DL-Propargylglycine HCl (DL-Propargyl Glycine HCl) is a potent irreversible inhibitor of cystathionine γ-cleaving enzyme and can be used in the study of heart failure.

Podophyllotoxinone a natural compound found in Dysosma versipellis shows inhibitory activity against L1210 leukemia and KB cells in vitro.

5-Hydroxymethyl-2-furancarboxylic acid (Sumiki's acid) is a naturally occurring human metabolite. Sumiki's acid was first identified in the urine of a leukemia patient who was excreting an abnormal amount of its glycine derivative. Sumiki's acid has been found to be a byproduct of the fungus Aspergillus and probably other species of fungi and yeast as well.