Antimalarial activity of traditional Kampo medicine Coptis Rhizome extract and its major active compounds

Abstract

Background: The herbal medicine has been a rich source of new drugs exemplified by quinine and artemisinin. In this study, examined a variety of Japanese traditional herbal medicine (Kampo) for their potential antimalarial activities.Methods: We designed a comprehensive screening to identify novel antimalarial drugs from a library of Kampo herbal extracts (n = 120) and related compounds (n=96). The antimalarial activity was initially evaluated in vitro against chloroquine/mefloquine-sensitive (3D7) and -resistant (Dd2) strains of Plasmodium falciparum. The cytotoxicity was also evaluated using primary Adult Mouse Brain cells. After being selected through the first in vitro assay, positive extracts and compounds were examined for possible in vivo antimalarial activity.Results: Out of 120 herbal extracts, Coptis Rhizome showed the highest antimalarial activity (IC50 1.9 µg/mL of 3D7 and 4.85 µg/mL of Dd2) with a high selectivity index (SI) > 263 (3D7) and > 103 (Dd2). Three major chlorinated compounds (coptisine, berberine, and palmatine) related to Coptis Rhizome also showed antimalarial activities with IC50 1.1, 2.6, and 6.0 µM (against 3D7) and 3.1, 6.3, and 11.8 µM (against Dd2), respectively. Among them, coptisine chloride exhibited the highest antimalarial activity (IC50 1.1 µM against 3D7 and 3.1 µM against Dd2) with SI of 37.8 and 13.2, respectively. . Finally, the herbal extract of Coptis Rhizome and its major active compound coptisine chloride exhibited significant antimalarial activity in mice infected with P. yoelii 17X strain with respect to its activity on parasite suppression consistently from day 3 to day 7 post-challenge. The effect ranged from 50.38 to 72.13% (P <.05) for Coptis Rhizome and from 81 to 89% (P <.01) for coptisine chloride.Conclusion: Coptis Rhizome and its major active compound coptisine chloride showed promising antimalarial activity against chloroquine-sensitive (3D7) and -resistant (Dd2) strains in vitro as well as in vivo mouse malaria model. Thus Kampo herbal medicine is a potential natural resource for novel antipathogenic agents.