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Uncommon chlorinated xanthone and other antibacterial compounds from the lichen Cladonia incrassata
Amandine Dieu1, Marion Millot1, Yves Champavier2
1Laboratoire de Chimie des Substances Naturelles (EA 1069), Faculté de Pharmacie, Université de Limoges, Limoges, France.
Abstract:
Bioassay-guided fractionation of an extract of the lichen Cladonia incrassata against Staphylococcus aureus led to a novel compound, 1,5-dihydroxy-2,4,6-trichloro-7-methylxanthone (1), along with six known compounds: (-)-usnic acid (2), didymic acid (3), condidymic acid (4), squamatic acid (5), thamnolic acid (6), and prasinic acid (7). Didymic, condidymic, and prasinic acids were isolated for the first time from C. incrassata. Didymic, condidymic, and (-)-usnic acids were active against S. aureus (a minimum inhibitory concentration of 7.5 µg/mL).
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