Arthropeptide A, an antifungal cyclic tetrapeptide from isolated from disease suppressive compost.

In an effort to describe bioactive antifungal compounds from antagonistic bacteria with potential for biocontrol of plant pathogens, a strain of was collected from plant disease suppressive compost prepared from composted material of marine origin. Few natural products have been characterized from the non-filamentous Actinobacteria genus . A new cyclic tetrapeptide, cyclo-(L-Pro-L-Leu-L-γHyp-L-Tyr); arthropeptide A (), was isolated from the EtOAc soluble culture filtrate extract of M9-17 grown in MOLP broth. Its structure was confirmed by HRMS, interpretation of NMR data, and a modified Marfey's method. Arthropeptide A () displayed antifungal activity towards , the causal agent of disease in numerous host plant species, which had shown the previous susceptibility to . The newly identified compound may be responsible, in part, for the inhibitory activity of the bacterium against fungal plant pathogens.