Rapid in vivo metabolism of a methylether derivative of (+/-)-BW373U86: the metabolic fate of [3H]SNC121 in rats.

Activation of opioid delta receptors produces antinociception without some of the side-effects associated with activation of mu and kappa receptors. (+/-)-BW373U86 [(+/-)-4-[(alpha-R*)-alpha-((2S*,5R*)-4-allyl-2, 5-dimethyl-1-piperazinyl)-3-hydroxybenzyl]-N,N-diethylbenzamide] is a first generation, racemic nonpeptide, partially delta-selective opioid agonist that produces short-lived antinocioception. After systemic, but not central, administration, (+/-)-BW373U86 is also a naltrindole-reversible convulsant. SNC80 [(+)-4-[9-alpha-R)-alpha-((2S,5RO-4-allyl-2, 5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide] is a chiral methylether derivative of (+/-)-BW373U86 with decreased potency, but greater selectivity for the delta-opioid receptor. Like BW373U86, SNC80 produces brief, nonlethal seizures when administered peripherally, albeit at higher doses. Radiolabeling of SNC80 yields a compound with similar pharmacology named [3H]SNC121. [3H]SNC121 was investigated to determine the relationship between its time course of metabolism and the physiological actions of SNC80. The biotransformation of i.p. administered [3H]SNC121 was established in rats in vivo and in vitro via high-performance liquid chromatography analysis of extracted radioactive tissues and fluids. Radioactive equivalents were characterized by their high-performance liquid chromatography retention times and opioid binding activity in rat brain membranes. The kidney, and especially the liver (within 5 min), rapidly metabolize SNC121 to a metabolite with delta-opioid activity coeluting with BW373U86. Direct i.c.v. administration of [3H]SNC121 resulted in minimal metabolism after 1 hr. We conclude that i.p., but not i.c.v., administered [3H]SNC121 can be metabolized rapidly and substantially by the liver to a BW373U86-like compound. The in vivo time course of metabolism after i.p. administration of [3H]SNC121 is consistent with the duration of SNC80 antinociception, and the rapid formation of a BW373U86-like metabolite may also account, in part, for its convulsant properties.

Structurally modified ibogaine analogs exhibit differing affinities for NMDA receptors.

Based on both preclinical findings and anecdotal evidence in man, the psychoactive indole alkaloid ibogaine has been suggested to have anti-addictive properties. Previous studies indicate that blockade of NMDA receptors may mediate at least some of the putative anti-addictive actions of ibogaine. The potencies of a series of ibogaine analogs to inhibit (+)-[3-3H]5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10- imine ([3H]MK-801) binding to NMDA receptors were examined. This series of analogs included the putative ibogaine metabolite O-desmethylibogaine, its metabolism resistant analog O-t-butyl-O-desmethylibogaine, the iboga alkaloids (+/-)-ibogamine, (+/-)-coronaridine, tabernanthine, harmaline, and the indolotropanes endo-3-(1-methylindol-2-yl)-8-methyl-8-azabicyclo[3.2.1]loctane (RS 075194-190), exo-3-(1-methylindol-2-yl)-8-methyl-8-azabicyclo[3.2.1]octane (RS 075237-190), and endo-3-(indol-2-yl)-8-methyl-8-azabicyclo[3.2.1]octane (RS 025989-190). Among these compounds, ibogaine was the most potent inhibitor of [3H]MK-801 binding (Ki = approximately 1.2 microM), whilst the compounds with the greatest structural similarity to ibogaine, O-desmethylibogaine and O-t-butyl-O-desmethylibogaine were less potent (Ki = approximately 5.5 and 179.0 microL, respectively). In morphine-dependent mice, ibogaine, but not O-desmethylibogaine or O-t-butyl-O-desmethylibogaine, attenuated naloxone precipitated withdrawal jumping. These findings are consistent with the hypothesis that inhibition of the expression of morphine dependence by ibogaine is related to its NMDA receptor antagonist properties.

Probes for narcotic receptor-mediated phenomena. 21. Novel derivatives of 3-(1,2,3,4,5,11-hexahydro-3-methyl-2,6-methano-6H-azocino[4,5-b]indol- 6-yl)-phenols with improved delta opioid receptor selectivity.

