## 2 Results and Discussion
### Identification of Pharmacologically Active Volatiles of Houttuynia cordata Thunb by GC/SAW
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Peak No.**} & \multirow{2}{*}{**Compound**} & \multicolumn{6}{c}{**_Houttuynia cordata_ Thunb} \\ \cline{3-8}  & & \multicolumn{2}{c}{**Leaves**} & \multicolumn{2}{c}{**Aerial Stems**} & \multicolumn{2}{c}{**Underground Stems**} \\ \cline{3-8}  & & **GC/SAW** & **HS-SPME** & **GC/SAW** & **HS-SPME** & **GC/SAW** & **HS-SPME** \\ \hline a & _cis_-3-Hexenal & 1.1(14.81) & 0.3 (3.85) & 2.1(12.78) & - & 0.9(3.71) & - \\
1 & Hexanal & - & 0.3(31.33) & - & - & - & - \\
2 & 2-Hexenal & - & 1.2(22.09) & - & - & - & - \\ b & 3-Hexen-1-ol & 3.5(9.75) & 2.5(10.80) & 0.2(4.68) & 1.1(6.67) & - & - \\
3 & \(\alpha\)-Thujene & - & 0.1(8.93) & - & 0.2(9.01) & - & 0.2(5.56) \\ c & \(a\)-Pinene & 8.3(3.28) & 0.2(6.48) & 4.2(4.39) & 5.3(4.31) & - & 15.3(6.10) \\ d & Camphene & - & - & 0.6(3.14) & 1.8(3.16) & 1.9(17.06) & 1.3(3.99) \\ e & Sabinene & 0.8(13.09) & 3.0(4.64) & 2.1(9.92) & 4.5(4.92) & 3.2(1.49) & 6.9(2.23) \\ f & \(\beta\)-Pinene & 0.3(14.28) & 0.3(5.86) & - & 4.0(7.11) & 1.5(2.81) & 28.8(3.07) \\ g & \(\beta\)**-Myreene** & 15.8(5.71) & 26.2(8.39) & 23.3(9.32) & 48.1(10.76) & 33.9(10.50) & 14.3(7.21) \\
4 & \(\delta\)-3-Carene & - & 0.1(30.34) & - & - & - & - \\
5 & \(a\)-Terpinene & - & 0.1(12.78) & - & 0.1(8.98) & - & 0.1(7.95) \\
6 & \(p\)-Cymene & - & 0.1(9.81) & - & 0.4(6.23) & - & 0.2(4.61) \\ h & **Limonene** & 0.6(12.57) & 0.1(8.61) & 2.3(7.47) & 4.0(5.13) & 17.4(8.06) & 9.4(4.33) \\ i & _cis_-Ocimene** & 18.4(5.93) & 18.2(2.33) & 11.1(14.55) & 6.6(4.63) & 15.9(16.93) & 0.2(2.15) \\
7 & _trans_-Ocimene & - & 0.5(21.92) & - & 0.2(15.73) & - & 0.2(13.76) \\
8 & \(\gamma\)-Terpinene & - & 0.1(2.81) & - & 0.2( 3.45) & - & 0.2(1.09) \\
9 & _trans_-Sabinene hydrate & - & - & - & - & - & t \\ j & \(a\)-Terpinolene & 0.1(4.02) & - & 0.9(15.06) & - & 0.8(14.96) & 0.5(5.67) \\
10 & _cis_-Sabinene hydrate & - & - & - & - & - & t \\
11 & Nonanal & - & 0.2(11.95) & - & 0.1(13.32) & - & t \\
12 & 2,6-Dimethyl-1,3,5,7-octatetraene & - & 0.1(5.35) & - & - & - & - \\
13 & _neo-allo_-Ocimene & - & 0.3(5.30) & - & 0.1(3.94) & - & - \\
14 & 1-Nonanol & - & 0.1(9.66) & - & 0.1(5.31) & - & 0.1(6.11) \\
15 & Terpinene-4-ol & - & 0.1(10.14) & - & 0.1(8.83) & - & 0.1(4.31) \\ k & **Decanal** & 36.8(11.58) & 26.8(49.82) & 15.7(15.00) & 1.4(30.23) & 1.2(1.46) & 0.1(15.36) \\
16 & \(a\)-Fencyl acetate & - & - & - & - & - & t \\
17 & \(\beta\)-Cyclocitral & - & 0.3(24.19) & - & 0.1(19.12) & - & 0.3(17.42) \\
18 & Thymyl methyl ether & - & - & - & - & - & t \\
19 & Citral & - & - & - & - & - & 0.1(9.53) \\
20 & 1-Decanol & - & 0.8(50.12) & - & 0.2(35.29) & - & - \\
1 & **Bornyl acetate** & 1.7(6.75) & 0.2(12.92) & 17.4(8.06) & 9.3(9.54) & 14.6(9.16) & 7.2(6.63) \\ m & **2-Undecanone** & 1.3(10.49) & 0.7(9.56) & - & 0.7(8.90) & - & 2.3(7.19) \\
21 & Undecanal & - & 1.3(1.66) & - & 0.3(4.73) & - & 0.1(3.71) \\
22 & \(a\)-Cyclogenanyl acetate & - & 0.9(26.34) & - & 0.4(17.71) & - & 0.8(15.03) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Composition and identification of volatiles of leaves, aerial stems, and underground stems for _Houttuynia cordata_ Thunb by fast GC/SAW and HS-SPME-GC-MS.  
Sixteen compounds were identified. \(\beta\)-Myrcene, _cis_-ocimene and decanal, which comprise 71.0% of the total amounts, are the dominant volatile components of leaves of _H. cordata_ Thunb. 2-Undecanone and lauraldehyde were found to be the characteristic components comprising 1.3% and 3.5% of the total amounts, respectively. Monoterpenes such as \(\alpha\)-pinene, sabinene, \(\beta\)-pinene, and \(\alpha\)-terpinolene as minor constituents were also found. In addition, the amount of limonene and bornyl acetate varied from low to moderate concentrations for leaves, aerial stems, and underground stems. It was reported that the principal component in the essential oil of this medicinal plant, decanoyl acetaldehyde, is known to have pharmacological effects, but it is unstable and easily converted into 2-undecanone by oxidation and decarboxylation [2, 31].