Glycosylated platycosides: I dentification by enzymatic hydrolysis and structural determination by LC – MS / MS

In this study, enzymatic hydrolysis and chemometric methods were utilized to discriminate glycosylated platycosides in the extract of P latycodi R adix by LC – MS . Laminarinase, whose enzymatic activity was evaluated using gentiobiose and laminaritriose, was a suitable enzyme to identify the glycosylated platycosides. The laminarinase produced deapi‐platycodin D and platycodin D from the isolated deapi‐platycoside E and platycoside E through the loss of two glucose units by enzymatic reaction, respectively. After hydrolyzing a crude extract by laminarinase, the reconstructed total ion chromatogram generated by a chemometric technique sorted peaks of deglycosylated platycosides easily. Structural information of the glycosylated isomers was revealed through fragment ions generated by the sodiated C 0β ion corresponding to reduced disaccharides in the positive MS 4 spectra. Characteristic fragment ions of G lc‐(1→6)‐ G lc moieties were observed through ring cleavages of 0,2 A 0β , 0,3 A 0β , and 0,4 A 0β , whereas G lc‐(1→3)‐ G lc moieties produced only 0,3 A 0β ions. Lithium‐adducted platycosides allowed more detailed structural analysis of glycosidic bond cleavage corresponding to Y 1β and B 1β in addition to ring cleavage.