Tumor-inhibiting antibiotic produced by Streptomyces griseoplanus from soil near Williamsburg, Iowa: De Voe et al., Antibiot. Annu. 1956-7, p 730. Peptide consisting of one mole α-alanine and two moles of a C6 diazo keto amino acid oxidizable to glutamic acid: E. L. Patterson et al., Antimicrob. Agents Chemother. 1965, 115-118. Anti-tumor activity: T. Hata et al., J. Antibiot. 26, 181 (1973). Toxicity: J. B. Thiersch, Proc. Soc. Exp. Biol. Med. 97, 888 (1958).