Valeriaquinone A, a unique anthraquinone–coumarin hybrid with selective inhibition of PTP1B from Knoxia valerianoides

Valeriaquinone A ( 1 ), an unprecedented anthraquinone–coumarin hybrid, was isolated from the roots of Knoxia valerianoides . Its structure was determined by extensive spectroscopic analyses and X-ray diffraction. The plausible biosynthetic pathways for 1 were proposed. Compound 1 exhibited strong protein tyrosine phosphatase 1B (PTP1B) inhibition with high selectivity (> 30 fold) over homologous T cell protein tyrosine phosphatase (TCPTP) potentially by binding to an allosteric site predicted by kinetic analysis and molecular docking. Moreover, compound 1 showed significant cytotoxic activities against three human hepatoma cell lines (HepG2, QGY-7703, and SMMC-7721) with half maximal inhibitory concentration (IC 50 ) values of 1.39 ± 0.2, 10.34 ± 2.09, and 5.56 ± 0.47 µmol/L, respectively. Valeriaquinone A, a unique anthraquinone–coumarin hybrid, was isolated from Knoxia valerianoides . Valeriaquinone A exhibited strong protein tyrosine phosphatase 1B (PTP1B) inhibition with high selectivity (> 30 fold) over homologous T cell protein tyrosine phosphatase (TCPTP) potentially by binding to an allosteric site, and also showed significant cytotoxic activities.