Peroxy acid as a partial structure of neocarzinostatin (NCS) chromophore.

Sir: Neocarzinostatin (NCS) chromophore was obtained as a separable component from polypeptide antitumor antibiotic NCS by us1,2) and GOLDBERG et al.3,4), independently. This chromophore, which was demonstrated to have biological activities such as growth inhibition of bacterial and tumor cells1), inhibition of DNA synthesis in cultured mammalian cells, strand scission of DNA in vitro and in vivo5,6) and inhibition of protein kinase7,8), is thought to be the active center of NCS. Considerable evidence shows that bacterial and tumor cellular DNA is the most important target in the action of NCS and the chromophore. The NCS chromophore, as well as NCS, is inactivated irreversibly under irradiation with ultraviolet light, exposure to heat or incubation with mercaptans prior to the introduction to DNA. The chromophore exhibited an optical rotation of [a]li -171°1) , the molecular weight of 661 and the molecular formula of C35H35NO12, by mass spectrometry9). Two compounds, 2-hydroxy-5methoxy-7-methyl-l-naphthalenecarboxylic acid (I)2) and N-methylfucosamine (II)9) have been proposed as components of this compound. Compounds I and II have no antibacterial activity. Therefore, it has been suggested that the residual part of unknown structure is responsible for biological activities"