The role played by a sustained angiogenesis in cancer and other diseases stimulates the
interest in the search for new antiangiogenic drugs. In this manuscript, we provide evidence that
1,8- dihydroxy-9,10-anthraquinone (danthron), isolated from the fermentation broth of the marine
fungus Chromolaenicola sp. (HL-114-33-R04), is a new inhibitor of angiogenesis. The results obtained
with the in vivo CAM assay indicate that danthron is a potent antiangiogenic compound. In vitro
studies with human umbilical endothelial cells (HUVEC) reveal that this anthraquinone inhibits
certain key functions of activated endothelial cells, including proliferation, proteolytic and invasive
capabilities and tube formation. In vitro studies with human breast carcinoma MDA-MB231 and
fibrosarcoma HT1080 cell lines suggest a moderate antitumor and antimetastatic activity of this
compound. Antioxidant properties of danthron are evidenced by the observation that it reduces the
intracellular reactive oxygen species production and increases the amount of intracellular sulfhydryl
groups in endothelial and tumor cells. These results support a putative role of danthron as a new
antiangiogenic drug with potential application in the treatment and angioprevention of cancer and
other angiogenesis-dependent diseases.