Difference between revisions of "Kaurane"

Revision as of 19:51, 8 March 2010

IUPAC

CAS

The two different structures referred to as kaurane.

Kaurane is a parent hydride used in the IUPAC nomenclature of natural products and also, distinctly, in CAS nomenclature. It is a diterpene with a rigid four-ring structure and six chiral centres.

The conventional numbering of kaurane: for the numbering of the methyl groups at C-18 and C-19, see text.

The stereochemistry of the six chiral centres is defined by convention: however, IUPAC and CAS use different opposite enantiomers, which also leads to a slight difference in numbering between the two systems. IUPAC conventional kaurane has (5S,8S,9S,10S,13S,15R)-stereochemistry, and is drawn with the five-membered ring receding into the plane of the image.^[1] CAS conventional kaurane has (5R,8R,9R,10R,13R,15S)-stereochemistry, and is drawn with the five-membered ring protruding from the plane of the image.^[2] For the two methyl groups attached to carbon-4, the two number systems are identical (but see below): the methyl group receding into the plane of the image is numbered carbon-18 and the one protruding from the plane of the image is numbered carbon-19. Revised Section F: Natural Products and Related Compounds (IUPAC Recommendations 1999). Pure Appl. Chem., 71 (4), 587–643. DOI: 10.1351/pac199971040587

The name ent-kaurane is sometimes used to refer to the CAS conventional kaurane,^[3] and so to distinguish it from the IUPAC stereochemistry, in particular by the International Union of Biochemistry and Molecular Biology (IUBMB).^[4] This is the structure of the cyclic skeleton of all naturally occurring kaurane terpenes. However, the numbering system is distinct between CAS nomenclature and IUBMB nomenclature: the metabolic intermediate kaurenoic acid, which has the (4S)-configuration, is kaur-16-en-18-oic acid in CAS nomenclature but ent-kaur-16-en-19-oic acid in IUBMB nomenclature.^[2]^[4]^{[note 1]}

Kaurane diterpenes have been extracted from a variety of plant species,^[3]^[5] in particular Stevia sp., the source of the steviol glycosides stevioside and rebaudioside-A that have been used as artificial sweetners.^[6] They are intermediates in gibberellin biosynthesis, leading to a group of important plant hormones (gibberellins):^[7] gibberellin A₁₂ is biosynthesized from ent-kaurene by six successive oxidations catalyzed by ent-kaurene oxidase (EC 1.14.13.78) and ent-kaurenoic acid oxidase (EC 1.14.13.79).^[4] The ent-kaurane skeleton is also found in veatchine and other Garrya alkaloids.^[8]

Notes and references

Notes

↑ The reason for this difference is that the ent nomenclature operation reverses the configuration of every chiral centre in the molecule, and so maps C-19 onto C-18 and vice versa.

