#### 2.2.2 Flavonoids  
Compared to WS's abundance of bufadienolides, flavonoids were more abundant in RS, with several being reported for the first time in this current study. Beside a positive mode, improved detection of flavonoids was observed in a negative mode, with MS2 fragments found to be characteristic of flavonoids, i.e., amu 151, 125 and 153 as well as neutral loss of amu \(-\)28 \"CO\", \(-\)18 \"H\({}_{2}\)O\" and \(-\)44 \"CO\({}_{2}\)\" [38; 39]. The next subsection shall summarize identification of the different flavonoid subclasses and distribution in _Urginea_ species.  
Identification of Flavonols/Flavonols  
Identified flavanols in L22 and its methylated derivative in L24 at _m_/z 305 (C\({}_{15}\)H\({}_{13}\)O\({}_{7}\)) \({}^{+}\) [M+H] \({}^{+}\) and _m_/z 319 (C\({}_{16}\)H\({}_{15}\)O\({}_{7}\))\({}^{+}\) were annotated as dihydroquercetin (taxifolin) and dihydroxorhmentin (methyl taxifolin), respectively [40]. Flavonols were also detected in peak L40 at _m_/z 303 (C\({}_{15}\)H\({}_{11}\)O\({}_{7}\))\({}^{+}\) [M+H]\({}^{+}\) identified as quercetin, as well as its glycosides L41 and L32 (Table 2).  
Another major flavanol was detected in peak in RS L17 _m_/z 289 (C\({}_{15}\)H\({}_{13}\)O\({}_{6}\))\({}^{+}\) [M+H]\({}^{+}\) and N13 _m_/z 287 (C\({}_{15}\)H\({}_{11}\)O\({}_{6}\))\({}^{-}\) [M-H]\({}^{-}\) and were annotated as dihydrokaempferol [29; 41; 42] along with its glycoside in L16 (Figure S1I), N6 (Figure S1I), N7, N9 and N10. Furthermore, catechin and its hexoside belonging to flavanols, (C\({}_{21}\)H\({}_{23}\)O\({}_{11}\))\({}^{-}\) and (C\({}_{15}\)H\({}_{15}\)O\({}_{6}\))\({}^{+}\) were detected in red squill as N3 and L14 (_m_/z 451 and 291), respectively [43].  
Flavonols, such as N16 _m_/z 465 (C\({}_{21}\)H\({}_{21}\)O\({}_{12}\))\({}^{-}\) and N24 _m_/z 447 (C\({}_{21}\)H\({}_{19}\)O\({}_{11}\))\({}^{-}\) with loss of 180 amu (hexose + H\({}_{2}\)O) moieties and \(-\)162 hexose moiety, were identified as kaempferol-O-glucose [44] (Table 2).  
Identification of Flavones/Flavanones  
Compared to the abundance of flavonoids, the flavone subclass was detected in few peaks exemplified in L20 at m/z 271 (C\({}_{15}\)H\({}_{11}\)O\({}_{5}\))\({}^{+}\) [M+H]\({}^{+}\) apigenin and its sugar glycoside in L28 and L33 (Table 2) [41]. L93 m/z 285 (C\({}_{16}\)H\({}_{13}\)O\({}_{5}\))\({}^{+}\) was interpreted as dihydroxymethoxysidavone [45].  
L94 m/z 317 (C\({}_{17}\)H\({}_{17}\)O\({}_{6}\))\({}^{+}\), annotated as dihydroxy dimethoxy flavanone, represented an example of flavanone as well as N22 _m_/z 595 (C\({}_{27}\)H\({}_{31}\)O\({}_{15}\))\({}^{-}\), with MS\({}_{2}\)_m_/z 271 attributed to the loss of two hexose units (\(-\)324 amu) and annotated as naringenin-O-dihexoside [46].  
Finally, N12 _m_/z 479 (C\({}_{22}\)H\({}_{23}\)O\({}_{12}\))\({}^{-}\) is annotated as noidesol A or B [47], and this is the first report of Noidesol in _Urginea_ species (Figure S1K).  
Compared to flavonoids richness in red squill, anthocyanins were likewise identified exclusively in RS, accounting for its characteristic reddish color. Major anthocyanins included L3 at _m_/z 475 (C\({}_{21}\)H\({}_{31}\)O\({}_{12}\))\({}^{+}\), annotated as hydroxycinnamyl-O-dihexoside [9] (Figure S1L), and L13 at _m_/z 307 (C\({}_{15}\)H\({}_{15}\)O\({}_{7}\))\({}^{+}\) [M+H]\({}^{+}\), identified as leucocyanidin [3] (Figure S1M).  
Identification of Coumarins  
The hydroxycournarin class has been annotated in both squill types, represented as L29 and N15 _m_/z 163 (C\({}_{9}\)H\({}_{7}\)O\({}_{3}\))\({}^{+}\) and 161 (C\({}_{9}\)H\({}_{5}\)O\({}_{3}\))\({}^{-}\), respectively, and is in agreement with previous reports for coumarins in _U. indicia_ species [48; 49].