Akuammine and Dihydroakuammine, Two Indolomonoterpene Alkaloids Displaying Affinity for Opioid Receptors

Akuammine [1], an indolomonoterpene alkaloid, which is the major component of the seeds of Picralima nitida, was reduced to dihydroakuammine [4]. This compound has structural analogy with eseroline [7], for which affinity for opiate receptors was reported. The present investigation showed that 1 and 4 also bind (with lower affinity however) to mu and kappa opiate receptors. 1H- and 13C-nmr spectra of 1 and 4 have been fully assigned by 2D nmr experiments.