Kaurenes

The mode of action of CCC is attributed to the inhibition of / Akaurene synthetase A, the enzyme that drives the biosynthesis of geranyigeranylpyrophosphate by copalyl pyrophosphate to /-kaurene. The compound is registered in Europe to control lodging and is registered with the EPA. 

Other experiments with Gibberellafujikuroi the fungus that produces gibbereUin, indicate that GA production is blocked by BAS 111. Very detailed and carehil experiments conducted with enzymes in ceU-free systems strongly support this mode of action, ie, using /-kaurene oxidase and cinnamate 4-mono-oxygenase isolated from pea apices and soybean suspension cells, and avanone-2-hydtoxylase and dibydroxypterocarpane 6-hydtoxylase from soybean suspension cells (31). 

Since GAs as diterpenes share many intermediates in the biosynthetic steps leading to other terpenoids, eg, cytokinins, ABA, sterols, and carotenoids, inhibitors of the mevalonate (MVA) pathway of terpene synthesis also inhibit GA synthesis (57). Biosynthesis of GAs progresses in three stages, ie, formation of / Akaurene from MVA, oxidation of /-kaurene to GA 2" hyde, and further oxidation of the GA22-aldehyde to form the different GAs more than 70 different GAs have been identified. 

Most of the GA-synthesis inhibitors characterized so far affect two segments of the compHcated pathway from MVA to the many different GAs identified. The cycHzation reactions that produce / Akaurene are inhibited by the onium growth retardants, and the oxidations of /-kaurene to /-kaurenoic acid are sensitive to heterocycHc triazoles such as paclobutrazol and similar compounds. Other enzymes in the pathway are points for pathway dismption by as yet undeveloped GA biosynthesis inhibitors (236). 

Some kaurane and kaurene compounds found in green coffee beans their glycosides are listed in Table 15. 

Cationic cyclization. A key step in the synthesis of the diterpenes cafestol5 and atractyligenin4 involves a novel cation cyclization of bicyclic cyclopropanes to the tetracyclic systems of the diterpenes (equations I and II). Thus treatment of 1 with a slight excess of triflic anhydride and 2,6-lutidine effects cyclization to the rather unstable pentacycle 2 with the kaurene system. The related conversion of 3 to 4 can be effected with triflic anhydride and 2,6-di-r-butyl-4-methylpyridine in 1-nitropropane. 

Ent-kaurene Diterpene Glycosides from the Leaves of Stevia rebaudiana... 

Obermann, H. andG. Spiteller. 16,17-dihydroxy-9-kauren-l8-oic acid. A compound of roasted coffee. Chem Ber 1975 108 1093. 

Moore, T. C., H. Yamane, N. Muro-fushi, and N. Takahashi. Concentrations of ENT-kaurene and squalene in vegetative rice shoots. J Plant Growth Regul 1988 7(3) 145-151. 

Naturally Occurring Substances.—Beyeria (Euphorbiaceae) species have been the source of a number of tetracyclic diterpenoids. Some of these were new or poorly defined species and their classification has now been clarified. " The presence of enf-kaurenal has again been recorded in Fusarium monoliforme, whilst ent-kaur-16-en-19-oic acid (72) has been isolated from Mikania hirsutissima (Composi-tae). Microbiological hydro xylation of ent-kaur-16-en-19-oic acid by... 

Diterpenoid Alkaloids.—The structure and synthesis of the diterpenoid alkaloids have been reviewed. The subject is also covered in detail in the Specialist Periodical Report on the Alkaloids. A number of new alkaloids with the ent-kaurene skeleton have been isolated from Anopterus glandulosus and A. macleayanus. The structure of the major alkaloid anopterine (104) was assigned ... 

Takano et al. 69) exploited the asymmetric aldolization for the synthesis of more functionalized chiral products which possess units suitable for the construction of certain tetracyclic triterpenes, such as gibberellins and kaurenes. They described the enantioselective synthesis of the tricyclic enone (33) from the symmetric triketone (32) and its conversion into the gibbane framework. Again, (S)-proline was used as the catalyst. 

Varieties of sunflower (Helianthus annums, Asteraceae) that are resistant to attack by larvae of the sunflower moth (Homeosoma electellum) contain high concentrations of trachyloban-19-oic acid and (-)-16-kauren-19-oic acid in their florets (84,132). 

Aralia chinensis L. A. cordata Thunb. var. continentalis (Kitag.) Y. C. Chu A. elata (Miq.) Seem. A. elata (Miq.) Seem. F. subinermis Y. C. Chu Jia Mu, Du Huo (Aralia) (root) Diterpenoids such as (-) pimaradene, (-) kaurene derivatives, l-pimara-8, 15-dien-19-oic acid, aralosides, araligenin, oleanolic acid, beta-taralin, alpha-taralin.20 48 50 Carminative, for arthralgia, gastroenteritis, headache, diuretic, antidiabetic, antiseptic. 

Podocarpus macrophyllus (Thunb.) D. Don Luo Han Song (Southern yew) (stem bark, leaf, root, fruit) Pinene, camphene, cadinene, podocarpene, neocryuptomerin, kaurene, ecdysterone, ponasterone, makisterones, hinokiflavone, sciadopitysin, podocarpus flavones, macrephyllic acid, podototarin, totarol.54 For ringworms, blood disorders, tonic for heart, kidneys, lungs, stomach. 

Kaempferol Kaempferol Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kaempferol-Kansuinine Kanugin Karabin Karanjin Kaurene... 

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