Natural products have been utilized sophisticatedly as traditional medicines for millennia1. In recent decades, an increasing discovery of natural products provided prolific sources of new chemical entities served as therapeutic drugs or lead compounds2. The genus Hypericum (Guttiferae) has triggered wide investigations of the scientific community3, owing to phloroglucinol derivatives possessing diversiform structures, and appealing bioactivities such as antidepressant4, antibacterial5, anticancer6, and antiviral7 properties. In our continuous course of systematic study on the genus Hypericum8,9, one pair of enantiomers (±)-hyperjaponols H (1a/1b), two pairs of epimers hyperjaponols J-M (3-6), as well as hyperjaponol I (2), six new hetero-Diels-Alder adducts of polymethylated phloroglucinol and sesquiterpene motifs giving shape to filicinic acid¯ based meroterpenoids, along with 6/6/10 ring skeletons (Figure 1), were isolated from the entire herbs of Hypericum japonicum. Their structures with absolute configurations were characterized on the extensive analyses of NMR spectra, ECD calculations, and the experimental ECD data. The aforementioned metabolites exhibited moderate inhibitory effects on lytic replication of Epstein-Barr virus (EBV).
References
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