Diterpenes kauranes

One of the most significant differences between Arabica and Robusta coffees is in the caffeine content. Robusta coffees contain almost twice the caffeine found in Arabica coffees. There are some other differences recognized thus far Robustas contain almost no sucrose and only very small amounts of the kaurane and furokaurane-type diterpenes they contain higher proportions of phenols, complex carbohydrates (both soluble and hydrolyzable), volatile fatty acids on roasting, and sulfur compounds, all in comparison with Arabicas. References to these distinctions can be found in Chapter 6 of this book. 

Several alicyclic compounds identifiable in roasted coffee are terpenes and these contribute presumably to the coffee oil. The kaurane and furokaurane type diterpenes are discussed in Section VIII.D. 

The plant is used to treat leprosy the roots are used to heal ulcers and to cure ringworm infection. A decoction of the leaves is drunk to treat tuberculosis and to improve general weakness. In Cambodia, Laos, and Vietnam, an infusion of the bark is used to correct nervous affections. The plant is known to elaborate lupane triter-pene saponins and kaurane diterpenes including 16-aH, 17-isovalerate-ent-kauran-19-oic acid, which strongly inhibited the enzymatic activity of cyclooxygenase in vitro (76,77). 

Kiem PV, Cai XF, Minh CV, Lee JJ, Kim YH. Kaurane-type diterpene glycoside from the stem bark of Acanthopanax trifoliatus. Planta Med 2004 70 282-284. 

Malacria and coworkers346 prepared phyllocladane and kaurane types of diterpenes by means of [3 + 2]/[2 + 2 + 2]/[4 + 2] cascade reaction sequences. A representative example of such a reaction sequence has been outlined in equation 171. The five-membered ring of 598 was built by a 1,3-dipolar cycloaddition between 596 and an all-carbon 1,3-dipole generated from 597. The reaction of 598b with 568h afforded benzocyclobutene 599. The intramolecular [4 + 2] cycloaddition afforded diastereomers 600 and 601 in a 5 1 ratio. It is noteworthy that the exocyclic double bond in 598b neither participates in the [2 + 2 + 2] cycloaddition reaction nor isomerizes under the reaction conditions applied. 

Isodon diterpenes. Highly oxygenated.- -seco-ent-kaurane diterpenoids, the isodons (Figure 7), isolated from species of Isodon (now Rhabdosia)... 

Solldago is a mostly North American genus of about 125 species. It belongs to the Asteraceae (Compositae), a family with a very distinctive chemistry (57, 58). The genus itself contains several different classes of secondary compounds including a number of diterpenes (59). During the 1960 s and 1970 s Anthonsen in Finland, and McCrindle and his coworkers in Canada, isolated about twenty-five different compounds from the roots of Solidago species, mainly clerodanes and labdanes. But in the last five years attention has turned to the aerial parts of the plant and compounds of several other classes of diterpenes, abietanes and kauranes, have been isolated (60-79) (Table II). 

Watanabe, M., Y. Sakai, T. Teraoka, OS026 et al. Novel C19-kaurane type of diterpenes (oryzalide A), a new antimicrobial compound isolated from healthy leaves of a bacterial leaf blight OS027 resistant cultivar of rice plant. Agr... 

In the case of diterpenes, a different mechanism may be involved in antiinflammatory activity. Interference with DNA-binding activity of p50 protein of NF-kB factor seems to be a mechanism, as shown with kamebakaurin, a kaurane diterpene. This compound did not prevent degradation of ItcB-a isoform or nuclear translocation of NF-kB factor, and the covalent modification of cysteine 62 of p50 by kamebakaurin was proven. Prevention of the induced expression of anti-apoptotic genes and an increase in the induced caspase 8 activity were also observed. These... 

Encelin from Montanoa speciosa is inhibitory to growth and development of fungal cells of Mucor rouxii. Other cytotoxic sesquiterpene lactones from Montanoa tomentosa ssp. microcephala have been reported.45,46 A number of kaurane diterpenes and e/tf-kauranoids have been reported that are potentially useful because of their cytotoxicity against human tumor cells, anti-HIV activity, and trypanosomicidal activity.47 56 New structures are frequently discovered, and probably we will learn new effects in humans and animals in the future.57,58 Paradoxically, these plant natural products probably have specific and important effects in the plants, but we are still ignorant of these roles. 

LEE, J.H., KOO, T.H., HWANG, B.Y., LEE, J.J., Kaurane diterpene, kamebakaurin, inhibits NF-kappa B by directly targeting the DNA-binding activity of p50 and blocks the expression of antiapoptotic NF-kappa B target genes., J. Biol. Chem., 2002,277,18411-18420. 

BATISTA, R CHIARI, E., DE OLIVEIRA, A.B., Tiypanosomicidal kaurane diterpenes from Wedeliapaludosa., Planta Med., 1999,65,283-284. 

Excisanin A (kaurane diterpene) Isodonjaponicus (Lamiaceae) l iNOS expression [blocks LPS-induced macrophage NFkB activation, iNOS COX-2 expression NO PGE2 production]... 

Four structural types of diterpenes are known from Helianthus labdanes, kauranes, atisiranes and trachylobanes (Figure 2), with the tetracyclic kaurane type being the most widespread in the genus. The majority of Helianthus diterpenes have an Ol-oriented carboxylic acid function attached to carbon 4. 

Examples of other antimicrobial diterpenoids from the Anthemideae tribe also included a nor-ent-kaurane diterpene, Fig. (26) from the aerial parts of Antennaria geyeri L. [196], three new diterpenes jasonin A-C isolated from the aerial parts of Jasonia montana [206] and the terpenes 15-hydroxy-7-labden-17-oic acid, Fig. (27) and their acetate from Eupatorium glutinosum Matico, which were active against 2 Gram (-) and 2 Gram (-I-) bacteria [207,208]. 

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

Diterpenes (C20) can be linear as in the phytol part of chlorophyll or mono- to tetracyclic.87 Very well researched are the tricyclic taxanes of which taxol A from the Taxus baccata tree inhibits cell division and has found use in anticancer treatment. Certain labdanes inhibit blood platelet aggregation and kaurane norditer-pene glycosyl ester atractylosides from the Mediterranean thistle block the ATP/ADP translocation - such diterpenes are very toxic when ingested. Ubiquitous plant-derived kaurane-type diterpenes are the plant hormones (gibberellins) or defense substances (phytoalexins). 

---