Wilsonglucinols A–C, homoadamantane-type polycyclic polyprenylated acylphloroglucinols with unusual fused epoxy ring skeletons from Hypericum wilsonii

Abstract

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.