Derivatives of racemic and optically pure levorotatory 3-(1,2,3,4,5,11-hexahydro-3-methyl-2,6-methano-6H-azocino[4,5-b]in dol-6-yl)phenols containing methoxy substituents in the C10', C9', and C8' positions (compounds 9-11, respectively) were synthesized and characterized by spectroscopic and X-ray methods. The binding affinities for the mu, delta and kappa 1 opioid receptors and activity in the guinea pig ileum (GPI) and mouse vas deferens (MVD) functional bioassays were determined for these compounds. A methoxy substituent in the C8' position decreases the binding affinity for both the mu and delta receptors, while a C10' methoxy substituent has little effect on either binding affinity. Interestingly, a methoxy group at the C9' position in the levorotatory series provides compound (-)-10 which exhibits both enhanced in vitro affinity and selectivity for the delta opioid receptor relative to the unsubstituted derivative (-)-8 and is the most selective (mu/delta IC50 ratio 17.9, kappa 1/delta IC50 ratio 314) and highest affinity (IC50 3.7 nM) delta receptor ligand for this novel class of compounds. The results of the GPI and MVD bioassays are more dramatic and indicate that (-)-10 is an agonist for the delta receptor (IC50 49.0 nM) with substantial selectivity for the delta versus the mu receptor borne out by a GPI/MVD IC50 ratio of > 612.

(E)-8-benzylidene derivatives of 2-methyl-5-(3-hydroxyphenyl)morphans: highly selective ligands for the sigma 2 receptor subtype.

The determination of the structure and function of the sigma receptor subtypes and their physiological role(s) has been impeded by the unavailability of selective ligands. We have developed a new class of sigma subtype selective receptor ligands that are (E)-8-benzylidene derivatives of the synthetic opioid (+/-)-, (+)-, and (-)-2-methyl-5-(3-hydroxyphenyl)morphan-7-one (1). The derivatives can be prepared by reaction of 1, (+)-1, and (-)-1 with the appropriate benzaldehyde under Claisen-Schmidt conditions. Incorporation of substituted (E)-8-benzylidene moieties onto the 7-keto precursor of (+)-2-methyl-5-(3-hydroxyphenyl)morphan, (+)-1, produces compounds (-)-2 through (-)-7 (5.8-32.0 nM, sigma 1), which have between a 25- and 131-fold increase in affinity for the sigma 1 receptor subtype relative to the keto precursor (+)-1 (Ki = 762 nM, sigma 1). Compound (-)-2 is the most selective of this group (16-fold) for the sigma 1 subtype versus sigma 2. Substitution of an (E)-8-benzylidene moiety onto the 7-keto precursor of (-)-2-methyl-5-(3-hydroxyphenyl)morphan, (-)-1, produces compounds (+)-2-(+)-9 (6.4-52.6 nM, sigma 2), which have at least a 475-3906-fold increase in affinity for the sigma 2 receptor subtype relative to the keto precursor (-)-1 (Ki = 25 x 10(3) nM). This enhancement of sigma 2 receptor affinity is accompanied by substantial selectivity of all of these dextrorotatory products for the sigma 2 relative to the sigma 1 subtype (32-238-fold), and thus, they are among the most sigma 2 selective compounds currently known. Furthermore, the sigma 1 subtype is highly enantioselective for the levorotatory isomers, (-)-2-(-)-7 (41-1034-fold), whereas the sigma 2 subtype is only somewhat enantioselective for the dextrorotatory isomers, (+)-2-(+)-7 (2.6-9.3-fold). All of these derivatives retain substantial affinity for the mu opioid receptor. Despite the high affinity of the dextrorotatory derivatives for the mu opioid receptor, the high affinity and selectivity for sigma 2 over sigma 1 sites will surely prove beneficial as tools for the delineation of the function and physiological role of sigma 2 receptors.

Ibogaine and its congeners are sigma 2 receptor-selective ligands with moderate affinity.

