The Spatial Distribution of Alkaloids in Psychotria prunifolia (Kunth) Steyerm and Palicourea coriacea (Cham.) K. Schum Leaves Analysed by Desorption Electrospray Ionisation Mass Spectrometry Imaging

Abstract

ABSTRACT:Introduction -Species of the genera Psychotria and Palicourea are sources of indole alkaloids, however, the distribution of alkaloids within the plants is not known. Analysing the spatial distribution using desorption electrospray ionisation mass spectrometry imaging (DESI-MSI) has become attractive due to its simplicity and high selectivity compared to traditional histochemical techniques. Objectives -To apply DESI-MSI to visualise the alkaloid distribution on the leaf surface of Psychotria prunifolia and Palicourea coriacea and to compare the distributions with HPLC-MS and histochemical analyses. Methodology -Based upon previous structure elucidation studies, four alkaloids targeted in this study were identified using high resolution mass spectrometry by direct infusion of plant extracts, and their distributions were imaged by DESI-MSI via tissue imprints on a porous Teflon surface. Relative quantitation of the four alkaloids was obtained by HPLC-MS/MS analysis performed using multiple-reaction monitoring (MRM) mode on a triple quadrupole mass spectrometer. Results -Alkaloids showed distinct distributions on the leaf surfaces. Prunifoleine was mainly present in the midrib, while 10-hydroxyisodeppeaninol was concentrated close to the petiole; a uniform distribution of 10-hydroxyantirhine was observed in the whole leaf of Psychotria prunifolia. The imprinted image from the Palicourea coriacea leaf also showed a homogeneous distribution of calycanthine throughout the leaf surface. Conclusion -Different distributions were found for three alkaloids in Psychotria prunifolia, and the distributions found by MSI were in complete accordance with HPLC-MS analysis and histochemical results. The DESI-MSI technique was therefore demonstrated to provide reliable information about the spatial distribution of metabolites in plants.

Recent development in mass spectrometry and its hyphenated techniques for the analysis of medicinal plants

“…leaves, remains a challenge due to the disturbance of the wax, cuticle and epidermal cell wall on plant material surface . This problem can be solved by transferring the constituents of sample leaves onto a porous surface, instead of direct sampling for DESI‐MS analysis …”

“…Rohitukine and its derivatives may be served as the defence compounds due to their potential of cyclin‐dependent kinase (CDK) inhibitors. Similarly, Kato et al . investigated the alkaloid distribution on the leaf surface of Psychotria prunifoli a and Palicourea coriacea .…”

Identification of Metabolites in Basil Leaves by Desorption Electrospray Ionization Mass Spectrometry Imaging after Cd Contamination

“…5,10 The monitoring of metabolites is probably one of the best approaches to find responses related to the mechanisms involved in the external stress to toxic metals. 11 In this sense, metabolomic analysis is an essential field of "omics" sciences for understanding the metabolite dynamics, biosynthesis, and transport within the plant plant tissue by desorption electrospray ionization (DESI) have been reported, for instance, the distribution of flavonoids, 12 alkaloids, 13 and other metabolites in leaves 14,15 and indole alkaloids in leaves and cross-sections of fruits and roots. 16 When one considers the different applications in plant tissues, DESImass spectrometry imaging (MSI) requires minimum or no sample treatment.…”

Identification of Sassafras albidum alkaloids by high‐performance thin‐layer chromatography tandem mass spectrometry and mapping by desorption electrospray ionization mass spectrometry imaging

“…The use of MSI allows the investigation of compounds and mapping their spatial distribution from the sample surface directly from plant tissues or indirectly from imprints. In plant metabolomics, it helps to understand the spatial context of metabolite biosynthesis, accumulation, and spatial localization 22–24 . DESI‐MSI has been used to describe the distribution of alkaloids, glycoalkaloids, glucosides, and flavonoids in different plant parts such as leaves, fruits, flower, and root 25–27 …”

“…In plant metabolomics, it helps to understand the spatial context of metabolite biosynthesis, accumulation, and spatial localization. [22][23][24] DESI-MSI has been used to describe the distribution of alkaloids, glycoalkaloids, glucosides, and flavonoids in different plant parts such as leaves, fruits, flower, and root. [25][26][27] In the face of the importance of isoquinoline alkaloids, the charac-…”