Streptomyces plicatus

Three more antibiotics, all discovered about 1953, are also derivatives of cytosine. Amicetin, bamicetin and plicacetin may all be isolated from Streptomyces plicatus and all have some activity against some acid-fast and Gram-positive bacteria as well as some other microbial systems (69MI21301). Structural work in this area is fascinating (62JOC2991). 

Antibiotic substances related in structure to amicetin have been isolated from other Streptomyces cultures. Sensi and coworkers166 have isolated amicetin B, which only differs from amicetin by the absence of the dexfro-a-methylserine moiety in its structure. This antibiotic substance is identical with Plicacetin, an antibiotic substance isolated by Haskell and coworkers167 176 from Streptomyces plicatus. The structural relationship of Plicacetin (amicetin B) to amicetin was also established by partial synthesis.167 Acylation of cytosamine (XXXVII) with p-nitrobenzoyl chloride, followed by reduction of the nitro group of the mono-acylated derivative, yielded Plicacetin. 

Mithramycin (Mithracin ) is a weakly acidic complex glycoside of the tetrahydroan-thracene chromomycine. It is obtained from Streptomyces plicatus. Its ability to inhibit nucleic acid synthesis appears to be primarily on RNA even though binding to DNA has also been demonstrated. Intercalation does not appear to be part of the process. It was proposed that binding of this antibiotic to the DNA template may simply prevent the polymerase enzyme from reading it. The result is inhibition of RNA synthesis. 

Bamlcetin a pyrimidine antibiotic (see Nucleoside antibiotics) synthesized by Streptomyces plicatus. It is effective in low concentrations against Mycobacterium tuberculosis. Structurally, it is very similar to Amicetin (see), differing merely in the structure of the amosamine moiety which possesses a monome-thylamino group in place of the dimethylamino group. 

Amicetin B (Plicacetin) Streptomyces plicatus Cytosine Amicetose Cytidine... 

C28H40N6O9 604.659 From Streptomyces plicatus. Shows antibiotic props. Cryst. Sol. MeOH, EtOH, acids fairly sol. EtOH, butanol, CHCI3, H2O poorly sol. hexane. 

C24H33N5O7 503.554 Nucleoside antibiotic. Isol. from Streptomyces plicatus. Active against gram-positive bacteria and mycobacteria. Needles (MeOH). 

A simple procedure described for the detection of encarbohydrate moiety of ribonuclease B has a-D-mannopyranosyl residues as terminal non-reducing groups, but such residues are lost as part of an oligosaccharide on action of the endo -o-l-acet-amido-2-deoxyglucanase, agarose immobilized concanavalin A was used to separate radioactive substrate (absorbed) from radioactive product (unadsorbed). The assay was used to follow the preparation of the enzyme from Streptomyces plicatus. 

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