<jats:p>Very little is known about the immunomodulatory potential of secondary metabolites isolated from marine microorganisms. In the present study, we characterized pyrenocine A, which is produced by the marine-derived fungus<jats:italic>Penicillium paxilli</jats:italic>Ma(G)K and possesses anti-inflammatory activity. Pyrenocine A was able to suppress, both pretreatment and posttreatment, the LPS-induced activation of macrophages via the inhibition of nitrite production and the synthesis of inflammatory cytokines and PGE2. Pyrenocine A also exhibited anti-inflammatory effects on the expression of receptors directly related to cell migration (Mac-1) as well as costimulatory molecules involved in lymphocyte activation (B7.1). Nitrite production was inhibited by pyrenocine A in macrophages stimulated with CpG but not Poly I:C, suggesting that pyrenocine A acts through the MyD88-dependent intracellular signaling pathway. Moreover, pyrenocine A is also able to inhibit the expression of genes related to NF<jats:italic>κ</jats:italic>B-mediated signal transduction on macrophages stimulated by LPS. Our results indicate that pyrenocine A has promissory anti-inflammatory properties and additional experiments are necessary to confirm this finding<jats:italic>in vivo</jats:italic>model.