Mithramycin compound

Mithramycin (24) bears the terminal sugar unit -mycarose. By a similar preparation as for the methyl-branched glycals and the -enantiomer of namely the labile g-mycaral 40 w s obtained ( ). Its NIS condensation with the 3, 4 -Saol disaccharide proceeds smoothly, but the reaction turned out to be rather slow with respect to the stability of the g-mycaral. This results in only a modest yield (12%) of the trisaccharide which was hydrogenolyzed to compound 4. This in turn constitutes an isomer of the trisaccharide sequence in... 

Mithramycin shows a completely P-linked chain of D-conflgurated saccharides. This requires a totally different approach for the synthesis which is also done by application of the DBE method. The previously obtained disaccharide 180 is P-glycosylated with the monosaccharide precursor 176 to give the trisaccharide 185. After reductive debromination (Bu3SnH), an acid deformylation deblocked the C-3" position which is oxidized with pyridinium dichromate. Nucleophilic attack at the carbonyl group by methyl lithium affords a 1 1.2 mixture of 186 and 187 none of which is the desired compound [93]. Obviously, the methyl branch is formed exclusively in the axial way. 

Members of this group feature tricyclic carbon framework decorated with two oligosaccharide chains. Mithramycin 48 and chromomycin A3 49 are two aureolic acids that have found their use in cancer chemotherapy. These compounds, interacting with Mg2+, bind GC-rich DNA in a nonintercalative way, and sugar chains are indispensable in stabilizing metal-antibiotic complexes. Carbohydrates are... 

Actinomycin D is a peptide antibiotic, produced by Streptomyces parvulu. It interacts with cellular DNA and inhibits the replication of mammalian viruses that depend on cellular functions, e.g., rabies virus [18]. Mithramycin is a related compound that inhibits influenza and pseudorabies viruses probably due to inhibition of host cell RNA polymerase II [18]. 

Aureolic acid, an antibiotic with antitumour activity isolated from a Strepto-myces species, has been shown to be identical with mithramycin [368, 369]. Acid hydrolysis of the compound has afforded [370] the aglycone chromo-mycinone (LXXVIIIb) and the sugars mycarose (LXXIXa), chromose C (LXXIXd), and oliose (LXXIXb). The points of attachment and sequence of the sugar chains, and the chirality of aureolic acid (LXXVIIIc) have been... 

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