Syncarpamide, a new antiplasmodial (+)-norepinephrine derivative from Zanthoxylum syncarpum

A new (+)-norepinephrine derivative, syncarpamide (1), along with a known coumarin, (+)-S-marmesin (2), and one known alkaloid, decarine (3), have been isolated from the stem of Zanthoxylum syncarpum. The structure of compound 1 was elucidated on the basis of 1D and 2D NMR, MS, IR, optical rotation, and CD analyses. Its absolute stereochemistry was elucidated by synthesis of its enantiomer and subsequent comparison of CD data. Characterizations of compounds 2 and 3 were based on spectral analysis and comparison with reported data. Compounds 1 and 3 showed antiplasmodial activity, with IC50 values of 2.04 and 1.44 muM against Plasmodium falciparum D-6 clone and 3.06 and 0.88 muM against P. falciparum W-2 clone, respectively. Compound 3 showed cytotoxicity at 56.42 muM, whereas compound 1 was not cytotoxic at 10.42 muM. Compound 1 was tested for hypotensive activity, but no activity was observed. Compound 2 showed no antiplasmodial or antimicrobial activities.