3,5-Dicaffeoylquinic acid isolated from Artemisia argyi and its ester derivatives exert anti-leucyl-tRNA synthetase of Giardia lamblia (GlLeuRS) and potential anti-giardial effects.

An aqueous ethanol extract of Artemisia argyi inhibited the aminoacylation activity of LeuRS from Giardia lamblia (GlLeuRS). The bioassay-guided fractionation of the extract led to the isolation of 3,5-dicaffeoylquinic acid (1), with an IC₅₀ of 5.82 μg/mL. The ester derivatives of 1 were also found to possess strong anti-GlLeuRS effects, with IC₅₀ values of 1.79, 5.51 and 2.56 μg/mL respectively. Anti-giardial assay showed that the derivatives, especially 3,5-dicaffeoylquinic acid propyl ester (4) (IC₅₀=4.62 μg/mL), were effective at killing G. lamblia.