S-2 methanandamide is a CB1 receptor ligand.

The cannabinoid receptor type 1 (CB1), is a G protein-coupled cannabinoid receptor located mainly in the central and peripheral nervous system. CB1 is also expressed in several cells relating to metabolism, such as muscle cells, fat cells, liver cells, and the digestive tract. The CB1 receptor has been involved in the maintenance of homeostasis in health and disease, preventing the development of excessive neuronal activity, reducing pain and other inflammatory symptoms. Enhanced receptor expression has been identified in human hepatocellular carcinoma tumor samples and human prostate cancer cells [2].

S-2 methanandamide was the second most potent CB1 receptor agonist in the methanandamide series. S-2 methanandamide activated the CB1 receptor with a Ki value of 26 nM. S-2 methanandamide was less prone to FAAH inactivation. S-2 methanandamide inhibited the murine vas deferens twitch response with an IC50 value of 47 nM.

References:
[1] Abadji V, Lin S, Taha G, et al.  (R)-methanandamide: a chiral novel anandamide possessing higher potency and metabolic stability[J]. Journal of medicinal chemistry, 1994, 37(12): 1889-1893.
[2] Howlett A C.  Cannabinoid receptor signaling[M]//Cannabinoids. Springer Berlin Heidelberg, 2005: 53-79.