Puromycin is an aminonucleoside antibiotic produced by the bacterium Streptomyces alboniger. It inhibits protein synthesis by disrupting peptide transfer on ribosomes causing premature chain termination during translation.

Cantharidin was first isolated in 1810 by Pierre Robiquet, a French chemist then living in Paris, from Lytta vesicatoria. Secreted by many species of blister beetle, most notably by the 'Spanish fly' (Lytta vesicatoria), cantharidin inhibits protein phosphatases 1 and 2A (PP1, PP2A).