In situ label-free imaging for visualizing the biotransformation of a bioactive polyphenol.
Although understanding the high-resolution spatial distribution of bioactive small molecules is indispensable for elucidating their biological or pharmacological effects, there has been no analytical technique that can easily detect the naïve molecular localization in mammalian tissues. We herein present a novel in situ label-free imaging technique for visualizing bioactive small molecules, using a polyphenol. We established a 1,5-diaminonaphthalene (1,5-DAN)-based matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) technique for visualizing epigallocatechin-3-O-gallate (EGCG), the major bioactive green tea polyphenol, within mammalian tissue micro-regions after oral dosing. Furthermore, the combination of this label-free MALDI-MSI method and a standard-independent metabolite identification method, an isotopic fine structure analysis using ultrahigh-resolution mass spectrometer, allows for the visualization of spatially-resolved biotransformation based on simultaneous mapping of EGCG and its phase II metabolites. Although this approach has limitations of the detection sensitivity, it will overcome the drawbacks associated with conventional molecular imaging techniques, and could contribute to biological discovery.
1] Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan [2].
Yoon Hee
YH
Kim
Yoshinori
Y
Fujimura
Takatoki
T
Hagihara
Masako
M
Sasaki
Daichi
D
Yukihira
Tatsuhiko
T
Nagao
Daisuke
D
Miura
Shinichi
S
Yamaguchi
Kazunori
K
Saito
Hiroshi
H
Tanaka
Hiroyuki
H
Wariishi
Koji
K
Yamada
Hirofumi
H
Tachibana
D015081:2-Naphthylamine / Q000031:analogs & derivatives / Q000737:chemistry; D000818:Animals; D001711:Biotransformation; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D007477:Ions; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D050217:Metabolic Detoxication, Phase II; D051379:Mice; D008810:Mice, Inbred C57BL; D057054:Molecular Imaging / Q000379:methods*; D059808:Polyphenols / Q000008:administration & dosage / Q000737:chemistry / Q000493:pharmacokinetics*; D012015:Reference Standards; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013194:Staining and Labeling; D014020:Tissue Extracts
D007477:Ions; D059808:Polyphenols; D014020:Tissue Extracts; C510889:1,5-diaminonaphthalene; D002392:Catechin; C045651:epigallocatechin gallate; D015081:2-Naphthylamine