Saccharide antibiotics

Novel Saccharide Antibiotics by Gene Replacement Experiments... 

The synthesis of the trimeric cyclic saccharide antibiotic anthrobacilin A has been reported. The structure of antibiotic T01718B has been examined by synthesis of the epimers 26. ... 

Some saccharides are branched and these types are found as constituents of various natural products. For example, D-apiose occurs widely in plant polysaccharides. Antibiotics produced by the microorganism Streptomyces are another rich source of branched chain sugars. 

S. antibioticus produces another unusual macrolide antibiotic [45] called chlorothricin (57) containing, in addition to the aglycone (modified methylsalicylic acid), saccharides, dideoxyhexoses in the first place. Their biosynthesis was investigated by the incorporation of stable isotopes [45-47]. The compounds were only active in a synthetic medium and inactive in a complex one [48]. Compounds designated MC031-034 (58-61) are similar to chlorothricin mentioned above and were isolated from the cultivation broth of Streptomyces sp. collected in Japan. Another compound, 2-hydroxychlorothricin (62), with antitumor activity, was isolated [66] from Streptomyces K818. 

South-American soil was a good source [54] of S. curacoi producing the antibiotic curamycin (58). This antibiotic also contains unusual saccharides, i.e. L-lyxose and 4-O-methyl-D-fucose. 

High-Fructose Corn Syrup (HFCS) occurs as a water white to light yellow, somewhat viscous liquid that darkens at high temperatures. It is a saccharide mixture prepared as a clear, aqueous solution from high-dextrose-equivalent corn starch hydrolysate by the partial enzymatic conversion of glucose (dextrose) to fructose, using an insoluble glucose isomerase preparation that complies with 21 CFR 184.1372 and that has been obtained from a pure culture fermentation that produces no antibiotics. It is miscible in all proportions with water. 

Scheme 13. The antitumor antibiotics daunomycin (29 = daunorubicin) and adiiamycin (30 = doxorubicin) are polyketides with an attached deox ugar moiety. Polyketide oligodeoxy-saccharides characterized by one or more deoxysaccharide chains include the anthracyclines arugomycin (31) [73a] and viriplanin (32), the angucyclines landomycin A (see 12 in Scheme 6) and vineomycin A, (33 = P1894B [74]), and the aureolic acid antibiotics mithramycin (34) and UCH9 (35).Also,orthosomydn antibiotics, such as avUamycin A (36) can be considered as polyketide oligodeoxysaccharides...

As its methyl thioglycoside, lincosamine (6-amino-6,8-dideoxy-D- /7r/tro-D-ga/acto-octo-pyranose) is the saccharide portion of the clinically important antibiotic lincomycin. Racemic 3-methyl lincosaminide was prepared by Danishefsky and coworkers [140] who utilize the hetero Diels-Alder addition of crotonaldehyde to the Danishefsky s diene 268 to afford E) cA-2-(l-propenyl)-3-(benzyloxy)-2,3-dihydro-4-pyrone. The ZnBr2-catalyzed cycloaddition of 268 to A-carbobenzoxy-0-protected-D-a//(9-threoninal gives a 2 1 mixture of adducts 270 and 271 that has been converted into 272, a protected form of 6-amino-6,8-dideoxy-D- 77f/iro-L-ga/acto-octopyranose (Scheme 13.78). Analogously, the ZnBr2-promoted cycloaddition of the D-threoninal derivative 273 to 268 leads to a 3 1 mixture of adducts. The major adduct... 

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