Flavonoids and other bioactive constituents from Ficus thonningii Blume (Moraceae) Yannick S.F. Fongang a,d,g,1 , Jean J.K. Bankeu c,2 , Muhammad S. Ali d,3 , Angelbert F. Awantu c,4 , Ahmed Zeeshan d,5 , Clement N. Assob f,6 , Lateef Mehreen e,7 , Bruno N. Lenta b,8 , Silvere A. Ngouela a, *, Etienne Tsamo a,9 a Department of Organic Chemistry, Faculty of Science, TWAS Research Unit (TRU) of the University of Yaounde ´ I, P.O. Box 812, Yaounde ´, Cameroon b Department of Chemistry, Higher Teachers’ Training College, University of Yaounde ´ 1, P.O. Box 47, Yaounde ´, Cameroon c Department of Chemistry, Faculty of Science, University of Bamenda, P.O. Box 39, Bambili, Cameroon d ICCBS, International Center for Chemical and Biological Sciences, University of Karachi, 75270, Pakistan e Pharmaceutical Research Centre of Pakistan Council of Scientific and Industrial Research Laboratories Complex, Karachi 75280, Pakistan f Programme in Medicine, Faculty of Health Science, University of Buea, P.O. Box: 63, SW Region, Cameroon g Department of Chemistry, Higher Teachers’ Training College of Maroua, University of Maroua, P.O. Box 55, Maroua, Cameroon 1. Introduction Belonging to the family Moraceae, the genus Ficus is among the largest genera of angiosperms with approximately 750 species of trees, epiphytes and shrubs in tropical and subtropical regions worldwide (Rønsted et al., 2008). From about 100 species in Africa, nearly 60 are present in Cameroon (Berg et al., 1985). Ficus thonningii Blume is an evergreen tree 6–21 m height, with a rounded to spreading and dense crown (Orwa et al., 2009), and extensively used in African ethnomedicine for the treatment of several ailments such as diarrhea, urinary tract infections, diabetes mellitus, respiratory infections, mental illnesses and sexually transmitted diseases such as chlamydia and gonorrhea (Dangar- embizi et al., 2013; Falade et al., 2014; Lansky and Paavilainen, 2011; Tchouamo and Njoukam, 2000). In our continued search for new bioactive compounds from Cameroonian medicinal plants of the Ficus genus (Bankeu et al., 2010, 2011; Mbosso et al., 2012), we have examined the methanolic extracts of the figs and the roots of F. thonningii. The present paper deals with the isolation and structural characterization of two new C-prenylated flavonoids named thonningiol (1) and thonningiisoflavone (2) together with nineteen known compounds. Based on the traditional use of the plant and the nature of isolates, antioxidant and antimicrobial testing were carried out and results are herein reported. Phytochemistry Letters 11 (2015) 139–145 A R T I C L E I N F O Article history: Received 19 August 2014 Received in revised form 21 November 2014 Accepted 24 November 2014 Available online 15 December 2014 Keywords: Ficus thonningii Thonningiol Thonningiisoflavone Antioxidant activity Antimicrobial activity A B S T R A C T Continued interest in the chemistry of Ficus spp. led to the investigation of the figs and the roots of Ficus thonningii Blume. Two new flavonoids, thonningiol (1) and thonningiisoflavone (2) along with nineteen known compounds were isolated. b-Isoluteone (13) was isolated here for the first time from a natural source. Their structures were elucidated on the basis of spectroscopic evidence. Interestingly, thonningiisoflavone (2) and hydroxyalpinumisoflavone (21) showed strong DPPH radical scavenging activity with IC 50 = 65.50 mM and 68.20 mM respectively compared to the standard BHA with IC 50 = 44.20 mM. The methanolic extract of figs, taxifolin (14), conrauiflavonol (17) and shuterin (19) exhibited moderate antimicrobial activity against six micro-organisms with MIC below 1.5 mg/mL. ß 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved. * Corresponding author at: Department of Organic Chemistry, Faculty of Science, TWAS Research Unit (TRU) of the University of Yaounde ´ I, P.O. Box 812, Yaounde ´, Cameroon. Tel.: +237 99 95 55 42. E-mail addresses: fongangfys@yahoo.fr (Yannick S.F. Fongang), bk_jeanjules@yahoo.fr (Jean J.K. Bankeu), shaiq303@hotmail.com (M.S. Ali), awantufusi@yahoo.fr (A.F. Awantu), ahmed.iccs@yahoo.com (A. Zeeshan), juleclement@yahoo.fr (C.N. Assob), meher_khan555@hotmail.com (L. Mehreen), lentabruno@yahoo.fr (B.N. Lenta), sngouela@yahoo.fr (S.A. Ngouela), tsamoet@yahoo.fr (E. Tsamo). 1 Tel.: +237 96 13 28 33. 2 Tel.: +237 77 95 56 30. 3 Tel.: +92 21 4824930; fax: +92 21 4819018 19. 4 Tel.: +237 70 39 96 15. 5 Tel.: +92 332 3340447. 6 Tel.: +237 99 62 94 52. 7 Tel.: +92 34 63273597. 8 Tel.: +237 75 09 75 61. 9 Tel.: +237 99 61 62 65. Contents lists available at ScienceDirect Phytochemistry Letters jo u rn al h om ep ag e: ww w.els evier.c o m/lo c ate/p hyt ol http://dx.doi.org/10.1016/j.phytol.2014.11.012 1874-3900/ß 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.