Resorcylic acid lactone derivatives with immunosuppressive activity from the endophytic Podospora sp. G214

Abstract

Nine previously unreported resorcylic acid lactone derivatives (1–6, 7a, 8a and 8b), together with three known analogues (7b, 9, 10), were isolated and identified from the solid rice-based culture of Podospora sp. G214. Their structures with absolute configurations were determined by extensive spectroscopic data analysis, electronic circular dichroism (ECD) calculations and single-crystal X-ray diffraction. Compounds 1–6 are rare naturally occurring oxidative degradation products of RALs, for which a plausible biosynthetic pathway was proposed. Compound 1 exhibited immunosuppressive activity on concanavalin A-induced T cell proliferation, with an IC₅₀ value of 12.2 μM, as well as on lipopolysaccharide-induced B cell proliferation, with an IC₅₀ value of 8.4 μM. Compounds 2, 8a and 8b showed modest immunosuppressive activity, with IC₅₀ values ranging from 22.2 to 40.9 μM.