Innate immunity comprises evolutionarily conserved self-defense mechanisms against microbial infections. In mammals, innate immunity interacts with adaptive immunity and has a key role in the regulated immune response. Therefore, innate immunity is a pharmaceutical target for the development of immune regulators. Using Drosophila ex vivo culture systems (Yajima et al. Biochem. J. 371, 205-210, 2003), a cyclopentanediol analogue is isolated from Aspergillus sp. as an immunosuppressive substance (Sekiya et al. Biochem. Pharm. 75, 2165-2174, 2008). This compound selectively suppresses activation of the imd pathway in Drosophila in vivo and the target molecules of the compound lie between the Imd adaptor protein and dTAK1 kinase in the imd pathway. In human cells, the compound suppresses TNF-a, but not IL-1β, stimulation-induced activation of NF-kB, suggesting that its target molecules are upstream of TAK1 in mammalian innate immunity. The compouns, TPS-17 and TPS-19, are developed from the cyclopentanediol analogue (Kikuchi et al. Eur.J.Med.Chem 46. 1263-1273, 2011).