oral application, indicating formation in the gastrointestinal tract. 3. To clarify whether 1-OH-HPA is produced from THPA via TCDA (hydroxylation via reduction) or by direct addition of H2O to its double bond (hydration), rats were orally administered 14C-labelled TCDA, and metabolites in urine and faeces were analysed. The observed lack of 1-OH-HPA indicated formation by direct addition of H2O to the double-bond of THPA. 4. To specify which tissues form reduced and hydrated metabolites, in vitro metabolism studies were carried out. Reduction to the cis-form was found to take place in blood cells, reduction to the trans-form took place in the gastrointestinal tract contents, and hydration took place in the liver and the intestinal tract contents.     

The hNT human neuronal cell line survives and migrates into rat retina

Pigs were fed a commercial conjugated linoleic acid (CLA) mixture, prepared by alkali isomerization of sunflower oil, at 2% of the basal diet, from 61.5 to 106 kg live weight, and were compared to pigs fed the same basal diet with 2% added sunflower oil. The total lipids from liver, heart, inner back fat, and omental fat of pigs fed the CLA diet were analyzed for the incorporation of CLA isomers into all the tissue lipid classes. A total of 10 lipid classes were isolated by three-directional thin-layer chromatography and analyzed by gas chromatography (GC) on long capillary columns and by silver-ion high-performance liquid chromatography (Ag+-HPLC); cholesterol was determined spectrophotometrically. Only trace amounts (<0.1%; by GC) of the 9,11-18:2 cis/trans and trans,trans isomers were observed in pigs fed the control diet. Ten and twelve CLA isomers in the diet and in pig tissue lipids were separated by GC and Ag+- HPLC, respectively. The relative concentration of all the CLA isomers in the different lipid classes ranged from 1 to 6% of the total fatty acids. The four major cis/trans isomers (18.9% 11 cis,13 trans-18:2; 26.3% 10 trans,12 cis-18:2; 20.4% 9 cis,11 trans-18:2; and 16.1% 8 trans, 10 cis-18:2) constituted 82% of the total CLA isomers in the dietary CLA mixture, and smaller amounts of the corresponding cis,cis (7.4%) and trans,trans (10.1%) isomers were present. The distribution of CLA isomers in inner back fat and in omental fat of the pigs was similar to that found in the diet. The liver triacylglycerols (TAG), free fatty acids (FFA), and cholesteryl esters showed a similar pattern to that found in the diet. The major liver phospholipids showed a marked increase of 9 cis,11 trans-18:2, ranging from 36 to 54%, compared to that present in the diet. However, liver diphosphatidylglycerol (DPG) showed a high incorporation of the 11 cis,13 trans-18:2 isomer (43%). All heart lipid classes, except TAG, showed a high content of 11 cis,13 trans-18:2, which was in marked contrast to results in the liver. The relative proportion of 11 cis,13 trans-18:2 ranged from 30% in the FFA to 77% in DPG. The second major isomer in all heart lipids was 9 cis,11 trans-18:2. In both liver and heart lipids the relative proportions of both 10 trans,12 cis-18:2 and 8 trans, 10 cis-18:2 were significantly lower compared to that found in the diet. The FFA in liver and heart showed the highest content of trans,trans isomers (31 to 36%) among all the lipid classes. The preferential accumulation of the 11 cis,13 trans-18:2 into cardiac lipids, and in particular the major phospholipid in the inner mitochondrial membrane, DPG, in both heart and liver, appears unique and may be of concern. The levels of 11 cis,13 trans-18:2 naturally found in foods have not been established.     

