Phencyclidine metabolism: resolution, structure, and biological activity of the isomers of the hydroxy metabolite, 4-phenyl-4-(1-piperidinyl)cyclohexanol

One of the major biotransformation pathways in the metabolism of phencyclidine is hydroxylation at C-4 of the cyclohexane ring to give 4-phenyl-4-(1-piperidinyl)cyclohexanol (1). Since the latter compound can exist as cis and trans isomers and the synthetic mixture has been reported to be biologically active, it was of interest to separate the isomers, test them for biological activity, and determine their ratio as metabolic products of phencyclidine. The synthetic mixture of 1 was separated by TLC and the individual isomers were characterized by 13C and 1H NMR and MS analyses. Preliminary testing of the isomers in the mouse rotarod assay indicates that the trans isomer (1b) is only slightly more active then the cis isomer (1a). Both isomers produced seizure activity and lethality at doses required to produce maximal ataxia.

Positive identification and quantitation of isomeric cocaines by high-performance liquid chromatography

A high-performance liquid chromatographic procedure for separating and identifying the four isomeric cocaines has been developed. Use of this procedure with an internal standard allows for the determination of the quantity of any isomeric cocaine in an unknown sample. The pitfalls and problems encountered in the use of gas chromatography and mass spectrometry in the analysis of cocaines and ecgonine methyl esters are discussed.

Synthesis of 2,4-disubstituted 6-methoxy-8-aminoquinoline analogues as potential antiparasitics

A series of 2,4-disubstituted 8-aminoquinoline analogues were synthesized and evaluated against Plasmodium berghei in mice and Leishmania donovani in hamsters. 8-[[6-(Diethylamino)hexyl]amino]-2-ethyl-6-methoxy-4-methylquinoline (8a) possessed significant activity against L. donovani. 2-Ethyl-4-methylprimaquine (7a) was evaluated against Plasmodium cynomolgi in rhesus monkey and found to have activity equal to that of primaquine.

Synthesis of 4-alkyl and 4-(beta-alkylvinyl) derivatives of primaquine as potential antimalarials

4(beta-Alkylvinyl)-6-methoxy-8-nitroquinolines (6) were prepared from 6-methoxy-8-nitroquinoline-4-carboxaldehyde (5) via a Wittig reaction. Stannous chloride reduction of 6 gave 4-(beta-alkylvinyl)-8-amino-6-methoxyquinolines (8), whereas catalytic reduction of 6 using Raney nickel catalyst gave 4-alkyl-8-amino-6-methoxyquinolines (7). Alkylation of 7 and 8 with 4-iodo-1-phthalimidopentane, followed by removal of the phthaloyl-protecting group with hydrazine, gave 4-alkyl and 4-(beta-alkylvinyl) derivatives of primiquine, respectively. These compounds were evaluated for antimalarial activity against P. berghei and P. berghei yoelii in mice and against P. cynomolgi in rhesus monkeys. Several of the compounds were active in the P. bergheii yoelii screen. None of the compounds showed significant activity in the other two screens.

Synthesis of some 4-substituted 8-amino-6-methoxyquinolines as potential antimalarials

The 4-vinyl, 4-ethyl, and three 4-[beta-(arylthio)ethyl] derivatives of primaquine and other 8-aminoquinoline antimalarial agents were prepared for antimalarial evaluation. 8-[(4'-Amino-1'-methylbutyl)amino]-4-ethyl-6-methoxyquinoline (4-ethylprimaquine), which showed activity approximately equal to that of primaquine against Plasmodia cynomolgi in Rhesus monkey, was the most active of the compounds tested. 4-Ethylprimaquine was also less toxic than primaquine, as measured in the Rane mouse screen.

Carbon-13 nuclear magnetic resonance identification of 2-hydroxy-3-O-methyl-6beta-naltrexol as a minor naltrexone metabolite

A carbon-13 nuclear magnetic resonance comparison of synthetic and biological samples was used to identify unequivocally 2-hydroxy-3-O-methyl-6beta-naltrexol as a minor naltrexone metabolite in humans. This study points up the increasing usefulness of natural abundance carbon-13 nuclear magnetic resonance techniques in metabolism studies.

