Eremophilane-type sesquiterpenes from cultured lichen mycobionts of Sarcographa tricosa

Chemical constituents of the mangrove-associated fungus Capnodium sp. SZ-F22. A new eremophilane sesquiterpene

“…Compounds 2-14 were identified as 1-hydroxyeremophil-7(11), 9(10)-di-en-8-one (2) (Sørensen et al 2007), warburgiadione (3) (Yamakawa et al 1979), ere-mofortine A (4) (Moreau et al 1980), 1b-hydroxypetasol (5) (Le et al 2013), 3b-hydroxy-7bH-eremophil-1(2),9(10),11(12)-trien-8-one (6) (Lin et al 2014), 1-ace-tyl-b-carboline (7) (Zhou et al 1998), regiolone (8) (Gulder et al 2012), 2-oxosk-atole (9) (Hoenicke et al 2002), tyrosol (10) (Wang et al 2009), 1-phenyl-1,2-et-hanediol (11) (Zhao et al 2006), α-acetylorcinol (14) (Nukina & Marumo 1977) by comparison of the NMR data with literature ( Figure 1).…”

Symbiosis-inspired approaches to antibiotic discovery

“…125 Lichens and their assorted biosynthetic capabilities have been recently reviewed 122, 123, 125, 126 though a number of advances support the ever-increasing interest in these symbiotic systems as beacons of antimicrobial drug discovery. Particularly notable recent findings in which precise lichen structures are known and/or associated with specific antimicrobial actions are: i) work by Lou and co-workers to rigorously elucidate the structures and bioactivities of NPs from Aspergillus versicolor isolated from the lichen Lobaria quercizans leading to the identification of 14 new NPs (as exemplified by diorcinols F–H, and a number of bisabolane sesquiterpenoids such as the hydroxysydonic acid congeners shown below) as well as 15 known agents; though a focus on cytotoxic activities was reported for many of these diverse structures a number were also shown to possess antifungal activities, 127 ii) recent efforts to unveil synergistic interactions between established and clinically relevant antimicrobials such as gentamycin and levofloxacin in combination with assorted (and previously characterized) lichen-derived NP such as lobaric, α-collatolic, protolichesterinic, perlatolic and epiforellic acids from Chilean environments (inclusive of Antarctic regions) giving rise to antibacterial activities against MRSA, 125, 128 iii) studies of usnic acid, arguably the most well studied of all known lichen-derived NPs, indicating its ability to inhibit biofilm forming processes essential to the pathogenicity of Streptococccus pyrogenes , 129 iv) the revelation that the lichen endophyte-derived NP pyridoxatin displays antifungal activity against Candida albicans by interfering with ergosterol production essential to biofilm synthesis, 130 v) the recent discovery that cultured mycobionts from Sarcographa tricosa lichens (isolated from trees in Vietnam) produce eremophilane-type sesquiterpenes 3- epi -petasol, dihydropetasol and sarcographol, in addition to a number of other previously known eremophilane sesquiterpenes for which a wide assortment of antimicrobial activities have been well established, 131 vi) the revelation that norlichexanthone a well-known lichen-derived PKS product, displays antibacterial activity against S. aureus by virtue of its ability to reduce the expression of hla and RNAIII while also inhibiting DNA associations with the key regulatory protein AgrA—the result being reduced production of key virulence factors and impaired biofilm formation, 132 and vii) recent studies of the Letharia vulipina metabolite vulpinic acid that reveal this lichen-derived NP to express activity against MRSA via cell membrane and cell division targeting; these findings were in support of earlier studies by St. Clair et al showing that extracts of 36 species of lichens displayed often potent activity against four different pathogenic bacteria, of these Letharia vulipina extracts composed almost exclusively of vulpinic acid proved to be the most broadly antibacterial. 133 …”

A Cytotoxic Pyranonaphthoquinone from Cultured Lichen Mycobionts of Haematomma sp.

“…[1][2][3][4][5] Some of these secondary metabolites from lichen thalli are also produced by isolated cultured mycobionts of lichens without the participation of their photobionts. 6 Furthermore, cultured lichen mycobionts have the ability under osmotically stressed conditions to produce unusual substances that have never been detected in the lichenized state, [6][7][8][9][10][11] and some of the metabolites showed significant biological activities. 11,12 Based on our interests in the biological activities of the metabolites from cultured lichen mycobionts, we re-investigated the metabolites of Haematomma sp.…”