Bioactivity-guided fractionation of a MeOH extract of the stem bark of Cyathocalyx zeylanica afforded a moderately bioactive new azafluorenone alkaloid, cyathocaline, the structure of which was established as 5,7-dihydroxy-6-methoxy-1-methyl-4-azafluoren-9-one [1] with the aid of spectroscopic data.