Presence of flavonoid glucosides in C. sativus stigmas. (A) HPLC-ESI-MS chromatogram of a MeOH extract of C. sativus stigmas at anthesis. Three flavonoid peaks, 1, 2, and 3 are denoted by arrows. The compound 4-methylumbelliferyl β-D-glucuronide was used as internal standard (IS). (B) Positive ion mass spectrum corresponding with the observed flavonoid peaks in A: 1, kaempferol 3-O-sophoroside-7-O-glucopyranoside; 2, kaempferol 3,7,4'-triglucoside, and 3, kaempferol 7-O-sophoroside acquired during the HPLC-ESI-MS analysis. (C) Relative kaempferol 3-O-sophoroside-7-O-glucopyranoside, kaempferol 3,7,4'-triglucoside and kaempferol 7-O-sophoroside levels at different stigma developmental stages.