## 3 Results  
### Structure Identification of the Isolated Compounds  
Since the ethyl acetate-soluble fraction of the hulls of _T. aestivum_ (50 ug/mL) showed a NO production inhibitory activity of 62.11% in LPS-stimulated RAW 264.7 cells, it was subjected to phytochemical investigation. As a result, eight known compounds **1-8** were isolated and their structures were identified as tricin (**1**) [24], tricin 4\({}^{\prime}\)-\(O\)-[_three_-\(\beta\)-guaiacyl-(7\({}^{\prime\prime}\)-\(O\)-methyl-9\({}^{\prime\prime}\)-\(O\)-acetyl)-glyceryl] ether (**2**) [25], tricin 4\({}^{\prime}\)-\(O\)-[_eryth_-\(\beta\)-guaiacyl-(7\({}^{\prime\prime}\)-\(O\)-methyl-9\({}^{\prime\prime}\)-\(O\)-acetyl)-glyceryl] ether (**3**) [25], tricin 4\({}^{\prime}\)-\(O\)-[_three_-\(\beta\)-guaiacyl-(7\({}^{\prime\prime}\)-\(O\)-methyl)-glyceryl] ether (**5**) [27], tricin 4\({}^{\prime}\)-\(O\)-[_eryth_-\(\beta\)-guaiacyl-(7\({}^{\prime\prime}\)-\(O\)-methyl)-glyceryl] ether (**6**) [27], tricin 4\({}^{\prime}\)-\(O\)-[_three_-\(\beta\)-4\({}^{\prime\prime}\)-hydroxyphenyl-(7\({}^{\prime\prime}\)-\(O\)-methyl)-glyceryl] ether (**7**) [28], and tricin 4\({}^{\prime}\)-\(O\)-[_eryth_-\(\beta\)-4\({}^{\prime\prime}\)-hydroxyphenyl-(7\({}^{\prime\prime}\)-\(O\)-methyl)-glyceryl] ether (**8**) [28], via the analysis of their spectroscopic data as well as the comparison of their data with published values (Figure 1).  
The relative stereochemistry of **2-8** was determined by a coupling constant (_J_) between H-7\" and H-8\". In the \({}^{1}\)H NMR spectra of **2-4** (in acetone-\(d_{4}\)), the large \(J_{\text{H-7\"-H-8\"}}\) value (6.3 and 6.7 Hz, respectively) of compounds **2** and **4** indicated a _three_ configuration, whereas the small \(J_{\text{H-7\"-H-8\"}}\) value (4.8 Hz) of compound **3** suggested an _eryth_ro configuration. In the \({}^{1}\)H NMR spectra of **5-8** (in acetone-\(d_{4}\)), the coupling constant of **5** and **7** showed a larger \(J_{\text{H-7\"-H-8\"}}\) value (6.7 and 6.8 Hz, respectively) than those of **6** and **8** (6.2 and 6.4 Hz, respectively), providing the 7\({}^{\prime\prime}\),8\({}^{\prime\prime}\)-_three_-configuration for **5** and **7** and the 7\({}^{\prime\prime}\),8\({}^{\prime\prime}\)-_erythro_-configuration for **6** and **8**. In addition, we also observed that the resonance for the methylene protons (H-9\"a and H-9\"b) in the \({}^{1}\)H NMR spectra of the _three_ type was shifted to upfield, compared to the corresponding proton signals in the _erythhro_ type. Most previous stereochemical studies of similar flavonolignans have reported their relative configurations [24; 25; 26; 27; 29; 30]. Although CD experiments could be suggested to establish the absolute configuration of the flavonolignans, the isolates **2-8** did not exhibit CD Cotton effects in our study. This phenomenon may be explained by their conformational mobility, as described in a previous study [31]. The CD spectrum depends on the weighted average of the spectra of all the conformers present in solution; there could thus appear different signs of the rotational intensity of a given transition. Therefore, it seems possible that the CD spectra of **2-8** were not observed, cancelling their overlapping spectra [32].