Optimization of anabaenopeptin extraction from cyanobacteria and the effect of methanol on laboratory manipulation

Anabaenopeptins are commonly occurring bioactive peptides of cyanobacterial origin. Cyanobacteria (blue-green algae) are known to be capable of producing a large number of biologically active peptides, but the widespread occurrence of anabaenopeptins in particular, makes them ideal candidates for investigating the reasons that cyanobacteria produce such a complex spectrum of peptides and the wider implications of their natural function(s). Despite the identification of these peptides in cyanobacterial samples, little is known about the concentrations produced. For this reason, methods for the quantitative extraction of anabaenopeptins from lyophilized cyanobacterial cells were optimized. Higher yields of anabaenopeptins were obtained using aqueous methanol extraction than using water alone. However, repeat extractions using 50, 70 or 90% aqueous methanol did not result in significantly different total yields of the anabaenopeptin variants, ABPN-A and -B. Similarly, little difference was found in the quantification of purified ABPN-A and -B by high performance liquid chromatography with photodiode array detection (HPLC-PDA) when analyzed in methanol solutions of different concentrations. The effects of solvent concentration on the laboratory handling of ABPN-A and -B in glass and plastic containers were also investigated. Significantly lower concentrations of dissolved ABPN-A and -B were found when aqueous solutions came into contact with plastics, but not 50 or 100% methanol.