Using LC-ESI-MS/MS methods, the profile of bioactive components
in EESC was characterized. As shown in Figure 1, 2 major
peaks were detected at 3.60 and 4.89 min of retention time, respectively,
by LC-PDA and identified based on comparison of their retention times with those of reference compounds and their elution
time. In addition, structural identification of major bioactive
components in EESC was based on the molecular ion detected in
the positive ion mode with mass fragmentation patterns obtained
by means of multiple-step mass spectrometry (MS1 andMS2) (Figure
1 and Table 1). In the mass spectra for the 1st peak, ([M+H]+)
ion at m/z 246 was obtained from MS1 and consequently fragmented
to mainly m/z 227, 199, and 134 in MS2 (Figure 1B and
1C). For the second one, ([M+H]+) ion at m/z 229 produced ion
at m/z 134 106, and 221 on MS2 (Figure 1B and 1C). Oxyresveratrol
and resveratrol were determined by matching ([M+H]+) ions
mass fragmentation patterns in both MS1 and MS2 by comparing
mass fragmentation patterns obtained from respective standard
(Figure 1D). The major compounds of each class of bioactive components
were quantified by external calibration using LC-PDA.
Resveratrol was the predominant bioactive components in Smilax
china root, with amount 267.22 mg/kg fresh weight (Table 1).
The content of oxyresveratrol measured in Smilax china root was
68.89 mg/kg fresh weight (Table 1). In addition, we identified
piceid that was coeluted with resveratrol at 4.89 min of retention
time by mass fragmentation analysis by using MS (Figure 1D).
However, the amount of piceid was below the limit of detection
(1.53 μg/mL). Therefore, 2 major components including resveratrol
and oxyresveratrol were further studied as individual bioactive
components in EESC.