(1)H-NMR guided fractionation of the EtOAc extract from the culture of Myrothecium gramminum (strain no. 3.1968) led to the isolation of eight cytotoxic trichothecene macrolides ( 1 - 8), all being substantially inhibitory against HepG2 (human hepatocellular carcinoma) and KB (human nasopharynyeal epidermoid tumor) cell lines with IC (50) values ranging from 2.2 to 12.2 mug/mL. Their inactivity to or weaker action on Vero cells (IC (50) values > 20 microg/mL, originated from the African green monkey kidney) highlighted preliminarily the nature of the selective cytotoxicity of the fungal metabolites against the test cancer cell lines. In addition, verrucarin A ( 1) and roridin A ( 5) were found to be potent inhibitors of the radial growth of Echinochloa crusgalli with corresponding IC (50) values of (7.96 +/- 0.31) x 10 ( - 6) and (9.18 +/- 0.44) x 10 ( - 6) M, respectively, which were more potent than that of the positive control (2,4-dichlorophenoxyacetic acid) [(9.40 +/- 0.04) x 10 ( - 5) M].