Several species of
Aspidosperma
plants are used to treat diseases in the tropics, including
Aspidosperma ramiflorum
,
which acts against leishmaniasis, an activity that is experimentally confirmed. The species, known as guatambuyellow,
yellow peroba, coffee-peroba and matiambu, grows in the Atlantic Forest of Brazil in the South to the Southeast
regions. Through a guided biofractionation of
A. ramiflorum extracts, the plant activity against
Plasmodium falciparum
was evaluated in vitro for toxicity towards human hepatoma G2 cells, normal monkey kidney cells and nonimmortalised
human monocytes isolated from peripheral blood. Six of the seven extracts tested were active at low doses
(half-maximal drug inhibitory concentration < 3.8 μg/mL); the aqueous extract was inactive. Overall, the plant extracts
and the purified compounds displayed low toxicity in vitro. A nonsoluble extract fraction and one purified alkaloid
isositsirikine (compound 5) displayed high selectivity indexes (SI) (= 56 and 113, respectively), whereas compounds
2 and 3 were toxic (SI < 10). The structure, activity and low toxicity of isositsirikine in vitro are described here for the
first time in
A. ramiflorum, but only the neutral and precipitate plant fractions were tested for activity, which caused up
to 53% parasitaemia inhibition of
Plasmodium berghei in mice with blood-induced malaria. This plant species is likely
to be useful in the further development of an antimalarial drug, but its pharmacological evaluation is still required.