Quassinoids from Brucea Javanica Seeds Inhibiting the Replication of Tobacco Mosaic Virus

Active quassinoids extracted from Brucea javanica seeds were tested for their activities against Tobacco mosaic virus (TMV). Results from activity-guided assays indicated that the compounds can reduce the replication of the virus by up to 98.5% (50 μg/mL). The active quassinoids inhibit the replication of TMV genomic and subgenomic RNAs and the synthesis of TMV coat protein in vivo but did not destroy the integrality of the virus. Structure-activity relationship (SAR) analysis indicated that the positions of the furan ring, the α,β-conjugated ketone, and integrity of the A ring had significant impacts on the antiviral activity of quassinoids.