Protective effect of 6-O-methyl-scutellarein on repeated cerebral ischemia/reperfusion in rats

Abstract

Scutellarin (1) possesses protective effects against neuronal injury, while 6-O-methyl-scutellarein (3), as the main metabolite of scutellarin in vivo, has not been reported about its protective effects previously. The present study mainly investigated whether the neural injury caused by ischemia/reperfusion would be influenced by different doses of 6-O-methyl-scutellarein (3). The results of behavioral, neurological, and histological examinations indicated that 6-O-methyl-scutellarein (3) could improve neuronal injury, and exhibit significant difference among the various doses. More importantly, 6-O-methyl-scutellarein (3) had better protective effects than scutellarin in rat cerebral ischemia.     

Identification of ginkgolic acid (15:1) metabolites in rats following oral administration by high-performance liquid chromatography coupled to tandem mass spectrometry

1.?In this article, metabolites of ginkgolic acid (GA) (15:1) in rats plasma, bile, urine and faeces after oral administration have been investigated for the first time by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) with the aid of on-line hydrogen/deuterium (H/D) exchange technique and β-glucuronidase hydrolysis experiments.

2.?After oral administration of GA (15:1, M0) to rats at a dose of 10?mg/kg, it was found that metabolites M1-M5 together with parent compound (M0) existed in rat plasma; parent compound (M0) and metabolites M2–M5 were observed in rat bile, and parent compound (M0) with metabolites M1 and M2 were discovered in rat faeces, and there was no parent compound and metabolite detectable in rat urine.

3.?Two oxidative metabolites of GA (15:1, M0) were identified as 2-hydroxy-6-(pentadec-8-enyl-10-hydroxy) benzoic acid (M1) and 2-hydroxy-6-(pentadec-8-enyl-11-hydroxy-13-carbonyl) benzoic acid (M2), respectively. Metabolites M3, M4 and M5 were identified as the mono-glucuronic acid conjugates of parent compound (M0), M1 and M2, respectively.

4.?The results indicated that M1 and M2 with parent compound (M0) were mainly eliminated in faeces and three glucuronide metabolites (M3, M4 and M5) excreted in bile as the predominant forms after oral administration of GA (15:1) to rats.     

A microbial model of mammalian metabolism: biotransformation of 4,5-dimethoxyl-canthin-6-one using Cunninghamella blakesleeana CGMCC 3.970

1.?A filamentous fungus, Cunninghamella blakesleeana CGMCC 3.970, was applied as a microbial system to mimic mammalian metabolism of 4,5-dimethoxyl-canthin-6-one (1). Compound 1 belongs to canthin-6-one type alkaloids, which is a major bioactive constituent of a traditional Chinese medicine (the stems of Picrasma quassioides).

2.?After 72?h of incubation in potato dextrose broth, 1 was metabolized to seven metabolites as follows: 4-methoxyl-5-hydroxyl-canthin-6-one (M1), 4-hydroxyl-5-methoxyl-canthin-6-one (M2), canthin-6-one (M3), canthin-6-one N-oxide (M4), 10-hydroxyl-4,5-dimethoxyl-canthin-6-one (M5), 1-methoxycarbonl-β-carboline (M6), and 4-methoxyl-5-O-β-D-glucopyranosyl-canthin-6-one (M7).

3.?The structures of metabolites were determined using spectroscopic analyses, chemical methods, and comparison of NMR data with those of known compounds. Among them, M7 was a new compound.

4.?The metabolic pathways of 1 were proposed, and the metabolic processes involved phase I (O-demethylation, dehydroxylation, demethoxylation, N-oxidation, hydroxylation, and oxidative ring cleavage) and phase II (glycosylation) reactions.

5.?This was the first research on microbial transformation of canthin-6-one alkaloid, which could be a useful microbial model for producing the mammalian phase I and phase II metabolites of canthin-6-one alkaloids.

6.?1, M1?M5, and M7 are canthin-6-one alkaloids, whereas M6 belongs to β-carboline type alkaloids. The strain of Cunninghamella blakesleeana can supply an approach to transform canthin-6-one type alkaloids into β-carboline type alkaloids.     

The Metabolism of Terbutaline in Dog and Rat

Abstract

1. The metabolic fate of [³H]terbutaline has been studied in dog after oral, intravenous and subcutaneous administration and in rat after oral and intravenous administration. In 3–4 days the dog excreted 75% of the dose in the urine after oral administration and more than 90% after intravenous or subcutaneous administration; the remainder was in the faeces. The rat in 24 h excreted about 13% in the urine and 61% in the faeces after oral administration and 48% in the urine and 35% in the faeces after intravenous administration.

