The chemical structures for the novel phosphate-containing antitumor agents CI-920 (1), PD 113 270 (2), and PD 113271 (3) were determined by a combination of spectral and chemical means. Extensive analysis of NMR spectral data allowed tentative structures to be assigned for these compounds and their derivatives. These structures were confirmed by reducing CI-920 to 8-methyl-l-octadecanol and by cleaving dephosphorylated with sodium periodate to identified products.

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A new inhibitor of adenosine deaminase was isolated from the fermentation broths of an unidentified actinomycete, ATCC 39365. The inhibitor was shown by spectroscopic analysis to be a 2'-chloro analogue of pentostatin. Acetolysis of the glycosylic linkage gave l,3,5-tri-0-acetyl-2-chloro-2-deoxy-a,/3-D-ribofuranoses, thus establishing the structure of the nucleoside as (8R)-3-(2-chloro-2-deoxy-/3-D-ribofuranosyl)-3,6,7,8-tetrahydroimidazo[4,5d][l,3]diazepin-8-ol (2'-chloropentostatin). An unambiguous synthesis of the sugar moiety, along with its D-arabino isomer, was developed.(1) The chemical name is (8i?)-3-(2-chloro-2-deoxy-d-D-ribofuranosyl)- 3,6,7,8-tetrahydroimidazo[4,5-d][l,3]diazepin-8-ol.(2) Preliminary details of his work have been presented. See:

The isolation and properties of PD 118,576, a new cytotoxic antibiotic obtained from the culture broth of a Streptomyces sp., are described. The structure of this compound was established by spectral analyses of the parent compound and its triO -acetyl derivative. PD 118,576 proved to be related to the bafilomycins and therefore is a new member of this recently discovered family of macrolide antibiotics. During the course of our antitumor screening program a complex of antitumor macrolide antibiotics was isolated from the fermentation broth of an unidentified Streptomyces (WP 3913). The major component of this complex, PD 118,576, was found to exhibit in vitro activity against L1210 lymphocytic leukemia and HCT-8 human colon adenocarcinoma cell lines. The characteristics of 1450 THE JOURNAL OF ANTIBIOTICS NOV. 1985

Two antibiotics were isolated from culture broths of a Streptonryces sp. and identified as 8"-hydroxypactamycin and 7-deoxypactamycin. The latter antibiotic was shown to be identical to cranomycin. An additional compound, 8"-hydroxypactamycate, was also isolated.In the course of screening for new antitumor agents, a Streptomyces sp. (WP-4371) was found that produces a novel antibiotic with in vitro and in vivo antitumor activity. Fractionation of fermentation beers obtained from this organism yielded a new compound, PD 118,309, with a UV absorption spectrum identical to that of pactamycin (1)1-3). Examination of the 1H and 13C NMR spectra of these two compounds showed that PD 118,309 is 8"-hydroxypactamycin (2)'. The IC50 of PD 118,309 vs. leukemia L1210 cells is 0.014,ug/ml; the in vivo activity against lymphocytic leukemia P388 is presented in Table 1. During an earlier fractionation a related antibiotic, designated PD 113,618, was isolated in addition to PD 118,309.The NMR spectral data for PD 113,618 revealed that it is 7-deoxypactamycin (3). A comparison of the spectral properties of PD 113,618 and a sample of cranomycin4,5) an antibiotic reported