Synthesis and anti-cancer activity of naturally occurring 2,5-diketopiperazines.

Three naturally occurring oxyprenylated diketopiperazines were synthesized and preliminarily tested as growth inhibitory agents in vitro against various cancer cell lines. The compounds were tested on six human cancer cell lines with different sensitivity to proapoptotic stimuli using the MTT colorimetric assay. The data revealed that of the chemicals under study only deoxymicelianamide (11) displayed the highest activity, recording mean IC50 growth inhibitory values ranging from 2 to 23 μM. A comparative study with the non-geranylated saturated derivative of (11) revealed the importance of the presence of the geranyloxy side chain and the exocyclic 2,5-DPK double bond moiety for the observed activity.