Antiplasmodial remedies from European renaissance herbals: HPLC based activity profiling of Alisma plantago-aquatica extract for antiplasmodial activity, and isolation of active dammarane triterpenoids

Abstract

The common water plantain Alisma plantago-aquatica L. (Alismataceae) was used in the 16th and 17th centuries in Central Europe to treat Plasmodium vivax malaria (tertian fever). The Renaissance herbals by Bock (1532), Brunfels (1532), Mathioli (1560), and Zwinger (1696) described the internal use of alcohol extracts of the tubers to treat this disease, which was quite common in German speaking areas then [1]. In the course of a screen of remedies from Renaissance herbals an extract of water plantain tubers was active against P. falciparum (77% inhibition at 4.9µg/ml). With analytical scale time-based HPLC separation and testing of one-minute fractions in combination with HPLC hyphenated methods (HPLC-PDA, -MSn, HR-MS, off line microprobe NMR) the active substances were identified as acetylated dammarane triterpenes. Seven of these compounds were isolated using normal phase medium pressure column chromatography and semi-preparative HPLC. Structure elucidation was achieved by extensive 1H and 13C NMR analysis. The dammaranes had IC50s ranging from 3.3 to 7.0µM. This is the first report of antiplasmodial activity of this triterpenoid class, and the first result of our ongoing project of screening for antiprotozoal natural products from remedies used in European Renaissance medicine.