Methyl arachidonate- 13 C 4 (Arachidonic acid methyl ester- 13 C 4 )is 13 C labeled Methyl arachidonate. Methyl arachidonate (Arachidonic acid methyl ester) is a fatty acid methyl ester resulting from the formal condensation of the carboxy group of arachidonic acid with methanol. Methyl arachidonate has activity of human blood serum metabolite.