The disposition of allyl isothiocyanate in the rat and mouse

The urine was the major route of excretion of radioactivity (50-80% of dose) following the oral administration (2.5 and 25 mg/kg body weight) of allyl[14C]isothiocyanate (AITC) to male and female Fischer 344 rats and B6C3F1 mice. Smaller amounts were found in the faeces (6-12%) and expired air (3-7%). The major difference between the two species was the greater retention of radioactivity after 4 days within rats (18-24% of dose) when compared with mice (2-5% of dose). Three radioactive components were found in the urine of mice and two in rats. The three components were inorganic thiocyanate, allylthiocarbamoylmercapturic acid and allylthiocarbamoylcysteine in mice, but no cysteine conjugate was found in rat urine. In the mouse, approximately 80% of the 14C was present in the urine as the thiocyanate ion whereas in the rat some 75% was as the mercapturate. This indicates that in the mouse, hydrolysis of AITC was the major metabolic pathway whereas in the rat glutathione conjugation was the major route. A species difference was seen in the amount of [14C]AITC-derived radioactivity present in the whole blood of rats and mice; measurable levels of radioactivity remained within rat blood for a longer time period (up to 240 hr) when compared with mice (96 hr). Examination of the urinary bladders of male and female rats following oral dosing with [14C]AITC showed a sex difference with greater amounts of [14C]AITC and/or its metabolites within the bladder tissue of male rats. This data is discussed in terms of the known species- and sex-specificity of the urinary bladder tumours, which occurred after long-term administration to male rats, but not to female rats or mice of either sex, in a carcinogenicity study conducted by the National Toxicology Program in the USA.     

Biotransformation of 2-chloroaniline in the Fischer 344 rat: identification of urinary metabolites

1. The biotransformation of a single i.p. dose of [14C]2-chloroaniline (1.0 mmol/kg, approximately 60 microCi/rat) was investigated in the urine and faeces of the male Fischer 344 rat. 2. During 24 h, 53.1% of the administered radioactivity was eliminated into the urine, while < 1% of the radioactivity appeared in the faeces. 3. The major biotransformation pathways were para-hydroxylation and sulphate conjugation. 4-Amino-3-chlorophenyl sulphate was the major urinary metabolite comprising 31.6% of total urinary radioactivity. The para-hydroxylated metabolite, 4-amino-3-chlorophenol (10.8%), and its O-glucuronide conjugate (3.7%) were also urinary metabolites. The formation of direct conjugates of 2-chloroaniline, the N-sulphate and N-glucuronide, was significant with as much as 18.6 and 8.6%, respectively, of these metabolites excreted in the urine. The parent compound, 2-chloroaniline, accounted for 16.9% of urinary radioactivity. 4. N-Acetylated products were minor metabolites present in urine as 2-chloro-4-hydroxyacetanilide and its sulphate or glucuronide conjugate. Neither 2-chloroacetanilide nor its oxidation products, 2-chloroglycolanilide and 2-chlorooxanilic acid, were urinary metabolites.     

Excretion of DNA adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, PhIP-dG, PhIP-DNA and DiMeIQx-DNA from the rat

The heterocyclic aromatic amines, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) are formed during frying of meat. PhIP and 4,8-DiMeIQx have, after metabolic activation, been shown to form adducts with DNA at the C8 of guanine both in vitro and in vivo. In order to investigate possible urinary biomarkers for estimation of the genotoxic dose of PhIP and 4,8-DiMeIQx, [3H]PhIP-dG, [3H]PhIP-DNA and [14C]4,8-DiMeIQx-DNA were injected i.p. to rats and the excretion of radioactivity in urine and faeces were measured. For all three [3H]PhIP-dG, [3H]PhIP-DNA and [14C]4,8-DiMeIQx-DNA 15-20% of the dose were excreted in the urine and 80-85% of the dose were excreted in the faeces. Urinary excretion showed maximum to 24 h (90%) with a rapid decline, 10% to 48 h and 0% to 72 h. Faecal excretion also showed maximum to 24 h (60%) with a slower decline, 30% to 48 h and 10% to 72 h. HPLC analysis of samples of urine and extracts from faeces, from rats dosed with [3H]PhIP-dG, showed that approximately 90% of the radioactivity co-eluted with PhIP-dG, indicating that PhIP-dG is excreted unmetabolized. HPLC analysis of samples of urine and extracts from faeces, from rats dosed with [3H]PhIP-DNA, showed that approximately 85% of the radioactivity co-eluted with PhIP-dG, indicating that PhIP-DNA adducts is mainly excreted as nucleoside adducts. Approximately 5% of the radioactivity excreted in the urine co-eluted with PhIP-G, indicating loss of deoxyribose. HPLC analysis of samples of urine and extracts from faeces, from rats dosed with [14C]4,8-DiMeIQx-DNA, showed that approximately 90% of the radioactivity co-eluted with 4,8-DiMeIQx-dG, indicating that 4,8-DiMeIQx-DNA adducts is mainly excreted as nucleoside adducts. Man is able to eliminate compounds of a higher mol. wt in the urine than the rat, the percentage of PhIP-dG and 4,8-DiMeIQx eliminated in the urine of man would therefore be expected to be higher than in the rat. Measurement of urinary nucleoside adducts of PhIP and 4,8-DiMeIQx could therefore provide a basis for the development of a biomonitoring strategy for the genotoxic dose of these food derived HAA.     

