N-Arachidonylglycine

N-Arachidonylglycine (NAGly) is a carboxylic metabolite of the endocannabinoid anandamide (AEA).^[1][2] Since it was first synthesized in 1996,^[3] NAGly has been a primary focus of the relatively contemporary field of lipidomics due to its wide range of signaling targets in the brain, the immune system and throughout various other bodily systems. In combination with 2‐arachidonoyl glycerol (2‐AG), NAGly has enabled the identification of a family of lipids often referred to as endocannabinoids.^[4] Recently, NAGly has been found to bind to G-protein coupled receptor 18 (GPR18), the putative abnormal cannabidiol receptor.^[5][6] NaGly is an endogenous inhibitor of fatty acid amide hydrolase (FAAH) and thereby increases the ethanolamide endocannabinoids AEA, oleoylethanolamide (OEA) and palmitoylethanolamide (PEA) levels.^[7] NaGly is found throughout the body and research on its explicit functions is ongoing.

N-Arachidonylglycine

Names
IUPAC name N-[(5Z,8Z,11Z,14Z)-Icosa-5,8,11,14-tetraenoyl]glycine
Systematic IUPAC name [(5Z,8Z,11Z,14Z)-Icosa-5,8,11,14-tetraenamido]acetic acid
Other names N-Arachidonylglycine Arachidonoyl glycine NA-glycine
Identifiers
CAS Number	179113-91-8 Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	7652004
ChEBI	CHEBI:58961 Y
ChEMBL	ChEMBL161343 Y
ChemSpider	4446510 Y
MeSH	Anandamide
PubChem CID	5283389
UNII	5PB56SQA6E Y
CompTox Dashboard (EPA)	DTXSID5045124
InChI Key: LGEQQWMQCRIYKG-DOFZRALJSA-N Y InChI=1/C22H37NO2/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-22(25)23-20-21-24/h6-7,9-10,12-13,15-16,24H,2-5,8,11,14,17-21H2,1H3,(H,23,25)/b7-6-,10-9-,13-12-,16-15- Key: YLEARPUNMCCKMP-DOFZRALJSA-N InChI=1S/C22H35NO3/c1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18-19-21(24)23-20-22(25)26/h6-7,9-10,12-13,15-16H,2-5,8,11,14,17-20H2,1H3,(H,23,24)(H,25,26)/b7-6-,10-9-,13-12-,16-15-
SMILES O=C(NCC(=O)O)CCC\C=C/C\C=C/C\C=C/C\C=C/CCCCC O=C(NCC(=O)O)CCC\C=C/C\C=C/C\C=C/C\C=C/CCCCC
Properties
Chemical formula	C22H35NO3
Molar mass	361.526 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Biosynthesis and degradation

The biosynthesis and degradation of NaGly is not completely understood. Using biochemical approaches, two proposed pathways include: 1) enzymatic conjugation of arachidonic acid and glycine and 2) the oxidative metabolism of the endogenous cannabinoid anandamide.^[8][9] In support of the former "direct" pathway of arachidonic acid and glycine conjugation and hydrolysis, the secreted enzyme PM20D1 and the intracellular amidase FAAH has been identified as enzymatic regulators of NAGly metabolism in mice.^[10][11]

Research

Effects on the nervous system

NAGly has been hypothesized to have a neurophysiological function of pain suppression, supported by evidence that it suppresses formalin-induced pain behavior in rats.^[12] In particular, peripherally administered NAGly inhibited phase 2 pain behavior, suggesting either a direct suppression of nociceptive afferents on the nerve or an indirect modulation of the afferents' interstitial environment.^[12] In either case, these findings hold promise for NAGly as a means of mitigating postoperative or chronic pain. NAGly is also effective in acute pain models, reducing mechanical allodynia and thermal hyperalgesia induced by intraplantar injection of Fruend's complete adjuvant.^[13] Similar mechanical allydonia induced by partial ligation of the sciatic nerve was also reduced by NaGly.^[14] Other arachidonic acid-amino acid conjugates did not have the same effects and the actions of NaGly were not affected by cannabinoid receptor agonists in either study, suggesting a novel non-cannabinoid receptor mediated approach to alleviate inflammatory pain.^[13][14]

