Research Article Antimalarial Properties of Aqueous Crude Extracts of Gynostemma pentaphyllum and Moringa oleifera Leaves in Combination with Artesunate in Plasmodium berghei-Infected Mice Voravuth Somsak, Preeyanuch Borkaew, Chokdee Klubsri, Kittiyaporn Dondee, Panatda Bootprom, and Butsarat Saiphet Department of Clinical Chemistry, Faculty of Medical Technology, Western University, Kanchanaburi 71170, Tailand Correspondence should be addressed to Voravuth Somsak; voravuthsomsak@gmail.com Received 9 August 2016; Accepted 20 October 2016 Academic Editor: Sukla Biswas Copyright © 2016 Voravuth Somsak 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. Due to the emergence and spread of malaria parasite with resistance to antimalarial drugs, discovery and development of new, safe, and afordable antimalarial are urgently needed. In this respect, medicinal plant extracts are targets to optimize antimalarial actions and restore efcacy of standard antimalarial drugs. Te present study was aimed at determining the antimalarial activities of Gynostemma pentaphyllum and Moringa oleifera leaf extracts in combination with artesunate against Plasmodium berghei-infected mice. P. berghei ANKA maintained by serial passage in ICR mice were used based on intraperitoneal injection of 1 × 10 7 parasitized erythrocytes and subsequent development of parasitemia. Tese infected mice were used to investigate the antimalarial activity of artesunate (6 mg/kg) in combination with 500, 1,000, and 2,000 mg/kg of G. pentaphyllum and M. oleifera leaf extracts using 4-day suppressive test. It was found that these extracts showed signifcant ( < 0.05) antimalarial activity in dose-dependent manner with percentage of suppression of 45, 50, and 55% for G. pentaphyllum leaf extract and 35, 40, and 50% for M. oleifera leaf extract. Additionally, artesunate combined with these extracts presented higher antimalarial activity, compared to extract treated alone with percentage of suppression of 78, 91, and 96% for G. pentaphyllum leaf extract and 73, 82, and 91% for M. oleifera leaf extract. Te results indicated that combination treatment of G. pentaphyllum or M. oleifera leaf extracts with artesunate was able to increase the antimalarial activity by using low dose of artesunate. Hence, these results justifed the combination of these extracts and artesunate in antimalarial herbal remedies. 1. Introduction Malaria is a major parasitic disease with high mortality and morbidity, especially in the sub-Saharan Africa, Latin America, and Asia. About 3 billion people worldwide are exposed annually, with 1.2 billion at high risk, and some 200 million developed symptomatic malaria. Moreover, it was estimated that 1 million deaths have occurred in the world [1]. Tis disease is caused by malarial protozoa parasite from genus Plasmodium and transmitted by female Anopheles mosquito. Due to the lack of efective vaccine to prevent malaria, the global strategy for malaria mainly focuses on case management through provision of antimalarial drugs which are capable of reducing or eliminating malaria parasites. Unfortunately, malaria parasite has developed resistance to drugs used in malarial therapy except the artemisinin [2]. However, artemisinin produces fast recrudescence when used alone due to its short half-life. Hence, artemisinin used in combination with other antimalarials, a combination known as artemisinin-combination therapy (ACT), has been recommended [3]. In addition, resistance of mosquitoes to insecticides has led to an increase in severe malaria, com- plicating the eradication of the disease, and the resurgence of malaria [4]. Moreover, many antimalarials in use today have high toxicity that exposes patients’ health expenditure [5]. In this respect, medicinal plant extracts are potential Hindawi Publishing Corporation Journal of Tropical Medicine Volume 2016, Article ID 8031392, 6 pages http://dx.doi.org/10.1155/2016/8031392