Antiplasmodial and cytotoxic activity of lanostane type triterpenoids isolated from Leplaea mayombensis

Leplaeric acid E 5, leplazarin 6a and 21-epileplazarin 6b, three new 3,4-seco-lanostane type triterpenes have been isolated from the stem bark of Leplaea mayombensis (Pellegr.) Staner along with fourteen known compounds from the fruits and roots. Leplaeric acid E, leplazarin and 21-epileplazarin, 15-alpha-hydroxy-3,4-seco-lanosta-4 (28),8,24-triene-3,21-dioic acid, mayomlactones A and B, lanosta-7,24-dien-3-one, leplaeric acid A, B and C were screened in vitro for antiplasmodial activity against chloroquine-sensitive (Pf3D7) and chloroquine-resistant (PfINDO) strains of Plasmodium falciparum and for cytotoxicity against CAL-27, CaCo2, Skov-3, and HepG2 cells line. Three compounds including 15-alpha-hydroxy-3,4-seco-lanosta-4(28),8,24-triene-3,21-dioic acid (IC50 5.65-7.09 mu M), lanosta-7,24-dien-3-one (IC50 7.18-9.07 mu M), and leplaeric acid C (IC50 7.59-8.47 mu M) were the most active against both strains of P. falciparum. All the compounds exhibited cytotoxicity against the three-cell lines with IC50 ranging from 12.30 to 181.88 mu M. These results confirm the usage of the medicinal plant L. mayombensis for the management of malaria and suggest that further lead optimization studies on potent compounds identified from this study could lead to the identification of potential of lead molecules as scaffold for new antimalarial drug discovery.