Total synthesis of biologically active lipoteichoic acids

Abstract

Lipoteichoic acids (LTAs) are found in the Gram positive bacteria cell wall and consist of a lipid anchor connected to a repeating unit linked together with phosphate esters. Due to the resemblance with the immune active lipopolysaccharides (LPSs) found in Gram negative bacteria, there has been interest in studying their biological role. Isolation from bacteria is complicated, and has led to inconsistent conclusions. The best way to avoid biologically active impurities in the LTA is therefore chemical synthesis, but it was not until the total synthesis of Staphylococcus aureus LTA that a clear biological activity of synthetic material could be observed. This successful synthesis was followed up by the synthesis of derivatives as well as the preparation of two other LTAs, from Streptococcus pneumoniae and Streptococcus species DSM 8747, respectively.