Simplified hybrids of two anticancer bistetrahydroisoquinoline alkaloids ecteinascidin 743 and cribrostatin 4 and inhibitory activity against proliferation of cancer cells.

Ecteinascidin 743 is a famous marine drug used in anticancer treatments. In this work, a series of simplified hybrids/analogues have been synthesized by employing a newly developed chemistry that integrates the partial structural features of two anticancer bis-tetrahydroisoquinoline alkaloids ecteinascidin 743 and cribrostatin 4. The described Suzuki-coupling protocol enabled us to easily introduce variable functionalities at the C3 position of the basic skeleton of bis-tetrahydroisoquinoline alkaloids for the first time. Cytotoxic examination showed that analogue 21f exhibited inhibitory activities with IC₅₀ values in the low 10^-6 M range against the proliferation of the cancer cell lines A549, HepG2, and MDA-MB-231. This work reveals that diversifying the C3/C4 olefin in the skeleton of tetrahydroisoquinoline alkaloids is a useful means to generate potential pharmaceuticals.