Bijali Saha

O-1057, a potent water-soluble cannabinoid receptor agonist with antinociceptive properties.

Cannabinoids have low water solubility, necessitating the use of a solubilizing agent. In this paper we investigated whether a novel water‐soluble cannabinoid, 3‐(5′‐cyano‐1′,1′‐dimethylpentyl)‐1‐(4‐N‐morpholinobutyryloxy)‐Δ8‐tetrahydrocannabinol hydrochloride (O‐1057), would interact with cannabinoid receptors when water or saline were used as the only vehicle. O‐1057 displaced [3H]‐CP55940 from specific binding sites on Chinese hamster ovary (CHO) cell membranes expressing CB1 or CB2 cannabinoid receptors, with pKi values of 8.36 and 7.95 respectively. It also displaced [3H]‐CP55940 from specific binding sites on rat brain membranes (pKi=7.86). O‐1057 inhibited forskolin‐stimulated cyclic AMP production by both CB1‐ and CB2‐transfected CHO cells (pEC50=9.16 and 9.72 respectively), its potency matching that of CP55940 and exceeding that of Δ9‐tetrahydrocannabinol. In the mouse isolated vas deferens, O‐1057 inhibited electrically‐evoked contractions with pEC50 and Emax values of 9.73 and 76.84% respectively. It was antagonized by 100 nM SR141716A, the pKB of SR141716A against O‐1057 (8.90) approximating to that against CP55940 (8.97). O‐1057 also behaved as a CB1 receptor agonist in vivo, reducing mouse spontaneous activity and rectal temperature when injected intravenously and inducing antinociception in the mouse tail flick test when given intravenously (ED50=0.02 mg kg−1), intrathecally, intracerebroventricularly or by gavage. In all these assays, O‐1057 was more potent than Δ9‐tetrahydrocannabinol and, at 0.1 mg kg−1 i.v., was antagonized by SR141716A (3 mg kg−1 i.v.). These data demonstrate the ability of the water‐soluble cannabinoid, O‐1057, to act as a potent agonist at CB1 and CB2 receptors and warrant investigation of the clinical potential of O‐1057 as an analgesic.

Synthesis and Pharmacological Activity of a Potent Inhibitor of the Biosynthesis of the Endocannabinoid 2-Arachidonoylglycerol

Biosynthesis Inhibition: O‐5596, a new inhibitor of the biosynthesis of the endocannabinoid, 2‐arachidonoylglycerol, was synthesized and found to be potent (IC50=100 nM) and selective versus other proteins and enzymes of the endocannabinoid system in vitro and active in vivo at reducing food intake in mice.

Structural determinants of the partial agonist‐inverse agonist properties of 6′‐azidohex‐2′‐yne‐Δ8‐tetrahydrocannabinol at cannabinoid receptors

We have extended previous investigations of four analogues of Δ8‐tetrahydrocannabinol (Δ8‐THC): 6′‐azidohex‐2′‐yne‐Δ8‐THC (O‐1184), 6′‐azidohex‐cis‐2′‐ene‐Δ8‐THC (O‐1238) and octyl‐2′‐yne‐Δ8‐THC (O‐584) and its 1‐deoxy‐analogue (O‐1315). O‐1184, O‐1238 and O‐584 displaced [3H]‐CP55940 from specific binding sites on Chinese hamster ovary (CHO) cell membranes expressing CB1 or CB2 cannabinoid receptors, with pKi values of 8.28 to 8.45 (CB1) and 8.03 to 8.13 (CB2). The pKi values of O‐1315 were significantly less, 7.63 (CB1) and 7.01 (CB2). All the analogues inhibited forskolin‐stimulated cyclic AMP production by CB1‐transfected CHO cells (pEC50=9.16 to 9.72). Only O‐1238 behaved as a full agonist in this cell line. In mouse vasa deferentia, O‐1238 inhibited electrically‐evoked contractions (pEC50=10.18 and Emax=70.5%). Corresponding values for O‐1184 were 9.08 and 21.1% respectively. At 1 nM, O‐1184 produced surmountable antagonism of the cannabinoid receptor agonist, CP55940. However, at 0.1 nM, O‐1184 did not attenuate CP55940‐induced inhibition of cyclic AMP production by CB1‐transfected CHO cells. In CB2‐transfected CHO cells, cyclic AMP production was inhibited by CP55940 (pEC50=8.59), enhanced by O‐1184 and O‐584 (pEC50=8.20 and 6.86 respectively) and not significantly affected by O‐1238 or O‐1315. At 100 nM, O‐1184 and O‐1238 produced surmountable antagonism of CP55940 in CB2 cells, decreasing the pEC50 of CP55940 from 8.61 to 7.42 (O‐1184) or from 8.54 to 7.44 (O‐1238). These data support the hypothesis that increasing the degree of unsaturation of the aliphatic side‐chain of Δ8‐THC analogues has little effect on CB1 or CB2 receptor affinity but can reduce CB1 receptor efficacy and reverse the direction of responses elicited at CB2 receptors.

