Antiplasmodial-guided isolation of constituents from the stem bark of Balanites aegyptiaca

Abstract

The CH₂Cl₂/MeOH (1:1, v/v) extract of the stem bark of Balanites aegyptiaca showed moderate antiplasmodial activity against both the chloroquine sensitive Plasmodium falciparum 3D7 (Pf3D7) and multidrug-resistant Plasmodium falciparum Dd2 (PfDd2) strains with IC₅₀ values of 14.20 ± 1.92 and 42.14 ± 2.83 µg/mL, respectively. The extract was successively subjected to liquid-liquid partition with n-hexane, ethyl acetate, and n-butanol, and the fractions obtained were assessed for their antiplasmodial activity against the same strains. The ethyl acetate soluble fraction was the most active one with IC₅₀ values of 7.74 ± 0.74 and 19.27 ± 2.15 µg/mL against Pf3D7 and PfDd2, respectively, followed by the n-hexane fraction (IC₅₀ = values of 31.06 ± 2.60 and 90.67 ± 0.07 µg/mL against Pf3D7 and PfDd2, respectively). The n-butanol fraction was inactive (IC₅₀ > 50 µg/mL). Successive column chromatography of the active fractions led to the isolation of fifteen compounds including two new lignans [balanitals A (1) and B (2)], together with 13 known compounds (3–15). Their structures were established by means of spectroscopic methods. The isolated compounds were also assessed for their antiplasmodial activity against both Pf3D7 and PfDd2. Compound 4 exhibited a good antiplasmodial activity with an IC₅₀ value of 4.95 ± 0.70 µM against Pf3D7, while it was not active against PfDd2 (IC₅₀ > 100 µM).