Separation and identification of activity ingredients in potato flowers and their acaricidal activities

Two compounds,     6a     and     2′a    , with acaricidal activities against four species of mites using bioassay-guided methods were isolated from the ethyl acetate extract of potato flowers. These two compounds were identified as prunin (5, 7, 4′-trihydroxyflavanone-7-O-β-D-glucopyranoside) (     6a    ) and α-chaconine (     2′a    ) by mass spectrometry, ¹³C and ¹H nuclear magnetic resonance (NMR) and comparison with data from literatures. The former was first isolated from the Solanaceae plant potato. We determined the contact acaricidal activities of prunin and α-chaconine against four species of mites by slide-dip method and the results demonstrated that these compounds were more effective compared to pesticide rotenone, which was the positive control. The 24 h LC₅₀ for prunin against Tetranychus cinnabarinus, T. urticae and T. viennensis were 461.98, 338.76 and 732.08 mg/L, respectively, which were 1.17, 1.52 and 3.07 times more active than rotenone, respectively. The 24 h LC₅₀ for α-chaconine against T. urticae and T. viennensis were 480.79 and 834.98 mg/L, respectively, the relative toxicity are 1.07 and 2.69 times higher compared to rotenone, respectively. Obviously, prunin and α-chaconine have acaricidal activities and potential application value.