Biologically Important Phenoxazines and Industrial Uses

Recent investigations have shown the existence of a number of phenoxazine derivatives in nature, which, with a few exceptions only, 

Harfenist (Burroughs Wellcome Co.), British Patent 983,600 (1965) Chem. Abstr. 63, 615 (1965). 

The actinomycins represent a group of closely related, very toxic antibiotics produced by certain species of Streptomyces. Actinomycin A which was discovered in 1940 by Waksmann and WoodrufF87 was 

Eighteen different actinomycins have been described, differing in the amino acid sequence in the peptide chains and the total synthesis of some have been reported.88 Much of our knowledge of this class is due to the work of Brockmann, who has published comprehensive reviews.47,89 Recently Weinstein et al.90 reported the synthesis of simple actinomycin analogs, which might yield effective antibacterial compounds or antitumor agents less toxic than the natural actinomycins. 

A number of enzymes, isolated from mammalian tissues,91 from cell-free extracts of Streptomyces antibioticus,92 and from the leaves of 

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