2. After oral administration of [³H]terbutaline, the time course of radioactivity concentration was the same in lung, heart and serum; low levels of unchanged drug were found in all tissues. After intravenous administration, the concentration of unchanged drug was higher in lung and heart than in serum.

3. In dog, 1·7% of an intravenous dose was excreted into bile in 6 h. In rat, about 37% of the dose was recovered in the bile during 12 h.

4. Enzymic hydrolysis of urine showed that terbutaline is metabolized by conjugation, forming a glucuronide in rat but probably a sulphate in dog.     

Iridoid glucoside, (3<Emphasis Type="Italic">R</Emphasis>)-oct-1-en-3-ol glycosides,and phenylethanoid from the aerial parts of <Emphasis Type="Italic">Caryopteris incana</Emphasis>

Eleven compounds of interest were isolated from the aerial parts of Caryopteris incana, specifically a new acyl derivative (3) of 8-O-acetylharpagide, two new (3R)-oct-1-en-3-ol glycosides (5, 6), and 6-O-caffeoylphlinoside A (11) along with seven known compounds, 8-O-acetylharpagide (1), 6′-O-p-coumaroyl-8-O-acetylharpagide (2), (3R)-oct-1-en-3-ol (matsutake alcohol) O-α-l-arabinopyranosyl-(1″ → 6′)-O-β-d-glucopyranoside (4), apigenin 7-O-neohesperidinoside (7), 6′-O-caffeoylarbutin (8), and two phenylethanoids, leucosceptoside A (9) and phlinoside A (10). This paper deals with structural elucidation of the new compounds.     

Further flavonol and iridoid glycosides from Ajuga remota aerial parts

Five new iridoid glycosides characterised as 6-keto-8-acetylharpagide (1), 6,7-dehydro-8-acetylharpagide (2), 7,8-dehydroharpagide (3), 8-acetylharpagide-6-O-β-glucoside (4), harpagide-6-O-β-glucoside (5) together with three flavonol glycosides, myricetin 3-O-rutinoside-4′-O-rutinoside (6), myricetin 3-O-rutinoside-3′-O-rutinoside (7) and isorhamnetin 3-O-rutinoside-7-O-rutinoside-4′-O-β-glucoside (8) have been isolated from the aerial parts of Ajuga remota. Also isolated were two known compounds ajugarin IV and ajugarin V. Their structures were established using spectroscopic methods including UV, IR, FAB-MS, HR-MS, 1D and 2D NMR techniques.     

Absorption,distribution, metabolism and excretion of telmesteine,amucolitic agent,in rat

1. The metabolism and disposition of telmesteine, a muco-active agent, have been investigated following single oral or intravenous administration of ¹⁴C-telmesteine in the Sprague–Dawley rat.

2. ¹⁴C-telmesteine was rapidly absorbed after oral dosing (20 and 50mg kg^-1) with an oral bioavailability of > 90% both in male and female rats. The C_max and area under the curve of the radioactivity in plasma increased proportionally to the administered dose and those values in female rats were 30% higher than in male rats.

3. Telmesteine was distributed over all organs except for brain and the tissue/plasma ratio of the radioactivity 30min after dosing was relatively low with a range of 0.1–0.8 except for excretory organs.

4. Excretion of the radioactivity was 86% of the dose in the urine and 0.6% in the faeces up to 7 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 3% for the first 24 h. The unchanged compound mainly accounted for the radioactivity in the urine and plasma.

5. Telmesteine was hardly metabolized in microsomal incubations. A glucuronide conjugate was detected in the urine and bile, but the amount of glucuronide was less than 6% of excreted radioactivity.     

Identification of the metabolites of baicalein in human plasma

The metabolites of baicalein in human plasma were investigated after taking baicalein, which is one of the main bioactive flavones in Scutellaria baicalensis Georgi. Five metabolites (M1–M5) together with the parent drug baicalein (P) were detected and identified by the HPLC-diode-array detector (DAD) and LC-MS/MS methods. Among them, 7-methoxybaicalein 6-O-glucuronide (M5) is a new metabolite. Based on the results, the proposed metabolic pathway of baicalein in humans was inferred.     

Metabolites of isocorynoxeine in rats after its oral administration

This work presents the metabolites of isocorynoxeine (ICOR), which is one of four bioactive tetracyclic oxindole alkaloids isolated from Uncaria hooks used commonly in the traditional Chinese medicines and Kampo medicines. After oral administration of 40 mg kg^? 1 ICOR to rats, bile was drained and analyzed by LC-MS. Two phase I metabolites, namely 11-hydroxyisocorynoxeine (M1) and 10-hydroxyisocorynoxeine (M2), and two phase II metabolites, namely 11-hydroxyisocorynoxeine 11-O-β-d-glucuronide (M3) and 10-hydroxyisocorynoxeine 10-O-β-d-glucuronide (M4), were isolated from rat excreta and bile, respectively, whose structures were elucidated on the basis of CD, NMR, and MS.     

