Synthesen in der Polymyxin-Reihe. 7. Mitteilung. Synthese des hochaktiven cyclischen Decapeptids 7?

The synthesis of an antibiotic substance to which we assign the structure 7α, one of the four possible formulas proposed for natural polymyxin B1, is reported. Although both synthetic and the natural product have the same antimicrobial activity towards Brucella bronchiseptica in vitro (plate test), they are not identical, as shown by the lower optical rotation of the synthetic material.