Trace Amounts Of Metabolites Research Articles

Pharmacokinetics and metabolic disposition of a potent and selective kynurenine monooxygenase inhibitor, CHDI-340246, in laboratory animals

The disposition of a novel kynurenine monooxygenase inhibitor, CHDI-340246, was investigated in vitro and in animals. In vitro, there was minimal metabolic turnover of CHDI-340246 in all species. The protein binding was higher in human plasma (99.7%) relative to other species. In all species, blood clearance was low (<20% of liver blood flow) and volume of distribution was small (<0.5 L/kg). The terminal half-life was longer in monkeys (9 hr) than in mice, rats, or dogs (1–2 hr). CHDI-340246 was orally bioavailable (>60%) in all species. In rats, [14C]CHDI-340246 showed wide distribution of radioactivity in all tissues except brain and testes. In rats, the parent drug was the major circulating moiety with minor amounts of a sulphate conjugate of an O-dealkylated metabolite. The elimination occurred via the urinary route and to a lesser extent by biliary route, but mostly as metabolites. In cynomolgus monkeys, the parent drug predominated in plasma with only trace amounts of metabolites detected. Acyl glucuronide conjugate of CHDI-340246 was not detected in plasma of rats or monkeys. Overall, the ADME profile of CHDI-340246 was favourable in rats and monkeys for potential evaluation of KMO inhibition in humans.

Metabolism of the masked mycotoxin deoxynivalenol-3-glucoside in pigs

Plants can metabolize the Fusarium mycotoxin deoxynivalenol (DON) by forming the masked mycotoxin deoxynivalenol-3-β-d-glucoside (D3G). D3G might be cleaved during digestion, thus increasing the total DON burden of an individual. Due to a lack of invivo data, D3G has not been included in the various regulatory limits established for DON so far. The aim of our study was to contribute to the risk assessment of D3G by determination of its metabolism in pigs. Four piglets received water, D3G (116μg/kg b.w.) and the equimolar amount of DON (75μg/kg b.w.) by gavage on day 1, 5 and 9 of the experiment, respectively. Additionally, 15.5μg D3G/kg b.w. were administered intravenously on day 13. Urine and feces were collected for 24h and analyzed for DON, D3G, deoxynivalenol-3-glucuronide (DON-3-GlcA), deoxynivalenol-15-GlcA (DON-15-GlcA) and deepoxy-deoxynivalenol (DOM-1) by UHPLC–MS/MS. After oral application of DON and D3G, in total 84.8±9.7% and 40.3±8.5% of the given dose were detected in urine, respectively. The majority of orally administered D3G was excreted in form of DON, DON-15-GlcA, DOM-1 and DON-3-GlcA, while urinary D3G accounted for only 2.6±1.4%. In feces, just trace amounts of metabolites were found. Intravenously administered D3G was almost exclusively excreted in unmetabolized form via urine. Data indicate that D3G is nearly completely hydrolyzed in the intestinal tract of pigs, while the toxin seems to be rather stable after systemic absorption. Compared to DON, the oral bioavailability of D3G and its metabolites seems to be reduced by a factor of up to 2, approximately.

Metabolites from Carnivorous Fungus Arthrobotrys entomopaga and Their Functional Roles in Fungal Predatory Ability

The carnivorous fungus Arthrobotrys entomopaga (Drechsler) can develop adhesive knobs to capture nematodes. Chemical study on the culture medium of A. entomopaga producing adhesive knobs led to isolation of six trace amounts of metabolites, including two new metabolites, paganins A and B (1 and 2), blumenol A (3), talathermophilins A and B (4 and 5), and cyclo(glycyltryptophyl) (6). Compounds 3-6 were reported for the first time from carnivorous fungi. Compounds 1 and 2 promoted the formation of the predatory adhesive knobs with an increasing rate up to 118% at a concentration of 50 μM but showed moderate inhibitory activity at a concentration of 5 μM. Moreover, compounds 1 and 2 displayed strong inhibitory activities toward the formation of A. entomopaga conidiophores with inhibitory rates of 40-75%. Growth experiments suggested that compounds 1 and 2 could be involved in the regulation of the fungal predatory and reproductive abilities. Nematode chemotaxis bioassay indicated that compounds 1 and 3 displayed strong nematode-attracting abilities. These findings provided a new type of regulatory metabolite and support for the hypothesis that predators often evolve to respond to their metazoan prey.

