Shishijimicin C, a novel antitumor agent isolated from the ascidian Didemnum proliferum, exhibits highly potent cytotoxicities and anti-tumor activities. This compound also serves as a click chemistry reagent, featuring an alkyne group that can partake in copper-catalyzed azide-alkyne cycloaddition (CuAAc) with azide-containing molecules.

Shishijimicin C (compound 3) exhibits potent cytotoxic activity, outstripping the efficacy of both adriamycin and etoposide. Its notable action against cancer cells, particularly P388 leukemia cells, highlights its potential as a therapeutic agent. Compound 3 does this by targeting the DNA within cancer cells, causing severe damage and subsequently triggering cell death. This mechanism underpins its proposed use as an anticancer drug.