Contents lists available at ScienceDirect Phytochemistry Letters journal homepage: www.elsevier.com/locate/phytol Mini review Novel saponin and benzofuran isoflavonoid with in vitro anti-inflammatory and free radical scavenging activities from the stem bark of Pterocarpus erinaceus (Poir) Paul Djouonzo Toukam a,b, ⁎ , Maurice Fotsing Tagatsing b , Lauve Rachel Tchokouaha Yamthe a , Gakul Baishya c , Nabin Chandra Barua c , Alembert Tiabou Tchinda a , Joseph Tanyi Mbafor b, ⁎⁎ a Center for Studies on Medicinal Plants and Traditional Medicine (CRPMT), Institute of Medical Research and Medicinal Plants Studies (IMPM), P.O. Box 13033, Yaoundé, Cameroon b Department of Organic Chemistry, Faculty of Science, University of Yaoundé I, P.O. Box 812, Yaoundé, Cameroon c Natural Product Chemistry Division, North-East Institute of Science & Technology, Jorhat, Assam, India ARTICLE INFO Keywords: Pterocarpus erinaceus Isolation Radical scavenging Bovine albumin denaturation ABSTRACT The phytochemical study of the stem bark of Pterocarpus erinaceus led to the isolation of a new saponin (1) and a new benzofuran isoflavonoid (2) along with seven known compounds namely friedelin (3), triacontanoic acid (4), dotriacontanoic acid (5), 2,3-dihydroxypropyl hexacosanoate (6), octacosanoic acid (7), calycosin (8), stigmasterol glucoside (9). The structures of the new compounds were characterized on the basis of IR, UV, 1D and 2D NMR analyses in conjunction with EIMS, HRMS and literature review. The free radical scavenging activity and serum bovine albumin denaturation activity of the isolated compounds were evaluated. Compounds 2 (SC 50 , 12.63 ± 0.86 μg/mL) and 8 (SC 50 , 42.53 ± 1.77 μg/mL) showed antioxidant properties although lesser than that of the reference drug ascorbic acid (SC 50 , 5.99 ± 0.59 μg/mL). Compound 3 (IC 50 , 14.87 ± 1.51 μg/ mL) was the most active against the denaturation of the protein followed by compounds 1 (IC 50 , 28.60 ± 4.10 μg/mL) and 9 (IC 50 , 35.94 ± 2.10 μg/mL). Sodium diclofenac (IC 50 , 7.20 ± 0.97 μg/mL) was used as reference drug. 1. Introduction Pterocarpus erinaceus is a deciduous tree, 15–25 m tall and belongs to the Fabaceae family. It is found in the savanna zone of West and Central Africa (Duvall, 2016). Its stem bark is used as a decoction to treat in- flammatory disorders and has been scientifically proven to possess the activity (Noufou et al., 2012). The stem bark also demonstrated other significant biological activities including antioxidant (Toukam et al., 2016), antimalarial (Karou et al., 2003), antimycobacterial (Ibrahim et al., 2004), antianemic (Nadro and Modibo, 2014), anticancer (Noufou et al., 2016; Ngulde et al., 2015), anthelmintic (Chabi-China et al., 2014)and neuroprotective (Hage et al., 2015). Previous phyto- chemical studies on P. erinaceus reported the isolation of friedelin, lu- peol, epicatechin, 3α-hydroxyfriedelan-2-one, α-sophoradiol, stigmas- terol, maltol-6-O-apiofuranoside-glucopyranoside, 2,3-dihydroxypropyl octacosanoate, β-sitosteryl-β-D-glucopyranoside and a mixture of β- sitosterol, stigmasterol and campesterol (Noufou et al., 2012, 2017; Tittikpina et al., 2018). The traditional use and the pharmacological activities exhibited by the stem bark of this plant, prompted us to carry out isolation, char- acterization, antioxidant and anti-inflammatory studies of its secondary metabolites. This paper reports the occurrence of a new benzofuran isoflavonoid and a new saponin alongside seven known compounds. 2. Results and discussion 2.1. Characterization of isolated compounds The dried powder (5 kg) of P. erinaceus was successively extracted by percolation using hexane, ethyl acetate and the mixture methanol- dichloromethane (1:1). All extracts were subjected to column chroma- tography over silica gel and sephadex LH-20. Two compounds were https://doi.org/10.1016/j.phytol.2018.09.006 Received 14 January 2018; Received in revised form 14 August 2018; Accepted 3 September 2018 ⁎ Corresponding author at: Center for Studies on Medicinal Plants and Traditional Medicine (CRPMT), Institute of Medical Research and Medicinal Plants Studies (IMPM), P.O. Box 13033, Yaoundé, Cameroon. ⁎⁎ Corresponding author. E-mail addresses: touks241@yahoo.fr, paultoukam@yahoo.fr (P.D. Toukam), jtmbafor@yahoo.com, mbaforjt53@gmail.com (J.T. Mbafor). Phytochemistry Letters 28 (2018) 69–75 1874-3900/ © 2018 Phytochemical Society of Europe. Published by Elsevier Ltd. All rights reserved. T