Table 1. Eight types of major chemical constituents in GQD. The representative compounds, original herb, MS behavior in NL and PRE scans, major in vivo metabolic reactions, and distribution.
| Structural type | Compound | Herba | Neutral loss scanb (m/z) | Precursor ion scan (m/z) | Supplementary precursor ion scan (m/z) | Metabolic reactionc | Distributiond (P/U/F) | |
|---|---|---|---|---|---|---|---|---|
| A | Flavonoid C-glycoside | P2, P9, P10 | P, S | 15, 28, 120, 176, 252# | 119, 135, 225, 241, 253, 257, 267, 283, 295, 311, 321, 325, 333, 415, 417, 430, 431, 445 | 149, 268, 269, 297, 309, 429, 461 | H/S/G deM/M (C3′) RC (C-ring) | P/MP/MIP |
| B | Flavonoid O-glucuronide | S14, S15, S17 | S | 15, 18, 28, 80, 90, 120, 162, 176, 210 | 119, 241, 268, 269, 283, 295, 325, 385, 427, 431, 457, 459 | 101, 125, 151, 175, 177, 253, 285, 299, 301, 303, 330, 345, 349, 401, 425, 429, 445, 475 | H/G/Glc deM/M (C6,7) C-ring stable | MP/MP/MAP |
| C | Benzylisoquinoline alkaloid | C1, C2 | C | 15, 18, 45#, 176 (+) | 295, 307, 308, 309, 321, 322, 323, 324, 337, 338, 484 (+) | 292, 297, 340, 342, 354, 358, 372 (+) | deM/M/OH G | T/M/T |
| D | Flavonoid aglycone | Supplementary | NL/PRE feature | |||||
| D1 Isoflavone | G17 | G, P | P17, P18, P3 | NL CO2, CO, CH3,H2O, G, S, etc.Common PRE not available. | deM/M, RC, S/G | MP/MP/P | ||
| D2 Flavone | G3 | G, S | S2, S3, S10 | deM/M, G | T/M/P or T | |||
| D3 Flavanone | G10 | G | G4, G1 | RC, RH, S/G | MP/M/MIP | |||
| D4 Chalcone | G8 | G | G5, G2 | RC, RH, S/G | MP/M/MIP | |||
| E | Flavonoid O-glycoside | Supplementary | NL/PRE feature | |||||
| mono-O- | G1, G2 | G, P | P1, P4 | NL/PRE: G/A | H/S/G, RC | MP/MP/MAP | ||
| di-O- | G4, G5 | G, P | P6 | NL/PRE: G/A | H/S/G, RC | MP/MP/MAP | ||
| F | Coumarin | G11 | G | NL G, S, CO2 | OH/OdeH, S/G | MP/MP/P | ||
| G | Saponin | G6 | G | NL/PRE: A/G | H, G, OH | MP/MP/A | ||
| H | Atypical, abundant backbones | Initiate | Confirm | New scan | ||||
| pueroside | P12 | P | NL 80, 176 | EIC/PROD 391, 487 | PRE 311 | Unstable, H/S/G | M/M/T | |
| flavanonol | S1 | S | NL 176 | EIC/PROD 477, 479 | PRE 301, 303 | OdeH, S/G | MII/MP/P | |
| phenylethanoid glycoside | S17 | S | NL 162 | EIC/PROD 623 | PRE 461 | Unstable | T/M/T | |
| aporphine alkaloid | C6 | C | NL 176, 18 (+) | EIC/PROD 342 (+) | NL 45 (+) | deM/M/OH, G | T/M/T | |
| flavonol | S7 | S | NL 80 | EIC/PROD 345 | PRE 431 | RH, S/G | MII/M/P | |
aOrigin: P, Puerariae Lobatae Radix; S, Scutellariae Radix; C, Coptidis Rhizoma; G, Glycyrrhizae Radix et Rhizoma Praeparata cum Melle.
bMS scan mode: NL, neutral loss scan; PRE, precursor ion scan; PROD, product ion scan; EIC, extracted ion current; (+) determined in (+) ESI mode; data were obtained in (−) ESI mode unless otherwise stated; Scans marked with # were newly established from MS screening process.
cMetabolic reaction: G, glucuronidation; H, hydrolysis; M, methylation; deM, demethylation; OH, oxidation (hydroxylation); OdeH, oxidation (dehydrogenation); RH, reduction (hydrogenation); RC, ring cleavage; S, sulfation.
dDistribution, P, plasma; U, urine; F, Feces. Analyte type: M, metabolite; MI, phase I metabolite; MII, phase II metabolite; MA, metabolite formed by hydrolysis, namly aglycones; P, prototype (unchanged form) T, trace or low abundance.