The absorption, metabolism and excretion of flavan-3-ols and procyanidins following the ingestion of a grape seed extract by rats

Rats were fed a grape seed extract (GSE) containing (+)-catechin, (-)-epicatechin and dimers, trimers, tetramers and polymeric procyanidins. Liver, kidney, brain and gastrointestinal (GI) tract together with plasma, urine and faeces were collected over a 24 h period and their flavan-3-ol content was analysed by HPLC with tandem mass spectrometry and diode array detection. Small amounts of the GSE flavan-3-ols moved out of the stomach and into the duodenum/jejunum, and to a greater extent the ileum 1 h after ingestion, and into the caecum after 2 h with relatively small amounts being detected in the colon after 3 h. The GI tract contained the parent GSE flavan-3-ols and procyanidins with only trace amounts of metabolites and there were no indications that proanthocyanidins were depolymerised in the GI tract releasing monomeric flavan-3-ols. Plasma contained exclusively catechin glucuronides and methylated glucuronide metabolites which were also detected in the liver and kidneys. These metabolites were also present in urine together with sulphated metabolites and low amounts of the procyanidin dimers B1, B2, B3 and B4 as well as the trimer C2 and an unknown GSE trimer. The amounts of (+)-catechin and (-)-epicatechin metabolites excreted in urine relative to the quantity of the monomers ingested were 27 and 36 %, respectively, after 24 h. This is similar to the levels of urinary excretion reported to occur by other investigators after feeding (-)-epicatechin to rats and provides further, albeit indirect, evidence that the procyanidin oligomers in the GSE were not depolymerised to monomers to any extent after ingestion. No convincing analytical data were obtained for the presence of flavan-3-ol metabolites in the brain.

Uptake of flavonoids from Vicia villosa (Fabaceae) by the lycaenid butterfly, Polyommatus icarus (Lepidoptera: Lycaenidae)

Abstract Caterpillars of Polyommatus icarus were reared on inflorescences of Vicia villosa, a plant species acceptable for larval development, but not used as food source in nature. Vicia villosa flowers contained four flavonoids at a concentration of 18.34 mg g−1 dry weight. Three compounds were identified by MS and NMR as myricetin-3-0-rhamnoside (8.68%), quercetin-3-0-rhamnoside (56.30%), and kaempferol-3-O-rham-noside (32.18%). Larvae incorporated and metabolized only part of the flavonoids of their hostplant, while a larger proportion was excreted. Besides trace amounts of metabolites, adult butterflies contained mainly quercetin-3-O-rhamnoside and kaempferol-3-0-rhamnoside at a total concentration of 1.22-1.38 mgg−1. The main flavonoid in the butterflies was kaempferol-3-0-rhamnoside (55%). Females stored more flavonoids than males, and the flavonoid content was correlated with body mass. Butterflies raised on V. villosa as larval food differed qualitatively (number and chemical nature of flavonoids) and quantitatively from conspecifics reared on other hostplants. It is proposed that quantitative variation of flavonoids, which are incorporated into the wing patterns, could serve as a means of mate recognition and selection.

Metabolism of 25-hydroxycholecalciferol by kidney cell lines

The metabolism of 25-hydroxyvitamin D 3 to 24,25-dihydroxyvitamin D 3 by the rhesus monkey cell line LLC-MK 2 and similar reactions of the African green monkey cell lines, Vero and BSC-1, were observed. In addition, a second metabolite produced by the former cell line was identified as 25,26-dihydroxyvitamin D 3. Four other kidney cell lines, canine MDCK, bovine MDBK, embryonic bovine MA-115, and rabbit RK-13 produced only trace amounts of metabolites, and baby hamster kidney cells BHK-21 and owl monkey kidney cells OMK-21 synthesized no metabolites of 25-hydroxyvitamin D 3. Suspension cultures of LLC-MK 2 and Vero were found to produce oxidation products linearly for up to 3 h with specific activities of 5.23 and 2.40 pmol/h mg protein, respectively.

