title: Phytochemical investigation of the Australian lichens Ramalina glaucescens and Xanthoria parietina.
abstract: Phytochemical investigation of the Australian lichen, Ramalina glaucescens resulted in the isolation of a new halogenated depside, 5-chlorosekikaic acid 5, together with (+)-usnic acid 1, sekikaic acid 2, atranorin 6 and parietin 7, the latter of which was isolated from the associated (co-occurring) lichen, X. parietina. Compound 5 is suspected to be an artifact of the isolation procedure. All structures were assigned using spectroscopic methods and mass spectrometry. In addition to the full characterization of 5, this report represents the first application of 2D NMR spectroscopy to complete the unequivocal chemical shift assignment for compounds 2 and 7. Compounds 1-2 and 5-7 all displayed varying degrees of antitumor activity (ranging from an IC50 of 15 microM to >44 microM) with compounds 1, 2 and 5 also displaying antibacterial properties. Of these, (+)-usnic acid 1 displayed the most significant antitumor and antibacterial activities.
authors.affiliation: School ofApplied Sciences (Discipline of Applied Chemistry), RMIT University, GPO Box 2476V Melbourne 3001, Victoria, Australia.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Dias
authors.forename: Sylvia
authors.initials: S
authors.lastname: Urban
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D001315:Australia; D001419:Bacteria / Q000187:drug effects; D001572:Benzofurans / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D004354:Drug Screening Assays, Antitumor; D005658:Fungi / Q000187:drug effects; D007941:Leukemia P388 / Q000188:drug therapy; D008011:Lichens / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008826:Microbial Sensitivity Tests; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D000970:Antineoplastic Agents; D001572:Benzofurans; C073339:usnic acid