Abietadiene

Coniferales Pinaceae Pinus (pine resin, colophony) Abies (Strasbourg turpentine) Larix (Venice turpentine) Abietadienic acids, pimaradienic acids Abietadienic acids, pimaradienic acids, cis abienol Abietadienic acids, pimaradienic acids, epimanool, larixol, larixyl acetate... 

However, in many archaeological samples pimarane diterpenoids are often absent, and of the abietane compounds only dehydroabietic acid remains. In fact, dehydroabietic acid is present as a minor component in the fresh resins, but its abundance increases on ageing at the expense of the abietadienic acids since the latter undergo oxidative dehydrogenation to the more stable aromatic triene, dehydroabietic acid [2,18]. If oxygen is available, dehydroabietic acid can be oxidized to 7-oxodehydroabietic acid and 15-hydroxy-7-oxodehydroabietic acid. Since these diterpenoid compounds are often the dominant components in archaeological samples [95,97], they are considered characteristic for the presence of Pinaceae resins. 

In both the mass spectra, the simultaneous presence of ion fragments related to 7-oxo-dehydroabietic acid and highly oxidised tricyclic diterpenes demonstrates the higher degree of oxidation of the aged colophony with respect to the fresh pine resin [17 19]. In the mass spectra, the peaks attributed to abietadienic and pimaradienic acids are not evident, indicating their depletion in the course of the resin ageing. 

In Pinaceae resins, for instance, fully trimethylsilylated derivatives of 7-hydroxy-DHA, 15-hydroxy-DHA and 15-hydroxy-7-oxo-DHA have been identified, as well as all the other abietadiene and pimaranediene acids present in these resins. The derivatization was ineffective on some labdane alcohols such as larixyl acetate, a marker compound for Venice turpentine, but in general labdane compounds have been identified in their trimethylsilylated form. Labdane acids, such as communic, agathic, agathalic, agatholic and acetoxy agatholic acids, that are among the most important constituents of sandarac... 

RAVN, M. M., COATES, R. M., FLORY, J. E., PETERS, R. J., CROTEAU, R., Stereochemistry of the cyclization-rearrangement of (+)-copalyl diphosphate to (-)-abietadiene catalyzed by recombinant abietadiene synthase from Abies grandis, Org. Lett., 2000, 2,573-576. 

VOGEL, B. S WILDUNG, M. R., VOGEL, G., CROTEAU, R Abietadiene synthase from grand fir (Abies grandis) - cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase involved in resin acid biosynthesis, J. Biol. Chem., 1996,271, 23262-23268. 

Ro, D.K. and Bohlmann, J. (2006) Diterpene resin acid biosynthesis in loblolly pine (Pinus taeda) functional characterization of abietadiene/levopimaradiene synthase (PtTPS-LAS) cDNA and subcellular targeting of PtTPS-LAS and abietadienol/abietadienal oxidase (PtAO, CYP720B1). Phytochemistry, 67, 1572-8. 

To date over 30 plant terpenoid synthases have been cloned as cDNAs, and many of these were found to encode enzymes of secondary metabolism (43). Isolation and analysis of six genomic clones encoding monoterpene ((—)-pinene and (—)-limonene), sesquiterpene ((E)-a-bisabolene and S-selinene) and diterpene (abietadiene) synthases from Abies grandis, and a diterpene (taxadiene) synthase from Taxus brevifolia have been reported (44). Overexpression of a cotton farnesyl diphosphate synthase (EPPS) in transgenic Artemesia annua has resulted in 3- to 4-fold increase in the yield of the sesquiterpenoid anti-malarial drug, artemisinin, in hairy roots (45). 

Figure 6 Pathway of conifer diterpene resin acid biosynthesis. Bifunctional di-TPS convert geranylgeranyl diphosphate to various diterpenes, which are oxidized stepwise by multisubstrate and multifunctional cytochromes P450 to the corresponding diterpene acid. The oxidation of (-)-abietadiene to (-)-abietic acid is shown as an example.

Ro D-K, Arimura G, Lau SY, Piers E, Bohlmann J. Loblolly pine abietadienol/abietadienal oxidase PtAO (CYP720B1) is a multifunctional, multisubstrate cytochrome P450 monooxygenase. Proc. Natl. Acad. Sci. U.S.A. 2005 102 8060-8065. 

The photochemistry of the abietadienes continues to attract attention. In methanol solution, methyl abietate affords the adducts (80) and (81). On irradiation in ethanol, 8,13-cyclopropanes are also formed. However, methyl neoabietate undergoes a curious photochemical dehydrogenation to give (82). 18-Norabieta-8,ll,13-triene is obtained from the irradiation of the resin acids in acetone solution. 

R-(1 a,4ap,4ba,10aa)]-1,2,3,4,4a,4b,5,6,10,1 Oa-Deca-hydro-1,4a-dimethyi-7-(1-methylethyl)-1-phenanthrene-carboxyllcacid, 7,13-Abietadien-18-olc acid Abietate Abietic acid l-Abietic acid AI3-17273 CCRIS 3183 EINECS 208-178-3 13-... 

Ag f-a-bisabolene syn Pa isopimara-7,15-diene syn Pa levopimaradiene/abietadiene syn Ag abietadiene syn Gb levopimatadiene syn... 

More than 200 diterpenes with an abietane skeleton are reported to exist naturally Numerous representatives oeeur in conifers. Selected examples include palustra-diene, also referred to as (-)-8,13-abietadiene, from the pine tree Pintds palustris, from the so-called berries of the sade tree Juniperus sabina (Cupressaceae) and other species of juniper trees, (-)-abietenol from the pine Pinus silvestris and the fir Abies sibirica, (-)-abietic aeid belonging to the resin acids of turpentine and wide-spread in conifers such as various pines Pinus), larch trees Larix) and firs Abies), as well as (+)-palustric acid from the balm and the roots of Pinus palustris, isolated from gum rosin. 

Constit. of Salvia candicans. Lactol related to 7,12,20-Trihydroxy-11,14-dioxo-8,12-abietadien-19-oic acid, T-02080. 

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