Novel Abietane Diterpenoids and Aromatic Compounds from Cladonia rangiferina and Their Antimicrobial Activity against Antibiotics Resistant Bacteria

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3―6), four known labdane diterpenoids (7―10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having γ-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1―17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). In the course of our research program aimed at the discovery of biologically active compounds from fungi,1) we have initiated the chemical study of the Japanese lichen, Cladonia rangiferina (L.) WEB. (Cladoniaceae).