Ibogaine (12-methoxyibogamine) exhibited moderate affinity for sigma 2 sites (Ki = 201 nM) and low affinity for sigma 1 sites (Ki = 8554 nM), thus showing 43-fold selectivity for sigma 2 receptors. Tabernanthine (13-methoxyibogamine) and (+/-)-ibogamine had sigma 2 Ki = 194 nM and 137 nM, respectively. However, they showed 3- to 5-fold higher sigma 1 affinity compared to ibogaine, resulting in about 14-fold selectivity for sigma 2 sites over sigma 1. A potential ibogaine metabolite, O-des-methyl-ibogaine, had markedly reduced sigma 2 affinity relative to ibogaine (Ki = 5,226 nM) and also lacked significant affinity for sigma 1 sites. (+/-)-Coronaridine ((+/-)-18-carbomethoxyibogamine) and harmaline (1-methyl-7-methoxy-3,4-dihydro-beta-carboline) lacked significant affinity for either sigma subtype. Thus, sigma 2 receptors could play a role in the actions of ibogaine.

CB-64D and CB-184: ligands with high sigma 2 receptor affinity and subtype selectivity.

Four members of a novel class of sigma (sigma) ligands were investigated for sigma subtype selectivity. (-)-1S,5S- and (+)-1R,5R-(E)-8-Benzylidene-5-(3-hydroxyphenyl)-2-methylmorphan-7- one (CB-64L and CB-64D, respectively) exhibited sigma 1 Ki = 10.5 nM and 3063 nM; sigma 2 Ki = 154 nM and 16.5 nM, respectively. The corresponding 3,4-dichloro derivatives, (-)-1S,5S- and (+)-1R,5R-(E)-8-(3,4-dichlorobenzylidene)-5-(3-hydroxyphenyl)-2-++ +methylmorphan-7 - one (CB-182 and CB-184, respectively) were also examined. CB-182 ((-)-isomer) showed sigma 1 and sigma 2 Ki = 27.3 nM and 35.5 nM, respectively, whereas CB-184 ((+)-isomer) exhibited sigma 1 and sigma 2 Ki = 7436 nM and 13.4 nM, respectively. Thus, the two sigma subtypes showed opposite enantioselectivity for these compounds, with (-) > (+) at sigma 1 and (+) > (-) at sigma 2. Importantly, CB-64D and CB-184 showed high sigma 2 affinity and, respectively, 185-fold and 554-fold selectivity for sigma 2 receptors over sigma 1. While high sigma 2 selectivity relative to sigma 1 was achieved with these compounds, they both exhibited high affinity at mu (mu) opioid receptors (Ki = 37.6 nM and 4.5 nM, respectively). Despite this, CB-64D and CB-184 will be useful tools for further characterization of sigma 2 receptors.

Probes for narcotic receptor-mediated phenomena. 20. Alteration of opioid receptor subtype selectivity of the 5-(3-hydroxyphenyl)morphans by application of the message-address concept: preparation of delta-opioid receptor ligands.

Derivatives of racemic and optically active 5-(3-hydroxyphenyl)-2-methylmorphan (5-(3-hydroxyphenyl)-2-methyl-2-azabicyclo[3.3.1]nonane, 1) were synthesized containing additional aromatic moieties, as an application of the message-address concept targeted at producing delta-opioid receptor selective ligands. In vitro radioreceptor binding studies in rat brain revealed that both of the parent enantiomers, (-)- and (+)-1, had a high affinity for the mu-opioid receptor (21 nM), a slight affinity for kappa 1-opioid receptors (approximately 800-900 nM), and less than 1000 nM affinity for the delta-opioid receptor (mu/delta IC50 ratio of < 0.02 for both). A derivative of (-)-1 containing an indole moiety fused at the C6-C7 position of the phenylmorphan nucleus, (-)-11, displayed a > 180-fold increase in affinity for the delta-opioid receptor with an IC50 value of 6 nM. The parent compound (-)-1 had only 26% agonist activity at 30 microM in the mouse vas deferens (delta) bioassay, whereas compound (-)-11 had an IC50 of 393 nM in this preparation, indicating the importance of the indole moiety in imparting delta-opioid agonist activity to the phenylmorphan (-)-11. A structure-activity relationship (SAR) study of N-alkyl derivatives of the racemic nor 11 indicated similarities between the interaction of various derivatives with the mu- and delta- but not the kappa 1-opioid receptor. As studies on the molecular basis of the interaction of opioid ligands with their respective receptors continue to gain momentum, the SAR data described herein for the synthetic phenylmorphans will prove useful for further studies.

Reagents for bioorganic synthesis. 6. The design and synthesis of two novel polyfunctional organic reagents for biomacromolecular modification.

