title: Identification and characterisation of phenolics in Polygonum capitatum by ultrahigh-performance liquid chromatography with photodiode array detection and tandem mass spectrometry.
abstract: BACKGROUND
  Polygonum capitatum is a well-known Chinese medicinal plant widely used by the Miao people for the treatment of various urologic disorders. Previous investigations have shown the presence of various types of phenolics. Our ultrahigh-performance liquid chromatography with photodiode array detection and mass spectrometry (UPLC-PDA-MS) analysis indicated that flavonoid glycosides and polyphenolic glycosides were its major constituents and quite a number of phenolic compounds have not yet been identified. Identification or characterisation of the major compounds of this plant will contribute to the scientific understanding of the medicinal plant and the authentication of the plant material and its pharmaceutical preparations.
  
  
  OBJECTIVE
  To develop an efficient method for the identification and structural characterisation of the major compounds present in P. capitatum.
  
  
  METHODS
  Elution of the 70% ethanol extract of P. capitatum by 80% ethanol on a D101 macroporous resin column afforded a phenolics-enriched fraction, separation of which by Sephadex LH-20 column chromatography eluted with absolute ethanol gave a tannin-free phenolic fraction (TFPF). Compounds present in TFPF were identified and structurally characterised by UPLC-PDA-ESI-MS/MS.
  
  
  RESULTS
  An amino acid and 40 phenolics including a number of flavonoid glycosides and polyphenolic glycosides were identified or structurally characterised in TFPF. Among these compounds, four were new and 19 were described in the plant for the first time.
  
  
  CONCLUSIONS
  The study showed that TFPF of P. capitatum contained flavonoid glycosides and polyphenolic glycosides as its major principles. Polyphenolic glycosides were perhaps the most typical chemical markers of P. capitatum.
authors.affiliation: Provincial Key Laboratory of Pharmaceutics in Guizhou Province, School of Pharmacy, Guiyang Medical University, 9 Beijing Road, Guiyang, Guizhou, 550004, PR China.
authors.forename: Shang-Gao
authors.initials: SG
authors.lastname: Liao
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Fa
authors.initials: F
authors.lastname: Sun
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.forename: Xun
authors.initials: X
authors.lastname: He
authors.forename: Ai-Min
authors.initials: AM
authors.lastname: Wang
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Li
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.forename: Yan-Yu
authors.initials: YY
authors.lastname: Lan
authors.forename: Bo-Li
authors.initials: BL
authors.lastname: Zhang
authors.forename: Yong-Lin
authors.initials: YL
authors.lastname: Wang
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D028502:Polygonum / Q000737:chemistry*; D059808:Polyphenols / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D005419:Flavonoids; D010936:Plant Extracts; D059808:Polyphenols
keywords: Polygonum capitatum; Tandem mass spectrometry; UPLC-PDA-MS/MS; phenolics