The metabolic fate of the coronary vasodilator 4-(3,4,5-Trimethoxycinnamoyl)-1-(N-pyrrolidinocarbonylmethyl)piperazine (cinepazide) in the rat, dog and man

1. An oral dose of the coronary vasodilator 4-(3,4,5-trimethoxy[14C]cinnamoyl)-1-(N-pyrrolidinocarbonylmethyl)piperazine was well absorbed and more than 60% of the dose was excreted within 24 h. In 5 days, rats, dogs, and man excreted in the urine and faeces respectively 36.7% and 58.3%, 33.4% and 68.6%, and 61.3% and 38.1% dose. Faecal radioactivity was probably excreted via the bile. 2. Plasma concentrations of radioactivity reached a maximum within about 1 h in all three species and declined fairly rapidly (t0.5 less than 3 h). For several hours, more than 50% of the plasma radioactivity was due to unchanged drug. After correction for dose and body weight (normalization), peak plasma concentrations of unchanged drug in man, rat and dog were in the approximate ratio 100 :30:1. 3. Similar metabolites were excreted by the three species, but the relative proportions differed. Rats and man excreted 17.2% and 15.9% respectively as unchanged drug in the urine whereas dogs excreted only 3.6%. Rat bile and urine contained 4.3% and 9.8% dose respectively as glucuronides of the mono-O-demethylated compounds and dog and human urine contained 9.0% and 2.6% respectively of these metabolites. The corresponding pyrrolidone accounted for 2.5%, 5.5% and 5.1% respectively in rat, dog and human urine. Complete O-demethylation also occurred since 4-(3,4,5-trihydroxycinnamoyl)-1-(N-pyrrolidinocarbonylmethyl)piperazine was present in rat faeces (22.1% dose).     

A new conjugated linoleic acid isomer, 7 trans, 9 cis-octadecadienoic acid, in cow milk, cheese, beef and human milk and adipose tissue

The identity of a previously unrecognized conjugated linoleic acid (CLA) isomer, 7 trans, 9 cis-octadecadienoic acid (18:2) was confirmed in milk, cheese, beef, human milk, and human adipose tissue. The 7 trans, 9 cis-18:2 isomer was resolved chromatographically as the methyl ester by silver ion-high-performance liquid chromatography (Ag+-HPLC); it eluted after the major 9 cis, 11 trans-18:2 isomer (rumenic acid) in the natural products analyzed. In the biological matrices investigated by Ag+-HPLC, the 7 trans, 9 cis-18:2 peak was generally due to the most abundant minor CLA isomer, ranging in concentration from 3 to 16% of total CLA. By gas chromatography (GC) with long polar capillary columns, the methyl ester of 7 trans, 9 cis-18:2 was shown to elute near the leading edge of the major 9 cis, 11 trans-18:2 peak, while the 4,4-dimethyloxazoline (DMOX) derivative permitted partial resolution of these two CLA isomers. The DMOX derivative of this new CLA isomer was analyzed by gas chromatography-electron ionization mass spectrometry (GC-EIMS). The double bond positions were at delta7 and delta9 as indicated by the characteristic mass spectral fragment ions at m/z 168, 180, 194, and 206, and their allylic cleavages at m/z 154 and 234. The cis/trans double-bond configuration was established by GC-direct deposition-Fourier transform infrared as evidenced from the doublet at 988 and 949 cm(-1) and absorptions at 3020 and 3002 cm(-1). The 7 trans, 9 cis-18:2 configuration was established by GC-EIMS for the DMOX derivative of the natural products examined, and by comparison to a similar product obtained from treatment of a mixture of methyl 8-hydroxy- and 11-hydroxyoctadec-9 cis enoates with BF3 in methanol.     

