Of possible interest as well:
Medline (PMID=10919562)
Synthesis and analgesic activity of N,N'-dicarbonyltryptamines.Dongmei H, Chao W, Ming Z, Shiqi P.
5-Methoxytryptamine and L-tryptophan methyl ester were acylated with malonic acid, dimethyl malonate, or succinic anhydride to produce the corresponding N,N'-dicarbonyltryptamine derivatives. The analgesic activity was evaluated by the tail flick test. All of the compounds exhibited desirable analgesic potency. This result is consistent with that of N-(N-acetyl-L-tryptophanyl)-5-methoxytryptamine and confirmed that introducing substituted tryptamine into the amide chain of melatonin does enhance analgesic potency.