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Phytochemical investigation of the Australian lichens Ramalina glaucescens and Xanthoria parietina
journal contributionposted on 2023-03-07, 04:29 authored by DA Dias, S Urban
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 μM to >44 μM) with compounds 1, 2 and 5 also displaying antibacterial properties. Of these, (+)-usnic acid 1 displayed the most significant antitumor and antibacterial activities.
AnimalsAnti-Bacterial AgentsAntifungal AgentsAntineoplastic AgentsAustraliaBacteriaBenzofuransCell Line, TumorChromatography, High Pressure LiquidDrug Screening Assays, AntitumorFungiLeukemia P388LichensMagnetic Resonance SpectroscopyMiceMicrobial Sensitivity TestsSpectrometry, Mass, Electrospray IonizationScience & TechnologyLife Sciences & BiomedicineChemistry, MedicinalFood Science & TechnologyPharmacology & PharmacyNatural productsRamalina glaucescensXanthoria parietinasekikaic acid5-chlorosekikaic acidatranorinparietin(+)-usnic acidbiological activityCOMPLETE NMRACIDCONSTITUENTSSUBSTANCESCELASTRIDEPSIDESOrganic ChemistryPlant BiologyEcology