No abstract

No abstract

Seldomycin factor 5 is shown to be 4-0-[2,6-diamino-2,4,6-trideoxy-a-D-xylo-hexo. pyranosyl]-6-O-[2, 3-diamino-2, 3-dideoxy-4-O-methyl-a-D-xylo-pyranosyl]-2-deoxystreptamine.Seldomycin factor 5 is the most active antibiotic isolated from the fermentation broth of Streptomyces hofunensis. The taxonomy and fermentation of this organism have been described.) The isolation procedure and the physical properties'' of seldomycin factor 5 characterize this antibiotic as a watersoluble basic compound of the aminoglycoside class. The antibacterial spectrum of seldomycin factor 5 indicates that this compound is probably a close relative of the kanamycin-gentamicin group. Moreover, the activity or lack of activity of seldomycin factor 5 against a number of isolates having known mechanisms of resistance, involving in each case the modification of a functional group, was strongly suggestive of the absence or presence of these groups in the structure of seldomycin factor 5.2) Spectrometric analysis of seldomycin factor 5 and a number of degradation products has allowed for the definition of the structure and stereochemistry of this antibiotic. Results and DiscussionThe mass spectrum of the free base of seldomycin factor 5 (Table 1) shows an M+ I peak at 451 amu in agreement with the molecular formula C18H38N6O72) The degradation pattern is indicative of a diglycoside of 2-deoxystreptamine in which each of the three basic carbohydrate units has the same molecular formula, namely C6H,4N203. The per-N-acetyl-per-O-trimethylsilyl derivatives) of seldomycin factor 5 was prepared and the mass spectrum obtained from this derivative (Table 2, Fig. 1) indicates the presence of six primary or secondary amino groups in the parent molecule, two in each of the subunits. Also, each of two adjacent subunits of the parent bears an hydroxyl group.++ Also known as XK-88-5 * Present address:

The structure of XK-62-2 has been firmly established to be 6'-N-methylgentamicin C1a (3) by application of spectroscopic methods in conjunction with chemical degradation. The data obtained in every case are completely consistent with the proposed structure. The gentamicin C complex1) has been reported to consist of 3 antibiotics1,3) designated C1, C. and Cla (1, 2 and 4)4). These compounds differ only in the methyl substitution pattern of the hexo-or heptopyranoses attached to the 4-position of 2-deoxystreptamine-purpurosamines A, B and COQ. We now wish to report the structure of XK-62-26.n which is 6'-Nmethylgentamicin C1a (3) the missing member of the gentamicin C complex. This compound completes the identification of all monoand di-methyl substituted purpurosamine compounds.