Metabolism of tamsulosin in rat and dog

1. The metabolism of tamsulosin hydrochloride (TMS), a potent α₁-adrenoceptor blocking agent, was studied after a single oral administration to rat and dog.

2. Eleven metabolites (1, 2, 3, 4 and their glucuronides, sulphates of 1 and 3, and A-1) were identified from the urine and bile of rat and dog administered TMS.

3. Unchanged drug and metabolites in urine and bile were quantified in rat and dog dosed with ¹⁴C-TMS (1?mg/kg). In rat the main metabolic routes were de-ethylation of the o-ethoxyphenoxy moiety, demethylation of the methoxybenzenesulphonamide moiety, and conjugation of the resultant metabolites by glucuronic acid and sulphuric acid. In dog the main pathways were de-ethylation of the ethoxyphenoxy moiety, conjugation of the de-ethylated product by sulphuric acid, and oxidative deamination of the side chain.

4. The organ responsible for the metabolism of TMS in rat was estimated using 9000g supernatants of liver, kidney, small and large intestine homogenate and plasma. The drug was rapidly metabolized in liver but hardly metabolized in the other organs or plasma.     

Identification of circulatory and excretory metabolites of a novel nitric oxide donor ZJM-289 in rat plasma,bile, urine and faeces by liquid chromatography–tandem mass spectrometry

1. ZJM-289, [2-(1-diethylaminoacetoxy)pentyl] benzoic acid-{2-methoxy-4-[2-(4-nitrooxybutoxy carbonyl)-vinyl]}phenyl ester hydrochloride, is a novel nitric oxide–donating derivative of 3-n-butylphthalide synthesised on the hypothesis that it may be hydrolysed in vivo into 3-n-butylphthalide, ferulic acid and nitric oxide in hope that the three components may exert effects on the platelets as well as on central nervous system synergistically.

2. In this study, ZJM-289 was extensively metabolised in rats. Eight major metabolites were identified by liquid chromatography (LC)–mass spectrometry (MS)/MS in rat plasma, bile, urine and faeces after intravenous administration. Metabolites M1, M2, M3, M4 and M5 were hydrolytic products of ZJM-289, M6 and M7 was a hydroxylation product of M5, and M8 was a glucuronide of M1.

3. The pharmacologically active metabolite ferulic acid (M3) was a major metabolite in all the biological matrixes examined. 3-n-Butylphthalide was also present at a moderate level in the circulation. And along with the previous research, the anti-platelet activity of ZJM-289 was more potent than that of 3-n-butylphthalide both in vivo and in vitro. All these findings validated the theory of drug design.

     

In vitro and in vivo metabolism of 14C-AZ11, a novel inhibitor of bacterial DNA gyrase/type II topoisomerase

Abstract

1.?(2R,4S,4aS)-11-Fluoro-2,4-dimethyl-8-((S)-4-methyl-2-oxooxazolidin-3-yl)-2,4,4a,6-tetrahydro-1H,1'H-spiro [isoxazolo[4,5-g][1,4]oxazino[4,3-a]quinoline-5,5′-pyrimidine]-2′,4′,6′(3′H)-trione (AZ11) is a novel mode-of-inhibition bacterial topoisomerase inhibitor that entered preclinical development for the treatment of Gram-positive bacteria infection.

2.?The in vitro biotransformation studies of AZ11 using mouse, rat, dog and human hepatocytes showed low-intrinsic clearance in all species attributed to microsomal metabolism.

3.?After a single intravenous administration of [¹⁴C]AZ11 in bile duct cannulated rats, the mean percentage of dose recovered in rat urine, bile and feces was approximately 18, 36 and 42%, respectively. Unchanged AZ11 recovered in rat urine and bile was less than 9% of the dose, indicating that AZ11 underwent extensive metabolism in rats.

4.?The most abundant in vivo metabolite detected in urine and bile was M1 formed via ring opening on the piperidine and morpholine rings accounting for 20% of the administered dose. The major fecal metabolite was M5, which accounted for approximately 32% of administered dose. M5 was not formed when AZ11 incubated with rat intestinal microsomes and cytosol but was formed when incubated with fresh rat feces, suggesting that unchanged AZ11 was directly excreted into gut lumen where M5 formed as an intestinal microflora-mediated product. This process could have significant impact on bioavailability or exposure of AZ11 in rat.     