References

↑ Revised Section F: Natural Products and Related Compounds (IUPAC Recommendations 1999). Pure Appl. Chem., 71 (4), 587–643. DOI: 10.1351/pac199971040587.
↑ ^2.0 ^2.1 57817-89-7 – Kaur-16-en-18-oic acid, 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-, β-D-glucopyranosyl ester, (4α)-. In Common Chemistry; Chemical Abstracts Service, <http://www.commonchemistry.org/ChemicalDetail.aspx?ref=57817-89-7>. (accessed 5 September 2009).
↑ ^3.0 ^3.1 Nagashima, Fumihiro; Tanaka, Hironao; Takaoka, Shigeru; Asakawa, Yoshinori Ent-kaurane-type diterpenoids from the liverwort Jungermannia exsertifolia ssp. cordifolia. Phytochemistry 1996, 41 (4), 1129–41. DOI: 10.1016/0031-9422(95)00755-5. Arriaga-Giner, Francisco Javier; Rumbero, Angel; Wollenweber, Eckhard 16α,19-Diacetoxy-ent-kaurane, a New Natural Diterpene from the Exudate of Ozothamnus scutellifolius (Asteraceae). Z. Naturforsch. C 1999, 54, 602–4. Harinantenaina, Liva Rakotondraibe Romuald; Kasai, Ryoji; Yamasaki, Kazuo Ent-kaurane Diterpenoid Glycosides from the Leaves of Cussonia racemosa, a Malagasy Endemic Plant. Chem. Pharm. Bull. 2002, 50 (2), 268–71. DOI: 10.1248/cpb.50.268. Ding, Lan; Zhang, Zhang-Jing; Liu, Guo-An; Yang, Dong-Juan; Guo, Guo-Cong; Wang, Han; Sun, Kun Three New Cytotoxic ent-Kaurane Diterpenoids from Isodon weisiensis C. Y. Wu. Helv. Chim. Acta 2005, 88 (9), 2502–7. DOI: 10.1002/hlca.200590185. Batista, Ronan; García, Pablo A.; Castro, Maria A.; del Corral, José M. Miguel; San Feliciano, Arturo; de Oliveira, Alaíde B. New oxidized ent-kaurane and ent-norkaurane derivatives from kaurenoic acid. J. Braz. Chem. Soc. 2007, 18 (3), 622–27. DOI: 10.1590/S0103-50532007000300020. Zhao, Yong; Pu, Jian-Xin; Huang, Sheng-Xiong; Ding, Li-Sheng; Wu, Ying-Li; Li, Xian; Yang, Li-Bin; Xiao, Wei-Lie, et al. ent-Kaurane diterpenoids from Isodon pharicus. J. Nat. Prod. 2009, 72 (6), 988–93. PMID 19425589. DOI: 10.1021/np9000366.
↑ ^4.0 ^4.1 ^4.2 EC 4.2.3.19 – ent-kaurene synthase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/2/3/19.html>. (accessed 18 September 2009). EC 1.14.13.78 – ent-kaurene oxidase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/78.html>. (accessed 5 September 2009). EC 1.14.13.79 – ent-kaurenoic acid oxidase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/79.html>. (accessed 5 September 2009).
↑ Nagashima, Fumihiro; Kondoh, Masuo; Uematsu, Toshinari; Nishiyama, Akiko; Saito, Sayaka; Sato, Masao; Asakawa, Yoshinori Cytotoxic and apoptosis-inducing ent-kaurane-type diterpenoids from the Japanese liverwort Jungermannia truncata nees. Chem. Pharm. Bull. 2002, 50 (6), 808–13. DOI: 10.1248/cpb.50.808. Bruno, Maurizio; Piozzi, Franco; Arnold, Nelly Apostolides; Başer, K. Hüsnü Can; Tabanca, Nurhayat; Kirimer, Neşe Kaurane Diterpenoids from Three Sideritis Species. Turk. J. Chem. 2005, 29 (1), 61–64, <http://journals.tubitak.gov.tr/chem/issues/kim-05-29-1/kim-29-1-7-0402-1.pdf>. Kim, Ki Hyun; Choi, Sang Un; Lee, Kang Ro Diterpene glycosides from the seeds of Pharbitis nil. J. Nat. Prod. 2009, 72 (6), 1121–27. PMID 19435339. DOI: 10.1021/np900101t.
↑ Jaitak, Vikas; Bikram Singh, Bandna; Kaul, V. K. An efficient microwave-assisted extraction process of stevioside and rebaudioside-A from Stevia rebaudiana (Bertoni). Phytochem. Anal. 2009, 20 (3), 240–45. PMID 19358287. DOI: 10.1002/pca.1120.
↑ Brandle, J. E.; Telmer, P. G. Steviol glycoside biosynthesis. Phytochemistry 2007, 68 (14), 1855–63. DOI: 10.1016/j.phytochem.2007.02.010.
↑ Pelletier, S. William; Mody, Naresh V. The Chemistry of C₂₀-Diterpenoid Alkaloids. In The Alkaloids: Chemistry and Pharmacology; Manske, R. H. F.; Rodrigo, R. G. A., Eds.; Academic Press: New York, 1981; Vol. 18, pp 102–21. ISBN 0-12-469518-3.

External links

Kaurane Chemical Structure (shows the IUPAC conventional structure)
Diterpenes, Kaurane – Research News and Information

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This page is currently licensed under the Creative Commons Attribution 3.0 Unported license and any later versions of that license.

[5] The reason for this difference is that the ent nomenclature operation reverses the configuration of every chiral centre in the molecule, and so maps C-19 onto C-18 and vice versa.

[IUPAC-1] Revised Section F: Natural Products and Related Compounds (IUPAC Recommendations 1999). Pure Appl. Chem., 71 (4), 587–643. DOI: 10.1351/pac199971040587.

[CAS-2] 2.0 ^2.1 57817-89-7 – Kaur-16-en-18-oic acid, 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-, β-D-glucopyranosyl ester, (4α)-. In Common Chemistry; Chemical Abstracts Service, <http://www.commonchemistry.org/ChemicalDetail.aspx?ref=57817-89-7>. (accessed 5 September 2009).

