The structures of the new azoxy antibiotics maniwamycinsA and B have been determined by means of spectral analyses and chemical studies.ManiwamycinsA and B are new antifungal antibiotics produced by a Streptomyces sp. In the preceding paper, we reported the taxonomy of the producing strain, fermentation, isolation, physico-chemical properties and biological properties of these antibiotics.1}In this paper, we describe the structure determination of maniwamycins A and B. Structure of ManiwamycinA The fast atom bombardment (FAB)-MS ofmaniwamycin A revealed an ion peak at m/z 199 (M +H).Through the high-resolution electron impact (HREI)-MS of the ion peak at m/z 198 (found 198.1363; calcd for C10H18N2O2 198. 1 369) the molecular formula ofmaniwamycin A was established as C10H18N2O2. The UVabsorption maximumat 235nm (e 12,400) and the characteristic band near 1500cm"1 in the IR spectrum implied the presence of an azoxy group. 13C NMRdata (Table 1) showed the presence of three C-methyls, three methylenes, one sp3 methine, two olefinic methines and one carbonyl carbon. Assignment of the signals for C-l', C-2' and C-3' were confirmed by the 1H-13C correlation spectroscopy (COSY) spectrum (Fig. 1). The position of the oxygen atom in the azoxy group was determined to be on the olefin group side by the proton chemical shift (S 4.52) of the sp3 methine adjacent to the azoxy group2~4) and by the UVabsorption maximum.2) This is similar to elaiomycin5) and

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A new aminoglycoside antibiotic belonging to the apramycin group, KA-5685 has been isolated from the culture broth of Saccharopolyspora hirsuta ATCC 278751). This strain also coproduced apramycin2). In this communication, the isolation, characterization and structural elucidation of the antibiotic KA-5685 are reported. S. hirsuta ATCC 27875 was cultured at 27•‹C for 5 days in 500-ml Erlenmeyer flasks containing 50 ml of a medium, composed of 2 % glycerol,

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