Chemical constituents and biological activities of parasitic plant Cuscuta japonica Choisy on Dimocarpus longans Lour.

Cuscuta japonica is a unique parasitic vine that belongs to the family Convolvulaceae, which is obligatory dependent upon a host plant for nourishment in order to survive. We studied on the parasite plants C. japonica growing on different plants including, Dimocarpus longans Lour, Litchi chinensis Sonner, Ficus microcarpa L. f. and Duranta repens L. exhibited different constituents which have been detected by HPLC analyses. Determination of the major metabolites present in the parasites showed a clear relationship with compounds. Three new phenolic glycosides (1-3) and 21 known compounds were isolated and characterized from the methanol extract of the parasite plant C. japonica on D. longan Lour. The structures were established by spectroscopic analyses and comparisons with data from related references. Two phenolic glycosides (1-3), two caffeoylquinic acid derivatives (4-5), and two fatty acids (23-24) exhibit significant activities against influenza virus A (H1N1).