Kaurane diterpenes

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). 

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]... 

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...

Some pairs of diastereomeric eitf-kaurane diterpenes were identified such as T2-T3, T4-T5, T8-T9, and T20-T21 [102], Crucial NMR shift values are listed in Tables 15 to 6 to help distinguish these diastereomers. In Table 4, H-l6 H NMR resonance signals of T2 and T3 are significantly different, because the anisotropic effect of the ent-kaurane C-ring made the H-16a shift downfield. It also caused the 13C NMR chemical shift of the 17-carboxylic acid to the upfield. On the other hand, the anisotropic effect of the carboxylic acid affected the resonance of C-15 (by about 5 ppm). The difference offers important evidence to distinguish this type of diastereomer. In the NOESY spectrum of T3, correlations between H-16a and H-13 or H-16a and H-14 proved its stereochemistry. The H-16 3 stereochemistry of T2 was reconfirmed by the NOE correlation between H-16(3 and H-l 1. 

Resembling methods used to elucidate the NOE correlation between H-17 and H-l 1 or H-17 and H-13 helped establish the stereochemistries of the 16,17-dihydroxy-enf-kaurane diterpenes. Relative to the 17-hydroxy-16a-ent- kaurane diterpenes, a 16a-hydroxy group results in the H NMR chemical shift of the 17-oxymethene more deshielded, but a 16 3-hydroxy group makes the 13C NMR shift of C-17 more deshielded. Diagnostic carbon signals of C-13 and C-16, especially C-13, are also key points to identify this type of diastereomer (see Table 17). Similar results (Table 18) were observed from the NMR data measured in different solvents. 

Fig. (3). Secondary metabolites from Montanoa lomeniosa include a. Kaurane diterpenes, B. Oxepanes and their acyclic precursors, C. Flavonoids, and D. Guaianolides and heliangolides.

In 2014, Canesi s group also reported on a remarkable application of their chemistry that enabled them to develop an asymmetric synthesis of the tetracyclic main core of kaurane diterpenes [131]. The phenolic non-conjugated enyne 249 was elaborated to fulfill the reactivity and stereochemistry requirements of the intended oxidative cationic polycyclization [132], in tandem with apinacolic transposition. After chlorination of the benzylic alcohol of 249 with inversion of configuration, the use of BTI rapidly promoted this dearomative tandem process, which thus... 

Novel diterpenoids are namral products made up of 4 isoprene units. Ent-kaurane diterpenes is a diterpene with significant biological activity. This series of compounds include two main categories C-20-non-oxygenated ent-kauranes and C-20 oxidized ent-kauranediterpene (Fig. 1.4), and nine subcategories under them [12, 13]. 

Kaurane diterpenes (I) and phenolic amides (II) from Xylopia aethiopica, as well as phenethylalkylketones (III) from Aframomum melegueta are now being patented as leads to new wood-protecting agents. Kaurane diteipenes have previously been found to deter feeding of Lepidopteran larvae (9) and aphids (10) and may thus have a rather broad spectrum of activities, and represent an interesting new class of active compounds. 

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