Macbecins I and II, new antitumor antibiotics. II. Isolation and characterization.

Abstract
New antitumor antibiotics, macbecins I and II, were isolated from the culture broth of Nocardia sp. No. C-14919. Macbecins I and II belong to the ansamycin group and have a benzoquinone and hydroquinone nucleus, respectively. Both showed antitumor activity against murine leukemia P 388 in vivo.