The following compounds have been isolated from the lichen RAMALINA HIERRENSIS, collected on savin, and endemic to the Canary Islands: ursolic acid, iso-arborinol acetate, beta-sitosterol, ergosterol peroxide, cerevisterol, (-)-sandaracopimaric acid, parietin, (+)-usnic acid, (+)-iso-usnic acid, divaricatic acid, atranorin, stictic acid, gangaleodin, variolaric acid, montagnetol, and hierridin. The structures of all compounds were elucidated by physical, spectral, and chemical methods.
Column chromatography of the acetone extract of the lichen Stereocaulon azoreum afforded several substances identified by chemical and spectral means; α-amyrin, lupeol, taraxerol, ursolic acid, ergosterol peroxide, brassicasterol, cerevisterol, stictic acid and an acetone-condensation derivative, lobaric acid. Furthermore atranorin, methyl β-orsellinate, atranol and, for the first time from the genus Stereocaulon, cryptostictic acid and the dibenzofuran, strepsilin were isolated.
Column chromatography of the acetone extract of the lichen Cladina macaronesica (Sephadex LH-20, silica gel and silver nitrate-im pregnated silica gel) afforded eight triterpenes identified by chemical and spectral m eans. α-Amyrenone, lupenone, taraxerol, taraxerone and /so-arborinol acetate were isolated for the first time from lichens and (-)-usnic acid and five mononuclear phenolic compounds were also obtained, four for the first time as natural products. The possible transformation of perlatolic acid into these phenolic compounds is briefly outlined.
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