[ent-3] 3.0 ^3.1 Nagashima, Fumihiro; Tanaka, Hironao; Takaoka, Shigeru; Asakawa, Yoshinori Ent-kaurane-type diterpenoids from the liverwort Jungermannia exsertifolia ssp. cordifolia. Phytochemistry 1996, 41 (4), 1129–41. DOI: 10.1016/0031-9422(95)00755-5. Arriaga-Giner, Francisco Javier; Rumbero, Angel; Wollenweber, Eckhard 16α,19-Diacetoxy-ent-kaurane, a New Natural Diterpene from the Exudate of Ozothamnus scutellifolius (Asteraceae). Z. Naturforsch. C 1999, 54, 602–4. Harinantenaina, Liva Rakotondraibe Romuald; Kasai, Ryoji; Yamasaki, Kazuo Ent-kaurane Diterpenoid Glycosides from the Leaves of Cussonia racemosa, a Malagasy Endemic Plant. Chem. Pharm. Bull. 2002, 50 (2), 268–71. DOI: 10.1248/cpb.50.268. Ding, Lan; Zhang, Zhang-Jing; Liu, Guo-An; Yang, Dong-Juan; Guo, Guo-Cong; Wang, Han; Sun, Kun Three New Cytotoxic ent-Kaurane Diterpenoids from Isodon weisiensis C. Y. Wu. Helv. Chim. Acta 2005, 88 (9), 2502–7. DOI: 10.1002/hlca.200590185. Batista, Ronan; García, Pablo A.; Castro, Maria A.; del Corral, José M. Miguel; San Feliciano, Arturo; de Oliveira, Alaíde B. New oxidized ent-kaurane and ent-norkaurane derivatives from kaurenoic acid. J. Braz. Chem. Soc. 2007, 18 (3), 622–27. DOI: 10.1590/S0103-50532007000300020. Zhao, Yong; Pu, Jian-Xin; Huang, Sheng-Xiong; Ding, Li-Sheng; Wu, Ying-Li; Li, Xian; Yang, Li-Bin; Xiao, Wei-Lie, et al. ent-Kaurane diterpenoids from Isodon pharicus. J. Nat. Prod. 2009, 72 (6), 988–93. PMID 19425589. DOI: 10.1021/np9000366.

[EC-4] 4.0 ^4.1 ^4.2 EC 4.2.3.19 – ent-kaurene synthase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/2/3/19.html>. (accessed 18 September 2009). EC 1.14.13.78 – ent-kaurene oxidase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/78.html>. (accessed 5 September 2009). EC 1.14.13.79 – ent-kaurenoic acid oxidase. In IUBMB Enzyme Nomenclature, <http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/79.html>. (accessed 5 September 2009).

[6] Nagashima, Fumihiro; Kondoh, Masuo; Uematsu, Toshinari; Nishiyama, Akiko; Saito, Sayaka; Sato, Masao; Asakawa, Yoshinori Cytotoxic and apoptosis-inducing ent-kaurane-type diterpenoids from the Japanese liverwort Jungermannia truncata nees. Chem. Pharm. Bull. 2002, 50 (6), 808–13. DOI: 10.1248/cpb.50.808. Bruno, Maurizio; Piozzi, Franco; Arnold, Nelly Apostolides; Başer, K. Hüsnü Can; Tabanca, Nurhayat; Kirimer, Neşe Kaurane Diterpenoids from Three Sideritis Species. Turk. J. Chem. 2005, 29 (1), 61–64, <http://journals.tubitak.gov.tr/chem/issues/kim-05-29-1/kim-29-1-7-0402-1.pdf>. Kim, Ki Hyun; Choi, Sang Un; Lee, Kang Ro Diterpene glycosides from the seeds of Pharbitis nil. J. Nat. Prod. 2009, 72 (6), 1121–27. PMID 19435339. DOI: 10.1021/np900101t.

[7] Jaitak, Vikas; Bikram Singh, Bandna; Kaul, V. K. An efficient microwave-assisted extraction process of stevioside and rebaudioside-A from Stevia rebaudiana (Bertoni). Phytochem. Anal. 2009, 20 (3), 240–45. PMID 19358287. DOI: 10.1002/pca.1120.

[8] Brandle, J. E.; Telmer, P. G. Steviol glycoside biosynthesis. Phytochemistry 2007, 68 (14), 1855–63. DOI: 10.1016/j.phytochem.2007.02.010.

[9] Pelletier, S. William; Mody, Naresh V. The Chemistry of C₂₀-Diterpenoid Alkaloids. In The Alkaloids: Chemistry and Pharmacology; Manske, R. H. F.; Rodrigo, R. G. A., Eds.; Academic Press: New York, 1981; Vol. 18, pp 102–21. ISBN 0-12-469518-3.

