Polycyclic polyprenylated acylphloroglucinol derivatives with neuroprotective effects from Hypericum monogynum.

A new polycyclic polyprenylated acylphloroglucinol (PPAP), hypermonin C (1), along with nine known PPAPs (2-10) were obtained from the leaves and twigs of Hypericum monogynum. The structures of the isolates were determined on the basis of extensive spectroscopic analysis. The neuroprotective effects of the isolates against several chemical-induced injuries in SH-SY5Y and PC12 cells were assessed, and most of the compounds exhibited significant protective effects at 10 µg/ml. Especially, three compounds (1, 3, and 7) showed excellent neuroprotective activity with a cell viability of 92.4% ∼ 95.8% in KCl-induced SH-SY5Y cell injury. Their preliminary structure-activity relationship was also discussed and the configuration of substituent in furohyperforin may be critical for the neuroprotective activity of PPAP derivatives.

Hyperfols A and B: Two Highly Modified Polycyclic Polyprenylated Acylphloroglucinols from Hypericum perforatum.

Two novel polycyclic polyprenylated acylphloroglucinols (PPAPs), hyperfols A (1) and B (2), and two known biosynthetically related precursors (3 and 4) were isolated from Hypericum perforatum. Compound 1 possesses an unprecedented 2,3-seco-PPAP with a fused 5/5/9/5 tetracyclic skeleton, and 2 features a 30-norPPAP. Their structures were established by spectroscopic analysis, computer-assisted structure elucidation software, and electronic circular dichroism calculations. Moreover, compounds 1 and 4 exhibit significant cytotoxicity against human erythroleukemia cells by inducing cell apoptosis.

Cytotoxic phenolic constituents from Hypericum japonicum.

Nine undescribed compounds, including five xanthone derivatives, two flavonoids, one 2-pyrone derivative, and one undescribed naturally occurring compound, along with 30 known phenolic compounds, were isolated from Hypericum japonicum. In addition, hyperjaponols A and B were identified as racemates. The structures and absolute configurations of the undescribed compounds were determined by comprehensive MS, NMR spectroscopy, and electronic circular dichroism (ECD) calculations. The cytotoxic effects of the isolated compounds on two human tumour cell lines (HEL and MDA-MB-231) were evaluated by the MTT assay. Eighteen compounds showed good inhibitory activities against the HEL cell line, with IC50 values of 3.53-18.7 µM, while nine compounds exhibited moderate cytotoxicity against the MDA-MB-231 cancer cell line, with IC50 values ranging from 4.92 to 10.75 µM. Their preliminary structure-activity relationship of the isolated compounds was also discussed.