# Metabolite Profiling of _Christia__vevertilionis_ Leaf Metabolome via Molecular Network Approach
## 3 Results and Discussion
### C-glycosflavone Derivatives  
A detailed inspection of the MS/MS spectral data for Clusters D (positive ion mode), and P (negative ion mode), as shown in Figure 3, also revealed the presence of mono-, di-, and acylated \(C\)-glycosflavones. The MS/MS spectral data of the identified compounds were mainly characterized by the neutral losses of 90 and 120 Da, together with the formation of the [aglycone \(+\) 12]\({}^{-\bullet}\) radical fragment ion, which indicates the occurrence of C-glycosidic linkage within the parent structure of these compounds. Automated dereplication conducted by GNPS spectral library matching for both Clusters D and P (Figure 3) permitted the annotation of two known mono-\(C\)-glycosflavones, namely, luteolin-6-\(C\)-glucoside (**27**) and apigenin-6-\(C\)-glucoside (**35**). The nodes with precursor ions at \(m/z\) 449.108 [M \(+\) H]\({}^{+}\) and 447.093 [M \(-\) H]\({}^{-}\) were annotated as luteolin-6-\(C\)-glucose (**27**), commonly known as isoorientin, whereas nodes with precursor ions at \(m/z\) 433.113 [M \(+\) H]\({}^{+}\) and 431.098 [M \(-\) H]\({}^{-}\) corresponded to apigenin-6-\(C\)-glucose (**35**), commonly known as isovitexin. The identity of both compounds was verified as mono-\(C\)-glycosflavone based on the existence of fragment ions of [aglycone \(+\)71]\({}^{-}\), and [aglycone \(+\) 41]\({}^{-}\), attributable to the neutral losses of 90 and 120 Da, respectively, along with the characteristic fragment ion of [aglycone \(+\) 12]\({}^{-\bullet}\). Furthermore, the attachment of the glucosyl moiety at the C-6 position of the aglycone moiety for these compounds was in agreement with the presence of diagnostic fragment ions for [(M\(-\)H)-18]\({}^{-}\) in **27** and [(M\(+\)H)-4H\({}_{2}\)O]\({}^{+}\) in **35**, as reported by [PERSON] et al. [23] and [PERSON] et al. [24], respectively. With a mass difference of 14 Da (CH\({}_{2}\)) from that of **27**, the nodes with precursor ions at \(m/z\) 463.124 [M \(+\) H]\({}^{+}\) and 461.109 [M \(-\) H]\({}^{-}\) in Clusters D and P, respectively, were initially proposed as an \(O\)-methylated derivative of **35**. Subsequently, the identity of these nodes was elucidated as diosmein-6-\(C\)-glucose (**40**) based on direct comparison of its MS/MS fragmentation pattern in positive ion mode with a previous study by [PERSON] et al. [24], in which the existence of a fragment ion at \(m/z\) 151 [\({}^{0,2}\) B]\({}^{+}\) specifically justified that the \(O\)-methylated group was linked to ring-B. An identical fragmentation pattern to **35** was also observed for the spectral node at \(m/z\) 431.192 [M \(-\) H]\({}^{-}\), which allowed its identification as the structural isomer of **35**, known as apigenin-8-\(C\)-glucose or vitexin (**38**). By considering the mass differences of 136, 86, 68, and 42 Da from that of apigenin-6-\(C\)-glucose (**35**), five nodes with precursor ions at \(m/z\) 567.073 [M \(-\) H]\({}^{-}\), 519.114 [M \(+\) H]\({}^{+}\), 517.098 [M \(-\) H]\({}^{-}\), 499.085 [M \(-\) H]\({}^{-}\), and 473.109 [M \(-\) H]\({}^{-}\) were suggested to be the aliphatic and aromatic acyl derivatives of **35**. These mass differences were proposed as dihydroxybenzoyl (C\({}_{7}\)H\({}_{4}\)O\({}_{3}\)), malonyl (C\({}_{3}\)H\({}_{2}\)O\({}_{3}\)), crotonyl (C\({}_{4}\)H\({}_{4}\)O), and acetyl (C\({}_{2}\)H\({}_{2}\)O) groups, which were congruent with the molecular mass of 136, 86, 68, and 42 Da, re spectively. The interpretation of their MS/MS fragmentation data in negative ion mode disclosed that these compounds possessed similar MS/MS features as **35**, at \(m/z\) 269 for [(M\(-\)H)-acylhexose]\({}^{-}\), 282 for [aglycone + 12]\({}^{-}\)\({}^{\bullet}\), 311 for [(M\(-\)H)-acyl-120]\({}^{-}\), and 341 for [(M\(-\)H)-acyl-90]\({}^{-}\). The formation of identical fragment ions at \(m/z\) 311 for [(M\(-\)H)-acyl-120]\({}^{-}\) and 341 for [(M\(-\)H)-acyl-90]\({}^{-}\) for these compounds were consistent with the attachment of the acyl groups on the hydroxyl part of the sugar unit.