In vivo analysis and spatial profiling of phytochemicals in herbal tissue by matrix-assisted laser desorption/ionization mass spectrometry

Kwan Ming Ng*, Zhitao LIANG, Wei Lu, Ho Wai Tang, Zhongzhen ZHAO, Chi Ming Che, Yung Chi Cheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)

Abstract

Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was developed for spatial profiling of phytochemicals and secondary metabolites in integrated herbal tissue without solvent extraction. Abundant alkaloid ions, including (+)-menisperine (m/z 356), magnoflorine (m/z 342), stepharanine (m/z 324), protonated sinomenine (m/z 330), protonated sinomendine (m/z 338), and a metabolite at m/z 314, could be directly desorbed from α-cyano-4- hydroxycinnamic acid- (CHCA-) coated stem tissue of Sinomenium acutum upon N2 laser (337 nm) ablation, while the ion signals desorbed from sinapinic acid- (SA-) coated and 2,5-dihydroxybenzoic acid- (DHB-) coated stem tissue were at least 10 times weaker. Solvent composition in the matrix solution could have significant effects on the ion intensity of the metabolites. Under optimized conditions that maximize the ion intensity and form homogeneous matrix crystals on the tissue surface, spatial distributions of the metabolites localized in different tissue regions, including cortex, phloem, xylem, rim, and pith, and their relative abundances could be semiquantitatively determined. The three metabolites detected at m/z 356, 342, and 314 showed specific distributions in the herbal samples collected from different growing areas, while others were not. By applying principal component analysis (PCA), the characteristic metabolites in specific tissue regions could be easily determined, allowing unambiguous differentiation of the herbal samples from different geographic locations.

Original languageEnglish
Pages (from-to)2745-2755
Number of pages11
JournalAnalytical Chemistry
Volume79
Issue number7
DOIs
Publication statusPublished - 1 Apr 2007

Scopus Subject Areas

  • Analytical Chemistry

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