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

Abstract

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 g g-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).

Uncommon Chlorinated Xanthone and Other Antibacterial Compounds from the Lichen Cladonia incrassata

“…Furthermore, didymic acid is active and seems to be more effective than condidymic acid. This result is consistent with a previous study performed by the disc diffusion method [27]. To our knowledge, biological activity of prasinic acid has not been previously described in the literature, and its antibacterial activity against S. aureus is presented here for the first time.…”

Inhibition of nitric oxide production in RAW 264.7 macrophages by diterpenoids from Phellinus pini

“…*Indicates a significant difference from control, *p < 0.01, **p < 0.001. (Tapia et al, 1997;Xue et al, 2004;Yoshikawa et al, 2008), compound 2 was identified as dehydroabietic acid. To the best of our knowledge, neither compound has been isolated from P. pini.…”

Synthesis and antimicrobial evaluation of novel analogues of dehydroabietic acid prepared by C H-Activation

“…Antibiotic-resistant bacteria, so-called "superbugs", unfortunately constitute a renewed threat to mankind, which persuaded us to undertake an initial screening for antimicrobial activity. Only few reports of inhibition by tree resins [23][24] or abietane-type natural products [25][26][27] against methicillin resistant Staphylococcus aureus (MRSA) can be found. DHAA was reported to have antimicrobial acitivity against several resistant bacterias, including methicillin resistant [28] and oxacillin sensitive strains of S. aureus [29] or biofilm formation of MRSA [30].…”