Enantiomeric α-pyrone derivatives with immunosuppressive activity from Talaromyces adpressus

Five pairs of undescribed enantiomeric α -pyrone derivatives (±)-adprepyrones A−E (± 1 −± 5 ), together with an unreported congener adprepyrone F ( 6 ), and 6-[( E )-3-Hydroxyprop-1-enyl]-4-methoxy-5-methyl-2-pyrone ( 7 ), recently reported as synthetic compound, were isolated from the fungus Talaromyces adpressus . Their structures with absolute configurations were elucidated by HRESIMS, 1D and 2D NMR , electronic circular dichroism calculations, and single-crystal X-ray diffraction analyses. (±)-Adprepyrone A (± 1 ) possesses an unreported carbon skeleton formed by the fusion of an α -pyrone derivative with nicotinamide . Compounds (+)- 2 , (±)- 4 , (±)- 5 , and 7 showed moderate inhibitory activity against concanavalin A (ConA)-induced T lymphocyte proliferation with IC 50 values ranging from 8.9 to 19.8 μM.