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From our efforts to identify marine natural products with cytotoxic and antitumor activity, we found an extract from a deep water marine sponge, Dragmacidon sp. Hallman, 1917, 2 which inhibited the in vitro growth of P388 murine leukemia cells. The active constituent of the extract is a new bis (indole) alkaloid, dragmacidin (la)(6, 7-dibromo-3-[5-(6-bromoindol-3-yl)-4-methyl-2-piperazinyl]-indol-4-ol. 3 In in vitro assays, la yielded IC^ values of 15 pg/mL against P388 cells and 1-10 pg/mL against A-549 (human lung), HCT-8 (human colon), and

MDAMB (human mammary) cancer cell lines. Although numerous marine natural products contain an indole or a tryptamine unit, 4 few marine natural products contain two such groups, and none, to our knowledge, contains an unoxidized piperazine ring. The molecular formula of la was deduced as C21H19-Br3N40 from HRFABMS and DEPT and proton-decoupled 13C NMR …