Polyphenolic compounds from the leaves of Koelreuteria paniculata Laxm

From the fresh leaves of Koelreuteria paniculata Laxm (Sapindaceae), four new compounds, named ethyl p-trigallate (1), 3"-O-galloyl-4'-O-galloyl-4-O-galloyl-gallic acid (2), ethyl p-heptagallate (3) and 3"-galloylquercitrin (4), together with 12 known compounds namely catechin (5), galloylepicatechin (6), isorhamnetin (7), kaempferol-3-O-arabinopyranoside (8), quercetin-3'-O- g -D-arabinopyranoside (9), quercitrin (10), methyl p-digallate (11), methyl m-digallate (12), p-digalloyl acid (13), m-digalloyl acid (14), hyperin (15) and kaempferol-3-O- f -L-rhamnoside (16) were isolated by extensive column chromatographic separation. Their structures were elucidated on the basis of chemical and spectroscopic methods. Compound 9 was not reported previously with pyranoside of arabinose at C-3'. Compounds 4 and 9 possessed the activity for PTK inhibition.     

Aromatic glycosides from the flower buds of Lonicera japonica

Six new glycosides (1–6) have been isolated from the flower buds of Lonicera japonica. Their structures including the absolute configurations were determined by spectroscopic and chemical methods as ( ? )-2-hydroxy-5-methoxybenzoic acid 2-O-β-d-(6-O-benzoyl)-glucopyranoside (1), ( ? )-4-hydroxy-3,5-dimethoxybenzoic acid 4-O-β-d-(6-O-benzoyl)-glucopyranoside (2), ( ? )-(E)-3,5-dimethoxyphenylpropenoic acid 4-O-β-d-(6-O-benzoyl)-glucopyranoside (3), ( ? )-(7S,8R)-(4-hydroxyphenylglycerol 9-O-β-d-[6-O-(E)-4-hydroxy-3,5-dimethoxyphenylpropenoyl]-glucopyranoside (4), ( ? )-(7S,8R)-(4-hydroxy-3-methoxyphenylglycerol 9-O-β-d-[6-O-(E)-4-hydroxy-3,5-dimethoxyphenylpropenoyl]-glucopyranoside (5), and ( ? )-4-hydroxy-3-methoxyphenol β-d-{6-O-[4-O-(7S,8R)-(4-hydroxy-3-methoxyphenylglycerol-8-yl)-3-methoxybenzoyl]}-glucopyranoside (6), respectively.     

The metabolism of trans-sobrerol in the rat

1. The biotransformation of trans-sobrerol, a potent mucofluidifying agent, has been investigated in rat urine, bile and faeces after single p.o. and i.v. administration.

2. The identification of the isolated metabolites was carried out by g.l.c.-mass spectrometry, n.m.r. and i.r. spectroscopy.

3. The metabolic pathways involve oxidation of the allylic C (sp³) atoms, and mono-β-glucuronylation of the secondary or tertiary alcoholic group.

4. The mono-β-glucuronides of sobrerol excreted in bile undergo enterohepatic circulation.     

A potential inhibitor of rat aortic vascular smooth muscle cell proliferation from the pollen of <Emphasis Type="Italic">Typha angustata</Emphasis>

By various chromatographic methods, three flavonoids, (2S)-naringenin (1), isorhamnetin 3-O-(2-O-α-l-rhamnopyranosyl) β-d-glucopyranoside (2), typhaneoside (3), and two sterol glycosides, β-sitosterol-3-O-(6-octadecanoyl) β-d-glucopyranoside (4) and β-sitosterol-3-O-(6-octadeca-9Z,12Z-dienoyl) β-d-glucopyranoside (5), were isolated from the pollen of Typha angustata. Their structures were determined on the basis of spectroscopic analyses. The flavonoids (1–3) were evaluated for their effects on the viability and proliferation of rat aortic smooth muscle cells. (2S)-naringenin (1) significantly inhibited cell proliferation in a dose-dependent manner without cytotoxic at concentrations of 30, and 50 μM; it reduced the number of cells following PDGF-BB treatment to 1.83 ± 0.30 × 10⁴ and 2.20 ± 0.60 × 10⁴ cells/well, respectively. These findings suggest that (2S)-naringenin has antiproliferative effects on aortic smooth muscle cells.     

Metabolism of 2-Benzylthio-5-Trifluoromethyl Benzoic Acid (BTBA) by the Rat,Dog and Man

Abstract

1. Benzylthio-5-trifluoromethylbenzoic acid (BTBA) is well absorbed by rat, dog and man. The time course of disappearance from plasma in all three species suggests enterohepatic circulation.

