NADPH-dependent metabolism of estrone by human liver microsomes.

We characterized the NADPH-dependent metabolism of estrone (E1) by liver microsomes of 21 male and 12 female human subjects. The structures of 11 hydroxylated or keto metabolites of E1 formed by human liver microsomes were identified by chromatographic and mass spectrometric analyses. 2-Hydroxylation of E1 was the dominant metabolic pathway with all human liver microsomes tested.

Characterization of the NADPH-dependent metabolism of 17beta-estradiol to multiple metabolites by human liver microsomes and selectively expressed human cytochrome P450 3A4 and 3A5.

We characterized the NADPH-dependent metabolism of 17beta-estradiol (E2) by liver microsomes from 21 male and 12 female human subjects. A large number of radioactive estrogen metabolite peaks were detected following incubations of [3H]E2 with male or female human liver microsomes in the presence of NADPH. The structures of 18 hydroxylated or keto estrogen metabolites formed by these microsomes were identified by gas chromatography/mass spectrometry analysis.

Strong inhibition of estrone-3-sulfatase activity by pregnenolone 16alpha-carbonitrile but not by several analogs lacking a 16alpha-nitrile group.

In recent years, development of potent inhibitors for estrogen sulfatases has become an actively pursued strategy for chemoprevention and/or chemotherapy of estrogen-dependent human breast cancers. We report here our findings that pregnenolone 16alpha-carbonitrile (PCN) is a potent inhibitor of estrone-3-sulfatase activity of rats and also humans. PCN inhibited in a concentration-dependent manner the desulfation of estrone-3-sulfate catalyzed by liver microsomal and nuclear fractions of female Sprague-Dawley rats.

Selected pharmacodynamic and biochemical properties of selenonium choline.

1. Five minutes after intravenous administration of 50 mg/kg of the novel choline analogue selenonium choline [(CH3)2Se + CH2CH2OH, SeCh], only 8% of the administered dose was accounted for in blood, brain, liver, heart, and kidney tissues. 2.

Modification of the duration of action and pharmacodynamics of arecoline by tetraisopropylpyrophosphoramide.

Tetraisopropylpyrophosphoramide (ISO-OMPA) pretreatment in the mouse was examined for its ability to prolong the time course of arecoline (ARE) concentration using brain ARE concentration as an index. Brain ARE levels were also correlated with acetylcholine (ACh) and choline concentrations. Pretreatment with 40 mg kg-1 ISO-OMPA increased ARE brain concentrations from 3 nmoles g-1 to 76 nmoles g-1 15 min after i.

Synthesis of novel tellurium containing analogues of choline and acetylcholine and their quantitation by pyrolysis-gas chromatography-mass spectrometry.

Methods for the synthesis and quantitation of the novel choline analogues, telluronium choline and acetyltelluronium choline, are described. An assay procedure utilizing pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) with cold trapping was developed with [2H4]telluronium choline and [2H4]acetyltelluronium choline as internal standards. The telluronium compounds were ion-pair extracted from tissue with dipicrylamine, washed with 2-butanone, and pyrolyzed prior to GC-MS analysis.

Further biological activities of the novel choline analogs selenonium choline and acetylselenonium choline.

The pharmacological actions of the novel choline analog, selenonium choline [(CH3)2Se+CH2CH2OH] and its acetyl ester acetylselenonium choline (ASeCh) were studied in vivo and in vitro. ASeCh produced a dose-related decrease in mean arterial pressure in the rat similar to acetylcholine (ACh) but was 1% to 2% as potent. ASeCh demonstrated agonist activity on the rat isolated ileum and was approximately 2% as active as ACh.

Elucidation of the rapid in vivo metabolism of arecoline.

1. The metabolism of arecoline (ARE) was examined in homogenates of mouse blood, brain, kidney, and liver tissue. 2.

Synthesis and cholinergic properties of N-aryl-2-[[[5-[(dimethylamino)methyl]-2-furanyl]methyl]thio]ethylamino analogs of ranitidine.

A series of N-aryl-2-[[[5-[(dimethylamino)methyl]-2- furanyl]methyl]thio]ethylamino analogs of the H2-antagonist, ranitidine, was synthesized and the abilities of the compounds to alleviate the cholinergic deficit characteristic of Alzheimer's disease evaluated. The compounds were initially tested for their ability to inhibit human erythrocyte acetylcholinesterase activity in vitro. Selected compounds were further evaluated for butyrylcholinesterase inhibition, M1 and M2 cholinergic receptor binding, potentiation of ileal contractions, and the ability to elevate brain acetylcholine levels in mice.

Selected biological activities of novel selenonium choline analogs.

1. The novel choline analogs selenonium choline (SeCh) and acetylselenonium choline (ASeCh) have been examined for selected biological activities. 2.

Simultaneous quantitation of arecoline, acetylcholine, and choline in tissue using gas chromatography/electron impact mass spectrometry.

A capillary gas chromatography/mass spectrometry (GC/MS) assay for the simultaneous quantitation of arecoline (ARE), acetylcholine (ACh), and choline (Ch) in biological tissue has been developed. The method utilizes hexadeuterated ARE and nonadeuterated ACh and Ch as internal standards. The compounds were ion-pair extracted from tissue using sodium tetraphenylboron in 3-heptanone.

Synthesis and cholinergic properties of bis[[(dimethylamino)methyl]furanyl] analogues of ranitidine.

