Aeruginosins from a <i>Microcystis</i> sp. Bloom Material Collected in Varanasi, India

Two novel biologically active short peptides, aeruginosins IN608 and IN652, were isolated from the cyanobacterium <i>Microcystis</i> sp. strain BHU006, which was collected from Durgakund water reservoir in Varanasi, India. Aeruginosins IN608 and IN652 are linear modified peptides containing four building blocks, one of which is the arogenate-derived modified amino acid 2-carboxy-6-hydroxyoctahydroindole. Aeruginosin IN608 and aeruginosin IN652 inhibit the activity of the proteolytic enzyme trypsin with IC₅₀’s of 4.3 and 4.1 μM, respectively