Resorcylic acid lactones from a Podospora sp. that induce apoptosis in activated T cells through MAPKs/AKT pathway.

Podomycins A-L (1-12), 12 undescribed hypothemycin-type resorcylic acid lactones (RALs), were characterized from Podospora sp. G214, an endophyte harbored in the roots of Sanguisorba officinalis L. Their structures were addressed by spectroscopic data, X-ray crystallography, the modified Mosher's method, together with Mo(OAc)- and Rh(OCOCF)-induced electronic circular dichroism (ICD) experiments. Podomycins A-C (1-3) represent the first class of natural RALs with a 13-membered macrolactone ring, while 4-12 are rearranged methoxycarbonyl substituted RALs. Biologically, compounds 2, 6, 8, 10, and 12 displayed immunosuppressive activities against T cell proliferation with IC values of 14.5-21.9 μM, and B cell proliferation with IC values of 22.3-36.5 μM, respectively. Further mechanism of action research demonstrated that podomycin F (6) distinctly induced apoptosis in activated T cells via MAPKs/AKT pathway.