Curvularin, a fungal metabolite and a potent mycotoxin naturally isolated from Curvularia lunata, inhibits cytokine-induced nitric oxide synthase (iNOS), with an IC50 of 9.5 µM[1][2].
References:
[1]. Kumar CG, et al. Metabolite profiling and biological activities of bioactive compounds produced by Chrysosporium lobatum strain BK-3 isolated from Kaziranga National Park, Assam, India. Springerplus. 2013 Dec;2(1):122.
[2]. Yao Y, et al. Sporogen, S14-95, and S-curvularin, three inhibitors of human inducible nitric-oxide synthase expression isolated from fungi. Mol Pharmacol. 2003 Feb;63(2):383-91.