NaGly was shown to be endogenous ligand for the G-protein couple receptor GPR92 along with farnesyl pyrophosphate.^[15] In the dorsal root ganglia (DRG), where GPR92 was found to be localized NaGly increased intracellular calcium levels in DRG neurons, indicating a role of NaGly in the sensory nervous system through the activation of GPR92.^[15]

Effects on the immune system

NAGly has been the focus of research on the immune system because of its antinociceptive effects and inhibitory action on components of the immune system. Specifically, it significantly inhibited TNFα and IFNγ production, and it shows potential as a therapeutic treatment for chronic inflammation.^[16] Moreover, NAGly has been shown to act as a substrate for cyclooxygenase-2 (COX-2), the enzyme primarily known for producing prostaglandins associated with increases in inflammation and hyperalgesia. In many mammalian tissues that express COX-2, significant levels of NAGly are naturally present, and in these tissues COX-2 selectively metabolizes NAGly prostaglandin (PG) H₂ glycine and HETE-Gly.^[17]

Cell migration

NAGly has been hypothesized to induce cell migration in BV-2 microglia cells.^[5] The same research suggests that this migration occurs through GPR18. This was verified using GPR18 transfected HEK-293 cells. The same migration wasn't witnessed using non-transfected and GPR55 transfected HEK-293.^[5] Additionally, tetrahydrocannabinol and NaGly are full agonists at the GPR18 receptors and induce migration in human endometrial HEC-1B cells.^[18] Understanding functions of NaGly in such structures provides a promising future in helping treat diseases such as endometriosis.

Cellular respiration

NAGly powerfully stimulates oxygen consumption in multiple cell lines, including murine C2C12 myoblasts and human HEK293T cells.^[19] This respiratory bioactivity of NAGly is by increased uncoupled (state4u) mitochondrial respiration and depends on the presence of fatty acid desaturation.^[20] NAGly respiration bioactivity can be also abrogated in the presence of serum albumin, which functions as an NAGly carrier in murine blood plasma.^[21]

Other targets

Insulin secretion

NaGly was identified as a novel insulin secretagogue and was shown to increase intracellular calcium concentration through stimulation of voltage dependent calcium channels.^[22] Additionally, this action was dependent on extracellular glucose level.^[22]

Additional biochemical interactions

NaGly has been shown to inhibit the glycine transporter GLYT2a in a non-competitive fashion with arachidonic acid and secondary messenger systems of GLYT2a, suggesting a novel recognition site for the N-arachidonyl amino acids, especially because other conjugated amino acids had similar effects.^[23]

