似我萌and broader spectrum of cytotoxic activities against all six human tumor cell lines with IC50values of all lower than50l M.
In contrast to the harmine series,9-substituted b-carbo-line series failed to exhibit obviously increased cytotoxi-cities.The compound3having no substituent on ring system showed a good cytotoxic activity against PLA-801and Lovo cell pounds4a–d displayed al-most equal cytotoxic activities while the compound4d showed higher and selective cytotoxic activity against Lovo cells with IC50values of48l M.
