Three new isoflavones from the <i>Pueraria montana var. lobata</i> (Willd.) and their bioactivities

<p>Three new isoflavones, 7-acetyl-4′,6-dimethoxy-isoflavone (<b>1</b>), 7-acetyl-4′-hydroxy-6-methoxy-isoflavone (<b>2</b>) and 7-acetyl-6,8-dimethoxy-4′-hydroxy-isoflavone (<b>3</b>), together with five known flavones (<b>4</b>–<b>8</b>), were isolated from the <i>Pueraria montana var. lobata</i> (Willd.). Their structures were elucidated by spectroscopic methods, including extensive 1D- and 2D NMR techniques. Compounds <b>1</b>–<b>8</b> were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compounds <b>1</b> and <b>2</b> exhibited high anti-TMV activities with inhibition rates of 36.8 and 33.6%, respectively. The inhibition rates are higher than that of positive control. The other compounds also showed potential anti-TMV activities with inhibition rates in the range of 21.8~28.4%, respectively. The cytotoxicities of compounds <b>1</b>–<b>3</b> against five human tumour cell lines (NB4, A549, SHSY5Y, PC3 and MCF7) were also tested. The results revealed that compounds <b>1</b>–<b>3</b> showed weak inhibitory activities against some tested human tumour cell lines with IC<sub>50</sub> values in the range of 1.2–3.6 μM.</p>