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Article
Biologically active dibenzofurans from Pilidiostigma glabrum, an endemic Australian myrtaceae
Journal of Natural Products
  • Qing-Yao Shou, Southern Cross University
  • Linda K Banbury, Southern Cross University
  • Dane Renshaw, Southern Cross University
  • Eleanore Lambley, Southern Cross University
  • Htwe Mon, University of South Australia
  • Graham A Macfarlane, University of Queensland
  • Hans J Griesser, University of South Australia
  • Michael Heinrich, Southern Cross University
  • Hans Wohlmuth, Southern Cross University
Document Type
Article
Publication Date
1-1-2012
Peer Reviewed
Peer-Reviewed
Abstract
In an effort to identify new anti-inflammatory and antibacterial agents with potential application in wound healing, five new dibenzofurans, 1,3,7,9-tetrahydroxy-2,8-dimethyl-4,6-di(2-methylbutanoyl)dibenzofuran (1), 1,3,7,9-tetrahydroxy-2,8-dimethyl-4-(2-methylbutanoyl)-6-(2-methylpropionyl)dibenzofuran (2), 1,3,7,9-tetrahydroxy-2,8-dimethyl-4,6-di(2-methylpropionyl)dibenzofuran (3), 1,3,7,9-tetrahydroxy-4,6-dimethyl-2-(2-methylbutanoyl)-8-(2-methylpropionyl)dibenzofuran (4), and 1,3,7,9-tetrahydroxy-4,6-dimethyl-2,8-di(2-methylpropionyl)dibenzofuran (5), were isolated from the leaves of Pilidiostigma glabrum together with one previously described dibenzofuran. Structure elucidation was achieved by way of spectroscopic measurements including 2D-NMR spectroscopy. Compounds with 2,8-acyl substitutions had potent antibacterial activity against several Gram-positive strains (MIC in the low micromolar range), while compounds with 4,6-acyl substitutions were less active. All compounds except 3 inhibited the synthesis of nitric oxide in RAW264 macrophages with IC50 values in the low micromolar range. Compounds with 2,8-acyl substitutions also inhibited the synthesis of PGE2 in 3T3 cells, whereas 4,6-acyl-substituted compounds were inactive. None of the compounds inhibited the synthesis of TNF-α in RAW264 cells. The compounds showed variable but modest antioxidant activity in the oxygen radical absorbance capacity assay. These findings highlight that much of the Australian flora remains unexplored and may yet yield many new compounds of interest. Initial clues are provided on structure/activity relationships for this class of bioactives, which may enable the design and synthesis of compounds with higher activity and/or selectivity.
Disciplines
Citation Information

Shou, Q, Banbury, LK, Renshaw, DE, Lambley, EH, Mon, H, Macfarlane, GA, Griesser, HJ, Heinrich, MM & Wohlmuth, H 2012, 'Biologically active dibenzofurans from Pilidiostigma glabrum, an endemic Australian myrtaceae', Journal of Natural Products, vol. 75, no. 9, pp. 1612-1617.

Publisher version available from: http://dx.doi.org/10.1021/np300433r