Iso-masticadienonic acid

Figure 12.4 THM GC/MS curve of mastic resin. Peak assignments 1, nor f3 amyrone 2, (8R) 3 oxo hydroxypolipoda 13E,17E,21 triene 3, nor 28 olean 18 en 3 one 4, moronic acid methyl ester 5, oleanonic acid methyl ester 6, oleanonic aldehyde 7,8, (iso)masticadienonic acid methyl ester...

Several studies have dealt with the problem of discriminating between mastic and dammar, and three marker compounds of mastic have been identified moronic, masticadienonic and acetyl masticadienolic acids [42], The chemical structure of (iso)masticadienonic acid and 3-0-acetyl-3-epi(iso)masticadienonic acid is characterized by a side chain, as for dammarane molecules, but with a carboxylic acid end group (Table 12.1). Under pyrolysis conditions this side chain is susceptible to cleavage as demonstrated by the presence, among the pyrolysis products of mastic, of 2-methyl-pent-2,4-dienoic acid, that perfectly matches with the chemical structure of the side chain end. In addition 3-(9-acetyl-3-epi-(iso)masticadienolic acid also loses the acetyl group and, in contrast to masticadienonic acid, is not detected at all. 

The first online TLC-MS attempt in the field of triterpenoids was done only in 2005 in the study of the photo-oxidation of natural di- and triterpenoid resins used as paint varnishes [10], The resinous samples were applied onto a cellulose-coated TLC plate, which afterward was subjected to direct MALDI-TOF-MS analysis without any development. The plates were only sprayed with a saturated ethanol solution of 2,5-dihydroxybenzoic acid as matrix to assist the ionization of compounds. Triterpenoids were observed as protonated molecules or as sodium clusters. Dammaradienone, dammaradienol, nor-a-amyrone, and dammarenolic, oleanonic, and ursonic acid were detected in dammar resin moronic acid, masticadienonic acid, and 3-0-acetyl-3-epi(iso)masticadienonic acid were found in mastic resin and diterpenoid abietane and pimarane acids were present in colophony. The induced aging process produced oxidized triterpenoids, which were observed in the MS spectra... 

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