Meroterpenes and prenylated acylphloroglucinol from the aerial parts of Hypericum erectum.

Abstract

Two previously undescribed specialized metabolites, erecricins F (1) and G (2), along with two known metabolites, erectumins A (3) and B (4), were isolated from the aerial parts of Hypericum erectum Thunb. (Hypericaceae). Detailed spectroscopic analyses revealed erecricin F (1) to be a C₃₀ meroterpene with four isoprene units, and erecricin G (2) to be a prenylated acylphloroglucinol biogenetically related to 1. The relative configurations of erecricins F (1) and G (2) were assigned by NOESY analysis and GIAO NMR calculation, while their absolute configurations were deduced by comparison of the ECD spectra with TDDFT calculated spectra. The relative configurations of 3 and 4 were also elucidated by the similar method as for 1 and 2. Erecricins F (1) and G (2) and erectumins A (3) and B (4) were evaluated for their inhibitory effect against IL-1β release from LPS-stimulated murine microglial cells and anti-ferroptosis activity using human hepatoma Hep3B cells.