Sumner H. Burstein

Metabolism of cardiac glycosides—I: Metabolism of digitoxin-7αT by normal rabbits and rabbits with heart failure☆

Abstract A method of obtaining specifically labeled digitoxin-7αT from Digitalis purpurea plants previously fed pregnenolone-7αT is described. The metabolism of digitoxin-7αT by normal rabbits and by rabbits with surgically induced heart failure was investigated. Digitoxin-7αT was injected into both groups of rabbits, and the urinary excretion of radioactivity was evaluated. By means of countercurrent distribution and thin-layer chromatography, a difference in metabolism of digitoxin-7αT between the two groups was observed. The data show that rabbits with heart failure required much longer periods of time to excrete an equal amount of radioactivity as compared with the normal rabbits. Further, although the radiochromatographic patterns of the two groups were qualitatively identical, the profiles showed that in the group with heart failure the conversion of digitoxin-7αT to its relatively more polar metabolites was substantially hindered.

Isolation and Characterization of Two Major Urinary Metabolites of Δ1-Tetrahydrocannabinol

Two of the major metabolites which appear in rabbit urine after the administration of Δ1-tetrahydrocannabinol have been isolated and their structures have been tentatively established. The available evidence indicates that they are 7-carboxy-Δ1-tetrahydrocannabinols with an additional hydroxyl group on the side chain. The substances occur both free and as conjugates.

Prostaglandins and cannabis—II inhibition of biosynthesis by the naturally occurring cannabinoids☆

Abstract A series of the naturally occurring cannabinoids were tested for possible effects on the biosynthesis of prostaglandins. Most of the substances examined were able to inhibit in varying degrees the conversion of 8,11,14-eicosatrienoic acid to prostaglandin E 1 (PGE 1 ) when incubated with bovine seminal vesicle microsomes. The order of activity starting with the most potent was cannabinol, cannabidiolic acid, A6tetrahydrocannabinol (Δ 6 -THC), cannabidiol, cannabichromene and Δ 1 -THC; cannabicyclol showed almost no inhibitory activity. It is suggested that certain of the pharmacological actions of some of these cannabinoids may be explained by a similar effect in vivo . Olivetol, which represents a partial structure for all of the compounds tested, showed high activity, indicating that the inhibitory power of the cannabinoids resides in the aromatic portion of the molecule.

Prostaglandins and cannabis—VI: Release of arachidonic acid from HeLa cells by δ1-tetrahydrocannabinol and other cannabinoids

Abstract Treatment of HeLa cells in suspension culture with [14C]arachidonic acid led to a rapid incorporation of this fatty acid into cellular phospholipid pools. Exposure of these labeled cells to Δ1-tetrahydrocannabinol and other cannabis constituents led to a dose-related release of arachidonic acid into the culture medium. Cannabinol and cannabichromene were also effective, whereas other cannabinoids were less potent and noncannabinoid constituents such as eugenol were without activity. This action of the cannabinoids could have direct effects on cell membrane structure and, in addition, could alter the biosynthesis of prostaglandins and related metabolites of arachidonic acid.

Metabolism of dimethyl sulfide, dimethyl sulfoxide, and dimethyl sulfone in the rabbit

Abstract The subcutaneous injection of either dimethyl sulfide or dimethyl sulfoxide leads to the excretion of dimethyl sulfoxide and dimethyl sulfone in the urine of rabbits and to the expiration of a malodorous material (presumably dimethyl sulfide). Dimethyl sulfone, however, is not reduced to either the sulfoxide or the sulfide but is excreted unchanged. Dimethyl sulfone is also found in the urine of untreated rabbits.

The removal of testosterone binding globulin from plasma by affinity chromatography

Abstract The use of steroid immobilized on an insoluble polysaccharide for the separation of a specific binding protein from human plasma is described. An androstane derivative covalently bound to agarose was effective in removing testosterone binding globulin from plasma. The protein could subsequently be separated from the reagent in low yield by means of guanidine.

