# Metabolite Profiling of _Christia__vevertilionis_ Leaf Metabolome via Molecular Network Approach
## 3 Results and Discussion
### Structural Elucidation of Isolated Compounds
The attachment of the \(\alpha\)-apiofuranose moiety to ring-B of the apigenin unit was further supported by the TOCSY experiment, which showed the spin system between H-1\({}^{\prime\prime\prime}\) (\(\delta_{\rm H}\) 5.69) and the protons of ring-B at \(\delta_{\rm H}\) 7.20 (H-3\({}^{\prime}\), H-5\({}^{\prime}\)) and \(\delta_{\rm H}\) 7.93 (H-2\({}^{\prime}\) and H-6\({}^{\prime}\)) (Figure S27). The completely assigned NMR data of **28** is shown in Table 2. Based on the spectral evidence, the structure of **28** was elucidated as apigenin-6-\(C\)-\(\beta\)-glucoside 4\({}^{\prime}\)-\(O\)-\(\alpha\)-apiofuranoside (Figure 9). The characterization of apigenin-6-\(C\)-\(\beta\)-glucoside was also confirmed by comparison of the NMR data with those reported by [PERSON] et al. [42]. Meanwhile, the identity of the pentosyl moiety as apiofuranose was confirmed by comparison with the NMR data reported by [PERSON] et al. [43]. Compound **47** was obtained as a light yellow amorphous solid. Its molecular formula was determined as C\({}_{32}\)H\({}_{32}\)O\({}_{20}\) based on the deprotonated molecular ion peak observed at \(m/z\) 735.214 in negative ion mode ESI-MS/MS spectrum (Figure S11). The \({}^{1}\)H-NMR spectrum and the correlations observed in the HSQC and HMBC spectrum, as well as the proton spin system exhibited by the TOCSY experiment on the compound, were found to be similar to those of compound **28**, except for the presence of additional signals attributable to two malonyl units (\(\delta_{\rm H}\) 3.80, \(\delta_{\rm H}\) 3.71, \(\delta_{\rm C}\) 175.21, and \(\delta_{\rm C}\) 176.58), in accordance with the structure of a dimalonylated derivative of **28** (Figures S29-S31). Notably, due to the obscuration of the proton signal belonging to the anomeric proton of the C-glucoside at \(\delta_{\rm H}\) 4.91 (H-1'') by the water resonance, its coupling constant could not be determined. However, since the proton and carbon chemical shifts, as well as the configuration of apiofuranosyl of this compound, were consistent with that of **28**, the anomeric configuration of the C-glucose was thus deduced to be the same as in **28**. A detailed analysis of the HMBC spectral data allowed the assignment of one of the malonyl groups that is O-linked to position C-6'' of the glucoside unit, denoted as M\({}_{1}\). This was deduced from the \({}^{3}J\) correlation observed from H-6'' (\(\delta_{\rm H}\) 3.76) to the carbonyl carbon of M\({}_{1}\) at \(\delta_{\rm C}\) 175.21 (C\({}_{1}\)-M\({}_{1}\)) (Figure S31). In addition, two sets of one proton singlet at \(\delta_{\rm H}\) 3.80 (H-M\({}_{1}\)) and another at \(\delta_{\rm H}\) 3.71 (H-M\({}_{2}\)) were observed to show correlations with \(\delta_{\rm C}\) 175.21 (C\({}_{1}\)-M\({}_{1}\)), and \(\delta_{\rm C}\) 176.58 (C\({}_{1}\)-M\({}_{2}\)), respectively (Figure S31). These were assigned to the proton signal arising from the methylene protons (OCOCH\({}_{2}\)CO) of M\({}_{1}\) and M\({}_{2}\), respectively. Instead of appearing as a 2H singlet signal for each of the methylene groups, it was suspected that there was a presence of residual water (D\({}_{2}\)O) in the deuterated solvent (CD\({}_{3}\)OD), which possibly caused the exchange of one proton in the methylene groups with the deuteron of water to form CHD, resulting in a significant reduction in the integral value of the methylene protons. Correlations between the sugar protons to the carbonyl carbon of M\({}_{2}\) were not observed in the HMBC experiment for some inexplicable reason. To further support the assignment of M\({}_{2}\), information from the ESI-MS/MS analysis, as discussed in Section 3.1.2, was relied on. Moreover, the RP-HPLC elution order and longer elution time for compound **47** (R\({}_{\rm T}\) = 40.14) compared to **28** (R\({}_{\rm T}\) = 20.05), as shown in Figure 8, suggested a more hydrophobic characteristic for **47**, which was in agreement with the presence of the bulky dimalonyl moieties in its structure.