References

1. Burstein SH, Huang SM, Petros TJ, Rossetti RG, Walker JM, Zurier RB (October 2002). "Regulation of anandamide tissue levels by N-arachidonylglycine". Biochemical Pharmacology. 64 (7): 1147–50. doi:10.1016/S0006-2952(02)01301-1. PMID 12234618.
2. Bradshaw HB, Rimmerman N, Hu SS, Benton VM, Stuart JM, Masuda K, Cravatt BF, O'Dell DK, Walker JM (May 2009). "The endocannabinoid anandamide is a precursor for the signaling lipid N-arachidonoyl glycine by two distinct pathways". BMC Biochemistry. 10: 14. doi:10.1186/1471-2091-10-14. PMC 2689249. PMID 19460156.
3. Sheskin T, Hanus L, Slager J, Vogel Z, Mechoulam R (February 1997). "Structural requirements for binding of anandamide-type compounds to the brain cannabinoid receptor". Journal of Medicinal Chemistry. 40 (5): 659–67. doi:10.1021/jm960752x. PMID 9057852.
4. Bradshaw HB, Rimmerman N, Hu SS, Burstein S, Walker JM (2009). Novel endogenous N-acyl glycines identification and characterization. Vitamins & Hormones. Vol. 81. pp. 191–205. doi:10.1016/S0083-6729(09)81008-X. ISBN 9780123747822. PMID 19647113.
5. McHugh D, Hu SS, Rimmerman N, Juknat A, Vogel Z, Walker JM, Bradshaw HB (March 2010). "N-arachidonoyl glycine, an abundant endogenous lipid, potently drives directed cellular migration through GPR18, the putative abnormal cannabidiol receptor". BMC Neuroscience. 11 (1): 44. doi:10.1186/1471-2202-11-44. PMC 2865488. PMID 20346144.
6. Kohno M, Hasegawa H, Inoue A, Muraoka M, Miyazaki T, Oka K, Yasukawa M (September 2006). "Identification of N-arachidonylglycine as the endogenous ligand for orphan G-protein-coupled receptor GPR18". Biochemical and Biophysical Research Communications. 347 (3): 827–32. doi:10.1016/j.bbrc.2006.06.175. PMID 16844083.
7. Tegeder I (February 2016). "Endocannabinoids as Guardians of Metastasis". International Journal of Molecular Sciences. 17 (2): 230. doi:10.3390/ijms17020230. PMC 4783962. PMID 26875980.
8. Bradshaw HB, Rimmerman N, Hu SS, Benton VM, Stuart JM, Masuda K, Cravatt BF, O'Dell DK, Walker JM (May 2009). "The endocannabinoid anandamide is a precursor for the signaling lipid N-arachidonoyl glycine by two distinct pathways". BMC Biochemistry. 10 (1): 14. doi:10.1186/1471-2091-10-14. PMC 2689249. PMID 19460156.
9. Aneetha H, O'Dell DK, Tan B, Walker JM, Hurley TD (January 2009). "Alcohol dehydrogenase-catalyzed in vitro oxidation of anandamide to N-arachidonoyl glycine, a lipid mediator: synthesis of N-acyl glycinals". Bioorganic & Medicinal Chemistry Letters. 19 (1): 237–41. doi:10.1016/j.bmcl.2008.10.087. PMC 2798806. PMID 19013794.
10. Long JZ, Roche AM, Berdan CA, Louie SM, Roberts AJ, Svensson KJ, Dou FY, Bateman LA, Mina AI, Deng Z, Jedrychowski MP, Lin H, Kamenecka TM, Asara JM, Griffin PR, Banks AS, Nomura DK, Spiegelman BM (July 2018). "Ablation of PM20D1 reveals N-acyl amino acid control of metabolism and nociception". Proc Natl Acad Sci U S A. 115 (29): E6937–45. Bibcode:2018PNAS..115E6937L. doi:10.1073/pnas.1803389115. PMC 6055169. PMID 29967167.
11. Kim JT, Terrell SM, Li VL, Wei W, Fischer CR, Long JZ (April 2020). "Cooperative enzymatic control of N-acyl amino acids by PM20D1 and FAAH". eLife. 9: e552115. doi:10.7554/eLife.55211. PMC 7145423. PMID 32271712.
12. Huang SM, Bisogno T, Petros TJ, Chang SY, Zavitsanos PA, Zipkin RE, Sivakumar R, Coop A, Maeda DY, De Petrocellis L, Burstein S, Di Marzo V, Walker JM (November 2001). "Identification of a new class of molecules, the arachidonyl amino acids, and characterization of one member that inhibits pain". The Journal of Biological Chemistry. 276 (46): 42639–44. doi:10.1074/jbc.M107351200. PMID 11518719.
