Antimicrobial and hemolytic activities of cyclolipopeptides.

<p>Sequences of the cyclolipopeptides grouped according to their structure are depicted. Antimicrobial activity is given as the minimal concentration that inhibits growth (MIC). The MIC axis is in logarithmic scale and for each sequence the lowest values of the MIC range are represented. The hemolytic activity was measured at 250 μM and is expressed as a percentage compared to melittin as a standard. Data can be found in Tables C and D in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0151639#pone.0151639.s001" target="_blank">S1 File</a>.</p

Solid-Phase Synthesis of Cyclic Depsipeptides Containing a Tyrosine Phenyl Ester Bond

The first solid-phase strategy for the synthesis of cyclic depsipeptides containing a phenyl ester linkage in their structure is described. The key steps of the synthesis were the formation of the phenyl ester bond and the on-resin head-to-side-chain cyclization. The amino acid configuration significantly influenced the formation and the stability of the cyclic depsipeptides. The presence of a l-Tyr¹ and a d-Tyr⁷ led to the most stable sequences

Relationship between phytotoxicity and hemolysis at 250 μM of cyclolipopeptides derived from BPC194 active against three pathogens with MIC <25 μM.

<p>Peptides in bold display MIC <12.5 μM against three pathogens.</p

Structure of cyclolipopeptides derived from BPC194.

<p>Structure of cyclolipopeptides derived from BPC194.</p

Kinetics of survival of <i>X</i>. <i>axonopodis</i> pv. <i>vesicatoria</i> in the presence of BPC194 (△) or selected cyclolipopeptides.

<p>Bacterial suspensions were untreated (□) or treated with 5 μM concentrations of <b>BPC500</b> (⧫), <b>BPC676</b> (●), <b>BPC686</b> (■), <b>BPC714</b> (+) and <b>BPC728</b> (π). Viable cells were determined at different time intervals.</p

Sequences of the cyclolipopeptides.

<p>Sequences of the cyclolipopeptides.</p

Phytotoxicity of BPC194 and a set of cyclolipopeptides.

<p>Phytotoxicity was determined at 50, 100, 150, and 250 μM, as the size of the lesions in infiltrated tobacco leaves. Phytotoxicity was compared to melittin. Vertical bars within each column indicate confidence interval at the mean.</p

Synthetic Cyclolipopeptides Selective against Microbial, Plant and Animal Cell Targets by Incorporation of D-Amino Acids or Histidine

<div><p>Cyclolipopeptides derived from the antimicrobial peptide c(Lys-Lys-Leu-Lys-Lys-Phe-Lys-Lys-Leu-Gln) (<b>BPC194</b>) were prepared on solid-phase and screened against four plant pathogens. The incorporation at Lys⁵ of fatty acids of 4 to 9 carbon atoms led to active cyclolipopeptides. The influence on the antimicrobial activity of the Lys residue that is derivatized was also evaluated. In general, acylation of Lys¹, Lys² or Lys⁵ rendered the sequences with the highest activity. Incorporation of a D-amino acid maintained the antimicrobial activity while significantly reduced the hemolysis. Replacement of Phe with a His also yielded cyclolipopeptides with low hemolytic activity. Derivatives exhibiting low phytotoxicity in tobacco leaves were also found. Interestingly, sequences with or without significant activity against phytopathogenic bacteria and fungi, but with differential hemolysis and phytotoxicity were identified. Therefore, this study represents an approach to the development of bioactive peptides with selective activity against microbial, plant and animal cell targets. These selective cyclolipopeptides are candidates useful not only to combat plant pathogens but also to be applied in other fields.</p></div

General strategy for the synthesis of cyclolipopeptides

<p>General strategy for the synthesis of cyclolipopeptides</p

Sequences, retention times and purities on HPLC, and mass spectrometry data of lipopeptides.

<p>Sequences, retention times and purities on HPLC, and mass spectrometry data of lipopeptides.</p