In vitro assessment of antiprotozoal and antimicrobial activities of fractions and isolated compounds from Pallenis hierochuntica

Abstract

The antiprotozoal and antimicrobial properties of the extract and fractions of the whole plant of Pallenis hierochuntica were investigated against a panel of pathogenic organisms. Fractionation of the methanol extract of the whole plant of Pallenis hierochuntica using reverse-phase chromatography gave 28 fractions and led to the isolation of 2 new bisabolone hydroperoxides, 6,10 β,11-trihydroxy-bisabol-2-ene-1-one (1a), 6,10 α,11-trihydroxy-bisabol-2-ene-1-one (1b) and also 6,10 β-dihydroxy-bisabol-2,11-diene-1-one (2). They were characterised by extensive spectrometric analysis. Anti-infective investigations of the fractions revealed that 22 to 26 possessed significant antimalarial activity against the D6 and W2 strains of Plasmodium falciparum with IC₅₀ = 7.62 – 9.91 µg/mL and 5.49 – 6.08 µg/mL, respectively, and SI>6.0 on average. Fractions 7, 16 to 24 exhibited good activity against Leishmania donovani promastigotes (IC₅₀ = 6.71 – 18.77 µg/mL). Fractions 25 to 28 were active against T. brucei trypomastigotes, 25 being the most potent (IC₅₀ = 4.13 µg/mL). Only 11 to 13 were active against Aspergillus fumigatus (IC₅₀ = 13.406 µg/mL). 1a and 2 were not promising against the organisms tested. 1a and 1b were characterised for the first time.