Glass-reinforced hydroxyapatite: a comprehensive study of the effect of glass composition on the crystallography of the composite

A rapid, simple, and sensitive method is described for the determination of the anomeric configuration of sugar 1-phosphates, sugar nucleotides, and polyisoprenyl-phospho-sugars. Negative-ion electrospray ionization of picomole amounts of glycosyl 1-phosphate derivatives produces an intense signal of the [M-H]-deprotonated molecule which, by collision-induced dissociation, decomposes in a characteristic manner depending on cis/trans configuration of the 2-hydroxyl and phosphate groups of the glycosyl residue. A distinct feature of the product ion spectra of glycosyl 1-P and polyisoprenyl-P-sugars with cis configuration is the presence of abundant ions that correspond to the [M-H2O-H]- dehydration product and the [R-PO4-(C2H3O]- fragment arising from a cleavage across the sugar ring, where R is -H or -polyprenyl/dolichyl for glycosyl 1-P and polyisoprenyl-P-sugar, respectively. These two fragments, [M-H2O-H]- and [R-PO4-(C2H3O)]- are absent from the product ion spectra of sugar 1-P and polyisoprenyl-P-sugars with trans configuration. For sugar nucleotides, compounds with cis configuration produce, in tandem mass spectrometry, only one abundant fragment of nucleoside monophosphate, whereas those with trans configuration give nucleoside diphosphate as a major fragment ion. Accordingly, the anomeric configuration of a glycosyl 1-phosphate derivative can be easily determined by using electrospray-ionization tandem mass spectrometry provided that the glycosyl residue of known absolute configuration has a free 2-hydroxyl group and no other charge location.     

Preparation of platinum(II) complexes with L-serine using KI. X-ray crystal structure, HPLC and 195Pt NMR spectra

The preparation of platinum(II) complexes containing L-serine using K(2)[PtCl(4)] and KI as raw materials was undertaken. The cis-trans isomer ratio of the complexes in the reaction mixture differed significantly depending on whether KI was present or absent in the reaction mixture. One of the two [Pt(L-ser-N,O)(2)] complexes (L-ser=L-serinate anion) prepared using KI crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=8.710(2) A, b=9.773(3) A, c=11.355(3) A, Z=4. The crystal data revealed that this complex has a cis configuration. The other [Pt(L-ser-N,O)(2)] complex also crystallizes in the monoclinic space group P2(1)2(1)2(1) with unit cell dimensions a=7.0190(9) A, b=7.7445(6) A, c=20.946(2) A, Z=4. The crystal data revealed that this complex has a trans configuration. The 195Pt NMR chemical shifts of trans-[Pt(L-ser-N,O)(2)] and cis-[Pt(L-ser-N,O)(2)] complexes are -1632 and -1832 ppm, respectively. 195Pt NMR and HPLC measurements were conducted to monitor the reactions of the two [Pt(L-ser-N,O)(2)] complexes with HCl. Both 195Pt NMR and HPLC showed that the reactivities of cis- and trans-[Pt(L-ser-N,O)(2)] toward HCl are different: coordinated carboxyl oxygen atoms of trans-[Pt(L-ser-N,O)(2)] were detached faster than those for cis-[Pt(L-ser-N,O)(2)].     

