Eremophilane sesquiterpenoids from the whole plant of Parasenecio albus with immunosuppressive activity.

Abstract Fifteen new highly oxygenated eremophilane sesquiterpenoids, parasubolides A-O (1–15), were obtained from the whole plant of Parasenecio albus. The structures of 1–15 were elucidated based on the interpretation of NMR and HRESIMS data, along with experimental electronic circular dichroism (ECD) and single-crystal X-ray diffraction analysis. Compounds 1–6, and 9–14 represent the first class of 1,2,10-trioxygenated eremophilane lactones. Selected isolates were evaluated for their immunosuppressive activities. Compounds 4, 5, and 12 exhibited moderate inhibition against LPS-induced B-cell proliferation with IC50 values of 23.1, 33.8, and 26.6 μM, respectively.