Leucine aminopeptidase M inhibitors, cyanostatin A and B, isolated from cyanobacterial water blooms in Scotland

Abstract Two leucine aminopeptidase M inhibitors, cyanostatin A and B, were isolated from cyanobacterial water blooms at Loch Rescobie in Scotland, and specifically from a Microcystis species. Both inhibitors were lipopeptides containing 3-amino-2-hydroxydecanoic acid and weak inhibitors of protein phosphatase (PP2A). Both strongly inhibited the activity of leucine aminopeptidase M with IC 50 values of 40 and 12 ng/ml, respectively.