Cytotoxic Dimeric Quinolone-terpene Alkaloids from the Root Bark of Zanthoxylum Rhetsa

Four quinolone-terpene alkaloids, chelerybulgarine (1), 2'-episimulanoquinoline (3), 2,11-didemethoxyvepridimerine B (4), and rhetsidimerine (5) were isolated from the root bark of Zanthoxylum rhetsa DC. Chelerybulgarine (1) is a C-C linked terpene alkaloid where the C-6 of dihydrochelerythrine is linked to C-11 of the sesquiterpenoid 10β-methoxybulgarene. 2'-Episimulanoquinoline is a dimeric alkaloid containing dihydrochelerythrine and 8-methoxy-N-methylflindersine moieties, whereas 2,11-didemethoxyvepridimerine B and rhetsidimerine are dimeric prenylated quinolone alkaloids. Seven of the isolated compounds exhibited weak cytotoxicity when tested against a panel of six human stomach-cancer cell lines.