Resolution of antimalarial agents via complex formation with alpha-(2,4,5,7-tetranitro-9-fluorenylideneaminooxy) propionic acid

The resolution of several antimalarial agents via pi-complex formation with alpha-(2,4,5,7-tetranitro-9-fluorenylideneaminooxy) propionic acid (TAPA) is reported. Since this represents the first use of this agent for the resolution of amines, some details of the separations are presented. The method proved successful for resolving weakly alkaline amines that did not form stable salts with common resolving acids, highly insoluble amines that did not form soluble salts with usual resolving acids, and amines that did not form crystalline salts with commonly available resolving acids. The optical isomers of several antimalarial agents were evaluated against Plasmodium berghei in the mouse. None of the optically active forms showed any significant differences. The curative activity of (+)- and (-)-primaquine against Plasmodium cynomolgi in the rhesus monkey was essentially identical; however, significant differences in toxicity were noted.

Synthesis and biological evaluation of 10-oxa-11-deoxyprostaglandin E1 and 10-nor-9,11-secoprostaglandin F1 and their derivatives

Three 10-oxa-11-deoxyprostaglandin E1 and two 10-nor-9,11-secoprostaglandin F1 analogues were prepared. The compounds were evaluated for pregnancy interruptions, oxytocin-like activity (uterine strip), and antiprostaglandin activity. One of the 10-nor-9,11-secoprostaglandin F1 analogues displayed activity as a PGE2 antagonist in the gerbil colon smooth muscle preparation.

Reduced 8-aminoquinoline analogues as potential antimalarial agents

The synthesis of 1-alkyl-8-(aminoalkylamino)-6-methyl1-1,2,3,4-tetrahydroquinolines, 8-(4'-amino-1'-methylbutylamino)-6-methoxy-1-methyl1-1,2-dihydroquinoline, 5-substituted 8-(4'-amino-1'-methylbutylamino)-1-methyl-1,2-dihydroquinolines, 8-alkylamino-1-(2-N,N-diethylaminoethyl)-6-methoxy-1,2,3,4-tetrahydroquinolines, 1-)2-N,N-diethylaminoethyl)-6-methoxy-1,2,3,4-tetrahydroquinoline, 1-(2-N,N-diethylaminoethyl)-8-(2-N,N-diethylaminoethylamino)-6-methoxy-1,2,3,4-tetrahydroquinoline, and 2-substituted 8-methoxy-5,6,-dihydro-4-imidazo [i,j]quinolines is described. These compounds as well as most of the intermediates used in their preparation were tested against Plasmodium berghei in mice, and a few compounds were tested for prophylactic activity against Plasmodium cynomolgi in rhesus monkeys.

Circular dichroism and carbon-13 nuclear magnetic resonance spectra of (S)-5-alkyl-5-(2'-pentyl)-2-thiobarbituric acids

The circular dichroism (CD) and carbon-13 nuclear magnetic resonance (13C NMR) spectra of (S)-5-(2'-pentyl)-2-thiobarbituric acid and several (S)-5-alkyl-5-(2'-pentyl)-2-thiobarbituric acids were obtained. The results were compared to CD and 13C NMR spectral data obtained from (S)-5-(2'-pentyl)bartituric acid and (S)-5-alkyl-5-(2'-pentyl)barbituric acids.

Etonitazene. An improved synthesis

1-(BETA-Kiethylaminoethyl)-2-(p-ethoxybenzyl)-5-nitrobenzimidazole (u, etonitazene) is a potent analgesic that has value in drug addiction studies. We have developed a simple high-yield synthesis of 1 that is adaptable to alrge scale preparations. The synthesis involves the condensation of 2-(beta-diethylaminoethylamino)-5-mitroaniline and p-ethoxyphenylacetic acid in Thf in the presence of EEDQ.

Synthesis and absolute stereochemistry of 5-alkyl-5-(3'-hydroxy-1'-methylbutyl)barbituric acid and 5-alkyl-5-(3'-hydroxy-1'-methylbutyl)-2-thiobarbituric acids

5-Alkyl-5-(3-hydroxy-1-methylbutyl) barbituric acid (2) and 5-alkyl-5-(3-hydroxy-1-methylbutyl)-2-thiobarbituric acids (3) are matabolites of 5-alkyl-5-(2-pentyl) barbituric acid and 5-alkyl-5-(2-pantyl)-2-thiobarbituric acid, respectively. We have synthesized the four possible optical isomers of 2 and 3 by a procedure which established the absolute stereochemistry of each isomer. The two racemic pairs in each case were also prepared. The properties of these synthetic samples of 2 and 3 of known stereochemistry are compared to the properties of 2 and 3 which have been isolated from metabolism studies.