关键词: Lycogarubin C, Lycogalic acid, Suzuki-Miyaura偶联, DNA拓扑异构酶2

Lycogarubin C and lycogalic acid were first isolated independently by Steglich and Akazawa from Lycogala epidendrum in 1994. Lycogarubin C showed a potential cytotoxic activity. Lycogalic acid is an inhibitor of Hes1 dimmer of helix-loop-helix (bHLH) transcriptional repressor factor. Lycogalic acid is also the key intermediate in the biosynthesis of indolo[2,3-a]carbazole alkaloids that exhibit broad spectrum of bioactivity. Two efficient synthetic pathways of lycogarubin C and lycogalic acid were completed in this study. The first pathway included eight steps started from the commercially available indole and pyrrole to produce lycogarubin C with an overall yield of 27%. The second pathway was completed in seven steps with an overall yield of 25%. The key reactions are palladium-catalyzed Suzuki-Miyaura coupling of bis-iodo or bis-triflate derivative and indolboronic acid derivatives and Hinsberg-type synthesis of dimethyl N-benzyl-3,4-dihydroxypyrrole-2,5-dicarboxylate, respectively. Treatment of lycogarubin C with sodium hydroxide in ethanol under refluxing followed by acidification afforded lycogalic acid quantitatively. Lycogarubin C and lycogalic acid showed the antiproliferative activities against four human tumor cell lines of MDA-MB-231, A549, HeLa and PC3. Further study showed that lycogarubin C inhibited the activity of DNA topoisomerase 2.

Key words: lycogarubin C, lycogalic acid, Suzuki-Miyaura coupling, DNA topoisomerase 2