Abstract
In our search for new antiplasmodial agents, the CH2Cl2/CH3OH (1:1) extract of the roots of Tephrosia aequilata was investigated, and observed to cause 100% mortality of the chloroquine-sensitive (3D7) strain of Plasmodium falciparum at a 10 mg/mL concentration. From this extract three new chalconoids, E-2′,6′-dimethoxy-3′,4′-(2′′,2′′-dimethyl)pyranoretrochalcone (1, aequichalcone A), Z-2′,6′-dimethoxy-3′,4′-(2′′,2′′-dimethyl)pyranoretrochalcone (2, aequichalcone B), 4′′-ethoxy-3′′-hydroxypraecansone B (3, aequichalcone C) and a new pterocarpene, 3,4:8,9-dimethylenedioxy-6a,11a-pterocarpene (4), along with seven known compounds were isolated. The purified compounds were characterized by NMR spectroscopic and mass spectrometric analyses. Compound 1 slowly converts into 2 in solution, and thus the latter may have been enriched, or formed, during the extraction and separation process. The isomeric compounds 1 and 2 were both observed in the crude extract. Some of the isolated constituents showed good to moderate antiplasmodial activity against the chloroquine-sensitive (3D7) strain of Plasmodium falciparum.
Highlights
Tephrosia is a pantropical genus encompassing more than 350 species, 110 of which are found in Africa, and 30 of these in Kenya [1]
UV spectra were recorded on a Specord S600 (Analytik Jena AG, Jena, Germany) spectrophotometer, optical rotations were measured on PerkinElmer 341-LC (PerkinElmer, Wellesley, MA, USA) whereas CD experiments were run on a Jasco J-715 spectropolarimeter (Jasco, Corp., Tokyo, Japan)
NMR spectra were acquired on Bruker Advance 600 or a Bruker Advance III HD
Summary
Tephrosia (family Leguminosae) is a pantropical genus encompassing more than 350 species, 110 of which are found in Africa, and 30 of these in Kenya [1]. Some Tephrosia species are traditionally used in herbal medicine, while other members of this genus are known as a fish poison and as insecticides [1,2]. In East Africa, the roots of Tephrosia aequilata are used to cure venereal diseases and to reduce pain [4]. Previous phytochemical investigation of the roots of this plant yielded a new pterocarpan, 3,4:8,9-dimethylene- dioxypterocarpan, and four known chalconoids, namely praecansone A, praecansone B, Z-praecansone A and demethylpraecansone. As Tephrosia aequilata was reported to produce chalconoids [1], we chose to investigate this plant. (2), 400 -ethoxy-300 -hydroxypraecansone methylene-dioxypterocarpene (4), along with seven known compounds (5–11). B (3), and 3,4:8,9-di-methylene-dioxypterocarpene (4), along with seven known compounds (5–11). The characterizationactivities and the of antiplasmodial activities of these compounds are discussed here
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