Pimarane diterpene

Pimarane diterpenes with an antipodal backbone have been isolated from Cleistanthus schlechteri. These included ent-3)8-hydroxypimara-8,l5-diene, ent-3)3,12 -dihydroxypimara-8,l 5-diene (16), and the corresponding C-12 ketone. The location of the carbonyl group at C-12 was inferred from bromination and dehydrobromination and from the multiplicity of the C—H resonance of the C-12 alcohol. Macarangonol (17) has been isolated from Macaranga tanarius. 

Six pimarane diterpenes (297-302) were obtained from the rhizomes of an imnamed Kaempferia (Thai name jang-ngung) [270]. Rhizomes of K. pulchra were found to contain two pimarane diterpenes (303,304) [271], which were reported to possess anti-inflammatory action [272]. Isopimaric acid, a well-known pimarane derivative, was also isolated from the chloroform extract of the rhizomes oiKaempferia sp.[256]. 

Terpenoids. Mono- and sesquiterpenoids are the common constituents of all nine genera. Labdane-type diterpenes are found mainly in Aframomum, Alpinia and Hedychium. Only plants in the genus Kaempferia are able to produce pimarane diterpenes. Steroidal compounds and steroidal saponins are found only in plants of the genus Costus. 

Costantino, V, Fattorusso, E., Mangoni, A., Perinu, C., Cirino, G., De Gruttola, L., and Roviezzo, F. (2009b) Tedanol A potent antiinflammatory ent-pimarane diterpene from the Caribbean sponge Tedania ignis. Bioorg. Med. Chem., 17, 7542-7547. 

Ellestad, G. A., M. P. Kunstmann, and G. O. Morton Conversion of a Pimarane Diterpene into the Cleistanthane Ring System. Chem. Commun. 1973, 312. 

Diterpene phytotoxins sphaeropsidins A—F, tri- and tetracyclic unrearranged pimarane skeleton, are isolated from Sphaeropsis sapinea, a fungus that causes a canker disease of Italian cypress. Sphaeropsidin A is the major toxic substance showing nonhost-selective phytotoxic activity326 (Figure 36). 

About 80% of the diterpene acids of the genus Finns have an abietane skeleton, with abietic acid (structure 3) as the predominant component. Other diterpene acids have a pimarane skeleton (structure 4). All compounds with the abietane skeleton are distinguished by the presence of an isopropyl group. 

We ve classified more than 550 diteipenoids (listed in Table 3 whith corresponding sources) from all the reported Salvia species which we ve divided into 2 categories. The first one contains the monocyclic and bicyclic diterpenoids including labdanes and clerodanes and related diterpenes. The second category concerns tricyclic and tetracyclic diterpenes including pimaranes and abietanes and related diterpenes. The clerodane type diterpenes are mainly represented by american species while abietane type are found in european and asian species. 

In general, very little has been written about diterpenes from the Latin American Celastra-ceaeas these structures are not often found. Abietriene type diterpenes have been the general rule in the Celastraceae although the chemical study of the minor constituents of Orthosphenia mexicana and Rzedowskia tolantonguensis did enable pimarane type diterpenes to be isolated and chemically characterized [43,45] and the second of these species afforded a series of new diterpenes with an isopimarane skeleton, described for the first time in the Celastraceae. 

A group of diterpenes with the pimarane skeleton (1). In R, the methyl group at C-10 is cis to the ethyl group at C-13, whereas in the isopimaranes it is in the transposition. Both enantiomers of not only the R but also of the isopimaranes occur in nature. R are formed by a further cyclization of the labdane skeleton. Examples are annonalide, momilactones A and B (both growth inhibitors for plants ), leucophleol and ent-8(14),15-pimaradiene. In the past the R were also known as sandaracopimaranes. 

C20H28O2, Mr 300.44, pale-yellow gum, [a]p -3.0 (CHCI3). A diterpene of the cleistanthane group, isolated from the roots of Cunuria spruceana (Euphorbi-aceae). S. exhibits antitumor properties. The cleistan-thanes are formed biosynthetically from pimaranes or isopimaranes by migration of an ethyl group. 

The biogenesis of pimarane, the parent compound of many polycyclic diterpenes, is assumed to arise from Ko-geranylgeranylpyrophosphate After dissociation of the pyrophosphate anion, the remaining acyclic allylic cation undergoes a 1,3-sigmatropic hydrogen shift and thereby cyclizes to a monocyclic carbenium ion which, itself, isomerizes to the ionic precursor of the pimarane skeleton. 