Comparative stereochemistry in the aziridine ring openings of N-methylmitomycin A and 7-methoxy-1,2-(N-methylaziridino)mitosene

A useful method was found for the conversion of mitomycin C into N-methylmitomycin A. The latter compound gave only two products on acid hydrolysis, the cis- and trans-1-hydroxy-7-methoxy-2-methylaminomitosenes. This selectivity allowed the cis--trans ratio to be quantitatively determined as 4:1. Such a predominance of the cis isomer is unexpected in view of the trans stereochemistry obtained in the opening of simple aziridines. In order to determine if the 9a-methoxy group of mitomycins controlled the direction of aziridine ring opening 7-methoxy-1,2-(N-methylaziridino)mitosene, which lacks this substituent, was prepared and hydrolyzed in acid. It gave the same two products in a 3:1 cis-trans ratio. In the induction of lambda-bacteriophage in Escherichia coli cis-1-hydroxy-7-methoxy-2-methylaminomitosene was more active than the corresponding trans isomer, but both of these compounds were less active than the aziridinomitosene or the mitomycins. Mitomycin A, mitomycin C, and N-methylmitomycin A were active against P388 leukemia in mice.     

Effects of specific fatty acids (8:0, 14:0, cis-18:1, trans-18:1) on plasma lipoproteins, early atherogenic potential, and LDL oxidative properties in the hamster

Although comparative studies of the cholesterolemic properties of trans fatty acids relative to cis-unsaturates and saturates have been conducted in humans and animals, there is no recent information relating these lipid responses to susceptibility to atherosclerosis. Therefore, hamsters were fed diets containing equivalent amounts of cholesterol (0.12% wt/wt) and test fats (20% wt/wt) for 8 weeks. Each test fat contained between 50-52% of the-total triacylglycerols as a single fatty acid, i.e., 8:0, 14:0, 18:0, cis-18:1, or trans-18:1 while the balance consisted of 16:0, cis-18:1 and 18:2 that were the same for all groups. Plasma total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), and high density lipoprotein cholesterol (HDL-C) levels were not different for 8:0, cis-18:1, and trans-18:1, whereas 14:0 caused a significant rise in plasma TC, LDL-C, and HDL-C. LDL oxidation measurements showed that the lag phase of conjugated diene formation was longest for the trans-18:1 and cis-18:1 groups while rate of conjugated diene formation was lowest for the trans-18:1 and cis-18:1 groups. The trans-18:1- and cis-18:1-fed animals had significantly higher levels of LDL alpha-tocopherol relative to the 8:0- and 14:0-fed animals. Aortic fatty streak formation was highest for the 14:0- and 8:0-fed animals and lowest for the trans-18:1. In conclusion, the plasma lipid and antioxidant properties of trans-18:1 and cis-18:1 were comparable while the trans-18:1-fed hamsters had the least amount of early atherosclerosis. In addition, 8:0-fed animals unexpectedly had early atherosclerosis formation similar to the 14:0-fed animals.     

The clinical skills of community psychiatric nurses working with patients who have severe and enduring mental health problems: an empirical analysis

Both cis-[Pt(NH3)2(4-Me-Py)Cl]+ and trans-[Pt(NH3)2(4-Me-Py)Cl]+ bind DNA covalently at the N7 site of guanine residues forming mono-dentate adducts. However, like cisplatin and transplatin, only the cis isomer has anti-cancer activity, whereas the trans-isomer does not. In order to understand the molecular basis of the different activities associated with cis-[Pt(NH3)2(4-Me-Py)Cl]+ and trans-[Pt(NH3)2(4-Me-Py)Cl]+, the interactions of these two platinum compounds with the DNA heptamer CCTG*TCC:GGACAGG duplex (G* is the platinated guanine) have been examined. The reaction rate of cis-[Pt(NH3)2(4-Me-Py)Cl]+ with the single-stranded CCTGTCC is significantly faster than that of the trans isomer. The solution structure of the platinum-DNA adducts has been studied by two-dimensional NMR spectroscopy. Both the cis-platinum adducts and the trans-platinum adducts destabilize the DNA duplex significantly. The melting temperature (Tm) of the platinated heptamer duplex is estimated to be 10 degrees C lower than for the unplatinated duplex by NMR. At 2 degrees C, the base pairs located on the 5' side of the oligonucleotide, beyond the platinum lesion site, are disrupted. Over time, the platinum-DNA complex decomposes and the cis-[Pt(NH3)2(4-Me-Py)] platinum complex is gradually detached from DNA. No interstrand crosslinking is observed. The biological implications of the structural studies are discussed.     

