The Identification of New Triterpenoids in Eucalyptus globulus Wood.

Ana Lourenço,Jorge Gominho,António Velez Marques

doi:10.3390/molecules26123495

Ana Lourenço, Jorge Gominho + Show 1 more

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https://doi.org/10.3390/molecules26123495

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Abstract

Eight polyhydroxy triterpenoid acids, hederagenin, (4α)-23-hydroxybetulinic acid, maslinic acid, corosolic acid, arjunolic acid, asiatic acid, caulophyllogenin, and madecassic acid, with 2, 3, and 4 hydroxyl substituents, were identified and quantified in the dichloromethane extract of Eucalyptus globulus wood by comparing their GC-retention time and mass spectra with standards. Two other triterpenoid acids were tentatively identified by analyzing their mass spectra, as (2α)-2-hydroxybetulinic acid and (2α,4α)-2,23-dihydroxybetulinic acid, with 2 and 3 hydroxyl substituents. Two MS detectors were used, a quadrupole ion trap (QIT) and a quadrupole mass filter (QMF). The EI fragmentation pattern of the trimethylsilylated polyhydroxy structures of these triterpenoid acids is characterized by the sequential loss of the trimethylsilylated hydroxyl groups, most of them by the retro-Diels-Alder (rDA) opening of the C ring with a π-bond at C12-C13. The rDA C-ring opening produces ions at m/z 320 (or 318) and m/z 278 (or 277, 276, 366). Sequential losses of the hydroxyl groups produce ions with m/z from [M - 90] to [M - 90*y], where y is the number of hydroxyl substituents present (from 2 to 4). Moreover, specific cleavage in ring E was observed, passing from m/z 203 to m/z 133 and conducting other major fragments such as m/z 189.

Highlights

Terpenoids are secondary metabolites commonly produced by higher plants in different parts of the plant, such as flowers, barks, and roots [1]
Terpenoids are known as isoprenoids, presenting a great variety in number and in their structure. Their classification can be based on the structural organization of the isoprene units (C5), for example, when constituted by one isoprene unit, two, three, four, five, six, eight, and others [1]
Several studies have emphasized the potential of triterpenoids, in particular those with a skeleton of lupane, oleanane, and ursane-type that have been strongly associated with a broad spectrum of pharmacological activities—including anti-inflammatory, antiangiogenic, antiviral, antiallergic, antihypertensive, antioxidant, and other activities—and have sparked increasing interest in their potential application in the treatment of cancer [4,5,6,7,8]

Summary

Introduction

Terpenoids are secondary metabolites commonly produced by higher plants in different parts of the plant, such as flowers, barks, and roots [1]. These compounds play an essential role in gene expression for plant defense, plant response to stress, and plant interactions: plant–insect, plant–pathogen, and plant–plant interactions [1,2,3]. Terpenoids are known as isoprenoids, presenting a great variety in number and in their structure Their classification can be based on the structural organization of the isoprene units (C5), for example, when constituted by one isoprene unit (hemiterpenoids), two (monoterpenoids), three (sesquiterpenoids), four (diterpenoids), five (sesterpenoids), six (triterpenoids), eight (tetraterpenoids), and others [1]. From the commercial point of view, the major challenge of their application is related to a constant and sustainable supply

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