Diterpenes isolation

Milanova R, M Moore, Y Hirai (1994) Hydroxylation of synthetic abietane diterpenes by Aspergillus and Cunninghamella species novel route to the family of diterpenes isolated from Tripterygium wilfordii. J Nat Prod 5T 882-889. 

Finally, the antifungal properties of a-pinene and limonene, two monoter-penes frequently found in the defensive secretion of Nasutitermes termites, was studied. In vitro assays showed that these molecules reduce spore germination of the fungus Metarhizium anisopliae through direct and indirect (vapor) contact [225]. Moreover, some diterpenes isolated from these insects have also an antibiotic activity on Bacillus subtilis, Staphylococcus aureus, and Enterococcus faecalis [226]. 

Fig. 6.2 Diterpenes isolated from Ajuga cliamaepytis ssp. laevigata...

In a very recent example, Chiu and co-workers (84-86) used the tandem ylide-cycloaddition methodology to prepare advanced intermediates directed toward the synthesis of the pseudolaric acids. Pseudolaric acids are a family of diterpenes isolated from the root bark of Pseudolarix kaempferi. These novel compounds have shown antimicrobial activity comparable to that of amphotericin B and have demonstrated cyctotoxicity against several cancer cell lines (Fig. 4.5). 

Mancini, I. Guella, G. Zibrowius, H. Laurent, D. Pietra, F. (1999A) A novel type of second epoxy bridge in eunicellane diterpenes isolation and characterization of massileunicellins A-C from the gorgonian Etmicella cavolinii. Helv. Chim. Acta, 82, 1681-9. 

A reversed-phase high performance liquid chromatographic method for the determination of salvinorin A, a psychotropic diterpene isolated from the Mexican sage Salvia divinorum, has been developed. Extracts from several plant collections were examined on a C-18 column with UV detection and isocratic elution with acetonitrile water (45 55). This assay allowed quantification of salvinorin A in extracts of leaves and stems of A , divinorum and has also been applied to the screening of related species for the production of salvinorin A. Levels of salvinorin A in leaves range from 0.89 to 3.70 mg/g dry weight. 1999 John Wiley Sons, Ltd. 

A series of other labdane diterpenes isolated from various sources have also been reported to exhibit antimicrobial activity. Aulacocarpinolide and aulacocarpines A and B, labdane diterpenes isolated from the Cameroonian spice Aframonum aulacocarpos (Zingiberaceae), exhibited weak antibacterial activity against B. subtilis and fungus Mucur miehei [166],... 

Enf-Labdane-diterpenes isolated from Ruppia maritima. 

From the hairy roots of Salvia broussonetia (Lamiaceae), 14-deoxycoleon U (198) and demethylsalvicanol (199) were isolated together with other diterpenes. Of all the diterpenes isolated, 14-deoxycoleon U was a strong antifeedant against L. decemlineata,12 whereas 199 exhibited only moderate activity. Several compounds similar to 198 were not active, suggesting a possible role for the unsaturation of ring B, a feature missing in 6a-hydroxydemethylcryptojaponol (200), which was not active. None of the isolated abietanes exhibited any antifeedant activity against S. littoralis. 

Taxol la is an antitumor plant diterpene isolated from the yew tree Taxus spp. in the late 1960s. It was named taxol at the time of its first isolation by Wani et al. In the 1990s, when Bristol-Myers Squibb (BMS) launched it on the market, Taxol was registered as an anticancer product, and Taxol was assigned a generic name, pacli-taxel. Both taxol and paclitaxel are referred to in this chapter to describe the same compound. 

Ageladine A (132), which is a 9-methyladenine derivative of diterpene isolated from a sponge Agelas sp., is antimicrobial and inhibitory against Na, K-ATPase (12). A novel, chlorinated diterpenoid, chlorolissoclimide (133), which was isolated from the ascidian Lissoclinum forskalii, inhibits eukaryotic protein synthesis (38). 

Taxol (paclitaxel) (Bl), a taxane diterpene isolated from the bark of the Pacific yew tree Taxus brevifolia Nutt. (Taxaceae family). 

Bioassay-guided fractionation of an aqueous extract from a Philippine Islands collection of the soft coral Lohophytum spp. yielded cembranoid diterpenes, Fig. (3), which exhibited moderate HIV-inhibitory activity in a cell-based in vitro anti-HIV assay [44], while new isomalabaricane triterpenes. Fig. (4), have been isolated from the sponge Stelletta spp. [45]. Other anti-HIV diterpenes also included the dolabellane diterpenes isolated from the Brazilian brown algae Dictyota pfaffi [46] and Dictyota menstrualis [47]. To investigate the effect of these diterpenes in the reverse transcription of the viral genomic RNA, the recombinant HIV-1 RT was assayed in vitro in the presence of each compound. All compounds inhibited the RNA-dependent DNA-polymerase activity of HIV-1 RT and consequently virus replication. 

Fig. (26). Structure of nor-ent-kaurane diterpene isolated from Antennaria geyeri...

Figure 2 Selected mulinane and azorellane diterpenes isolated from Azorella ssp, cushion plants of the high southern Andes. References in text.

Figure 20. Possible biosynthetic route to mulinane, azorellane, yaretane, and madreporane carbon skeletons of diterpenes isolated from high elevation Azorella cushion plants, according to Loyola et ah, 2002. Note the unusual demethylation step in the azorellane - yaretane conversion.

Tripterifordin (26) is an anti-HIV diterpene isolated in 1992 from a Chinese plant Tripterygium wilfordii by Lee and coworkers. Although it is not a plant hormone, its structural similarity with gibberellins attracted me to synthesize it. 

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