A radioimmunoassay for the initial metabolites of the F prostaglandins

Abstract Antibodies to the F metabolite 9α, 11α-dihydro-15-keto-prostanoic acid (I), produced in the rabbit, do not cross react with any of the primary PGs. There is a 50% cross reaction with the metabolite 9α, 11α-dihydroxy-15-keto-prost-5-enoic acid (III), and a 23% cross reaction with 9α,11α,15-trihydroxy prostanoic acid (F0α). No cross reactivity resulted with this antiserum when tested against 9α,11α,15-trihydroxy-5-enoic acid (VII) or with 9α,11α-dihydroxy-15-ketoprost-5,13-dienoic acid (VIII). Utilizing this antibody in a radioimmunoassay, some preliminary data are presented on levels of these F metabolites (I and III) for human adult male samples of plasma, urine and seminal plasma.

Prostaglandin biosynthesis and stimulation of cyclic AMP in primary monolayer cultures of epithelial cells from mouse mammary gland

Cyclic AMP levels in primary monolayer cultures of epithelial cells prepared from mid-pregnant mice are stimulated by prostaglandin E1 and E2. Prostaglandin F1alpha and F2alpha have only a slight effect upon cyclic AMP levels. In the absence of phosphodiesterase inhibitors the rise in cyclic AMP produced by PGE1 is only transient and the levels return to normal within 30 minutes. High concentrations (16 mM) of theophylline are needed to prevent this decline, suggesting that the phosphodiesterase activity of epithelial cells in culture is high. However, theophylline alone produced only a small increase in basal cyclic AMP levels even over a 2-hour period indicating that basal cyclic AMP is turned over more slowly than cyclic AMP produced in response to stimulation with PGE1. Both PGE and PGF synthesis were monitored using radioimmunoassay procedures previously reported. The observed levels were found to decrease as cell density increased and were sensitive to the addition of agents such as collagen and naproxen.

Elevation of prostaglandin and cyclic AMP levels by arachidonic acid in primary epithelial cell cultures of C3H mouse mammary tumors.

Arachidonic acid causes a sharp transient increase in cyclic AMP levels in primary epithelial cell cultures obtained from C3H mouse mammary tumors. The effect is evident within two minutes and is enhanced by theophylline or 3-isobutyl-1-methylxanthine. Maximum increase in cyclic AMP levels are observed with a dose of 100 mug/ml of arachidonic acid (AA). At higher dose levels the increase in cyclic AMP levels is reduced. Naproxen, an inhibitor of prostaglandin synthesis in this system markedly reduces the stimulation of cyclic AMP by arachidonic acid but it does not affect the increase in cyclic AMP levels observed after the addition of prostaglandin Es, epinephrine or cholera enterotoxin. Arachidonic acid, under the same conditions, also causes a significant elevation of PGE and PGF media levels which is slower and more sustained than the cAMP response. The data strongly suggest that a metabolic of arachidonic acid is responsible for the cyclic rise, however, it is not certain whether this is due to PGE2 or some other product.

Reactions of 20-hydroxylated steroids with bovine adrenal tissue preparations

Abstract The reactivities of 20-methylpregn-5-ene-3β, 20-diol (I) and 22-dideuterocholest-5-ene-3β, 20-diol (II) were studied and compared with cholest-5-ene-3β, 20-diol (III) in a system prepared from bovine adrenal mitochondria. II and III both underwent the expected cleavage reaction between carbons 20 and 22 to give pregnenolone and subsequent products. The rates were very similar to each other indicating that if hydroxylation occurs at C-22, it is not a rate determining step in this system. Compound I did not undergo side-chain cleavage, but was rapidly converted to the corresponding 4-ene-3-one (V). No further reaction was observed during a 32-minute reaction period. V appeared to inhibit 21-hydroxylation of progesterone, however, no effect was observed on 11β-hydroxylation of 11-desoxycorticosterone. I was tested for inhibition of side-chain cleavage of III and for inhibition of the conversion of pregnenolone to progesterone. No effect was observed under our experimental conditions.