The retention time, observed mass, mass difference, fragment ions, and proposed compounds of six peaks are listed in Table
1. The major components of SMGGT were identified by comparing both UV and MS spectra to their spectroscopic data in the literature [
20‐
22]. The peak 1 and peak 4 showed identical protonated ion of
m/z 417 in the positive ion mode but the fragment ion peaks were differentiated as the neutral loss of 120 Da in peak 1 (
m/z 297, [M + H-C
4H
9O
4]
+) attributed to the characteristic cleavage of
C-glycosides and the neutral loss of 162 Da in peak 4 (
m/z 255, [M + H-C
6H
10O
5]
+) attributed to the characteristic cleavage of
O-glycosides. Based on the molecular ions and their fragmentation patterns, peak 1 and peak 4 were identified as puerarin (daidzein-8-
C-glucoside) and daidzin (daidzein-7-
O-glucoside), respectively. Likewise, the peak 3 showed protonated ion at
m/z 447 and the neutral loss of 120 Da same as in peak 1. Based on the retention time, MS spectrum, and 30 Da difference compare to the protonated puerarin ion at
m/z 417, peak 3 was identified as 3’-methoxylpuerarin. The peak 2 represented protonated ion at
m/z 481 and fragmented ion at
m/z 179 due to the loss of single glucose and benzoic acid which specified it to be paeoniflorin. The peak 6 showed protonated ion at
m/z 419 and fragmented ion at
m/z 257 attributed to the loss of a glucose molecule and it was identified as liquiritin (liquiritigenin-4'-
O-glucoside). Six major phytochemicals in SMGGT were identified as follows: isoferulic acid (from Cimicifugae Rhizoma), puerarin, 3'-methoxypuerarin, daidzin (from Puerariae Radix), paeoniflorin (from Paeoniae Radix), and liquiritin (from Glycyrrhizae Radix). The identities of KFDA- certified herbal medicines were reconfirmed by HPLC-ESI-MS to ensure the quality of the herbal medicines contained in SMGGT.
Table 1
The observed and calculated mass numbers of HPLC peaks of SMGGT
1 | 51.93 | 417.11854 | 417.11338 | −5.16 | 297.06931 | puerarin | |
2 | 53.96 | 481.17096 | 481.17640 | 5.44 | 179.06642 | paeoniflorin | |
3 | 55.91 | 447.12910 | 447.12316 | −5.94 | 429.11301 327.07994 | 3'-methoxypuerarin | |
4 | 64.31 | 417.11854 | 417.11534 | −3.20 | 255.05128 | daidzin | |
5 | 67.74 | 195.06573 | 195.05935 | −6.38 | 177.05273 149.05859 | isoferulic acid | |
6 | 73.83 | 419.13416 | 419.13338 | −0.78 | 257.07896 | liquiritin | |