The histaminergic H2 antagonist, ranitidine, has also been found to significantly inhibit acetylcholinesterase (AChE) in vitro. In an effort to develop novel, nonquaternary AChE inhibitors capable of penetrating into the CNS and alleviating the cholinergic deficit characteristic of Alzheimer's disease, a series of bis[[(dimethylamino)methyl]furanyl] analogues of ranitidine has been synthesized. All compounds were evaluated for human erythrocyte AChE inhibitory activity and compared to ranitidine, physostigmine, and tetrahydro-9-aminoacridine (THA).

Muscarinic and nicotinic activities of the novel acetylcholine analog acetylselenonium choline.

The present paper further characterizes the cholinergic properties of acetylselenonium choline (ASeCh, (CH3)2Se+CH2CH2OCOCH3). The data demonstrate that ASeCh possesses muscarinic receptor agonist properties as evidenced by vasodepressor and smooth muscle contractile activities which are enhanced by physostigmine and antagonized by atropine. ASeCh also possessed nicotinic agonist activity on frog rectus abdominis tissue which was potentiated by physostigmine, and blocked by d-tubocurarine.

A comparison of the cholinergic activity of selected H2-antagonists and sulfoxide metabolites.

Famotidine and selected H2-antagonists were evaluated with respect to toxicity and selected pharmacological activities. When administered intraperitoneally to mice at a dose equivalent to 10 times their respective H2-antagonist ED50 values, no deaths were observed. Similarly, no alteration in brain ACh concentrations or overt pharmacological effects were noted.

Prevention of physostigmine-, DFP-, and diazinon-induced acute toxicity by monoethylcholine and N-aminodeanol.

1. Choline, and the choline analogues monoethylcholine (MEC) and N-aminodeanol (NAD) were examined for prophylactic activity in acute acetylcholinesterase inhibitor toxicity in mice. The rank order of potency of the compounds was MEC greater than NAD greater than choline.

Antagonism of acute physostigmine and neostigmine toxicity in mice by hemicholinium-3.

Hemicholinium-3 (HC-3) was administered intraperitoneally to mice concurrently with the intraperitoneal administration of physostigmine or neostigmine. HC-3 increased the LD50 values for both physostigmine and neostigmine but did not alter the effect on brain ACh levels produced by these agents. Since HC-3 does not cross the blood brain barrier after intraperitoneal administration, the antidoting action of HC-3 is peripherally mediated and does not solely involve an inhibition of ACh synthesis.

The effect of hemicholinium-3 and physostigmine on choline in rat brain.

Physostigmine and hemicholinium-3 were examined for their effects on rat brain choline levels after microwave irradiation and after postmortem incubation. Hemicholinium-3 and physostigmine increased choline levels in the cerebellum and striatum when measured after microwave irradiation, but decreased the level of choline produced after postmortem incubation of the brain areas. Addition of the drugs in vitro to whole brain homogenates also decreased postmortem choline production.

Is propionylcholine present in or synthesized by electric organ?

When small blocks comprising four columns of electrocytes were excised from electric organs of Torpedo marmorata after stimulation in vivo via the electric lobe at 1 Hz for 1 h and allowed to recover at 20-22 degrees C for several hours in medium containing 100 microM d4 choline and 500 microM propionate, small quantities of propionylcholine amounting to no more than 1% of the endogenous acetylcholine of the tissue could be detected in tissue extracts by gas chromatography-mass spectrometry (GCMS). Kinetic studies demonstrated that there was no nonexchangeable propionylcholine in the tissue and in the absence of added propionate, propionylcholine levels were less than 0.2% of tissue acetylcholine.

In vivo acetylation of homocholine and beta-methylcholine in rat brain.

A nitrogen phosphorus-gas chromatographic procedure was modified to determine the extent of in vivo acetylation of the choline analogs homocholine and beta-methylcholine. Infusion of homocholine (18 mumoles) for 2 hours into the lateral ventricle of the rat produced 2.3 nmoles/gram of acetylhomocholine which represented 0.

Separation of recycling and reserve synaptic vesicles from cholinergic nerve terminals of the myenteric plexus of guinea pig ileum.

Acetylcholine-rich synaptic vesicles were isolated from myenteric plexus-longitudinal muscle strips derived from the guinea pig ileum by the method of Dowe, Kilbinger, and Whittaker [J. Neurochem. 35, 993-1003 (1980)] using either unstimulated preparations or preparations field-stimulated at 1 Hz for 10 min using pulses of 1 ms duration and 10 V .

Benzyl carbamyl analogue of lignocaine: vasodepressor mechanism of action.

1. The benzyl carbamyl analogue of lignocaine [2-(diethylaminoacetamido)-3-carbamyl-4-methyl-5-benzylpyrrole] at an intravenous dose of 4 mg/kg caused a blood pressure decrease of 54 mmHg. 2.

Peripheral toxicity of hemicholinium-3 in mice.

1 The site (i.e. peripheral or central) of the toxicity produced by hemicholinium-3 in mice was investigated.

Synthesis and vasodepressor screen of a series of 2-(2-alkylaminoalkylamido)-3-carbamyl-4-methyl-5-benzylpyrroles.

A series of 2-(2-alkylaminoalkylamido)-3-carbamyl-4-methyl-5-benzylpyrroles was synthesized and screened for vasoactivity. The compounds were administered intraperitoneally as a suspension to approximate the oral route of administration and intravenously when solubilization could be affected with suitable solvents. The most active compound following intravenous or intraperitoneal administration lowered blood pressure 73 and 35.