Antimicrobial dendrimeric peptides

Dendrimeric peptides selective for microbial surfaces have been developed to achieve broad antimicrobial activity and low hemolytic activity to human erythrocytes. The dendrimeric core is an asymmetric lysine branching tethered with two to eight copies of a tetrapeptide (R4) or an octapeptide (R8). The R4 tetrapeptide (RLYR) contains a putative microbial surface recognition BHHB motif (B = basic, H = hydrophobic amino acid) found in protegrins and tachyplesins whereas the octapeptide R8 (RLYRKVYG) consists of an R4 and a degenerated R4 repeat. Antimicrobial assays against 10 organisms in high‐ and low‐salt conditions showed that the R4 and R8 monomers as well as their divalent dendrimers contain no to low activity. In contrast, the tetra‐ and octavalent R4 and R8 dendrimers are broadly active under either conditions, exhibiting relatively similar potency with minimal inhibition concentrations < 1 µm against both bacteria and fungi. Based on their size and charge similarities, the potency and activity spectrum of the tetravalent R4 dendrimer are comparable to protegrins and tachyplesins, a family of potent antimicrobials containing 17–19 residues. Compared with a series of linear