David R. Compton

Identification of an endogenous 2-monoglyceride, present in canine gut, that binds to cannabinoid receptors.

In this study, we report the isolation from canine intestines of 2-arachidonyl glycerol (2-Ara-Gl). Its structure was determined by mass spectrometry and by direct comparison with a synthetic sample. 2-Ara-Gl bound to membranes from cells transiently transfected with expression plasmids carrying DNA of either CB1 or CB2--the two cannabinoid receptors identified thus far--with Ki values of 472 +/- 55 and 1400 +/- 172 nM, respectively. In the presence of forskolin, 2-Ara-Gl inhibited adenylate cyclase in isolated mouse spleen cells, at the potency level of delta 9-tetrahydrocannabinol (delta 9-THC). Upon intravenous administration to mice, 2-Ara-Gl caused the typical tetrad of effects produced by THC: antinociception, immobility, reduction of spontaneous activity, and lowering of the rectal temperature. 2-Ara-Gl also shares the ability of delta 9-THC to inhibit electrically evoked contractions of mouse isolated vasa deferentia; however, it was less potent than delta 9-THC.

Design, Synthesis and Pharmacology of Cannabimimetic Indoles

Molecular modeling has been employed to design a new group of cannabimimetic 1-alkyl-2-methyl-3-(1-naphthoyl)indoles. Cannabinoid activity was evaluated in vivo in the mouse and in vitro by determining the binding to the cannabinoid receptor. Maximum activity was found for the 1-butyl, pentyl and hexyl analogs. A rationalization for the alignment of these indoles with traditional cannabinoids is presented.

Stereochemical effects of 11-OH-Δ8-THC-dimethylheptyl in mice and dogs ☆

Abstract The effects of the enantiomers of 11-hydroxy- Δ 8 -tetrahydrocannabinol-dimethylheptyl (11-OH- Δ 8 -THC-DMH) on spontaneous activity, rectal temperature, tail-flick latency, and catalepsy were studied in mice and in the dog static-ataxia model to determine the relative potency of each enantiomer. The (−)-enantiomer was active in all tests between 3–100 μg/kg, while the (+)-enantiomer was inactive at 30 mg/kg in the mouse and 1 mg/kg in the dog. The (−)-enantiomer was 100–800 times more potent than Δ 9 -THC in the mouse. The high degree of enantioselectivity and potency are suggestive of an interaction at a specific site such as a receptor.

1-Alkyl-3-(1-naphthoyl)pyrroles: A new class of cannabinoid

Abstract The design and synthesis of a series of 1-alkyl-3-(1-naphthoyl)pyrroles is described. Molecular modeling studies were employed to aid in the design of these compounds. During the course of the synthesis the Friedel-Crafts reactions of N-aryl sulfonyl pyrroles were reinvestigated. The title compounds (4) were subjected to pharmacological evaluation and the data obtained have enabled these pyrroles to be classified as cannabinoids.

Pharmacological and behavioral evaluation of alkylated anandamide analogs

Anandamide (arachidonylethanolamide), isolated from porcine brain, has been shown to bind to the cannabinoid receptor and also to produce cannabimimetic activity in pharmacological assays. This study examined structure-activity relationships in alkylated anandamide analogs. The analogs were evaluated for their ability to displace [3H]CP-55,940 in a filtration binding assay using rat brain membranes in the presence and absence of the enzyme inhibitor phenylmethylsulfonyl fluoride (PMSF). Behavioral activity was assessed by the ability of the analogs to produce hypomotility and antinociception. Methylations at carbons 2 and 1 produced compounds stable in the absence of PMSF with similar affinities and behavioral activity as anandamide. Addition of larger alkyl groups at these positions or nitrogen methylation reduced receptor affinity and behavioral potency. These results indicate that methylations at specific carbons of anandamide confer stability in vitro.

Cannabinoid receptors in developing rats : detection of mRNA and receptor binding

Despite a large body of research directed at assessing the effects of perinatal cannabinoid exposure, little is known about the development of the cannabinoid receptor. Recent advances, including the cloning of the cannabinoid receptor, have afforded us the opportunity to plot the postnatal ontogeny of the cannabinoid receptor and its mRNA in whole brain using the methods of receptor binding and RNA blot hybridization, respectively. Our results indicate that cannabinoid receptor mRNA is present at adult levels as early as postnatal day 3. The Bmax, on the other hand, increases almost fifty percent with increasing postnatal age, while the affinity does not change. The Hill coefficients for all ages studied were approximately 1. These findings suggest the possibility of a developmental progression for cannabinoid receptor development with receptor mRNA appearing first, followed by a period of rapid proliferation of the receptors themselves.

