Ethnopharmacological communication In vitro antiplasmodial activity of selected Luo and Kuria medicinal plants B.O. Owuor a,b,n , J.O. Ochanda b , J.O. Kokwaro c , A.C. Cheruiyot d , R.A Yeda d , C.A. Okudo d , H.M. Akala d a Department of Biology, Catholic University of Eastern Africa, Langata Road, P.O. Box 62157, Nairobi, Kenya b Centre for Biotechnology and Bioinformatics, University of Nairobi, P.O. Box 30197, Nairobi, Kenya c School of Biological Sciences, University of Nairobi, P.O. Box 30197, Nairobi, Kenya d Department of Emerging Infectious Diseases (DEID) Program, United States Army Medical Research Unit-Kenya (USAMRU-K), Kenya Medical Research Institute (KEMRI)-Walter Reed Project, P.O. Box 54 Kisian-Kisumu, Kenya article info Article history: Received 9 April 2012 Received in revised form 9 July 2012 Accepted 19 September 2012 Available online 4 October 2012 Keywords: Medicinal plants Antiplasmodial activity Traditional medicine Africa abstract Ethnopharmacological relevance: Drug resistance in malaria is a recurring subject that threatens public health globally. There is an urgent need to seek new antimalarial agents. This study seeking new antimalarials from medicinal plants is guided by ethnobotany. Materials and methods: Medicinal plants of the Luo and Kuria ethnic groups of Kenya with high usage reports were screened in vitro for their antiplasmodial activity using the SYBR Green I fluorescence assay (MSF assay). Results: The IC50’s for drugs and total plant extracts ranged from 0.01217 to 10.679 mg/ml. Extracts were more active on chloroquine sensitive than resistant Plasmodium falciparum strains. Tylosema fassoglense, Ageratum conyzoides and Ocimum kilimandscharicum exhibited promising results. Plec- tranthus barbatus did not show activity. Conclusion: Ethnobotanical knowledge was sufficiently reliable for identifying plant extracts with antiplasmodial activity. & 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Malaria is caused by parasitic protozoa of the genus Plasmodium. There were 655000 malaria deaths in 2010 of which 91% were in Africa (WHO, 2011). Of these mortalities approximately 86% was of children under 5 years of age. Chemotherapeutic prophy- lactics sourced from plant species are the core of malaria treatment (Fabricant and Farnsworth, 2001). Most of these anti- malarials, quinolines and artemisinins originated from scientific study of remedies traditionally employed by various cultures. Over 1200 plant species are reportedly used for the treatment of malaria and fevers worldwide, and are potentially important sources of new anti-malarial treatments (Willcox and Bodeker, 2004). In vitro screening programs guided by ethnobotanical approach are important for providing leads for the identification of new active principles. In this study medicinal plants of the Kenyan Luo and Kuria ethnic groups with high ethnobotanical usage reports were screened for their antiplasmodial activity. The species studied were Acmella caulirhiza, Albizia coriaria, Ageratum conyzoides, Croton macrostachyus, Ocimum gratissimum, Ocimum kilimandscharicum, Plectranthus barbatus and Tylosema fassoglense. 2. Materials and methods 2.1. Selection and collection of plants The medicinal plants in this study were selected based on their consistent and high independent usage reports in oral interviews with Kuria and Luo healers. Plant material for bioactivity analysis was collected from several locations in the southwestern Nyanza province (Kadem, Kanyamkago and Awendo) and Karen area of Nairobi. They were tentatively identified in the field then further verified before deposition at the Nairobi University herbarium (NAI) with the assistance of Mr. Patrick Kyalo Mutiso. Voucher specimens of the medicinal plants, in duplicates, are deposited at the University of Nairobi herbarium (NAI). 2.2. Preparation of crude plant extracts For each plant species, 500 g of material was macerated, air dried and then ground using an electric mill. For each species, 30 g was extracted with 100 ml of 100% dichloromethane (DCM) and the products were evaporated in vacuo to an extract using a rotary evaporator at 40 1C and then dried extracts were stored in labelled sterile rubber capped bottles in a shaded cupboard. All the chemicals used in the experiment were of analytical grade; dichloromethane was purchased from Sharlab S. L., Spain. The yields of the medicinal plants shown in Table 1 are calculated Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/jep Journal of Ethnopharmacology 0378-8741/$ - see front matter & 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jep.2012.09.045 n Corresponding author at: Department of Biology, Catholic University of Eastern Africa, Langata Road, P.O. Box 62157, Nairobi, Kenya. Tel.: þ254 719558738. E-mail address: bowuor2001@yahoo.com (B.O. Owuor). Journal of Ethnopharmacology 144 (2012) 779–781