Lewis R. Mandel

5-Methyltetrahydrofolic Acid as a Mediator in the Formation of Pyridoindoles

Enzymes from chick and rat tissues catalyze the reaction of N-methyl tryptamine with 5-methyltetrahydrofolic acid to form 2,3,4,9-tetrahydro-2-methyl-1H-pyrido[3,4b] indole. N,N-Dimethyltryptamine was not formed. With tryptamine as substrate the product is 2,3,4,9-tetrahydro-1H-pyrido[3,4b] indole and not N-methyltryptamine. These pyridoindoles were not formed when S-adenosylmethionine was cosubstrare.

Blood and urine levels of N,N-dimethyltryptamine following administration of psychoactive dosages to human subjects

Psychoactive doses (0.7 mg/kg) of the hallucinogen N,N-dimethyltryptamine (DMT) were administered intramuscularly to 11 normal subjects. A gas chromatographic-mass spectrometric isotope dilution determination of DMT concentrations in whole blood and urine revealed that only a fraction of the injected dose was recovered and the blood DMT concentrations had a very similar time course o the subjectively reported “high”.

Dimethyltryptamine levels in blood of schizophrenic patients and control subjects

A gas chromatographic-mass spectrometric determination of blood N,N-dimethyltryptamine in normal controls and schizophrenic patients was carried out with a sensitivity limit of 0.05 ng/ml whole blood. Although the results appear to suggest that the mean DMT level was higher in the total patient group, those patients with acute psychosis, female patients and patients with suspiciousness scores on the BPRS of 4 or over, the differences were not statistically significant.

Gas chromatographic-mass spectrometric isotope dilution assay for N,N-dimethyltryptamine in human plasma

Abstract An isotope dilution assay for the determination of N,N-dimethyltryptamine in human plasma has been developed. Dideutero-N,N-dimethyltryptamine is added to the plasma as a carrier, and also serves as an internal standard in a gas chromatographic-mass spectrometric analysis of the final isolate. Mass spectrometric isotope intensity ratios for two ions are used to calculate the amount of endogenous N,N-dimethyltryptamine in the isolate at a sensitivity limit of 0.5 ± 0.2 ng/ml plasma.

Identification of N,N-dimethyltryptamine as the product of an in vitro enzymic methylation

Abstract Thin-layer chromatography, reverse isotope dilution assay, and combined gas-liquid chromatography-mass spectrometry have demonstrated that an enzyme obtained from human lung catalyzes the in vitro methylation of N -methyltryptamine by S -adenosylmethionine to form N,N -dimethyltryptamine. Isolation of the product of the enzymic reaction and its identification were facilitated by use of carbon-14 and deuterium labeling.

Prostaglandin antagonists: Studies on the mode of action of polyphloretin phosphate

Summary Studies with polyphloretin phosphate (PPP), a substance that has been reported to block the action of prostaglandins (PGE1 and PGF2α) in certain in vivo and in vitro situations, reveal it has no effect upon PGE1 stimulated cyclic AMP formation in mouse ovaries or rabbit myometrium. Instead, PPP is shown to act at a site subsequent to cyclic AMP formation, tentatively identified as the cyclic AMP dependent protein kinase step. Thus, PPP is not a true prostaglandin antagonist in these tissues, since it does not block the primary PGE1 event. The data presented, combined with the in vivo antiprostaglandin effect of PPP, support our earlier proposal that cyclic AMP is an obligatory intermediate in the action of prostaglandins.

Improved selective ion monitoring mass-spectrometric assay for the determination of N,N-dimethyltryptamine in human blood utilizing capillary column gas chromatography.

A gas—liquid chromatographic—mass spectrometric procedure is described for the assay of dimethyltryptamine (DMT) in whole blood. The use of a glass capillary column in combination with selective ion monitoring results in an assay with a high degree of specificity and sensitivity. 5-Methoxy-DMT is used as an internal standard and carrier in the isolation procedure. The superior resolving characteristics of the capillary column (as compared to previously employed packed columns) allows monitoring of the intense m/e 58 ion arising from the DMT side-chain. A sensitivity limit of 10 pg/ml blood is realized with a 10-ml blood sample.

