Saphenic Acid Derivatives

Figure 4. Saphenic acid derived isolates from Streptomyces sp.

Saphenic acid derivatives Esters R = R CO (63) Carbamates R = R NHCO (64)... 

Phenazines — These are dibenzopyrazine derivatives with fnnctional groups (hydroxy-, carboxy-) at C, and Cg and an oxygen or methyl gronp at Nj and N,o. There are also more complex structures, substituted phenazines, terpenoidal, and carbohydrate-containing phenazines and phenazines derived from saphenic acid. ... 

The more recently discovered and most unusual structures include the dimeric phenazine derivatives esmeraldin A (52) and esmeraldin B (53), which are produced by Streptomyces antibioticus Tii 2706 together with 49 [54]. Esmeraldins exhibit no antibacterial activity but 53 is effective against tumor cells. Much effort has been directed to the elucidation of the biosynthesis of the esmeraldins [55]. Some rare L-quinovose esters (55a-d) of saphenic acid have... 

The biosynthesis of saphenic acid (27) and derivatives thereof is based on addition of a one-carbon unit to phenazine-1,6-carboxylic acid (Iq, Scheme 3). The transfer of a methyl group from C2 of acetate is a well-known biosynthetic transformation and occurs when the thioester of acetyl coenzyme A is converted by acetyl-CoA carboxylase to malonyl-CoA. Malonyl-CoA undergoes a decarboxylative Claisen condensation with a mono-CoA thioester of phenazine-1,6-... 

---