Accumulation, metabolism and subcellular localization of daunorubicin, doxorubicin and their DNA-complexes in rat heart ventricles

The accumulation in rat heart ventricles, the presence of metabolites and the subcellular localization of daunorubicin (DNR), doxorubicin (DOX) and their DNA complexes were investigated. After intravenous perfusion of free DNR or DOX, equal amounts of the drugs are recovered in the heart, whereas after injection of their DNA complexes, the accumulation levels represent 42% (DNR) and 32% (DOX) of those reached with the free drugs. Daunorubicinol and daunomycinone are detected after administration of DNR or DNR-DNA but only trace amounts of metabolites are found with DOX and DOX-DNA. Subcellular distributions of DNR injected as free or DNA complex are similar. Isopycnic and differential centrifugations indicate that DNR could be associated with nuclear DNA and to a smaller extent with lysosomes. By contrast, after injection of free or complexed DOX the drug is almost exclusively associated with the nuclear DNA. The mechanisms by which these drugs are accumulated by the heart and the relation with their cardiotoxicities are discussed.

Dioxygenated metabolites of cannabidiol formed by rat liver.

The metabolism of cannabidiol (CBD) was studied in vitro using a 10 000 g supernatant from rat liver. After removal of unchanged CBD and its monohydroxylated metabolites, a polar fraction remained from which ten dioxygenated metabolites were isolated. Mass spectrometry and nuclear magnetic resonance spectroscopy were used to identify the following metabolites: 6,7-dihydroxy-CBD, 1 inch,7-dihydroxy-CBD, 3 inch,7-dihydroxy-CBD, 4 inch,7-dihydroxy-CBD, 5 inch,7-dihydroxy-CBD, 2 inch,6-dihydroxy-CBD, 3 inch,6beta-dihydroxy-CBD, 4 inch, 6beta-dihydroxy-CBD (tentative), 3 inch-hydroxy-6-oxo-CBD, and 4 inch-hydroxy-6-oxo-CBD. The abundance of isolated dihydroxy metabolites reflected the quantity of monohydroxy metabolites that was previously found. In both series, 7-hydroxylation occurred to the greatest extent. Side chain hydroxylation occurred predominantly at C-4 inch and to a lesser degree at C-3 inch. Trace amounts of metabolites were hydroxylated at C-1 inch,-2 inch, or 5 inch.

Release of prostaglandins from healthy and sensitized guinea-pig lung and trachea by histamine

The effects of histamine and its antagonists on the release of prostaglandin E and F 2α (PGE and PGF 2α) and the 15-keto-13,14-dihydro PGF 2α/E (metabolites) were examined in minced and whole perfused guinea pig lung. Lung fragments released considerable amounts of prostaglandins into the incubation media with time alone: parenchyma more PGF 2α than PGE, trachea more PGE than PGF 2α. The levels of PGF 2α found in the filtrates of both tissues on per gram basis were about the same, whereas the concentrations of PGE were several fold higher in the media of incubated trachea. In contrast to lung, trachea released only trace amounts of metabolites. These differences in synthesis and turnover are probably of importance for maintenance of the adequate ventilation-perfusion ratios. The process of sensitization caused a significant increase in the outflows of PGF 2α and metabolites from the lung fragments. The PGE to PGF 2α ratio was decreased in both parenchymal and tracheal tissues. Increased spontaneous release of prostaglandins was also found in whole perfused sensitized lung. This was consistent with the hypothesis that sensitization with antigen alters the biochemical properties of the organism. Incubation of lung fragments with histamine had only a small additional effect on the liberation of prostaglandins, since the baseline release was high due to the trauma of mincing. However, histamine perfusion of whole lung caused severalfold increase in the outflows of prostaglandins. Pretreatment with pyrilamine (histamine receptor 1 antagonist) decreased the subsequent release of PGF 2α by histamine. On the other hand, pretreatment with metiamide (histamine receptor 2 antagonist) diminished the subsequent release of PGE. It is suggested that stimulation of histamine receptor 1 is predominantly (but not solely) related to the synthesis of PGF 2α, and stimulation of the receptor 2 is related to the synthesis of PGE.