Discovery of metabolites from the ( Periplaneta americana )-derived endophytic Nigrospora oryzae SMU02 and their anti-inflammatory activity

Insect endophytic fungi represent a rich source of structurally diverse and biologically active compounds. From the endophytic fungus Nigrospora oryzae SMU02, isolated from the insect Periplaneta americana, five metabolites were obtained, including a novel citrinin trimer, neotricitrinol D (1) and four known dimers 2-5. Neotricitrinol D (1) features a novel carbon skeleton with a 6/6/5/5/6/6/6/6 octacyclic system, one of the few such structures reported to date. The chemical structure was determined based on spectral data and quantum chemical calculation. Additionally, the anti-inflammatory properties of the isolates 1-5 were also evaluated, compound 1 exhibited a significant inhibitory effect on NO production with IC₅₀ value of 3.93 μM.