Cyclo(L-Phe-L-Pro), isolated from Pseudomonas fluorescens and Pseudomonas alcaligenes cell-free culture supernatants is an antifungal cyclic dipeptide. Cyclo(L-Phe-L-Pro) inhibits IFN-β production by interfering with retinoic-acid-inducible gene-I (RIG-I) activation. Cyclo(L-Phe-L-Pro) exhibits free-radical scavenging activity with the IC50 of 24 µM in the DPPH assay.