ANTIPLASMODIAL ACTIVITY AND CYTOTOXICITY OF PHYLLANTHUS NIRURI L. Vol 38 No. 4 July 2007 609 Correspondence: Mustofa, Department of Pharma- cology and Toxicology, Faculty of Medicine, Gadjah Mada University, Sekip Utara, Yogyakarta 55281, Indonesia. Tel: 062-274-511103; Fax : 062-274-511103 E-mail: mustofajogja@yahoo.com INTRODUCTION Malaria is one of the most important health problems in sub-tropical and tropical countries. The World Health Organization estimates that 2,300 million people, or 41% of the total world population, live in areas with malaria risk. More than 300 to 500 million clini- cal cases are reported annually resulting in at least 1.5 to 2.7 million deaths. Approximately 1 million deaths among children under 5 years old are attributed to malaria alone or in com- bination with other diseases (WHO, 1997, 1998). In Indonesia alone, 87 million people live in areas at risk for malaria and it is esti- mated that 6 million cases are reported annu- ally. The National Household Health Survey of 1995 estimated that 32,000 deaths, or 2% of deaths, were caused by malaria annually. A significant increase in malaria occurred dur- ing 1997-2001 due to the monetary crisis in Indonesia. During that time, the incidence of malaria increased significantly each year, be- coming 0.62 per 1,000 people with an annual IN VITRO AND IN VIVO ANTIPLASMODIAL ACTIVITY AND CYTOTOXICITY OF EXTRACTS OF PHYLLANTHUS NIRURI L. HERBS TRADITIONALLY USED TO TREAT MALARIA IN INDONESIA Mustofa 1 , Eti Nurwening Sholikhah 1 and Subagus Wahyuono 2 1 Department of Pharmacology and Toxicology, Faculty of Medicine, Gadjah Mada University, Yogyakarta; 2 Department of Biology Pharmacy, Faculty of Pharmacy, Gadjah Mada University, Yogyakarta, Indonesia Abstract. In endemic areas where malaria is prevalent, medicinal plants are often used to treat malaria. This study was conducted to evaluate the in vitro and in vivo antiplasmodial activity and cytotoxicity of extracts of meniran (Phyllanthus niruri L.) herb traditionally used to treat malaria in Indonesia. Three extracts viz aqueous, methanolic and chloroformic extracts were obtained by maceration of the herbs. A radioactive method was used to evaluate the in vitro antiplasmodial activity of the extracts on chloroquine-resistant (FCR-3) and chloroquine-sensi- tive (D-10) strains of Plasmodium falciparum. In vitro antiplasmodial activity was expressed by the concentration inhibiting 50% of parasite growth (IC 50 ). Cytotoxicity was estimated on Hela cells and the Cytotoxicity Index (CI = IC 50 on HeLa cells/IC 50 on FCR-3 strain) was calculated to evaluate the safety of tested extracts. A standard 4-day test on P. berghei infected mice was used to evaluate the in vivo antiplasmodial activity of the extracts showing strong in vitro antiplasmodial activity, for both the methanolic and aqueous extracts. The in vivo antiplasmodial activity was expressed by the dose inhibiting 50% of parasite growth (ED 50 ). The IC 50 values obtained for these extracts against P. falciparum ranged from 2.3 to 202.4 μg/ml. The methanolic extract was the most active in vitro extract with an IC 50 that ranged from 2.3 to 3.9 μg/ml and a CI that ranged from 41.3 to 57.5. This was also the most in vivo active extract with an ED 50 of 9.1 mg/kg/d. Further study will be conducted to isolate and purify active compounds pre- sented in the methanolic extract.