Inhibitory effects of Alpinia zerumbet extract against plant virus infection in solanaceous plants.

Tomato mosaic virus (ToMV) and tobacco mosaic virus (TMV) are critical pathogens causing severe crop production losses of solanaceous plants. The present study was undertaken to evaluate the antiviral effects of extracts of Alpinia plants on ToMV and TMV infection in Nicotiana benthamiana. The aqueous extracts of Alpinia zerumbet (Pers.) B.L. Burtt and R.M. Smith and Alpinia kumatake, which grow widely in subtropical and tropical regions including East Asia, were effective in reducing ToMV infection when plants were treated prior to virus inoculation. We also found that the extracts of A. zerumbet isolated from Okinawa (Japan), locally referred to as shima-gettou, strongly inhibited ToMV and TMV infection. To obtain an active fraction, the aqueous extract of A. zerumbet isolate OG1 was separated by ethyl acetate, and the antiviral active compound was found to be present in the water layer. Based on our results, the extract of Alpinia plants has potential as an antiviral reagent for practical application in solanaceous crop production.