Antiparasitic Constituents of Beilschmiedia louisii and Beilschmiedia obscura and Some Semisynthetic Derivatives (Lauraceae).

The MeOH/CH ₂ Cl ₂ (1:1) extracts of the roots and leaves of Beilschmiedia louisii and B. obscura showed potent antitrypanosomal activity during preliminary screening on Trypanosoma brucei brucei . Phytochemical investigation of these extracts led to the isolation of a mixture of two new endiandric acid derivatives beilschmiedol B ( 1 ) and beilschmiedol C ( 2 ), and one new phenylalkene obscurene A ( 3 ) together with twelve known compounds ( 4 - 15 ). In addition, four new derivatives ( 11a - 11d ) were synthesized from compound 11 . Their structures were elucidated based on their NMR and MS data. Compounds 5 , 6 , and 7 were isolated for the first time from the Beilschmiedia genus. Additionally, the NMR data of compound 4 are given here for the first time. The isolates were evaluated for their antitrypanosomal and antimalarial activities against Tb brucei and the Plasmodium falciparum chloroquine-resistant strain Pf3D7 in vitro, respectively. From the tested compounds, the mixture of new compounds 1 and 2 exhibited the most potent antitrypanosomal activity in vitro with IC ₅₀ value of 4.91 μM.