Abietanes may formally be derived from pimaranes by migration of the methyl group C-17 from C-13 to C-15. In plants, however, they emerge from cyclization of geranylgeranyl diphosphate. Related parent diterpene hydrocarbons include 13,16-cycloabietanes, 17(15-16)-aZ)eo-abietanes in which the methyl group C-17 has shifted from C-15 to C-16, and totaranes. The latter formally arise from abietane when the isopropyl group migrates from C-13 to C-14. 

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 bicyclic labdanoid diterpenes are characteristic of the bark and needle resins of the Pinaceae, whereas tricyclic types (especially the abietanes and pimaranes) dominate in the wood resin (Croteau and Johnson, 1985) (Fig. 22.10). Highly oxygenated derivatives of the labdane series are widespread in the Asteraceae, Lamiaceae, Verbenaceae, and in the genus Croton of the Euphorbiaceae. 

Tricyclic diterpenes fall into four main classes those with the pimarane, abietane, rosane, or cassaine skeleta. Epimers at C-13 exist among many groups of tricyclic diterpenes [e.g., pimaric acid (31) and sandaracopimaric acid (32) (Fig. 22.1)]. 

Colophony is a complex mixture of resin acids (about 90%) and neutral substances, i.e. diterpene alcohols, aldehydes and hydrocarbons (about 10%). Its composition varies with the species from which it is obtained and also depends on the recovery processes and storage conditions. The acids are diterpenoid acids, of which the abietane- and pimarane-type structures are the most abundant (Fig. 1). Tail-oil rosin contains less abietane-type acids and more dehydroabietic acid than gum rosin does. This is due to oxidation-... 

Matsuo, A., S. Uto, M. Nakayama, S. Hayashi, K. Yamasaki, R. Kasai, and O. Tanabca (—)-Thermarol, a New E wr-pimarane-class Diterpene Diol from Jungermannia thermarum (Liverwort). Tetrahedron Letters 1976, 2451. 

Figure 15. Proposed biogenetic routes for tricyclic e /-pimarane, e /-abietane, erythroxane, cleistanthane and isocleistanthane diterpene skeletons derived from ent-labdane precursors.

Most of the approximately ninety Brickellia (Eupatorieae Alomiinae) species inhabit the North American deserts, although three species are South American disjuncts. The diterpene chemistries of the ten investigated taxa (Table 6 [p. 441] Figure 19 [pp. 457-461]) are remarkably uniform. Normal-labdanes often characterized by novel 2a,3o -hydroxylation/esterification occur in all diterpene-producing species. In B. eupatoriedes, these 2a,3a-substituted normal-labdanes co-occurred with cleistanthanes and other eAtf-pimarane-derived skeletal types. Production of normal-labdanes together with tri- and polycyclic ewMabdane-derived skeletons is an often-repeated theme in the diterpene chemistries of Compositae taxa. 

Figure 28. Structures of wMabdane (430, 447-449), e /-pimarane (976), ew/-abietane (614), ew/-helifiilvane (796-799), e /-trachylobane (791), en/-atisirane (783), enU stachane (764, 765, 767, 770, 771, 774) (Scheme A), and ewMcauranoid (Scheme B) diterpenes reported from Helichrysum (Inuleae).

Canonica, L., B. Rindone, and C. Scolastico A new diterpene with pimarane skeleton. Tetrahedron Lett. 4801 (1969). 

Pinto, A.C., M.L. Patitucci, R.S. Dasilva, P.P.S. Queiroz, and A. Kelecom Pimarane and cleistanthane diterpenes from Velloziaceae absolute configuration and biomimetic conversion. Tetrahedron 39, 3351 (1983). 

Schmitz, F.J., D.P. Michaud, and P.G. Schmidt Marine Natural Products Par-guerol, Deoxyparguerol, and Isoparguerol. New Brominated Diterpenes with Modified Pimarane Skeletons from the Sea Hare Aplysia dactylomela. J. Am. Chem. Soc. 104, 6415 (1982). Erratum J. Am. Chem. Soc. 106, 3385 (1984). 

Schmitz, F.J., Michaud, D.P., and Schmidt, P.G. (1982) Marine natural products parguerol, deoxy-parguerol and isoparguerol. New brominated diterpenes with modified pimarane skeletons from the sea hare Aplyda dactylomda. J. Am. Chem. Soc., 104, 6415-6423. 

Lastly, tedanol isolated from a Caribbean Tedania ignis collected in the mangroves of Sweeting Cay, Grand Bahama Island, is a brominated and sulfated diterpene with ent-pimarane skeleton. This original diterpene displays potent anti-inflammatory activity by inhibition of COX-2 (cyclooxygenase 2) expression thus, tedanol appears as a non-steroidal anti-inflammatory (Costantino et al, 2009b). 

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