Trypanocidal and antileishmanial dihydrochelerythrine derivatives from Garcinia lucida.

Three benzo[ c]phenanthridine alkaloids have been isolated from the stem bark of Garcinia lucida: dihydrochelerythrine ( 1), 6-acetonyldihydrochelerythrine ( 2), and its new derivative, ( S)1''-(9,10-dihydro-2',3'-dihydroxy-7,8-dimethoxy-10-methyl-1,2-benzophenanthridin-9-yl)propan-2''-one (lucidamine A) ( 3). The new diisoprenylated derivative of lucidamine B ( 4) was obtained by semisynthesis. These dihydrochelerythrine derivatives as well as the crude extract displayed attractive antiprotozoal activity against Trypanosoma brucei brucei and Leishmania donovani, with little toxicity to Vero cells and the host cells. This is the first trypanocidal and antileishmanial bioguided study of G. lucida, and the activity of the crude extract as well as of the dihydrochelerythrine derivatives are reported for the first time.