New analgesics synthetically derived from the paracetamol metabolite N-(4-hydroxyphenyl)-(5Z,8Z,11Z,14Z)-icosatetra-5,8,11,14-enamide.
N-(4-hydroxyphenyl)-(5Z,8Z,11Z,14Z)-icosatetra-5,8,11,14-enamide (AM404) is a metabolite of the well-known analgesic paracetamol. AM404 inhibits endocannabinoid cellular uptake, binds weakly to CB1 and CB2 cannabinoid receptors, and is formed by fatty acid amide hydrolase (FAAH) in vivo. We prepared three derivatives of this new (endo)cannabinoid using bioisosteric replacement (1), homology (2), and derivatization (3) of the 4-aminophenol moiety in AM404 and tested them against CB1, CB2, and FAAH. We found affinities toward both cannabinoid receptors equal to or greater than that of AM404. Shortening the acyl chain from C20 to C2 led to three new paracetamol analogues: N-(1H-indazol-5-yl)acetamide (5), N-(4-hydroxybenzyl)acetamide (6), and N-(4-hydroxy-3-methoxyphenyl)acetamide (7). Again, 5, 6, and 7 were tested against CB1, CB2, and FAAH without significant activity. However, 5 and 7 behaved like inhibitors of cyclooxygenases in whole blood assays. Finally, 5 (50 mg/kg) and 6 (275 mg/kg) displayed analgesic activities comparable to paracetamol (200 mg/kg) in the mouse formalin test.
Sinning
Christian
C
Institut fuer Pharmazie, Martin-Luther-Universitaet, Wolfgang-Langenbeck-Strasse 4, 06120 Halle, Germany.
Watzer
Bernhard
B
Coste
Ovidiu
O
Nüsing
Rolf M
RM
Ott
Ingo
I
Ligresti
Alessia
A
Di Marzo
Vincenzo
V
Imming
Peter
P
D000082:Acetaminophen / Q000031:analogs & derivatives*; D000581:Amidohydrolases / Q000737:chemistry; D000700:Analgesics / Q000138:chemical synthesis* / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000138:chemical synthesis* / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D005557:Formaldehyde / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D007700:Kinetics; D051379:Mice; D008956:Models, Chemical; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry; D051381:Rats; D043882:Receptors, Cannabinoid / Q000737:chemistry; D000099252:Fatty Acid Amide Hydrolases
D000082:Acetaminophen; D000581:Amidohydrolases; D000700:Analgesics; D001095:Arachidonic Acids; D005557:Formaldehyde; D011451:Prostaglandin-Endoperoxide Synthases; D043882:Receptors, Cannabinoid; D000099252:Fatty Acid Amide Hydrolases; C107594:N-(4-hydroxyphenyl)arachidonylamide