Resins diterpenoid

The plants that exude diterpenoid resins belong to the order of conifers. Pine resins (from the Firms genus), Strasburg turpentine (from the Abies genus), Venice turpentine (from Larix decidua) were extracted from Pinaceae. Sandarac, juniper and cypress resins were extracted from trees of the Cupressaceae family Tetraclinis articulata, Juniperus spp. and Cupressus semprevirens, respectively. Moreover, labdanum resin from the Cistaceae family (Cistus spp.) also belongs to the diterpenoid resins. 

Pine resin, namely rosin or colophony, is one of the most widespread diterpenoid resins and has been used for waterproofing, for treating wood and paper, as varnish, as incense and as an ingredient in scented ointments. The main compounds present in fresh Pinaceae resins... 

Resins older than 40 000 years are considered to be fossil resins. The fossilization of resins begins with polymerisation and forms ambers and copals. Most of the ambers are derived from components of diterpenoid resins with a labdanoid structure other ambers are based on polymers of sesquiterpene hydrocarbons such as cadinene, and may include triterpenoids less common ambers from phenolic resins derive from polymers of styrene. Figure 1.4 shows the skeletal structures of the components which make up the polymers occurring in fossil resins [141]. 

E. Ribechini, F. Modugno, M.P. Colombini, Direct exposure (chemical ionization) mass spectrometry for a rapid characterization of raw and archaeological diterpenoid resinous substances, Microchimica Acta, 162, 405 413 (2008). 

Despite the complexity of the chemical composition of the resinous materials, in a few minutes such techniques provide a mass spectral fingerprint, which highlights the compounds that are the main components in the sample. They avoid any sampling treatment before analysis. They have thus enabled diterpenoid resinous materials from Coniferae, and several triterpenoid materials to be clearly identified. In particular, the DE-MS technique is able to distinguish between different triterpenoid materials such as mastic resin, frankincense resin and birch bark tar. In fact, using PCA on DE-MS mass... 

Although the mass spectra of aged diterpenoid resins are generally not characteristic enough for a clear identification, some natural products show characteristic peaks above m/z 325. These signals can be explained by particular constituents of the respective resins, so-called biomarkers. For example, copaiba balsam shows an intense peak at m/z 385, which can be attributed to 3-acetoxy-copaiferic acid [51] (see Figure 5.11). Another... 

Several historic wax samples were analysed successfully with GALDI-MS. It was found that a group of eighteen white seals from medieval documents (thirteenth to fourteenth century) from the archive of the Canton of Lucerne (Switzerland) all mainly consisted of beeswax. For example, the mass spectrum of a white seal from 1377 (inventory no. URK636/12663) is shown in Figure 5.14b. The typical pattern of beeswax, as described for the reference sample, can be clearly recognised. An additional peak at m/z 303 may be caused by abietic acid in the form of the molecule cation (C2oH3o02, MW 302), as found for rosin (see Section 5.3.2). This hints at the use of a diterpenoid resin, which was a common hardener for beeswax. A more detailed discussion of the composition of medieval white wax seals has been published elsewhere [57]. 

B. Singer, R. McGuigan, The Simultaneous Analysis of Proteins, Lipids, and Diterpenoid Resins Found in Cultural Objects, Annali di Chimica, 97, 405 417 (2007). 

Py-GC/MS characterisation of diterpenoid resins using online trimethilsilylation with HMDS has been performed on fresh Pinaceae resins, manila Copal, sandarac, and Copaiba... 

L. Osete Cortina and M.T. Domenech Carbo, Analytical characterization of diterpenoid resins present in pictorial varnishes using pyrolysis gas chromatography mass spectrometry with on line trimethylsilylation, J. Chromatogr., A, 1065, 265 278 (2005). 

More recently on-line pyrolysis with HMDS has been performed successfully even if the pyrolysis interface was kept at 250°C. In fact, Domenech-Carbo and colleagues [57,58] have obtained very good results on a variety of art materials and on real paint samples as well. They have applied Py-GC/MS with on-line trimethylsilylation to the characterization of diterpenoid resins and, in contrast to previous literature data, the derivatization method enabled not only the identification of resinous carboxylic acids in the form of TMS esters, but also an efficient conversion of hydroxyl groups to TMS ethers. 

Figure 7.1 Total ion current (TIC) chromatogram obtained by GC-MS analysis of a resin (Pinus sylvestris). The diterpenoid resin acids were methylated (using diazomethane) to improve chromatographic performance. Peak identities 1, Methyl pimarate 2, Methyl sandaracopimarate 3, Methyl isopimarate 4, Methyl palustrate 5, Methyl dehydroabietate 6, Methyl abietate 7, Methyl neoabietate. For GC-MS operating conditions, see Heron and Pollard (1988).

Fig. 5.18 Possible diagenetic pathways for the formation ofretene from diterpenoidal resin components (large arrows indicate biogenic inputs after Simoneit 1977, 1986 Simoneit et al. 1986a Alexander et al. 1987). Note different number schemes for abietoids and phenanthrenes. (18-norabieta-8,ll,13-triene is also known as dehydroabietin.)...

The stereospecific synthesis of the C-4 epimeric diterpenoid resin acids has attracted considerable attention. Methylation of the keto-nitrile (144) gives a product possessing an equatorial methyl group, in contrast to methylations of... 

Naturally Occurring Substances.— Tall oil, obtained as a by-product of pulping conifer wood chips, contains a mixture of fatty and diterpenoid resin acids and neutral compounds. The latter include" pimara-8(14),15-diene-3/S,18-diol, abieta-8,ll,13-triene-15,18-diol, 19-hydroxy-15,16-bisnorlabda-8(17)-en-13-one, 8,13i8-epoxylabd-14-en-6a-ol (6a-hydroxy-13-epimanoyl oxide), and the 9,10-secoabietatriene (41). The latter was also isolated from the bark of the jack pine (Pinus banksiana) and western white pine (P. monticola). A range of 7-monohydroxy, 1,7- and 1,11-dihydroxy-, and 1,7,11-trihydroxy-sandaraco-pimaradienes and their acetates (42) have been obtained" from Zexmenia (Compositae) species. The l,ll-diacetoxy-7-ketone and 6,7-epoxide were also isolated. 

Kuehne, M.E. and Nelson, J.A. (1970) Stereospecific s5mtheses of epimeric diterpenoid. Resin acids through enolate anion reactions. J. Org. Chem., 35, 161-70. 

Ireland and co-workers used a Wichterle sequence in their stereoselective syntheses of diterpenoid resin acids when annulations with methyl vinyl ketone resulted in polymeric tars. Stereoselective alkylation of cyclohexanone 34 with Wichterle s reagent afforded 35 as a single stereoisomer. Studies performed on this system determined that alkylation was favored cis to the C2 methyl group. After hydrolysis of the vinylic chloride 35 to the diketone 36, cyclization proved difficult due to the large amount of steric hindrance present in the molecule. Base-catalyzed cyclization resulted in only partial conversion to the desired octalone 37. It was found that a significant portion of the material was cleaved to the starting material for this sequence, monoketone 34, via facile reverse Michael addition when the side chain adopted an equatorial confirmation. 

The diterpenoid constituents of resins analysed are usually seen as a group of peaks eluting at around 20 minutes retention time. All of the diterpenoid resins in Table I are coniferous and come from the Pinaceae and Araucariaceae families. To date, no evidence for the use of diterpenoid resins in association with archaeological ceramics has been found. 

Abietadiene is the main diterpenoid resin acid of oleoresin, which is secreted in response to wounding and herbivore attack. 

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