C-1027 enediyne chromophore: presence of another active form and its chemical structure.

structure in a 16-memberedmacrocyclic ring together with benzoxazolinate and aminosugar moieties as side chains7~9) (Fig. 1). The biological activity of the chromophore has been attributed to its ability to produce DNA damage following rearrangement to form a diradical species which abstracts hydrogen atoms from deoxyribose even in the absence of reducing agent10~ 12), in contrast to other enediyne antibiotics that required a reducing agent. It also has been shown that the