Type B polycyclic polyprenylated acylphloroglucinols from the roots of Hypericum beanii

Two new type B polycyclic polyprenylated acylphloroglucinols(PPAPs)(1 and 2) and a known biogenetic precursor hyperbeanol Q(3) were isolated from the root extract of Hypericum beanii, a medicinal plant widespread in southwest China. Their chemical structures were elucidated by 1 D/2 D NMR and HRESIMS data analysis, and absolute configurations were determined through detailed electric circular dichroism(ECD) analysis including ECD exciton chirality, Mo2(OAc)4-induced ECD, and ECD comparison. Of these compounds, hyperbeone A(1) is a typical [3.3.1]-type B PPAP with an unusual C-1 geranyl side chain, and hyperberin C(2) possesses a rare bicyclo[5.3.1]hendecane core. Taking compound 3 as a starting point, a plausible biosynthetic pathway to the bicyclic type B frameworks of 1 and 2 was proposed.