13. Succar R, Mitchell VA, Vaughan CW (August 2007). "Actions of N-arachidonyl-glycine in a rat inflammatory pain model". Molecular Pain. 3 (1): 1744-8069–3-24. doi:10.1186/1744-8069-3-24. PMC 2042976. PMID 17727733.
14. Vuong LA, Mitchell VA, Vaughan CW (January 2008). "Actions of N-arachidonyl-glycine in a rat neuropathic pain model". Neuropharmacology. 54 (1): 189–93. doi:10.1016/j.neuropharm.2007.05.004. PMID 17588618. S2CID 35178601.
15. Oh DY, Yoon JM, Moon MJ, Hwang JI, Choe H, Lee JY, Kim JI, Kim S, Rhim H, O'Dell DK, Walker JM, Na HS, Lee MG, Kwon HB, Kim K, Seong JY (July 2008). "Identification of farnesyl pyrophosphate and N-arachidonylglycine as endogenous ligands for GPR92". The Journal of Biological Chemistry. 283 (30): 21054–64. doi:10.1074/jbc.M708908200. PMC 2475705. PMID 18499677.
16. WO application 9738688, Ferrante A, Poulos A, Pitt M, Easton C, Sleigh M, Rathjen D, Widmer F, "Methods of Treating Immunopathologies Using Polyunsaturated Fatty Acids", published 23 October 1997, assigned to Peptide Technology Pty Ltd. and Women's and Children's Hospital Adelaide
17. Prusakiewicz JJ, Kingsley PJ, Kozak KR, Marnett LJ (August 2002). "Selective oxygenation of N-arachidonylglycine by cyclooxygenase-2". Biochemical and Biophysical Research Communications. 296 (3): 612–7. doi:10.1016/s0006-291x(02)00915-4. PMID 12176025.
18. McHugh D, Page J, Dunn E, Bradshaw HB (April 2012). "Δ(9) -Tetrahydrocannabinol and N-arachidonyl glycine are full agonists at GPR18 receptors and induce migration in human endometrial HEC-1B cells". British Journal of Pharmacology. 165 (8): 2414–24. doi:10.1111/j.1476-5381.2011.01497.x. PMC 3423258. PMID 21595653.
19. Long JZ, Svensson KJ, Bateman LA, Lin H, Kamenecka T, Lokurkar IA, Lou J, Rao RR, Chang MR, Jedrychowski MP, Paulo JA, Gygi SP, Griffin PR, Nomura DK, Spiegelman BM (June 2016). "The Secreted Enzyme PM20D1 Regulates Lipidated Amino Acid Uncouplers of Mitochondria". Cell. 166 (2): 424–435. doi:10.1016/j.cell.2016.05.071. PMC 4947008. PMID 27374330.
20. Lin H, Long JZ, Roche AM, Svensson KJ, Dou FY, Chang MR, Strutzenberg T, Ruiz C, Cameron MD, Novick SJ, Berdan CA, Louie SM, Nomura DK, Spiegelman BM, Griffin PR, Kamenecka TM (March 2018). "Discovery of Hydrolysis-Resistant Isoindoline N-Acyl Amino Acid Analogues that Stimulate Mitochondrial Respiration". J Med Chem. 61 (7): 3224–3230. doi:10.1021/acs.jmedchem.8b00029. PMC 6335027. PMID 29533650.
21. Kim JT, Jedrychowski MP, Wei W, Fernandez D, Fischer CR, Banik SM, Spiegelman BM, Long JZ (May 2020). "A Plasma Protein Network Regulates PM20D1 and N-Acyl Amino Acid Bioactivity". Cell Chem Biol. 27 (9): 1130–1139.e4. doi:10.1016/j.chembiol.2020.04.009. PMC 7502524. PMID 32402239.
22. Ikeda Y, Iguchi H, Nakata M, Ioka RX, Tanaka T, Iwasaki S, Magoori K, Takayasu S, Yamamoto TT, Kodama T, Yada T, Sakurai T, Yanagisawa M, Sakai J (August 2005). "Identification of N-arachidonylglycine, U18666A, and 4-androstene-3,17-dione as novel insulin Secretagogues". Biochemical and Biophysical Research Communications. 333 (3): 778–86. doi:10.1016/j.bbrc.2005.06.005. PMID 15967412.
23. Wiles AL, Pearlman RJ, Rosvall M, Aubrey KR, Vandenberg RJ (November 2006). "N-Arachidonyl-glycine inhibits the glycine transporter, GLYT2a". Journal of Neurochemistry. 99 (3): 781–6. doi:10.1111/j.1471-4159.2006.04107.x. PMID 16899062.