Pharmacological Characterization of Novel Water-Soluble Cannabinoids

Presently, there are numerous structural classes of cannabinoid receptor agonists, all of which require solubilization for experimental purposes. One strategy for solubilizing water-insoluble tetrahydrocannabinols is conversion of the phenolic hydroxyl to a morpholinobutyryloxy substituent. The hydrochloride salts of these analogs are water-soluble and active in vivo when administered in saline. The present investigation demonstrated that hydrochloride salts of numerous substituted butyryloxy esters are water-soluble and highly potent. The substitutions include piperidine, piperazine, and alkyl-substituted amino moieties. It was also discovered that incorporation of a nitrogenous moiety in the alkyl side chain increased the pharmacological potency of tetrahydrocannabinol. For example, an analog containing a pyrazole in the side chain (O-2545) was found to have high affinity and efficacy at cannabinoid 1 (CB1) and CB2 receptors, and when dissolved in saline, it was highly efficacious when administered either intravenously or intracerebroventricularly to mice. A series of carboxamido and carboxylic acid amide analogs exhibited high pharmacological potency, but their hydrochloride salts were not water-soluble. On the other hand, incorporation of imidazoles into the terminus of the side chain led to water-soluble hydrochloride salts that were highly potent when administered in saline to laboratory animals. It is now possible to conduct cannabinoid research with agonists that are water-soluble and thus obviating the need of solubilizing agents.

Protein kinase C modulators. Indolactams. 1. Efficient and flexible routes for the preparation of (-)-indolactam V for use in the synthesis of analogs

Abstract Three syntheses of the protein kinase C activator, (-)-indolactam V, are described and are compared for their potential utility in the preparation of ILV analogs. In one route the 4-amino functionality is introduced regiospecifically during the construction of the indole portion and enantiomeric control is achieved by the alkylation of the amine with a triflate derived from d -valine. One of the routes affords racemic ILV from which (-)-ILV is obtained by the first reported resolution of an indolactam.

Development of agonists, partial agonists and antagonists in the Δ8-Tetrahydrocannabinol series

Abstract Synthetic sequences were developed (Schemes 1 to 6) for the syntheses of various Δ8-THC analogs with either a rigid acetylenic linkage or a cis-double bond in different positions in the side chain. Various alkyne and cis-ene-Δ8-THC analogs were also synthesized carrying a functional group such as a cyano, isothiocyano, azido, amino, nitro, bromo, hydroxy, fluoro and a methoxy group at the chain terminal. The in vitro and in vivo pharmacology of these unique analogs have provided several ligands which are partial agonists or antagonists of the cannabinoid receptor CB1. The 2′-position in the side chain was found to be optimum for activity.

Protein kinase C modulators. Indolactams. 2.1 Alkylation of 4-nitroindole by Grignard reagents. Synthesis of (-)-7-octylindolactam V

Abstract A method for the C-alkylation of 4-nitroindole at the 5 and 7 positions by alkyl Grignard reagents has been developed. The 4-nitro-7-octylindole thus prepared has been used as a starting material for the synthesis of the lyngbyatoxin analog, (-)-7-octylindolactam V.

Synthesis of Some Angularly Cyclopentanone Fused Hydrophenanthrene and Hydrofluorene Derivatives by Acid-Catalyzed Intramolecular C-Alkylation of γ,δ - Unsaturated α′-Diazomethyl Ketones

Abstract A facile synthesis of a few new angularly cyclopentanone fused hydrophenanthrene and hydrofluorene derivatives is described based on intramolecular C-alkylation of γ,δ-unsaturated α′-diazomethyl ketones.

A novel synthetic method for angularly functionalized polycyclic systems by vinylogous wolff rearrangement of β, γ-unsaturated diazoketones

Abstract Decompositions of the rigid polycylic β,γ-unsaturated diazomethyl ketones ( 1a and b ) and ( 2a and b ) promoted by Cu(acac) 2 , Cu(OTf) 2 , Ni(acac) 2 or silver benzoatetriethylamine in the presence of methanol are shown to give the respective rearranged γ,δ-unsaturated angularly substituted esters ( 3a and b ) and ( 6a and b ) along with other products.

Antinociceptive effects of tetrahydrocannabinol side chain analogs : dependence upon route of administration

The role of flexibility of the alkyl side chain in the tetrahydrocannabinols to cannabinoid activity has been delineated in previous studies with side chain analogs of Delta(8)-tetrahydrocannabinol with double or triple bonds. This study investigated the site of antinociceptive action for these analogs through analysis of structure-activity relationships following different routes of administration. In analogs without terminal substitutions, potency was greater following intrathecal (i. t.) injection than with intracerebroventricular (i.c.v.). Further, optimal structural features differed for each route of administration. Absolute position of the double or triple bond best predicted i.t. potency. In contrast, i.c.v. potency was best predicted by the size of the alkyl substituent beyond the point of unsaturation. Terminal substitutions tended to increase i.c.v. potency while decreasing or not affecting i.t. These results suggest that receptor mechanisms for cannabinoid antinociceptive effects differ in brain and spinal cord, although potential pharmacokinetic differences in rate of local distribution cannot be eliminated.