Diterpenes-resin acids tricyclic

Two major steps exist in the biosynthesis of diterpene resin acids the formation of the diterpene and the stepwise oxidation of the diterpene to the corresponding acid. Most conifer diterpenes are tricyclic they are biosynthesized by bifunctional di-TPS that first cyclize geranylgeranyl diphosphate to (+)-copalyl diphosphate and then cyclize this intermediate even... 

Resemblance of the tricyclic diterpene skeleton to the ABC-ring system of common steroids prompted the suggestion that the diterpenes interfered with the pink bollworm s steroid metabolism. Insect hormones are produced from dietary phytosterols which are absorbed, transported, and biochemically altered. Interference by the diterpene resin acids at any stage of this process could significantly reduce larval viability. To test this hypothesis, feeding studies were conducted using a levopimaric acid test diet with added cholesterol (addition of... 

Tricyclic diterpenes-resln acids. Wood resin constituents, e.g. abietane derivatives, have also been implicated in pest resistance (Figure 4). Among the conifer-associated sawflles many prefer to feed... 

Rosin, the other major naval stores product, is a brittle solid that softens at 80°C. Chemically it is composed of about 90 percent resin acids and 10 percent neutral matter. The resin acids are mainly /-abietic acid and its isomers, C2oH3002. These are tricyclic mono-carboxylic acids and are diterpenes. 

Formula see abieta-7,13-diene. C20H30O2, Mr 302.46. A resin acid belonging to the diterpenes, monoclinic plates, mp. 172-175 C, [alf, -102° (C2H,0H). Occurs above all in Pinus and Abies species the most important component of colophony from which it can be separated by distillation. A. is a component of the defensive secretion of the trees against insects and infections by microorganisms. The biosynthesis fiom tricyclic abieta-7,13-diene (figure see... 

Again, becanse of the potential nnmber of compounds that could exist in a resin mixture, it is difficult to assign a definite strnctnre to any particular resin. However, it is known that the resin colophony (or rosin, the nonvolatile residne from the steam distillation of turpentine) is actually a mixture of resin acids which are derived from the diterpenes. One of the best-known constituents of this mixture is the tricyclic diterpene abietic acid (Figure 3.13). 

Regardless of its origin (gum, wood or tall oil), rosin is mainly composed (90-95 pa- cent) of diterpenic mono-carboxylic acids, commonly known as resin acids whose generic formula is C19H29COOH. The remaining components are essentially made up of neutral compounds, the nature of which depends on the specific origin of the rosin [5]. The most common resin acids found in pine rosin are derived from the three basic tricyclic carbon skeletons abietane, pimarane and isopimarane and the less common bicyclic labdane skeleton (Fig. 4.1). 

The tricyclic diterpene carboxylic acid, abietic acid, is widely distributed (see Chap. 8.1) and commonly available commercially. Fisher implicated it in a case of allergic contact dermatitis because it is the major constituent of violinist s resin (58). It is also found in colophony and pine resins, on which Karlberg et al. (92) performed a dermatological study. Wahlberg (182) studied dermatitis caused by abietic acid and colophony. Abietic acid derivatives are also common, so some derivatives (161) of it have also been studied, notably dihydroabietyl alcohol (49). A white powder from the bark of Betula sp. causes skin eruptions in mill workers... 

Resins are the products of various shrubs and trees, especially conifers. In addition to essential oils, resins contain resin acids, such as tricyclic diterpene abietic acid, resin alcohols (resinols), resin esters and other substances. Particularly weU known is Chios mastic gum. Real mastic is only produced in the south part of Chios Island, and comes from the mastic tree Pistacia lentiscus var. chia, Anacardiaceae). It is used to flavour alcohoHc beverages (especially Hqueurs and ouzo), wine, baked goods, chewing gum and some cosmetic products. The essential oil with a balsam-Hke odour has antiseptic properties as it contains a- and fS-pinene as essential ingredients. 

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. 

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