xanthone derivative Clusiaceae 5 Plant Bark 5 bark 5 heteronuclear multiple bond correlation 5 unclassified drug 5 Article 4 Molecular Structure 4 Xanthones 4 carbon nuclear magnetic resonance 4 chemical structure 4 chemistry 4 drug isolation 4 drug structure 4 Nuclear Magnetic Resonance, Biomolecular 3 mass spectrometry 3 nuclear magnetic resonance spectroscopy 3 plant extract 3 plant stem 3 proton nuclear magnetic resonance 3 Benzophenone 2 Calophyllum 2 Coumarins 2 Garcinia mangostana 2 Magnetic Resonance Spectroscopy 2 Malaysia 2 Mass Spectrometry 2 Plant Stems 2 Xanthone 2 antiinflammatory activity 2