Chemical profiles of birch and alder bark by ambient mass spectrometry

Abstract

Desorption atmospheric pressure photoionization (DAPPI) is an ambient mass spectrometry (MS) technique that allows the analysis of both polar and nonpolar compounds directly from the surfaces of various sample types. Here, DAPPI was used to study the chemical profiles in different parts of birch and alder tree barks. Four distinct fractions of Betula pendula (silver birch) bark were collected from three different developmental stages of the stem, after which the chemical profiles of the different tissue types were measured. Of special interest were triterpenoids, a class of important defensive substances, which are found in the bark of the silver birch. Additionally, the chemical profiles of lenticels and the surrounding surfaces in the phellem of B. pendula (silver birch), Alnus glutinosa (black alder), and Alnus incana (gray alder) were screened with DAPPI. Another ambient MS technique, laser ablation atmospheric pressure photoionization (LAAPPI), was further used for the mass spectrometry imaging of lenticels on the B. pendula phellem. All the studied birch bark fractions showed individual chemical profiles in DAPPI. The mass spectra from the young apical stem and the transition zone resembled each other more than the mature stem. Instead, the phellem was found to contain a high amount of triterpenoids in all the developmental stages of the stem. The most intense peaks in the DAPPI mass spectra of the birch bark fractions were those of betulin and lupeol. Betulinic and betulonic acid peaks were intense as well, and these compounds were detected especially in the lenticels of the tree samples. Graphical abstract Electronic supplementary materialThe online version of this article (10.1007/s00216-019-02171-9) contains supplementary material, which is available to authorized users.

Sub-100 μm Spatial Resolution Ambient Mass Spectrometry Imaging of Rodent Brain with Laser Ablation Atmospheric Pressure Photoionization (LAAPPI) and Laser Ablation Electrospray Ionization (LAESI)

“…34,35 Recently, two different OPO IR laser-beam-focus-ing techniques 36,37 have been reported that allow IR laser-ablation MSI with even 50-µm spatial resolution. Thus far, LAAPPI has been demonstrated in MSI of mouse brain, 36 whole sage leaves, 23 and birch bark 38 with 60-µm, 400-µm, and 400-µm spatial resolutions, respectively. On the other hand, LAESI has been widely used in MSI, such as in the analysis of whole rat brain, 30 bacterial colonies, 31 and A. squarrosa leaves.…”

Biocatalysis in the Chemistry of Lupane Triterpenoids

“…There are many other plant species that produce betulin ( 8 ) in low amounts, but to the best of our knowledge, none of them are used as important sources of it. Lupeol ( 9 ) is another lupane triterpene naturally occurring in plants; however, its quantities are usually lower than the quantities of 5 or 8, and it is usually obtained as a side-product of extractions of other triterpenes [ 49 , 50 , 51 ]. A basic summary of the main lupane triterpenoid sources is in Table 1 .…”

“… Methods of synthesis of betulinic acid [ 47 , 48 , 49 , 50 , 51 , 52 ]. Reagents and conditions: (i) chromium(VI) oxide; sulfuric acid, and acetone, H 2 O; (ii) sodium tetrahydroborate and isopropyl alcohol; (iii) 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxyl, sodium chlorite, tetrabutylammomium bromide, sodium hypochlorite, and phosphate buffer at 50 °C; (iv) 4-acetylamino-2,2,6,6-tetramethylpiperidine-N-oxyl, tetrabutylammomium bromide, sodium hypochlorite, and phosphate buffer (pH = 7.6) at 50 °C; (v) BAIB, TEMPO, NaH 2 PO 4 , NaClO 2 , 2-methyl-2-butene, BuOAc, water, and t-BuOH at 20 °C for 6 h; (vi) 2,6,6-tetramethyl piperidine-N-oxyl, tetrabutylammomium bromide, and sodium hypochlorite in phosphate buffer with dichloromethane for 6 h with pH = 6.8; (vii) sodium dihydrogenphosphate, sodium permanganate, DCM, water, and tert-butyl alcohol at 25 °C for 3 h; (viii) K 2 CO 3 and MeOH for 24 h; and (ix) KOH and MeOH with heating for 3 h. …”

A Perspective on therapeutic potential of weeds

“…Modern spectroscopic methods have been explored for structural elucidation of bioactive constituents present in weeds. LC-MS has been used for quantitative detection of xyloglucan oligosaccharide in Selaginella kraussiana [11], betulonic acid in Alnus glutinosa (Black alder) [12], jasmonic acid in Drosera capensis (Cape sundew) [20], lavonoids in Gunnera tinctoria (Chilean rhubarb) [24], pyrrolizidine alkaloid esters in Gymnocoronis spilanthoides (Senegal tea) https://doi.org/10.29328/journal.jpsp.1001050 [42]. NMR employed for characterization of compounds present in Fraxinus excelsior (Ash) [15], Berberis glaucocarpa (Barberry) [17], Ligustrum sinense (Chinese privet) [25], Rhamnus alaternus [26], Cestrum parqui (Green cestrum) [30], Ranunculus sardous (Hairy buttercup) [49].…”