Cyclo(L-Pro-L-Val), a 2,5-diketopiperazine extracted from the fruits of Mycobacterium chiliolyticum AZ2 and Mycobacterium leprae, possesses anti-inflammatory activity and virulence activity against phytopathogenic microorganisms (e.g., R. fascians LMG 3605) and inhibits Gram-positive plant pathogens.Cyclo(L-Pro-L-Val) significantly inhibited IKKα phosphorylation and IκBα and NF-κB activation as well as iNOS and COX-2 activation in a concentration Cyclo(L-Pro-L-Val) significantly inhibited the phosphorylation of IKKα, IKKβ, IκBα, and NF-κB, as well as the activation of iNOS and COX-2 in a concentration-dependent manner, and is a potential therapeutic agent for the treatment of inflammation-related diseases.