2.3. Isolation of segetoside I
Segetoside I (Fig. 1A: Purity >85%) was isolated in our laboratory
(Centre for Research and Development of New Drugs, Jiangsu
University) as previously described with some slight modification
[18]. Briefly, crude ethanol extract of V. segetalis was prepared and
the n-butanol fraction with bioactivity was run on silica column
chromatographyusing aCH2Cl2/MeOHmixture. The active subfraction
(CH2Cl2/MeOH, 1:1) was further purified on RP-8 and RP-18
columns successively with MeOH–H2O gradient elution to give
segetoside I (MeOH–H2O, 7:3). HPLC, TLC, LC–MS/MS (Fig. 1B) and
comparative spectroscopic literature analysis were used to authenticate
the purity and structure of segetoside I.