Background:

Arachidonoyl glycine (N-arachidonyl glycine; NAGly) has been isolated from cell cultures treated with arachidonoyl ethanolamide (AEA; anandamide),1 from extracts of mammalian brain,2,3 and has also been synthesized as an analog of AEA for structure/activity testing.4 NAGly may be produced endogenously via oxidation of AEA, or by transacylation of arachidonoyl CoA. NAGly is reported to have analgesic activities in whole animal experiments.[1],[2],[3] Since it seems to be a very poor ligand for the CB1 receptor,[4] these effects are probably mediated via other signaling pathways.

Reference:
[1]. Burstein, S.H., Rossetti, R.G., Yagen, B., et al. Oxidative metabolism of anandamide. Prostaglandins & Other Lipid Mediators 61, 29-41 (2000).
[2]. Huang, S.M., Bisogno, T., Petros, T.J., et al. Identification and characterization of an endogenous anandamide-like compound: N-arachidonylglycine (NAGly). ICRS 2001 Symposium on the Cannabinoids 78 (2001).
[3]. Huang, S.M., Bisogno, T., Petros, T.J., et al. Identification of a new class of molecules, the arachidonyl amino acids, and characterization of one member that inhibits pain. The Journal of Biological Chemisty 276(46), 42639-42644 (2001).
[4]. Sheskin, T., Hanus, L., Slager, J., et al. Structural requirements for binding of anandamide-type compounds to the brain cannabinoid receptor. Journal of Medicinal Chemistry 40, 659-667 (1997).