Abstract
Three previously unreported anthraquinones, fistulaquinones A–C (1–3), together with three known ones (4–6) were isolated from the twigs of Cassia fistula. Their structures were determined by means of extensive NMR and MS spectroscopic analyses. All the isolated compounds were tested for their anti-tobacco mosaic virus (anti-TMV) activity, and compound 3 showed significant activity with inhibition rate of 34.5% at 20 μM concentration, even more potent than positive control. Additionally, compounds 1–6 exhibited moderate cytotoxicity with IC50 values ranging from 2.8 to 9.4 μM for some tested human tumor cell lines.