Identification of fukinolic acid from Cimicifuga heracleifolia and its derivatives as novel antiviral compounds against enterovirus A71 infection

•Cimicifuga heracleifolia and Arnebia euchroma extracts inhibited in vitro EV-A71 infection.•By a combined effort of bioassay-guided purification, high-resolution mass spectrometry and NMR, we identified active peaks from the plant extracts.•Fukinolic acid and cimicifugic acid A/J and caffeic acid derivatives were deduced as C. heracleifolia and A. euchroma, active compounds, respectively.•Fukunolic acid derivatives, L- and D-chicoric acid, showed activity in the low micromolar range against EV-A71 clinical isolates. Human enterovirus 71 (EV-A71) infections cause a wide array of diseases ranging from diarrhoea and rashes to hand-foot-and-mouth disease and, in rare cases, severe neurological disorders. No specific antiviral drug therapy is currently available. Extracts from 75 Chinese medicinal plants selected for antiviral activity based on the Chinese pharmacopeia and advice from traditional Chinese medicine clinicians were tested for activity against EV-A71. The aqueous extract of the rhizome of Cimicifuga heracleifolia (Sheng Ma) and Arnebia euchroma (Zi Cao) showed potent antiviral activity. The active fractions were isolated by bioassay-guided purification, and identified by a combination of high-resolution mass spectrometry and nuclear magnetic resonance. Fukinolic acid and cimicifugic acid A and J, were identified as active anti-EV-A71 compounds for C. heracleifolia, whereas for A. euchroma, two caffeic acid derivatives were tentatively deduced. Commercially available fukinolic acid analogues such as L-chicoric acid and D-chicoric also showed in vitro micromolar activity against EV-A71 lab-strain and clinical isolates.