## 2 Results and Discussions  
### Chemical Composition of Essential Oils  
Volatile secondary metabolites were obtained by hydrodistillation of _P. pabularia_ roots growing wild in Tajikistan and were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). Identification of the oil components was based on their Kovats retention indices (RI) determined by reference to a homologous series of \(n\)-alkanes and by comparison of their mass spectral fragmentation patterns with those reported in the literature [26] and stored in the MS library. Forty-two compounds were identified in the volatile oil accounting for 97.3% of the composition; 5-Pentylcyclohexa-1,3-diene (44.6%), menthone (12.6%), 1-tridecyne (10.9%), and osthole (6.0%) were identified as major constituents of the volatile oil obtained from roots of _P. pabularia_ (Table 1). The structure of the osthole was established on the basis one-dimensional (1D) NMR and electrospray ionization (ESI)-MS spectroscopic studies, respectively [22]. The chemical structures of the main components of the essential oil from the roots of _P. pabularia_ are presented in Figure 1. The GC-MS chromatogram of the volatile oil of _P. pabularia_ is presented in Figure 2.  
Figure 1: Structures of the main components of _Prangos pabularia_ essential oil.  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**RT** & **RI** & **Compound** & **MS** & **Fragmentations, m/z (\%)** & **\%** \\ \hline
17.868 & 1399 & 3-Dodecyn-2-ol & 182.17 & 55 (100\%): 67 (99.69\%): 69 (76.48\%): 95 (72.69\%): 68 (56.92\%) & 2.1 \\
18.237 & 1414 & \(\beta\)-Longipinene & 190.17 & 91 (100\%): 77 (72.64\%): 93 (62.14\%): 161 (88.85\%): 105 (57.88\%) & 0.6 \\
18.406 & 1421 & \(\beta\)-Caryophyllene & 204.19 & 91 (100\%): 79 (86.59\%): 93 (67.92\%): 77 (66.15\%): 105 (55.12\%) & 1.0 \\
18.718 & 1433 & \(\gamma\)-Elemene & 204.19 & 12 (100\%): 17 (98.85\%): 91 (85.85\%): 93 (57.45\%): 107 (43.13\%) & 0.1 \\
18.781 & 1436 & _trans_-a-Berganomete & 204.19 & 93 (100\%): 91 (08.04\%): 19 (70.58\%): 77 (57.71\%): 69 (48.76\%) & 1.6 \\
19.331 & 1459 & (Z)-Dodecyn-1-ol & 184.18 & 67 (100\%): 55 (62.01\%): 81 (56.91\%): 54 (99.91\%): 82 (47.42\%) & 0.2 \\
19.768 & 1477 & \(Y\)-Gurjunene & 204.19 & 91 (100\%): 77 (87.25\%): 93 (83.89\%): 93 (86.86\%): 161 (67.2\%) & 0.1 \\
20.056 & 1489 & \(\beta\)-Selineen & 201.19 & 79 (00\%): 91 (57.67\%): 67 (57.83\%): 93 (63.45\%): 105 (61.85\%) & 0.5 \\
20.193 & 1494 & (32,6E)-e-Farresene & 204.19 & 119 (100\%): 91 (69.2\%): 79 (60.93\%): 81 (58.5\%): 75 (56.68\%) & 0.5 \\
20.231 & 1496 & Valencene & 204.19 & 91 (100\%): 79 (67.61\%): 105 (83.71\%): 93 (89.93\%): 77 (57.81\%) & 0.8 \\
20.274 & 1498 & \(\alpha\)-Selineen & 204.19 & 93 (100\%): 91 (83.33\%): 69 (83.3\%): 105 (50.37\%): 74 (92.2\%) & 0.3 \\
33.581 & 2141 & Osthole & 244.11 & 244 (100\%): 201 (93.94\%): 229 (93.95\%): 131 (65.60\%): 189 (63.98\%): 60 \\  & & Monoterene hydrocarbons & & 1.3 \\  & Oxygenated monoterrepenoids & & & 17.8 \\  & & Sesuiterpene hydrocarbons & & 5.5 \\  & Fatty acid derived & & & 19.8 \\  & Others & & & 53.0 \\  & Total Identified & & & 97.3 \\ \hline \end{tabular}
\end{table}
Table 1: _Cont._