Antipromastigote and cytotoxic activities of some chemical constituents of Hypericum lanceolatum Lam. (Guttifereae)

Abstract

Phytochemical investigation of the ethanol extract of the stem bark of Hypericum lanceolatum Lam. (Guttifereae) afforded eight known compounds including 2,2ʹ,5,6ʹ-tetrahydroxybenzophenone (1), 5-hydroxy-3-methoxyxanthone (2), 3-hydroxy-5-methoxyxanthone (3), betulinic acid (4), hydroquinone (5) 6,7-dihydroxy-1,3-dimethoxyxanthone (6), calophyllumin A (7), and 1,3,5,6-tetrahydroxy-4-prenylxanthone (8). Compound 1 was submitted to acetylation reaction to give 5-acetoxy-2,2ʹ,6ʹ-trihydroxybenzophenone (9), a new hemisynthetic derivative. Compounds 5 and 8 were isolated for the first time from this plant. The structures were established by extensive analysis of their mass spectrometry and nuclear magnetic resonance (NMR) spectroscopic data and comparison with those from the literature. The isolated compounds (1, 2, 4, 5, and 8) and the derivative of benzophenone (9) were tested for their antipromastigote and cytotoxic activities against visceral leishmaniasis parasite Leishmania donovani and macrophage RAW 264.7 cell line, respectively. Compound 9 was the most active with an IC50 value of 6.1 μg/ml, while compounds 1, 2, 4, and 8 were moderately active with IC50 values ranging from 11.4 to 34.8 μg/ml against L. donovani and were not cytotoxic except compound 5 that was very toxic and not active. The findings of the present study suggested that compounds 1, 2, 4, and 8 could be considered as a potential source of therapeutic medicine for the treatment of leishmaniasis