Anti-Tobacco Mosaic Virus (TMV) Quassinoids from Brucea javanica (L.) Merr.

Two new quassinoids, javanicolide E (1) and javanicolide F (2), along with fifteen known C-20 quassinoids were isolated from the seeds of Brucea javanica (L.) Merr. The antitobacco, mosaic virus (TMV) activity of these quassinoids was screened by the conventional half-leaf and leaf-disk method along with Western blot analysis. All of the seventeen quassinoids showed potent anti-TMV activity. Among them, eight compounds, brusatol (3), bruceine B (4), bruceoside B (5), yadanzioside 1 (6), yaclanzioside L (7), bruceine D (8), yadanziolide A (9), and aglycone of yadanziolide D (17), showed strong antiviral activities, with IC50 values in the range of 3.42-5.66 mu M, and were much more effective than the positive control, ningnanmycin (IC50 = 117.3 mu M). The antiviral structure-activity relationships of quassinoids against TMV were also discussed.