Linear diterpene

R. Vails, B. Banaigs, L. Piovetti, A. Archavlis and J. Artaud, Linear diterpene with antimitotic activity from the brown alga Bifurcaria biturcata, Phytochemistry, 34... 

F. Della Pieti, M. C. Breschi, R. Scatizzi and F. Cinelli, Relaxing activity of two linear diterpenes from Cystoseira brachycarpa var. balearica on the contractions of intestinal preparations, Planta Med., 61 (1995), 493-496. 

IPP and DMAPP react as shown in Scheme 102.4 to generate geranyl pyrophosphate (GPP), whose further reaction with IPP produce famesyl pyrophosphate (FPP) that reacts with another molecule of IPP to afford geranylgeranyl pyrophosphate (GGPP), representing the linear diterpene C20 precursor. 

Linear diterpenes are less distributed in nature. Phytol (1), a reduced form of geranylgeraniol, is an example of linear diterpenes, constituting the side-chain of chlorophylls, for example, phylloquinone, the vitamin Kj (2) and chlorophyll A (3). 

For linear diterpenes or the linear segments of cyclic compounds with ambiguous double bond stereochemistries, the steric relationship about the double bond is indicated by a Z or E suffix (e.g., 13(14)E, 2(3)Z). The Z or E assignment results from the comparison of the sequence-rule-preference of the four atoms attached to the doubly bonded carbons (as specified in Rule E-2.2. of the lUPAC Rules for Nomenclature of Organic Chemistry). Several examples of Z and E assignment are discussed below in order to familiarize the reader with this method. 

I. Linear diterpene example 15,19-dihydroxy-14-oxo-geranylnerol Skeleton (No. 1. Geranylnerol) ... 

Cyclization of the linear diterpene precursor usually proceeds along two alternative parallel routes (Figure 2 [p. 392]), one leading to the bicyclic normal labdane (normal-labdane) absolute stereochemistry and the other resulting in its antipodal, enantiomeric (e/iMabdane) absolute stereochemistry. As a consequence of these two parallel biosynthetic routes, diterpenes lack the homogeneous absolute stereochemistry of the triterpenes. 

Figure 3. Linear diterpene skeletal types and cyclic diterpene skeletal types derived from normal and e iMabdane precursors.

Despite early statements regarding the rarity of linear diterpenes in plants (279), linear diterpenes and their hetero- and carbocyclic derivatives are hardly rare within genera of the Compositae. 

Tillekerame, L.M.V. and Schmitz, F.J. (1984) 4,9-Diacetoxyudoteal a linear diterpene aldehyde from ihe green alga Halimeda opuntia. Phytochemistry, 23,1331-1333. 

The same species, DUophus fasciola, led to the isolation of an optically active ether of glycerol and geranylgeraniol. This is currently the only linear diterpene to be characterized in a Dictyotale (Amico et al., 1977), although this compound was later found in two other Dictyotales Taonia lacheana and Taonia atomaria ciliata (Tringali, Piattelli, and Spatafora, 1995). 

The spedes Bijurcaria bijurcata contains several trihy-droxylated linear diterpenes, and its diterpene composition has many similarities with that of another Fucale, Cystoseira brachycarpa (Culioli et al., 2004 Ortalo-Magne et al, 2005 El Hattab et al, 2008b). 

Group II Linear diterpenes Croup II Linear diterpenes Group II Linear diterpenes... 

Culioli, G., Ortalo-Magne, A., Daoudi, M., Thomas-Guyon, H., Vails, R., and Piovetti, L. (2004) Trihydroxylated linear diterpenes from the brown alga Bijurcaria bijurcata. Phytochemistry, 65, 2063-2069. 

Vails, R., Banaigs, B., Piovetti, L., Archavlis, A., and Artaud, J. (1993c) Linear diterpenes with antimitotic activity from the brown alga Bifurcaria hijurcata. Phytochemistry, 34,1585-1588. 

Sesqui- and diterpenes linear diterpenes pyrrole derivatives... 

Diterpenes of Desmoxyidae are varied, with linear compounds derived from geranyUinalool, and cyclic derivatives with classical and original skeletons. There are at least two chemotypes (chemical races) for the species Myrmekio-derma styx depending on depth, and it was observed that the species at shallow depths produced linear diterpenes, and that those found at the greatest depths were cyclic diterpenes (Sennett, Pomponi, and Wright, 1992). 

Albrizio, S., Fattomsso, E., Magno, S., Mangoni, A., and Pansini, M. (1992) linear diterpenes from the Caribbean sponge Myrmekioderma styx.J. Nat. Prod., 55,1287-1293. 

An undetermined sea anemone of the order Actiniaria (code C010505) yielded actiniarins A-C, three irregular linear diterpenes that may be the first examples of diter-penes from the Hexacorallia. The three derivatives are cytotoxic to A2780 cells (ovarian cancer) and are inhibitors... 

Figure 20.33 Atypical linear diterpenes of Pseudopterogorgia pinnata (according to Ospina et al., 2005).

The opening of the pseudopterane and cembrane rings between carbons 2 and 3 yielded original linear diterpenes. 

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