Mélanie Bourjot†, Pieter Leyssen‡, Cécilia Eydoux§, Jean-Claude Guillemot§, Bruno Canard§, Philippe Rasoanaivo, Françoise Guéritte†, and Marc Litaudon*†
† Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles (ICSN), CNRS, LabEx LERMIT, 1, Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France
‡ Rega Institute for Medical Research (KULeuven), Minderbroedersstraat, B3000, Leuven, Belgium
§ Laboratoire d’Architecture et de Fonction des Macromolécules Biologiques (AFMB-AMU-UMR7257), ESIL Case 925, 163, Avenue de Luminy, 13288 Marseille, France
Institut Malgache de Recherches Appliquées (IMRA), 102 Antananarivo, B.P.3833, Madagascar
J. Nat. Prod., Article ASAP
DOI: 10.1021/np300059n
Publication Date (Web): March 22, 2012
In an effort to identify novel inhibitors of chikungunya (CHIKV) and dengue (DENV) virus replication, a systematic study with 820 ethyl acetate extracts of madagascan plants was performed in a virus-cell-based assay for CHIKV, and a DENV NS5 RNA-dependent RNA polymerase (RdRp) assay. The extract obtained from the stem bark of Flacourtia ramontchi was selected for its significant activity in both assays. Six new phenolic glycosides, named flacourtosides A–F (1–6), phenolic glycosides itoside H, xylosmin, scolochinenoside D, and poliothrysoside, and betulinic acid 3β-caffeate were obtained using the bioassay-guided isolation process. Their structures were elucidated by comprehensive analyses of NMR spectroscopic and mass spectrometric data. Even though several extracts and fractions showed significant selective antiviral activity in the CHIKV virus-cell-based assay, none of the purified compounds did. However, in the DENV RNA polymerase assay, significant inhibition was observed with betulinic acid 3β-caffeate (IC50 = 0.85 ± 0.1 μM) and to a lesser extent for the flacourtosides A and E (1 and 5, respectively), and scolochinenoside D (IC50 values 10 μM).
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