In vitro and in vivo antimicrobial potential against various phytopathogens and chemical constituents of the aerial part of Rumex chinensis Campd

Plant pathogenic fungi and bacteria cause large losses in the yield and quality of important crops. During the screening of bioactive plants against plant pathogens, we found that methanol extract of the aerial part of Rumex chinensis exhibited potent efficacy against various plant diseases. The methanol extract was effectively active against phytopathogenic fungi Blumeria graminis f. sp. hordei and Colletotrichum coccodes that cause plant diseases in vivo. n-Hexane and ethyl acetate layers obtained by liquid-liquid partitioning of the methanol extract strongly suppressed these fungal diseases with control values from 83 to 100% at 3000 µg/mL. These layers also inhibited the bacterial growth of Acidovorax avenae subsp. cattleyae and Ralstonia solanacearum. Notably, the n-hexane layer was found to reduce the development of tomato bacterial wilt in vivo. Six anthraquinones and two sterols were isolated from the aerial part of R. chinensis. Besides, the high-performance liquid chromatography (HPLC) was used for the quantitative analysis of anthraquinone contents in the active layers. The aerial part of R. chinensis was proved to be rich in active substances physcion, chrysophanol and emodin and their glycoside derivatives. Our findings suggested that the extracts and metabolites from the aerial part of R. chinensis could be used as potent active ingredients for developing botanical fungicide and bactericide to control plant diseases.