Extract of Croton hurnilis L. were shown to contain N - [N - (2 - methylpropanoyl) - L glutaminoyl] - 2 - phenylethylarnine, N - [N - 2R - methylbutanoyl) - L - glutaminoyl] - 2 phenylethylamine, 2 - IN - (2 - methylpropanoyl)] - N - phenylethylglutarimide and 2 - [N - (2R methylbutanoyl)] - N - phenylethylglutarimide. Structural proof was based on acid degradation, spectral studies as well as the synthesis of N - [N - (2 - methylpropanoyl) - L - glutaminoyl] - 2 phenylethylamine and 2 - [N - (2 - methylpropanoyl] - N - phenylethylglutarimide.