The ecteinascidins (herein abbreviated Et or Et's) are exceedingly potent antitumor agents isolated from the marine tunicate Ecteinascidia turbinata. In particular, Et's 729, 743 and 722 have demonstrated promising efficacy in vivo, including activity against P388 murine leukemia, B16 melanoma, Lewis lung carcinoma, and several human tumor xenograft models in mice.
The isolation and characterization of natural Et 743 is taught in U.S. Pat. No. 5,089,273 which is hereby incorporated herein by reference. The preparation of synthetic Et 743 is taught in U.S. Pat. No. 5,721,362, which is hereby incorporated herein by reference.
The antitumor activities of ecteinascidin compounds, particularly Et 729 and Et 743 are well documented in the scientific literature. See for example, Goldwasser et al., Proceedings of the American Association for Cancer Research, 39: 598 (1998); Kuffel et al., Proceedings of the American Association for Cancer Research, 38: 596 (1997); Moore et al., Proceedings of the American Association for Cancer Research, 38: 314 (1997); Mirsalis et al., Proceedings of the American Association for Cancer Research, 38: 309 (1997); Reid et al., Cancer Chemotherapy and Pharmacology, 38: 329-334 (1996); Faircloth et al., European Journal of Cancer, 32A, Supp. 1, pp. S5 (1996); Garcia-Rocha et al., British Journal of Cancer, 73: 875-883 (1996); Eckhardt et al., Proceedings of the American Association for Cancer Research, 37: 409 (1996); Hendriks et al., Proceedings of the American Association for Cancer Research, 37: 389 (1996); the disclosures of which are hereby incorporated herein by reference.
Ecteinascidin 743 (Et 743) has the following structure: 
In view of the impressive antitumor activities of this class of compounds, the search continues for related structures that may possess equal or higher levels of antitumor activity. The present invention, which is directed to the isolation and characterization of natural metabolites of Et 743, is a result of these continued studies.