Two New Isoflavones from Pueraria lobata and Their Bioactivities.

Two new isoflavones, 4′,6-dimethoxy-8-hydroxy-7-hydroxymethylisoflavone (1) and 4′,8-dihydroxy-7-hydroxymethyl-6-methoxyisoflavone (2), together with three known isoflavones (3-5), were isolated from Pueraria lobata. Their structures were elucidated by spectroscopic methods, including extensive 1D and 2D NMR techniques. Compounds 1-5 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compound 2 exhibited high anti-TMV activity with inhibition rates of 32.6%. The other compounds also showed potential anti-TMV activities with inhibition rates in the range of 21.4-25.3%, respectively. The cytotoxic activity of compounds 1-5 against five human tumor cell lines (NB4, A549, SHSY5Y, PC3, and MCF7) was also tested. The results revealed that compounds 1-5 showed weak inhibitory activities against some human tumor cell lines, with IC50 values in the range of 6.9-9.8 μM. [ABSTRACT FROM AUTHOR]