Ericoside, a new antibacterial biflavonoid from Erica mannii (Ericaceae) Gabin Thierry M. Bitchagno a , Simplice B. Tankeo b , Apollinaire Tsopmo c , James D. Simo Mpetga a , Alembert T. Tchinda d , Serge Alain T. Fobofou a,e , Antoine Honoré L. Nkuete a , Ludger A. Wessjohann e , Victor Kuete b , Pierre Tane a, ⁎ a Department of Chemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon b Department of Biochemistry, University of Dschang, P.O. Box 67, Dschang, Cameroon c Food Science and Nutrition, Department of Chemistry, Carleton University, Ottawa, ON, Canada d Institute of Medical Research and Medicinal Plants Studies (IMPM), P.O. Box 6163, Yaounde, Cameroon e Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120 Halle (Saale), Germany abstract article info Article history: Received 25 October 2015 Received in revised form 13 December 2015 Accepted 15 December 2015 Available online 21 January 2016 A new dihydroflavonol–flavonol biflavonoid derivative, named ericoside was isolated from the ethanol extract of the whole plant of Erica mannii along with the known flavonoid, taxifolin 3-O-α-L-rhamnopyranoside; and two readily available sterols (sitosterol, sitosterol 3-O-β-D-glucopyranoside). The isolation was performed using chromatographic methods and the structure of purified molecules were elucidated using spectroscopic tech- niques (e.g. MS, NMR) and by comparison with literature data. The crude ethanol extract, ericoside, and taxifolin 3-O-α-L-rhamnopyranoside were tested against ten Gram-negative bacteria including multidrug resistant clini- cal isolates using a broth microdilution method. The crude ethanol extract showed no noteworthy activity. Of the purified compounds, ericoside displayed moderate activity against the resistant Escherichia coli AG100 with a MIC of 64 μg/mL. © 2016 Elsevier B.V. All rights reserved. Keywords: Ericaceae Erica mannii Biflavonoid Ericoside Antibacterial activity 1. Introduction Erica mannii is one of the 700 species of the genus Erica (Ericaceae family), many of which are distributed throughout Europe, the Middle East and Africa. Traditionally uses such as hypotensive, anti- inflammatory, urinary antiseptic, diuretic [1], and wounds healing [2] have been reported for members of this genus. Erica species are chemotaxonomically characterized based on their flavonoids [3] although, they are also known to possess 1,9-diarylnonanoids [4], phenylpropanoids [5], triterpenoids [6], and tannins [7,8]. In the course of our ongoing research on new bioactive compounds from Cameroonian medicinal plants, we have undertaken the isolation of the chemical constituents of E. mannii. We herein report, the isolation, the characterization and antibacterial activity of a new dihydroflavonol– flavonol biflavonoid derivative. Moreover, this is the first report of a biflavonoid from the genus Erica. 2. Materials and methods 2.1. General experimental procedures High resolution ESI mass spectra and the corresponding higher colli- sion dissociation (HCD) measurements (normalized collision energy 50%) were obtained on an Orbitrap Elite™ mass spectrometer (ThermoFisher Scientific, Bremen, Germany) equipped with an HESI ion source (spray voltage 4 kV; capillary temperature 275 °C, source heater temperature 40 °C; FTMS resolution 30.000). Nitrogen was used as the sheath gas. Sample solutions were introduced continuously via a 500 μL Hamilton syringe pump at 5 μL/min. Data were evaluated by Xcalibur™ software 2.7 SP1. LC-ESI/MS was performed using a Waters 2795 separations module coupled to a 2998 photodiode array detector and Waters Micromass Quatro Ultima triple quadrupole mass spec- trometer. The column was Phenomenex Kinetix C18 (100 × 4.60 mm, 2.6 μm, 100 Å (Torrance, California)) and the mobile phase consisted of acetonitrile–water (ACN–H 2 O) with formic acid (FA); [0.1%, (v/v)]. The solvent gradient was linear programmed from 5 to 100% ACN over 15 min at a flow rate of 1.0 mL min -1 . Positive ESI conditions included: capillary voltage 3.50 kV, cone voltage 20 V, source temperature 80 °C, desolvation temperature 180 °C, cone gas flow (N 2 ) 90 L/h, desolvation Fitoterapia 109 (2016) 206–211 ⁎ Corresponding author. E-mail address: ptane@yahoo.com (P. Tane). http://dx.doi.org/10.1016/j.fitote.2015.12.022 0367-326X/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Fitoterapia journal homepage: www.elsevier.com/locate/fitote