The metabolism of the xenobiotic triacylglycerols, rac-1- and sn-2- (3-phenoxybenzoyl)-dipalmitoylglycerol, following intravenous administration to the rat

The metabolism of 3-phenoxybenzoic acid (3PBA) in the form of triacylglycerol conjugates was compared with that of non-esterified 3PBA. Three radiolabeled triacylglycerols (rac-1-(3-phenoxy-[ring-14C]-benzoyl)-2,3-dipalmitoylglycerol (1(3PBA)DPG), sn-2-(3-phenoxy-[ring-14C]benzoyl)-1,3-dipalmitoylglycerol (2(3PBA)DPG) and the "natural" tri-[1-14C]oleoylglycerol) were incorporated into rat VLDL. Nonesterified 3PBA was prepared in rat serum albumin solution. Each preparation was administered i.v. to rats and serial blood samples were taken during the subsequent 6 hr. Urine and faeces were collected and tissue residues determined at 6 hr and 48 hr after administration. Biphasic elimination of 3PBA was observed with half-lives of 18 min and 2 hr. The triacylglycerols showed a rapid first phase and a longer second phase half-life: trioleoylglycerol 26 hr, 1(3PBA)DPG 7.6 hr and 2(3PBA)DPG 17.3 hr. The majority (63-76%) of 3PBA (whether esterified or not) was eliminated within 24 hr in urine, which contained similar profiles of metabolites. The triacylglycerols gave rise to higher tissue residues than did non-esterified 3PBA, particularly in adipose tissue which alone was not significantly depleted of radioactivity between 6 and 48 hr. The results accord with the rapid association of the VLDL-(3PBA)DPG complexes with lipoprotein lipase of the capillary epithelium, followed by hydrolysis to 3PBA, metabolism and elimination but with a proportion being redistributed into adipose tissue, re-esterified and then eliminated relatively slowly.     

Synthesis of deoxyglucose-1-phosphate, deoxyglucose-1,6-bisphosphate, and other metabolites of 2-deoxy-D-[14C]glucose in rat brain in vivo: influence of time and tissue glucose level

When the kinetics of interconversion of deoxy[14C]glucose ([14C]DG) and [14C]DG-6-phosphate ([14C]DG-6-P) in brain in vivo are estimated by direct chemical measurement of precursor and products in acid extracts of brain, the predicted rate of product formation exceeds the experimentally measured rate. This discrepancy is due, in part, to the fact that acid extraction regenerates [14C]DG from unidentified labeled metabolites in vitro. In the present study, we have attempted to identify the 14C-labeled compounds in ethanol extracts of brains of rats given [14C]DG. Six 14C-labeled metabolites, in addition to [14C]DG-6-P, were detected and separated. The major acid-labile derivatives, DG-1-phosphate (DG-1-P) and DG-1,6-bisphosphate (DG-1,6-P2), comprised approximately 5 and approximately 10-15%, respectively, of the total 14C in the brain 45 min after a pulse or square-wave infusion of [14C]DG, and their levels were influenced by tissue glucose concentration. Both of these acid-labile compounds could be synthesized from DG-6-P by phosphoglucomutase in vitro. DG-6-P, DG-1-P, DG-1,6-P2, and ethanol-insoluble compounds were rapidly labeled after a pulse of [14C]DG, whereas there was a 10-30-min lag before there was significant labeling of minor labeled derivatives. During the time when there was net loss of [14C]DG-6-P from the brain (i.e., between 60 and 180 min after the pulse), there was also further metabolism of [14C]DG-6-P into other ethanol-soluble and ethanol-insoluble 14C-labeled compounds. These results demonstrate that DG is more extensively metabolized in rat brain than commonly recognized and that hydrolysis of [14C]DG-1-P can explain the overestimation of the [14C]DG content and underestimation of the metabolite pools of acid extracts of brain. Further metabolism of DG does not interfere with the autoradiographic DG method.     

