Wilsonglucinols A–C, homoadamantane-type polycyclic polyprenylated acylphloroglucinols with unusual fused epoxy ring skeletons from Hypericum wilsonii†
Wilsonglucinols A–C (1–3), three new polycyclic polyprenylated acylphloroglucinols (PPAPs) possessing novel homoadamantane architectures based on unusual epoxy-ring-fused systems, along with four new analogues, wilsonglucinols D–G (4–7), were isolated from the aerial parts of Hypericum wilsonii. The structures of the new compounds were determined using a combination of NMR, HRESIMS data, electronic circular dichroism (ECD) comparisons, and X-ray crystallography. Structurally, wilsonglucinol A (1) features a new hexahydrofuro[2,3-c][1,2]dioxine motif, and wilsonglucinols B (2) and C (3) possess unusual decahydro-1,8:6a,10-dimethanocycloocta[1,2-b:1,8-b′]difuran fragments. More significantly, an in vitro bioassay showed that 1, 3, and 9 exhibited moderate immunosuppressive activities against the proliferation of murine splenocytes stimulated by anti-CD3/anti-CD28 monoclonal antibodies, with IC50 values of 9.7, 9.3, and 7.1 μM, respectively.