The design, synthesis, structure, and properties of two tetrafunctional organic reagents, namely, 2,2'-sulfonylbis[3-(carboxymethylamino)-(E,E)-N-(2-chloroeth yl)propenamide] (SBCCP) (1) and 2,2'-sulfonylbis[3-(carboxymethylamino)-(E,E)-N-(2-oxoeth yl)propenamide] (SBCOP) (2) are reported. Reagents 1 and 2 contain reactive bis(alkyl halide) and bis(aldehyde) functions, respectively, as well as bis(carboxylic acid) moieties. The reagents have potential applications for biomacromolecular cross-linking, in particular for the cross-linking of hemoglobin subunits. Single-crystal X-ray diffraction data of synthetic intermediates (4,5, and 12) provided information about structural features and tether lengths of the target reagents.

A marked change of receptor affinity of the 2-methyl-5-(3-hydroxyphenyl)morphans upon attachment of an (E)-8-benzylidene moiety: synthesis and evaluation of a new class of sigma receptor ligands.

The (E)-8-benzylidene and (E)-8-(3,4-dichlorobenzylidene), 7-ketone derivatives, 5 and 6, of the synthetic opiate 2-methyl-5-(3-hydroxyphenyl)morphan [5-(3-hydroxyphenyl)-2-methyl-2-azabicyclo[3.3.1]nonane, 1], were synthesized from the 7-ketone derivatives 2 or 4 via the Claisen-Schmidt reaction. The corresponding enantiomers of 5 and 6 were obtained in > 99% optical purity from the optical isomers of 4, resolved with the O,O'-dibenzoyltartaric acids. The absolute configurations of the enantiomers of 4 were determined by conversion, via Clemmensen reduction, to the enantiomers of 1, the configurations of which are known. The determination of the regioisomer and configurational isomer of 5, with respect to the introduced benzylidene group, was determined from a single-crystal X-ray analysis. 1H NMR data was used to confirm that 6 possessed the same configuration as 5. Radioreceptor binding studies in rat and guinea pig brain preparations revealed that (-)-(1S,5S)-5 displayed an 11-fold decrease in affinity for the opioid mu receptor and an increase in affinity for sigma receptors of 81-fold (low nanomolar affinity) relative to the ketone precursor (+)-(1S,5S)-4. An analogous, albeit less dramatic, trend was seen with compound (-)-(1S,5S)-6. Compounds (-)-(1S,5S)-5 and (-)-(1S,5S)-6 are distinct from the typical sigma-opiates in that they have very low affinity for either PCP sites or muscarinic receptors. The high affinity and selectivity of these novel sigma receptor ligands suggests that they will be valuable for the elucidation of the functional roles of sigma receptors.

A versatile, highly reactive, cross-linking reagent: 2,2'-sulfonylbis[3-methoxy-(E,E)-2-propenenitrile].

Adequate aqueous stability and cross-linking ability of the novel title reagent, recently discovered in this laboratory, have been demonstrated by comparison of its rate of hydrolysis with the rate of reaction with an amine nucleophile and by cross-linking deoxy- and oxyhemoglobins, as an example.

Structure of a potential cross-linking reagent: 2,2'-bis(methoxymethylene)-2,2'-sulfonyldiacetonitrile (MMSBA).

The title compound (I) was prepared as a potential cross-linking reagent for nucleic acids and/or proteins. The compound is a stable, but reactive, crystalline solid which can be stored indefinitely upon adequate protection. The reagent reacts with amine nucleophiles - primary, secondary as well as heterocyclic - to afford bis-enamines. C8H8N2O4S, Mr = 228.23, monoclinic, C2/c, a = 18.031 (5), b = 9.372 (3), c = 13.455 (6) A, beta = 108.08 (5) degrees, V = 2161 (1) A3, Z = 8, Dx = 1.40 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 2.81 cm1, F(000) = 944, T = 295 K. Final R = 0.041 for 1033 observed reflections. The bond distances in (I) are: S-O, 1.424 (3); S-C, 1.737 (4); C-CN, 1.417 (5); C=C, 1.342 (5); = C(H)-O, 1.295 (4); and C identical to N, 1.138 (5) A. The diagonal distance, alpha-alpha', between the two trans C atoms is 4.976 A.