Cyclographin, a New Depsidone From the Lichen Catarraphia dictyoplaca

Abstract

The new depsidone cyclographin (1) (methyl 2-chloro-4-formyl-3,7-dihydroxy-1,6,9-trimethyl-11-oxo-11H-dibenzo[ b,e ][1,4]dioxepin-8-carboxylate) has been isolated from the lichen Catarraphia dictyoplaca and the structure established by spectroscopic and degradative methods.

New meta -depsidones and diphenyl ethers from the lichen Parmotrema tsavoense (Krog & Swinscow) Krog & Swinscow, Parmeliaceae

“…14.15 These type of observations were reported for some lichen diphenyl ethers. 16,17,18 With this point of view, the A-and B-rings of compound 6 were not coplanar and the consequence was methoxy protons of the methoxycarbonyl group of the A-ring and the methyl protons H 3 -8′ of the B-ring were in close proximity to each other to have the NOESY correlations as mentioned above. The comparison of chemical shift values of protons of the A-ring (H-5, CH=O, H 3 -9) of 6 with corresponding ones of depsidones 1 and 5, having the same partial structure and being measured in the same deuterated solvent ( Table 1) showed clearly that protons of the diphenyl ether 6 were up-field shifted (∆δ = 0.25−0.34) due to the ring current effect.…”

“…Its molecular formula was established as C 18 In the HMBC spectrum ( Fig. 2) the aldehyde proton at δ 10.61 correlated to carbon signals at δ 111.6 (C-3), 116.7 (C-5), 164.1 (C-4).…”

α-Glucosidase Inhibitory Depsidones from the Lichen Parmotrema tsavoense

“…Subsequently, conveniently hydroxylated para-depside could undergo acyl migration to the corresponding meta-depside [15], which could turn into an isomeric diaryl ether for cyclization to the corresponding depsidone [16]. Accordingly, the closely-related chloroatranorin was envisaged as the precursor to both the meta-depsidone cyclographin and the para-depsidone physciosporin [17]. Isostructural depsidone/diphenylether pairs are of considerable generality in lichens since the latter can be obtained by simple hydrolysis of the former [18].…”

Dibenzofurans and derivatives from lichens and ascomycetes

“…Other dibenzofurans and derivatives are produced by two marine fungi 10 45 and 11a-11c 46 , one endophytic fungus (15a-15b) 47 or Aspergillus sp. (12a-12b 48 and 9a, 13 49 53,[17][18][20][21][22][23][24] -dibenzofurans bearing aliphatic chain(s) (4), mainly described in the genera Cladonia and also from Roccella hypomecha; 33-37, 54 30 -dibenzofurans with a lactone ring (5-7) resulted from the cyclization of the carboxylic function in C2 8,10 and found in numerous genera such as Letrouitia, Phyllospora, or Alectoria. 9, 21, 25-27, 38 35 Dibenzofurans from ascomycetes are much more diversified and display some specific features.…”

“…-Ascomatic acid and derivatives (1a-1g), which can be found in Bunodophoron patagonicum (ascomata) and cultured mycobionts of Evernia esoredosia, Usnea orientalis and Stereocaulon japonicum; 19,[40][41][42] -Pannaric and shizopeltic acids derivatives (2-3), isolated from various genera: Crocynea, Lepraria, Schizopelte, Psoroma, Roccella, Leproloma, Leprocaulon and Combea; 17,18,[20][21][22][23][24]53 -Dibenzofurans bearing aliphatic chain(s) (4), mainly described in the genera Cladonia and also from Roccella hypomecha; [33][34][35][36][37]54 -Dibenzofurans with a lactone ring (5-7) resulted from the cyclization of the carboxylic function in C2 8,10 and found in numerous genera such as Letrouitia, Phyllopsora, or Alectoria. 9,21,[25][26][27]38 Dibenzofurans from ascomycetes are much more diversied and display some specic features.…”