Brief Original Article Anti-malarial investigation of Acorus calamus, Dichapetalum gelonioides, and Leucas aspera on Plasmodium falciparum strains Md Fahad Zamil 1,2 , Saiful Arefeen Sazed 1 , Muhammad Riadul Haque Hossainey 1,3 , Anik Biswas 4 , Mohammad Shafiul Alam 1 , Hamida Khanum 2 , Priyanka Barua 2 1 International Centre for Diarrhoeal Disease Research Bangladesh (icddr,b), Mohakhali, Dhaka, Bangladesh 2 Department of Zoology, University of Dhaka, Dhaka, Bangladesh 3 Department of Biological Sciences, George Washington University, Washington, DC, United States 4 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Dhaka, Dhaka, Bangladesh Abstract Introduction: Malaria is a significant global health concern and adversely affects people in developing countries including Bangladesh. The causative agent Plasmodium falciparum is resistant to several currently available anti-malarial drugs, such as mefloquine, chloroquine, and artemisinin-based combination therapy (ACT), and this has been a major global challenge towards the control of the disease. There is urgent need for novel anti-malarial chemotherapeutic agents. Methodology: The present study aimed to evaluate antimalarial activity of methanolic extracts of three Bangladeshi medicinal plants- Acorus calamus, Dichapetalum gelonioides and Leucas aspera - against both chloroquine sensitive (3D7) and resistant (Dd2) strains of P. falciparum. Histidine-rich protein 2 (HRP2) based ELISA was used to evaluate the in vitro inhibitory activity of the extracts. Results: D. gelonioides extract showed moderate (IC50 = 19.15 µg/mL) and promising activity (IC50 = 10.43 µg/mL) against 3D7 and Dd2 strains respectively. A. calamus remained inactive against both 3D7 (IC50 = 72.29 µg/mL) and Dd2 strain (IC50 = 67.81 µg/mL). L. aspera initially remained inactive against 3D7 strain (IC50 = 60.51 µg/mL), but displayed promising activity (IC50 = 7.693) against Dd2 strain. Conclusions: This is the first time these plant materials have been assessed for their in vitro antimalarial properties. It is pivotal to conduct further phytochemical analysis of D. gelonioides and L. aspera to evaluate the presence of potential novel antimalarial drug compounds. Key words: Plasmodium; in vitro; anti-malarial resistance; 50% inhibitory concentration (IC50). J Infect Dev Ctries 2022; 16(11):1768-1772. doi:10.3855/jidc.16741 (Received 25 April 2022 – Accepted 05 September 2022) Copyright © 2022 Zamil et al. This 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. Introduction Malaria is a fatal disease caused by Plasmodium, a genus of protozoan parasite [1]. Each year, it affects between 200 and 400 million people, killing nearly 400,000 people and adversely affecting children in Sub- Saharan Africa [2]. The region with the highest malaria burden is Sub-Saharan Africa, where P. falciparum is the predominant form [3]. Bangladesh is a densely populated nation with endemic malaria. Most of the cases are found in the thirteen endemic districts near or bordering India and Myanmar [4,5]. The Chittagong Hill Tracts (Bandarban, Rangamati and Khagrachari) have the highest malaria burden accounting for nearly 90% of all malaria cases in Bangladesh [6]. Resistance to antimalarial drugs is a major concern in the global fight against malaria. Chloroquine and sulfadoxin-pyrimethamine resistance were reported in Bangladesh as early as 1970 and 1985, respectively [7,8]. Despite the fact that no clinical or molecular resistance to the current artemisinin-based chemotherapy (ACT) treatments have been documented in the country, it has been discovered that this is ineffective in the countries bordering on the east [9]. This highlights the need to identify new antimalarials in the near term, as a backup in case of ACT failure. Plants have been investigated as antimalarial agents as a direct outcome of the two potent antimalarial drugs, quinine and artemisinin, both of which are derived from plants [10]. The anti-malarial activity in plants is attributed to a variety of phytoconstituents such as alkaloids, terpenes, steroids, and flavonoids [11]. Traditional healthcare practitioners in Bangladesh have a long history of using medicinal plants [12]. In this study, we investigated three plants that grow locally in Bangladesh, Acorus calamus (sweet flag; locally known as bach), Dichapetalum gelonioides (gelonium poison-leaf; locally known as moacurra) and