Type B polycyclic polyprenylated acylphloroglucinols from the roots of Hypericum beanii.

Abstract

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 1D/2D 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.