Diketopiperazines from two strains of South China Sea sponge-associated microorganisms

The paper reports the isolation and structural elucidation of seven diketopiperazines from the title microorganisms. Although all isolates are known, three of which were isolated from the actinomycetes for the first time. And this is also the first report to isolate four DKPs from the D. avara-associated microorganism.

Research highlights
► Three diketopiperazines were isolated from the actinomycetes for the first time.
► The first report to isolate four DKPs from the Dysidea avara-associated microorganism.
► Reported microorganisms might provide antimicrobial defense for their host sponges.