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

Abstract An aqueous ethanol extract of Artemisia argyi inhibited the aminoacylation activity of LeuRS from Giardia lamblia ( Gl LeuRS). The bioassay-guided fractionation of the extract led to the isolation of 3,5-dicaffeoylquinic acid ( 1 ), with an IC 50 of 5.82 μg/mL. The ester derivatives of 1 were also found to possess strong anti- Gl LeuRS effects, with IC 50 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 ) (IC 50  = 4.62 μg/mL), were effective at killing G. lamblia .