## 2 Results and Discussion
### Identification of Absorbed Constituents in Rabbit Plasma and CSF by HS-SPME-GC-MS
\begin{table}
\begin{tabular}{c c c c c c c} \hline Compound & & & & & Group b & & Group c \\ No. & \(\text{t}_{\text{R}}\,\text{(min)}\) & RI \({}^{\text{b}}\)[12] & Constituents & & Plasma & CSF & Plasma & CSF \\ \hline G1 & 6.423 & 944 & \(\alpha\)-Pinene & + & + & – & – \\ G2 & 6.853 & 982 & Sabinene & + & + & – & – \\ G3 & 6.902 & 988 & \(\beta\)-Pinene & + & + & – & – \\ G4 & 7.000 & 993 & Myrcene & + & + & – & – \\ G5 & 7.170 & 1012 & \(\alpha\)-Phellandrene & + & + & – & – \\ G6 & 7.236 & 1018 & 3-Carene & + & + & – & – \\ G7 & 7.421 & 1035 & Limonene & + & + & – & – \\ G8 & 7.463 & 1040 & Eucalypt & + & + & – & – \\ G9 & 8.031 & 1096 & Terpinolene & + & + & – & – \\ G10 & 8.675 & 1158 & Camphor & + & + & – & – \\ G11 \({}^{\text{a}}\) & 8.724 & 1162 & Eucarvone & + & + & + & + \\ G12 \({}^{\text{a}}\) & 8.890 & 1178 & \(l\)-Borneol & + & + & + & + \\ G13 & 8.992 & 1188 & Terpinen-4-ol & + & + & – & – \\ G14 & 9.035 & 1192 & \(p\)-Cymen-8-ol & - & + & – & – \\ G15 & 9.118 & 1200 & \(\alpha\)-Terpineol & + & + & – & – \\ G16 & 9.179 & 1206 & Estragole & + & – & – \\ G17 \({}^{\text{a}}\) & 9.847 & 1275 & 3,5-Dimethoxytoluene & + & + & + & + \\ G18 \({}^{\text{a}}\) & 10.105 & 1300 & Safrole & + & + & + & – \\ G19 & 10.971 & 1400 & Tetradecane & + & + & – & – \\ G20 \({}^{\text{a}}\), G21 \({}^{\text{a}}\) & 11.030 & 1408 & 3,4,5-Trimethoxy-toluene/methyleugenol & + & + & + & + \\ G22 \({}^{\text{a}}\) & 11.106 & 1417 & 2,3,5-Trimethoxytoluene & + & + & + & + \\ G23 & 11.783 & 1501 & Pentadecane & + & + & – & – \\ G24 & 11.860 & 1510 & Asaricin & + & + & + & – \\ G25 & 12.191 & 1550 & 3,4-Methylenedioxy-propiophenone & + & + & – & – \\ G26 & 12.268 & 1560 & Elemicin & + & + & – & – \\ \hline Sum & & & 25 & 25 & 8 & 6 \\ \hline \end{tabular} \({}^{\text{a}}\) Confirmed by comparison with reference compounds, \({}^{\text{b}}\) retention index; \(+\) detected; – not detected.  
\end{table} 
Table 1: The absorbed constituents in rabbit plasma and cerebrospinal fluid (CSF) from Asari Radix et Rhiz (AR) EtOAc extract group (group **b**) and AR powder group (group **c**) identified by HS-SPME-GC-MS. In total, 23 absorbed constituents including eight lignans (**L1**-**L3**, **L5**, **L8**, **L10**, **L14**, **L15**), nine \(N\)-alkylamides (**L13**, **L16**-**L23**), four phenylpropanoids (**L4**, **L9**, **L11**, **L12**) and two benzene derivatives (**L6**, **L7**) were identified in the plasma of the AR EtOAc extract group, but only five of them (**L6**, **L7**, **L15**-**L17**) were detected in the CSF. As for the AR powder group, only two compounds (**L16**, **L17**) were detected in the plasma and no compounds could be detected in the CSF. Among the above compounds, **L4**, **L8**, **L12**, **L13**, and **L20**-**L23** were the compounds which did not reported in _A. heterotropoides_ var. _mandshuricum_. The results are summarized in Table 2 and Figure 6.  
Figure 5: Chemical structures of 26 absorbed constituents identified in rabbit plasma and CSF from AR EtOAc extract group and the AR powder group identified by HS-SPME-GC-MS.