Pharmacological evaluation of dimethylheptyl analogs of Δ9-THC: reassessment of the putative three-point cannabinoid-receptor interaction

The basic premise underlying the cannabinoid pharmacophore is that at least three functional groups are involved in the interaction between the ligand and the receptor and that these functional groups in delta 9-THC comprise (a) C11, (b) the phenolic hydroxyl, and (c) the side chain. In order to assess the relative importance of the C11 position and the side chain, a series of C11 substituted analogs were prepared which contained a dimethylheptyl side chain. Consistent with previous studies, incorporation of a dimethylheptyl side chain dramatically enhanced both pharmacological potency in mice and receptor affinity. Incorporation of a hydroxy at C11 along with this branched side chain resulted in an extremely potent cannabinoid with ED50S of 0.01, 0.04, 0.16 and 0.04 mumol/kg in depression of spontaneous activity, reduction in body temperature, antinociception, and immobility, respectively. This compound was also very potent as a discriminative stimulus in a drug discrimination procedure and exhibited an extended duration of action. Its high affinity for the cannabinoid receptor (Ki = 400 pM) was consistent with this pharmacological potency. Incorporation of an oxo rather than a hydroxy reduced potency somewhat, although this analog was much more potent than delta 9-THC in most behavioral assays. The most striking observation was that incorporation of a carboxylic acid to form 11-nor-delta 9-THC-DMH-9-carboxylic acid did not eliminate pharmacological activity. This analog was as potent as delta 9-THC. The improbability that all three of the functional groups are interacting in a similar fashion with the receptor provides further support that the C11 position is not an essential requirement for activity. On the other hand, it is possible that substituents in the C9 region are interacting somewhere within or near the same site, but differently.

Side chain methyl analogues of Δ8-THC

Abstract The synthesis of both side chain epimers of 1′-( 4 ), 2′-( 5 ), 3′-methyl-( 6 ) and 4′-methyl-Δ 8 -tetrahydrocannabinol ( 7 ) has been carried out. The synthetic approach entailed the acid catalyzed condensation of the appropriate substituted resorcinol with menthadienol to provide the Δ 8 -THC analogue. Both isomers of 1′-( 4 ) and 2t-Δ 8 -THC ( 5 ) were more potent than Δ 8 -THC, both in vitro and in vivo . The 3′-methyl isomers ( 6 ) were approximately equal in potency to Δ 8 -THC, and 4t-methyl-Δ 8 -THC was less potent. There was relatively little difference in potency between the epimers of 4 , 5 , and 6 .

A novel class of potent tetrahydrocannabinols (THCS): 2′-YNE-Δ8- and Δ9-THCS

Abstract A series of 3-alkyl-2′-yne (side chain) acetylenic analogs of Δ 9 -THC were synthesized and evaluated for in vitro and in vivo activity. Analogs were evaluated for receptor affinity in a [ 3 H]CP-55,940 displacement assay and for in vivo pharmacological activity in a mouse procedure utilizing a tetrad of measures. These compounds represent a preliminary exploration of the consequences of restricting the flexibility of the side chain regarding cannabimimetic activity. All analogs proved to have receptor affinities (4–11 nM) that were five to ten times greater than that observed for Δ 9 -THC. However, the in vivo activities of these compounds varied greatly. All analogs proved to possess, the greatest potency for production of antinociception, with activity similar to or less than that observed for the production of hypomotility, hypothermia, and catalepsy. The most potent analog 11b exhibited an ED 50 of 0.031 mg/kg in the tail-flick procedure, with values in other measures being between 0.5 and 1.0 mg/kg. The least active compound ( 11c ), though still possessing a K I of 11 nM, exhibited ED50 values of 3.1 and 9.3 mg/kg for tail-flick and temperature procedures, as well as 41 and 48 mg/kg for ring-immobility and spontaneous locomotor activity, respectively. This profile (high receptor affinity but low in vivo potency) would normally be suggestive of a compound with antagonist properties (at least for immobility and activity measures). It is unclear why these acetylenic analogs were so potent in vitro , while only one ( 11b ) exhibited the degree of in vivo potency anticipated based upon comparison to values for Δ 9 -THC. It is possible these side chain modifications do not interfere with receptor recognition, but limit receptor activation or second messenger signal transduction. Regardless, it is clear these novel analogs provide a basis for the further exploration of the cannabinoid receptor pharmacophore.

A rational search for the separation of psychoactivity and analgesia in cannabinoids.

The compound 9-beta-hydroxy-hexahydrocannabinol [(-)-9 beta-OH-HHC] was designed to fit a combined theoretical profile of an analgesic cannabinoid (equatorial alcohol at C-9, phenol at C-1 and a C-3 side chain) with reduced psychoactivity (axial C-9 substituent which protrudes into the alpha face). (-)-9 beta-OH-HHC was synthesized by the addition of methyl Grignard to 9-oxo-11-nor-HHC. Its alpha epimer was obtained by the regiospecific epoxide ring opening of 9 alpha, 10 alpha-epoxy-HHC acetate. (-)-9 beta-OH-HHC and (-)-9 alpha-OH-HHC were each evaluated in a battery of tests in mice and were found to be 10-25 times less potent than (-)-trans-delta 9-tetrahydrocannabinol (delta 9-THC) in all tests including the tail flick test for antinociception (analgesia). Molecular mechanics calculations [MMP2(85)] revealed that, in the global minimum energy conformation of (-)-9 beta-OH-HHC, the axial methyl at C-9 protrudes into the alpha face of the molecule, while the axial hydroxyl at C-9 in (-)-9 alpha-OH-HHC protrudes into this same face. These calculations also identified a higher energy carbocyclic ring (twist) conformer of each in which there is no protrusion of a C-9 substituent of the carbocyclic ring into the alpha face. The minimal activity of both compounds is attributed to these higher energy forms.(ABSTRACT TRUNCATED AT 250 WORDS)