METHODS AND RESULTS:
Subsequent isolation and structure elucidation yielded the known substances miltirone (1), tanshinone II a (2), 1,2 dihydrotanshinquinone (3), methylenetanshinquinone (4), 1-oxomiltirone (5), 11-hydroxymiltiodiol (6), tanshinone I (7), Methyl tanshinonate (8), and cryptotanshinone (9). The IC₅₀s of the compounds were determined against the two parasites and rat myoblast (L6) cells.
CONCLUSIONS:
They ranged from 4.1 µM to over 30 µM against P. falciparum K1 strain with selectivity indices (SI) from 0.3 to 1.9. IC₅₀s against T. brucei rhodesiense STIB 900 were from 0.5 µM (1, 4) to over 30 µM, and 4 showed the greatest selective activity with an SI of 24. |