The biosynthesis of 5-methoxy-N,N-dimethyltryptamine invitro

Abstract Indoleamine-N-methyltransferase from rabbit and human lung catalyzes the N-methylation of 5-methoxytryptamine to form 5-methoxy-N-methyltryptamine, which in turn, is converted to 5-methoxy-N,N-dimethyltryptamine. S-Adenosylmethionine is the methyl donor for these reactions. There was no evidence for the 0-methylation of bufotenin by either S-adenosylmethionine or 5-methyltetrahydrofolic acid using enzymes from rabbit lung, rat brain and liver, or chick heart.

Studies on the mechanism of action of halofenate

This paper reviews most of the preclinical studies on the mode of action of halofenate, an established hypolipidemic-hypouricemic agent in man. In yeast cultures and in isolated rat adipocytes, halofenate was found to inhibit the conversion of pyruvate to acetyl CoA. While pyruvate dehydrogenase was inhibited in vitro, halofenate also inhibited the activity of various other isolated enzymes. In rats maintained on halofenate in the diet (0.02–0.10%) for 2–14 days, there were 20–40% decreases in plasma cholesterol, trigly cerides, phospholipids, and free fatty acids. Inhibition of liver HMG-CoA reductase does not appear to account for the hypocholesterolemic effect, and activation of mitochondrial α-glycerophosphate dehydrogenase does not explain the hypotriglyceridemic action. Kinetic measurements of the serum appearance and disappearance of triglycerides in drug-treated rats suggest that the hypotriglyceridemic activity is due to a net inhibition of hepatic triglyceride synthesis. Reduction of very low density lipoprotein (VLDL) and high density lipoprotein (HDL) levels in rats with sucrose-induced hyperlipidemia and normalization of the altered apolipoprotein profiles are in accord with the effects of halofenate on plasma triglyceride and cholesterol levels. The reduced insulin-to-glucagon ratio observed in Zucker obese hyperlipemic rats is also consistent with halofenates hypotriglyceridemic activity. Preliminary experiments in rats on the mechanism of its hypoglycemic activity, observed in some diabetic hyperlipidemic patients, indicate that halofenate acts differently than conventional oral hypoglycemic agents. Some, but not all, of the effects of halofenate were observed with clofibrate at two to ten times higher levels.

Inhibition of cyclic 3′,5′-adenosine monophosphate phosphodiesterase by substituted imidazopyrazines

5-Chloro-6-(ethylamino)-1,3-dihydro-2H-imidazo[4,5-b]pyrazin-2-one (CE-IP), a new compound with bronchodilator, cardiac stimulant and peripheral vasodilatory properties was found to be approximately two to five times more potent than theophylline as an inhibitor of cyclic AMP phosphodiesterase from several sources. CEIP stimulated lipolysis in isolated fat cells and was synergistic with norepinephrine in increasing glycerol release and the accumulation of [14C] cyclic AMP from adenine8-14C pre-labeled fat cells. CEIP vivo produced up to a 10-fold increase in the cyclic AMP content of rat heart. While imidazopyrazines with a secondary amine substituent on position 6 were in general relatively potent phosphodiesterase inhibitors, substituents with a more basic character resulted in decreased enzyme inhibitory activity. 5-Chloro-6-[[2-(dimethyl-amino)ethyl] amino]-1,3-dihydro-2H-imidazo[4,5-b]pyrazin-2-one (CDIP) was less active than theophylline as a phosphodiesterase inhibitor but was nearly as active as theophylline in potentiating norepinephrine-stimulated lipolysis and cyclic AMP accumulation in isolated fat cells. CDIP in vivo has peripheral vasodilatory and bronchodilatory activity but is distinct from theophylline and CEIP in that it does not cause tachycardia.