Pharmacology and toxicology of artelinic acid: preclinical investigations on pharmacokinetics, metabolism, protein and red blood cell binding, and acute and anorectic toxicities

The pharmacokinetics, metabolism, protein binding, red blood cell (RBC) binding, stability in vitro, and acute and anorectic toxicity of artelinic acid (ARTL) were investigated in various animal species and human blood samples. Absorption and distribution following 10 mg/kg intramuscular or oral administration in dogs and rats were very rapid with t1/2 0.12-0.54; there were also a high AUC (11,262 ng/h/mL) and Vss (9.5 L/kg), low CL (15 mL/min/kg) and long elimination time (t1/2 = 2.6 h), compared with rat data. Oral bioavailability of ARTL was 79.7% in dogs and 30.1% in rats. The conversion of ARTL to dihydroartemisinin (DART) in dogs (0.1-0.5% of total dose) after 3 routes of administration (intravenous, intramuscular and oral) was 10-fold lower than that in rats. In rats dosed with [14C]ARTL, unchanged ARTL accounted for less than 13% of the total radioactivity after all 3 administration routes, suggesting that ARTL was extensively biotransformed. The half-lives of total radioactivity (21-49 h) in urine were much longer than that of unchanged ARTL in plasma (1.4-3.7 h), indicating that some long-lasting metabolites of ARTL were formed in rats. The mass balance data showed that 77-83% of total radioactivity was recovered in urine and faeces. High binding capacity (79-95%) and low binding affinity (1.1-9.3 x 10-7 M) of ARTL were measured in rat, rabbit, dog, monkey and human plasma. The RBC/plasma ratios of [14C]ARTL were 0.35 and 0.44 for dog and human plasma, respectively. ARTL was much more stable than artesunic acid (ARTS) in rat and dog plasma, and both ARTL and ARTS were more stable in dog plasma than in rat plasma in vitro. The 50% lethal dose (LD50) of ARTL in rats was about 535 mg/kg. Multiple intramuscular dosing for 7 d of 50 mg/kg/d of ARTL caused mild anorectic toxicity compared to ARTS in rats. In contrast to 4 other artemisinin derivatives, ARTL seems to be a good antimalarial candidate as it has the highest plasma concentration, the highest binding capacities in RBC, the highest oral bioavailability, the longest elimination half-life, the lowest metabolism rate and the lowest toxicity at equivalent dose levels.     

Metabolic disposition of chlorambucil in rats

1. The metabolic dispositionof chlorambucil, 4-p-(di-2-chloroethyl)aminophenylbutyric acid, was studied in the rat. 2. After oral administration of [14C]chlorambucil to rats, plasma, liver, and kidney showed the highest concentration of 14C. After intravenous administration, plasma and kidney were heavily labelled. Although plasma contained as much as 10% of the administered dose in the first few hours after administration, the level decreased to 1% by 24 h. Elimination of radioactivity was mainly through the kidney. 3. Ten metabolites were isolated and characterized by mass spectrometry. Most metabolites had undergone oxidation on the butyric acid side-chain to form phenylacetic acid and benzoic acid derivatives. Spontaneous degradation products of [14C]chlorambucil were analysed and compared with the metabolites.     

