Anti-inflammatory drimane sesquiterpene lactones from an Aspergillus species

IFN-γ inducible protein 10 (IP-10, CXCL10) is a 10 kDa chemokine, which is secreted from various cell types after exposure to pro-inflammatory stimuli. This chemokine is a ligand for the CXCR3 receptor and regulates immune responses by activating and recruiting leukocytes such as T cells, eosinophils, monocytes, and NK cells to sites of inflammation. Altered expression of CXCL10 has been associated with chronic inflammatory and infectious diseases and therefore CXCL10 represents a promising target for the development of new anti-inflammatory drugs. In a search for inhibitors of CXCL10 promoter activity, three structurally related drimane sesquiterpene lactones (compounds 1-3) were isolated from fermentations of an Aspergillus species. Compounds 1 and 2 inhibited the IFN-γ/TNF-α/IL-1β induced CXCL10 promoter activity in transiently transfected human DLD-1 colon carcinoma cells in a dose-dependent manner with IC50 values of 12.4 μM for 1 and 55 μM for 2, whereas 3 was devoid of any biological activity. Moreover, compounds 1 and 2 reduced CXCL10 mRNA levels and synthesis in IFN-γ/TNF-α/IL-1β stimulated DLD-1 cells.