Antiphytoviral activity of alkaloids from Cephalotaxus sinensis

The evaluation of pesticidal activity and the isolation of plant allelochemicals can lead to the discovery of new pesticides. This study confirmed that Cephalotaxus sinensis, an important Chinese medicinal species, has excellent activities against tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV) both indoors and outdoors; its control of the TMV is comparable to that of a commercialized antiviral agent (VA; active ingredient = a mixture of moroxydine hydrochloride and copper acetate). Using bioassay-guided fractionation, we isolated eight active alkaloids, which were identified as drupacine, 11-hydroxycephalotaxine, cephalancetine A, isocephalotaxine, cephalotaxine β-N-oxide, 4-hydroxycephalotaxine, wilsonine and cephalotaxine. At the same dosage, the inactivation activities against TMV were not significantly different among drupacine, 11-hydroxycephalotaxine, cephalotaxine and VA (inhibition ratio = 50.76% to 53.41%). The inhibiting TMV replications of all tested compounds were inferior to that of VA, but the inhibition ratios of drupacine and cephalotaxine were still greater than 50%. Thus, C. sinensis, in which drupacine and cephalotaxine are the main active constituents, has the potential for further development as a biological antiviral agent. This is the first report of the antiviral activities of eight alkaloids from C. sinensis.