Antrocarines A–F, antiplasmodial ergostane steroids from the stem bark of Antrocaryon klaineanum Pascal D. Douanla a , Turibio Kuiate Tabopda a , Alembert T. Tchinda b , Ewa Cieckiewicz c , Michel Frédérich c , Fabrice Fekam Boyom d , Nole Tsabang b , Samuel Yeboah e , Augustin E. Nkengfack a , Marguerite Hortence K. Tchuendem a,⇑ a Department of Organic Chemistry, Faculty of Science, The University of Yaounde-1, P.O. Box 812, Yaounde, Cameroon b Laboratory of Phytochemistry, Institute of Medical Research and Medicinal Plant Studies, (IMPM), P.O. Box 6163, Yaounde, Cameroon c Université de Liège, Laboratoire de Pharmacognosie, Centre Interfacultaire de Recherche sur le médicament (CIRM), Département de Pharmacie, Université de Liège, B36, B-4000 Liège, Belgium d Department of Biochemistry, Faculty of Science, The University of Yaounde-1, P.O. Box 812, Yaounde, Cameroon e Department of Chemistry, University of Botswana, Private Bag 00704, Gaborone, Botswana article info Article history: Received 13 January 2015 Received in revised form 24 June 2015 Accepted 15 July 2015 Keywords: Antrocaryon klaineanum Anacardiaceae Ergostane steroids Antiplasmodial activities abstract During a study on the chemistry and biological activity of Antrocaryon klaineanum Pierre, six new sterols including 4,24(28)-ergostadiene-6a,7a-diol (1), 6a-methoxy-4,24(28)-ergostadiene-7a,20S-diol (2), 6a-methoxy-4,24(28)-ergostadien-7a-ol (3), 20S-hydroxy-24(28)-ergosten-3-one (4), 7a-hydroxy- 4,24(28)-ergostadien-3-one (5), and 24(28)-ergostene-3b,6a-diol (6) were characterized by physical and spectroscopic means. The known steroids 7 and 8 were also isolated. The crude extract and the isolated compounds were evaluated for their ability to inhibit the 3D7 strain of Plasmodium falciparum. Compounds 2, 3, and 8 showed potent activity while that of the crude extract was moderate. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction The treatment of malaria in Africa is becoming increasingly dif- ficult due to the rising prevalence of Plasmodium falciparum resis- tant to chloroquine and to other antimalarial drugs. With an estimated 1 million children under the age of 5 years dying of malaria each year, there is an urgent need to evaluate the many traditional remedies that are used for treatment of this disease. This is necessary to determine the efficacy and safety of locally used preparations as well as to investigate their potential to pro- vide novel compounds as leads to new antimalarial agents. Anacardiaceae plants have been the subject of continued and growing interest due to the range of biological activities shown by many members of this family (Arbonnier, 2002; Adjanohoun et al., 1986; Kudi et al., 1999; Akinpelu, 2001; Gonçalves et al., 2005; Tchikaya et al., 2003; Pousset, 2004). Some plants of this family are used to treat stomachache, headache and fever which are malaria symptoms (Kone et al., 2004; Adjanohoun et al., 1987; Hodouto, 1990). To the best of our knowledge, there is no phytochemical report on the genus Antrocaryon. Antrocaryon klaineanum is a species which is distributed widely from South-eastern Nigeria to Central Africa, and South to the Democratic Republic of the Congo. It is a plant belonging to a genus that, in contrast to other genera of the Anacardiaceae family, has received little attention from biologists and phytochemists. In Gabon, the powdered bark is used to treat liver complaints and to facilitate the production of breast milk, the roots are used to treat abdominal and liver complaints (Kémeuzé and Nkongmeneck, 2011). As part of our ongoing search for natural antimalarial secondary metabolites (Kenmogne et al., 2006; Tchinda et al., 2012a,b), a chemical investigation of the stem bark of A. klaineanum was undertaken and resulted in the characteriza- tion of six new sterols and the isolation of two known compounds, 7,20S-dihydroxyergosta-4,24(28)-dien-3-one (Tchouankeu et al., 1996) (8) and 20S-hydroxyergosta-4,6,24(28)-trien-3-one (7), described previously in the literature as a semi-synthetic product (Roy et al., 1982). Here it is reported here from a natural source for the first time. Antiplasmodial assays of the crude extract and the isolated compounds were carried out. http://dx.doi.org/10.1016/j.phytochem.2015.07.011 0031-9422/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: mhkenmogne@yahoo.fr (M.H.K. Tchuendem). Phytochemistry 117 (2015) 521–526 Contents lists available at ScienceDirect Phytochemistry journal homepage: www.elsevier.com/locate/phytochem