Research Article Antimalarial Activity of Stem Bark of Periploca linearifolia during Early and Established Plasmodium Infection in Mice Wubetu Yihunie Belay, 1 Abyot Endale Gurmu , 2 and Zewdu Birhanu Wubneh 3 1 Department of Pharmacy, Debre Markos Referral Hospital, Debre Markos, Ethiopia 2 Department of Pharmacognosy, School of Pharmacy, University of Gondar, Gondar, Ethiopia 3 Department of Pharmacology, School of Pharmacy, University of Gondar, Gondar, Ethiopia Correspondence should be addressed to Zewdu Birhanu Wubneh; zbirhanu@gmail.com Received 7 September 2017; Revised 25 October 2017; Accepted 29 November 2017; Published 29 January 2018 Academic Editor: Juntra Karbwang Copyright © 2018 Wubetu Yihunie Belay et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background. In Ethiopia, stem bark of Periploca linearifolia is used for the treatment of malaria by the local community and demonstrated antimalarial activity in vitro. Despite its in vitro antimalarial activity, no scientifc study has been carried out to verify its activity in vivo. Terefore, the aim of the study was to evaluate the antimalarial activity of Periploca linearifolia stem bark extract in mice. Methods. Te dried stem bark of Periploca linearifolia was extracted with 80% methanol and evaluated for its antimalarial activity on both early and established Plasmodium berghei infected mice. Te extract was prepared at graded doses of 200, 400, and 600mg/kg. Chloroquine and distilled water were administered to the positive and negative control groups, respectively. Results. Te crude extract, at all tested doses, suppressed parasitemia signifcantly ( < 0.05) for 200 and 400 mg/kg and ( < 0.001) for 600mg/kg. Te suppression values at these doses were 56.98, 43.33, and 38.17 percent, respectively. Periploca linearifolia extract also demonstrated schizonticidal activity in the established malaria infection. Conclusion. Te plant Periploca linearifolia has a promising antimalarial activity in mice, supporting its in vitro fnding. Tus, it could be considered as a potential source to develop new antimalarial agent. 1. Background Malaria, among the most frequent infectious diseases world- wide, causes millions of deaths each year globally. Te infection mostly afects children below the age of fve. Fur- thermore, about 99% of the deaths are caused by P. falciparum [1]. Growth and multiplication of the Plasmodium parasite involve both the vector female Anopheles mosquitoes and humans [2]. Malaria in humans is attributable to 5 species of the parasite in the genus Plasmodium. Tese are P. falciparum, P. vivax, P. malariae, P. ovale, and P. knowlesi [3, 4]. Currently, malaria control is threatened not only by the development of mosquitoes resistant to the available insec- ticides but also by the currently existing antimalarial agents [1]. Developing antimalarial vaccine is very complex due to antigenic nature of the parasite, its ability to present a difer- ent subset of molecules for the immune system, the parasites ability to confuse, hide, and misdirect our immune system, and the possibility of having several plasmodial infections of not only diferent species but also diferent strains at the same time [5]. With remarkable eforts, a new antimalarial vaccine candidate RTS,S/AS01 has completed its phase III clinical trial successfully and will be available in Ghana, Malawi, and Kenya starting from 2018 [6]. Traditional medicine through use of natural products plays a great role in the discovery of antimalarial lead compounds and drug candidates like quinine from cinchona bark [7] and artemisinins from Artemisia annua [8]. Extract from stem bark of P. linearifolia (Asclepiadaceae) demonstrated a promising antiplasmodial activity in vitro [9]. Due to the emergence of antimalarial drug resistance and mosquito’s resistance to insecticides, there is a high interest in developing new antimalarial drugs [1, 10]. 2. Methods 2.1. Collection and Preparation of the Plant Material. Stem bark of P. linearifolia plant was collected from Lay Armachiho Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2018, Article ID 4169397, 7 pages https://doi.org/10.1155/2018/4169397