Anti-Tobacco Mosaic Virus Chromones from the Twigs of Cassia fistula

Two new chromones, fistulachromones A and B (1 and 2), together with three known chromones (3–5), were isolated from the twigs of Cassia fistula. Their structures were determined by means of HR-ESI-MS and extensive 1D and 2D NMR spectroscopic studies. Compounds 1 and 2 were tested for their anti-tobacco mosaic virus (anti-TMV) activities. Compounds 1 and 2 showed high anti-TMV activities with inhibition rates of 27.5 and 30.8%, respectively. These rates are close to that of positive control.