Extraction of the synthetic lytic peptide, cecropin B, from biological fluid and analysis using reversed-phase...

The lytic peptide cecropin B, originally isolated from the giant silk moth Hyalophora cecropia, has been found to possess antibacterial and cell lysis properties in vitro and some anticancer activity in vivo. An HPLC method was developed to study synthetic cecropin B concentrations in biological fluids. Cecropin B was recovered from culture medium by solid-phase extraction (40.0 +/- 2.4%), whereas in plasma it was highly protein-bound. The peptide was dissociated from proteins by citric acid and recovered by ultrafiltration (64.6 +/- 5.9%) and was unstable in plasma (half-life, 0.57 +/- 0.11 h). These analytical methods will facilitate future in vivo pharmacokinetic studies.