Antiproliferative activity of Luehea candicans Mart. et Zucc. (Tiliaceae).

Luehea candicans Mart. et Zucc. (Tiliaceae) is known as 'açoita-cavalo' and is one of the most important medicinal plants found in the Brazilian cerrado. The crude methanolic extracts of the branches and leaves and their fractions were evaluated using the following cancer cell lines: MCF-7 (breast), NCI-ADR (breast expressing the multidrug resistance phenotype), NCI-460 (lung), UACC-62 (melanoma), 786-0 (kidney), OVCAR (ovarian), PCO-3 (prostate), HT-29 (colon) and K-562 (leukaemia). The crude methanolic extracts from the branches (B) and leaves (L) were able to inhibit the growth of the K-562 and 786-0 cell lines in a dose-dependent manner, with GI(50) values of 8.1 and 5.4 µg mL(-1), respectively. The hexane (L1), chloroform (L2) and methanol (L4) fractions derived from extract L showed a high selectivity and pronounced cytostatic activity against 786-0 (GI(50) ~ 40 µg mL(-1)). A significant amount of lupeol was isolated from fraction L2. The chloroform (B2) and methanol (B3) fractions derived from extract (B) exhibited less selectivity, showing the highest cytostatic activity against K-562, NCI-ADR, OVCAR, MCF-7 and NCI-460 cells, with GI(50) values between 27 and 40 µg mL(-1). Lupeol, betulin, a mixture of steroids, (-)-epicatechin, vitexin and liriodendrin were isolated from these active fractions.