Three new flavones from the whole plants of Cassia auriculata Linn. and their antiviral activities.

Cassia auriculata , a widely grown medicinal plant in China, has not been fully studied in terms of its secondary metabolites. In our pursuit of new bioactive metabolites from Cassia plants, we conducted a phytochemical reinvestigation on C. auriculata. This investigation resulted in the isolation of three new (1−3) and six known (4−9) flavones. Their structures were elucidated by spectroscopic methods, including extensive 1D- and ²D NMR techniques. Interestingly, Compounds 1 - 3 are rare flavones bearing an unusual (4-methylfuran-2- yl)methyl moiety. In addition, Compounds 1 - 3 were evaluated for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that Compounds 1–3 exhibited potential anti-TMV activities with inhibition rates of 26.8%, 30.5% and 34.6% at a concentration of 20 μ M, respectively, and these rates are close to that of the positive control. Compounds 1 - 9 were also tested for their anti-rotavirus activities. The results revealed that 1–9 exhibited potential anti-rotavirus activity with therapeutic index (TI) values in the range of 13.3–20.8. These values are lower than that of the positive control (with a therapeutic index of 23.4). [Display omitted] • Three new flavones were isolated from Cassia auriculata. • Their structures were elucidated by spectroscopic analysis. • The results showed that compound 1–3 exhibited potential anti-tobacco mosaic virus activities. • The results revealed that compound 1–9 exhibited potential anti-rotavirus activity. [ABSTRACT FROM AUTHOR]