A Cytotoxic Melanin Precursor, 5,6-Dihydroxyindole, from the Folkloric Anti-Cancer PlantRhaphidophora Korthalsii

Abstract 5,6-Dihydroxyindole (1a) was isolated by bioactivity-directed fractionation from fresh leaves of Rhaphidophora korthalsii. The unstable compound and its stable diacetate (1b) were characterized spectroscopically and confirmed by synthesis. The ED50 of 1a against P388 cells was 3.5 μg/ml. Key Words: Rhaphidophora korthalsii 5,6-dihydroxyindole5,6-diacetoxyindolecytotoxicity