Bioactivity-directed fractionation of the MeCOEt extract of Trichilia emetica (Meliaceae) resulted in the isolation of the limonoids nymania 1 (1), drageana 4 (3), trichilin A (4), rohituka 3 (5), and Tr-B (7) and the novel seco-A protolimonoid 8. Of these, nymania 1 and Tr-B showed selective inhibitory activity toward DNA repair-deficient yeast mutants. The isolation, structure elucidation, 13C NMR spectral assignments, and biological activities of these compounds are reported.