Two New Cytotoxic Naphthoquinones from Mendoncia cowanii from the Rainforest of Madagascar
Russell B. Williams1
, Andrew Norris1
, James S. Miller2
, L. Jeremie Razafitsalama2
, Rabodo Andriantsiferana3
, Vincent E. Rasamison3
, David G. I. Kingston1
1Department of Chemistry, M/C 0212, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.A.
2Missouri Botanical Garden, St. Louis, Missouri, U.S.A.
3Centre National d’Application des Recherches Pharmaceutiques, Antananarivo, Madagascar
Bioassay-guided fractionation of the root and stem extracts of Mendoncia cowanii led to the isolation of two new and two known naphthoquinones. The structures of the new compounds, avicequinones D and E (1 and 2), were determined using 1D and 2D NMR spectroscopy and by chemical conversion of compound 1 to 2. The new compounds were active in the A2780 human ovarian cancer cell line with IC50 values of 7.4 - 50 μM, respectively, and 1, 3, and 4 were subsequently found to be weakly active in an assay for inhibition of the kinase Akt.
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