Hypersonins A–D, Polycyclic Polyprenylated Acylphloroglucinols with a 1,2-seco-Homoadamantane Architecture from Hypericum wilsonii

Hypersonins A–D (1–4), four 1,2-seco-homoadamantane type polycyclic polyprenylated acylphloroglucinols (PPAPs) possessing a new bicyclo[4.3.1]­decane-3-methoxycarbonyl architecture, were obtained from Hypericum wilsonii. The structures of hypersonins A–D were identified by spectroscopic data, electronic circular dichroism comparison, and X-ray crystallographic data. Hypersonins A–D are the first seco-homoadamantane-type PPAPs with cleavage at the C-1–C-2 bond. Hypersonin A (1) showed moderate inhibitory activity to anti-CD3/anti-CD28 monoclonal antibody-induced proliferation of murine splenocytes, with an IC50 value of 8.3 ± 0.2 μM.