2. The principal excretion product in rat urine has been identified as 2-mercapto-5-trifluoromethylbenzoic acid arising via S-dealkylation.

3. 2-Mercapto-5-trifluoromethylbenzoic acid is also converted to the disulphide metabolite, [2,2′-dithiobis(5-trifluoromethyl)benzoic acid], which is secreted together with BTBA and their glucuronide conjugates in rat bile. Rapid hydrolysis in the intestine results in faecal elimination of largely free BTBA and disulphide metabolite (2,2′-dithiobis[5-trifluoromethyl]benzoic acid).

4. In man, approximately 50% of the dose is recovered from urine as amino-acid and glucuronide conjugates of the drug and its debenzyl metabolite (2-mercapto-5-trifluoromethylbenzoic acid).

5. The drug is not readily metabolized by the dog and is secreted with bile and eliminated unchanged with faeces.     

Metabolism of alkenebenzene derivatives in the rat III. Elemicin and isoelemicin

1. The metabolites of elemicin (3,4,5-trimethoxyallylbenzene) and isoelemicin (3,4,5-trimethoxypropenylbenzene) in the rat were identified by g.l.c.-mass spectrometry.

2. The major metabolic reactions of elemicin follow the cinnamoyl pathway or the epoxide-diol pathway. The former route gives 3-(3,4,5-trimethoxyphenyl)propionic acid and its glycine conjugate as major urinary metabolites, whereas 3-(3,4,5-trimethoxyphenyl)propane-1,2-diol is the most prominent metabolite of the latter route. Small amounts of the epoxide of the 3-O-demethylated derivative of elemicin were identified in the urine.

3. Isoelemicin was metabolized by both aforementioned pathways; the cinnamoyl pathway predominated and 3-(3,4,5-trimethoxyphenyl)propionic acid was the major urinary metabolite.

4. All of the acidic metabolites detected were C₆-C₃ derivatives and further oxidation to benzoic acid derivatives did not occur.

5. Most of the urinary metabolites were also found in the bile, but in different relative amounts.     

Irritant and co-carcinogenic diterpene esters from the latex of Euphorbia cauducifolia L.

Ten (1–10) irritant and mild co-carcinogenic diterpene esters were isolated from the latex of Euphorbia cauducifolia L. using bioassay-guided countercurrent distribution and other chromatographic techniques. The isolated compounds were characterized on the basis of spectroscopic results and mass measurements. As an outcome, the ingenane-type esters were established with the following structures: 3-O-angeloyl-17-O-palmatoylingenol (1), 3-O-palmatoyl-5-O-angeloylingenol (2), 5-O-angeloyl-17-O-palmatoylingenol (3), 3-O-angeloyl-5-O-palmatoylingenol (4), 17-O-(2Z,4E,6Z)-2,4,6-tetradecatrienoyl-20-O-palmatoylingenol (5), 5-O-angeloyl-17-O-benzoylingenol (6), 5-O-angeloyl-17,20-diacetoxyingenol (7), 3-O-angeloyl-17-O-benzoyl-20-acetoxyingenol (8), 3-acetoxy-5-O-angeloyl-17-O-benzoylingenol (9), and 5-O-angeloyl-3,17,20-triacetoxyingenol (10). Their biological screening revealed that they are moderate irritants, and low to moderate tumor promoters compared to TPA, but hardly showed any solitary carcinogenic activity. The isolated esters represent new compounds and were not reported before from any source.     

The metabolism of the dual endothelin receptor antagonist macitentan in rat and dog

Abstract

1.?The metabolism of the endothelin receptor antagonist macitentan has been characterized in bile duct-cannulated rats and dogs.

2.?In both species, macitentan was metabolized along five primary pathways, i.e. conjugation with glucose (M9), oxidative depropylation (M6), aliphatic hydroxylation (M7), oxidative cleavage of the ethylene glycol linker (M4) and hydrolysis of the sulfamide moiety (M3). Most of the primary metabolites underwent subsequent biotransformation including conjugation with glucuronic acid or glucose, hydrolysis of the sulfamide group or secondary oxidation of the ethylene glycol moiety.

3.?Though there were species differences in their relative importance, all metabolic pathways were present in rat and dog. The depropylated M6 was the only metabolite present in plasma of both species.

4.?Metabolism was a prerequisite for macitentan excretion as relevant amounts of parent drug were neither detected in bile nor urine. Biliary excretion was the major elimination pathway, while renal elimination was of little importance.