Metabolism of linoleamides. I. Absorption, excretion and metabolism of N-(alpha-methylbenzyl)linoleamide in rat and man

1. In urine of rats dosed with N-(alpha-methylbenzyl)linoleamide (MBLA), three dicarboxylic acid monoamides, N-(alpha-methylbenzyl)succinic acid monoamide, N-(alpha-methylbenzyl)glutaric acid monoamide and N-(alpha-methylbenzyl)adipic acid monoamide, were identified. Conjugated alpha-methylbenzylamine, hippuric acid and conjugates of the dicarboxylic acid monoamides were also found in the urine. N-(alpha-Methylbenzyl)succinic acid monoamide was the main metabolite in rats. 2. Biliary excretion of radioactivity was studied in rats, cannulated for collection of bile and duodenal infusion, after oral administration of N-(alpha-methylbenzyl)[1-14C]linoleamide. With constant duodenal infusion of bile, about 7% of the dose was excreted in the bile, while excretion of radioactivity was negligible without bile infusion. 3. The g.l.c. analysis of human urine after oral administration of MBLA revealed that two dicarboxylic acid monoamides were present and N-(alpha-methylbenzyl)succinic acid monoamide was the main metabolite. 4. MBLA was excreted unchanged in the faeces of men who received MBLA to the extent of about 53% dose in 3 days. 5. MBLA was not detected (less than 1 mug/ml) in the serum of a volunteer who had been taking an oral daily dose of 1500 mg of MBLA for 3 months.     

Urinary metabolites of p-hydroxyamphetamine in man, rat and guinea-pig

1. The metabolism of (+/-)-p-hydroxy[14C]amphetamine has been studied in the rat, guinea-pig and man. 2. Most of the administered 14C was excreted in the urine within the first 24 h (64-92%), and was present mainly as free and conjugated p-hydroxy[14C]-amphetamine. In the female rat and female guinea-pig the conjugate was a glucuronide, but in man, who received a much smaller dose, the conjugate was a sulphate ester. A sex difference in conjugation was found in the rat, the female partly conjugating the drug but not the male. 3. Small quantities (1-6% of dose) of p-hydroxynorephedrine, a putative false neurotransmitter, were found in the urine of the three species. 4. Some oxidative degradation of the side chain of p-hydroxyamphetamine occurred in rat and guinea-pig since small amounts of p-hydroxybenzoic acid (1-3%) were detected in the urine.     

drp, a novel protein expressed at high cell density but not during growth arrest

In this study the disposition of 1,2-[14C]dibromoethane (1, 2-[14C]DBE) was investigated in male Wistar rats. 1,2-DBE is a cytotoxic and carcinogenic compound that has been used as an additive in leaded gasoline and as a fumigant. 1,2-[14C]DBE was administered orally or iv. Radioactivity was recovered (mostly within 48 hr after administration) in urine (75-82% of the dose), feces (3.2-4% of the dose), and expired air (0.53-7.2% of the dose). One hundred-sixty-eight hours after administration of 1,2-[14C]DBE, most of the radioactivity in tissues was found in the liver, lungs, and kidneys (<1% of the dose) and the red blood cells (0.3% of the dose). Identified urinary metabolites were S-(2-hydroxyethyl)mercapturic acid, thiodiacetic acid, and thiodiacetic acid sulfoxide, together accounting for, on average, 78% of the total amount of radioactivity in urine. In addition to S-(2-hydroxyethyl)mercapturic acid, thiodiacetic acid, and thiodiacetic acid sulfoxide, several compounds were anticipated as potential urinary metabolites of 1,2-DBE, i.e. S-(carboxymethyl)mercapturic acid, S-(2-hydroxyethyl)thioacetic acid, S-(2-hydroxyethyl)thiopyruvic acid, S-(carboxymethyl)thiopyruvic acid, S-(2-hydroxyethyl)thiolactic acid, and S-(carboxymethyl)thiolactic acid. All of the postulated urinary metabolites were synthesized and searched for in urine samples. None of these metabolites could be detected in urine, however. The data obtained in the present study might be useful for risk assessment and biomonitoring studies of 1,2-DBE and will also be used to further validate a physiologically based pharmacokinetic model for 1, 2-DBE in rats and humans that was recently developed.