Chromatographic fractionation of a dichloromethane extract from the leaves of Piper scutifolium yielded two new isobutyl amides, scutifoliamide A ( 1) and scutifoliamide B ( 2), together with the known compounds piperolactam C ( 3), piperovatine ( 4), piperlonguminine ( 5), corcovadine ( 6), isopiperlonguminine ( 7), and isocorcovadine ( 8). From the dichloromethane extract from the leaves of P. hoffmannseggianum two new isobutyl amides, hoffmannseggiamide A ( 9) and hoffmannseggiamide B ( 10), were obtained together with the known compounds isopiperlonguminine ( 7) and isocorcovadine ( 8), sitosterol, and stigmasterol. The structures of the new compounds were established on the basis of spectroscopic data analysis. The inhibitory activity of compounds 1-10 against the growth of the fungi Cladosporium sphaerospermum and C. cladosporioides was determined by bioautography.