Spatial Profiling of Gingerol and Shogaol Analogues in Intact Zingiber officinale Rhizomes Using MALDI Mass Spectrometry Imaging

TL;DR

This study uses advanced imaging to map anti-inflammatory compounds in ginger rhizomes, revealing their spatial distribution for the first time.

Contribution

First use of MALDI MSI with IMS to spatially profile gingerol and shogaol analogues in intact ginger rhizomes.

Findings

6-, 8-, and 10-gingerols are mainly found in the stele and cortex of ginger rhizomes.

Shogaols are more broadly distributed, including in the epidermis.

PCA of UPLC-ESI-QTOF-MS data shows clustering patterns among five ginger accessions.

Abstract

Ginger (Zingiber officinale) is a widely recognized functional food, known for its anti-inflammatory, antioxidant, and digestive health benefits largely attributed to gingerol-related compounds. While traditional extraction-based methods have been used to characterize these metabolites, they often compromise the spatial context within tissues. This study represents the first application of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) with ion mobility spectrometry (IMS) to map the detailed spatial distribution of key ginger metabolites (6-, 8-, and 10-gingerols and shogaols) in a complex matrix of an intact rhizome tissue. Rhizomes from five ginger accessions collected in Negros Occidental, Philippines, were cryosectioned at 20 μm, coated with 2,5-dihydroxybenzoic acid (DHB) matrix, and analyzed using MALDI MSI at 100 µm spatial resolution across an m/z range of 50–1200. The MALDI MSI revealed that 6-, 8-, and 10-gingerols were predominantly localized in the stele and cortex regions, while shogaols exhibited broader distribution, including the epidermis. Principal component analysis (PCA) on UPLC-ESI-QTOF-MS data of methanolic rhizome extracts revealed clustering patterns among the five ginger accessions. These findings provide a spatially resolved metabolomic profile of gingerols and shogaols, offering novel insights into the anatomical localization of bioactive compounds. This integrative approach establishes a foundation for future studies on ginger physiology, breeding, and quality control of ginger-derived natural products.

Figures