Phytochemical investigation of the ethanol extract of the stem bark of Hypericum lanceolatum Lam. (Guttifereae) afforded eight known compounds including 2,2',5,6'-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-2,2',6'-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 MS and NMR spectroscopic data and comparison with those from the literature. The isolated compounds (1, 2, 4, 5, and 8) and 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 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 which 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 treatement of leishmaniasis.
Key words: Guttiferae; Hypericum lanceolatum; benzophenone; antipromastigote activity; cytotoxicity.
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