[1]

[2]

[3]

[4]

[note 1]

[5]

[6]

[7]

[8]

@@ Line 11: / Line 11: @@
 [[File:Kaurane numbered.png|thumb|right|250px|The conventional numbering of kaurane: for the numbering of the methyl groups at C-18 and C-19, see text.]]
-The stereochemistry of the six chiral centres is defined by convention: however, IUPAC and CAS use different opposite [[enantiomer]]s, which also leads to a slight difference in numbering between the two systems. IUPAC conventional kaurane has (5''S'',8''S'',9''S'',10''S'',13''S'',15''R'')-stereochemistry, and is drawn with the five-membered ring receding into the plane of the image.<ref name="IUPAC">{{IUPAC natural products 1999}}.</ref> CAS conventional kaurane has (5''R'',8''R'',9''R'',10''R'',13''R'',15''S'')-stereochemistry, and is drawn with the five-membered ring protruding from the plane of the image.<ref name="CAS">{{citation | contribution = 57817-89-7 – Kaur-16-en-18-oic acid, 13-&#91;(2-''O''-β-<small>D</small>-glucopyranosyl-β-<small>D</small>-glucopyranosyl)oxy&#93;-, β-<small>D</small>-glucopyranosyl ester, (4α)- | url = http://www.commonchemistry.org/ChemicalDetail.aspx?ref=57817-89-7 | title = Common Chemistry | publisher = Chemical Abstracts Service | accessdate = 2009-09-05}}.</ref> Carbon-19 (one of the two methyl groups attached to carbon-4) is on the same side of the molecule as the five-membered ring in both systems: hence it is receding into the plane of the image in IUPAC nomenclature and protruding from the plane of the image in CAS nomenclature.
+The stereochemistry of the six chiral centres is defined by convention: however, IUPAC and CAS use different opposite [[enantiomer]]s, which also leads to a slight difference in numbering between the two systems. IUPAC conventional kaurane has (5''S'',8''S'',9''S'',10''S'',13''S'',15''R'')-stereochemistry, and is drawn with the five-membered ring receding into the plane of the image.<ref name="IUPAC">{{IUPAC natural products 1999}}.</ref> CAS conventional kaurane has (5''R'',8''R'',9''R'',10''R'',13''R'',15''S'')-stereochemistry, and is drawn with the five-membered ring protruding from the plane of the image.<ref name="CAS">{{citation | contribution = 57817-89-7 – Kaur-16-en-18-oic acid, 13-&#91;(2-''O''-β-<small>D</small>-glucopyranosyl-β-<small>D</small>-glucopyranosyl)oxy&#93;-, β-<small>D</small>-glucopyranosyl ester, (4α)- | url = http://www.commonchemistry.org/ChemicalDetail.aspx?ref=57817-89-7 | title = Common Chemistry | publisher = Chemical Abstracts Service | accessdate = 2009-09-05}}.</ref> For the two methyl groups attached to carbon-4, the two number systems are identical (but see below): the methyl group receding into the plane of the image is numbered carbon-18 and the one protruding from the plane of the image is numbered carbon-19. {{citation | title = Revised Section F: Natural Products and Related Compounds (IUPAC Recommendations 1999) | journal = Pure Appl. Chem. | volume = 71 | issue = 4 | pages = 587–643 | doi = 10.1351/pac199971040587}}
-The name ''ent''-kaurane is sometimes used to refer to the CAS conventional kaurane,<ref name="ent">{{citation | first1 = Fumihiro | last1 = Nagashima | first2 = Hironao | last2 = Tanaka | first3 = Shigeru | last3 = Takaoka | first4 = Yoshinori | last4 = Asakawa | title = ''Ent''-kaurane-type diterpenoids from the liverwort ''Jungermannia exsertifolia'' ssp. ''cordifolia'' | journal = Phytochemistry | volume = 41 | issue = 4 | year = 1996 | pages = 1129–41 | doi = 10.1016/0031-9422(95)00755-5}}. {{citation | first1 = Francisco Javier | last1 = Arriaga-Giner | first2 = Angel | last2 = Rumbero | first3 = Eckhard | last3 = Wollenweber | title = 16α,19-Diacetoxy-''ent''-kaurane, a New Natural Diterpene from the Exudate of ''Ozothamnus scutellifolius'' (Asteraceae) | journal = Z. Naturforsch. C | volume = 54 | pages = 602–4 | year = 1999}}. {{citation | title = ''Ent''-kaurane Diterpenoid Glycosides from the Leaves of ''Cussonia racemosa'', a Malagasy Endemic Plant | first1 = Liva Rakotondraibe Romuald | last1 = Harinantenaina | first2 = Ryoji | last2 = Kasai | first3 = Kazuo | last3 = Yamasaki | journal = Chem. Pharm. Bull. | year = 2002 | volume = 50 | issue = 2 | pages = 268–71 | doi = 10.1248/cpb.50.268}}. {{citation | title = Three New Cytotoxic ''ent''-Kaurane Diterpenoids from ''Isodon weisiensis'' C. Y. Wu | first1 = Lan | last1 = Ding | first2 = Zhang-Jing | last2 = Zhang | first3 = Guo-An | last3 = Liu | first4 = Dong-Juan | last4 = Yang | first5 = Guo-Cong | last5 = Guo | first6 = Han | last6 = Wang | first7 = Kun | last7 = Sun | journal = Helv. Chim. Acta | volume = 88 | issue = 9 | year = 2005 | pages = 2502–7 | doi = 10.1002/hlca.200590185}}. {{citation | first1 = Ronan | last1 = Batista | first2 = Pablo A. | last2 = García | first3 = Maria A. | last3 = Castro | first4 = José M. Miguel | last4 = del Corral | first5 = Arturo | last5 = San Feliciano | first6 = Alaíde B. | last6 = de Oliveira | title = New oxidized ''ent''-kaurane and ''ent''-norkaurane derivatives from kaurenoic acid | journal = J. Braz. Chem. Soc. | volume = 18 | issue = 3 | year = 2007 | pages = 622–27 | doi =  10.1590/S0103-50532007000300020}}. {{citation | last1 = Zhao | first1 = Yong | last2 = Pu | first2 = Jian-Xin | last3 = Huang | first3 = Sheng-Xiong | last4 = Ding | first4 = Li-Sheng | last5 = Wu | first5 = Ying-Li | last6 = Li | first6 = Xian | last7 = Yang | first7 = Li-Bin | last8 = Xiao | first8 = Wei-Lie | last9 = Chen | first9 = Guo-Qiang | last10 = Sun | first10 = Han-Dong | title = ''ent''-Kaurane diterpenoids from ''Isodon pharicus'' | journal = J. Nat. Prod. | year = 2009 | volume = 72 | issue = 6 | pages = 988–93 | doi = 10.1021/np9000366 | pmid = 19425589}}.</ref> and so to distinguish it from the IUPAC stereochemistry, in particular by the [[International Union of Biochemistry and Molecular Biology]] (IUBMB).<ref name="EC">{{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/2/3/19.html | contribution = EC&nbsp;4.2.3.19 – ''ent''-kaurene synthase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-18}}. {{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/78.html | contribution = EC&nbsp;1.14.13.78 – ''ent''-kaurene oxidase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-05}}. {{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/79.html | contribution = EC&nbsp;1.14.13.79 – ''ent''-kaurenoic acid oxidase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-05}}.</ref> This is the structure of the cyclic skeleton of all naturally occurring kaurane terpenes. However, the numbering system is distinct between CAS nomenclature and IUBMB nomenclature: the metabolic intermediate [[kaurenoic acid]], which has the (4''S'')-configuration, is kaur-16-en-18-oic acid in CAS nomenclature but ''ent''-kaur-16-en-19-oic acid in IUBMB nomenclature.<ref name="CAS"/><ref name="EC"/>
+The name ''ent''-kaurane is sometimes used to refer to the CAS conventional kaurane,<ref name="ent">{{citation | first1 = Fumihiro | last1 = Nagashima | first2 = Hironao | last2 = Tanaka | first3 = Shigeru | last3 = Takaoka | first4 = Yoshinori | last4 = Asakawa | title = ''Ent''-kaurane-type diterpenoids from the liverwort ''Jungermannia exsertifolia'' ssp. ''cordifolia'' | journal = Phytochemistry | volume = 41 | issue = 4 | year = 1996 | pages = 1129–41 | doi = 10.1016/0031-9422(95)00755-5}}. {{citation | first1 = Francisco Javier | last1 = Arriaga-Giner | first2 = Angel | last2 = Rumbero | first3 = Eckhard | last3 = Wollenweber | title = 16α,19-Diacetoxy-''ent''-kaurane, a New Natural Diterpene from the Exudate of ''Ozothamnus scutellifolius'' (Asteraceae) | journal = Z. Naturforsch. C | volume = 54 | pages = 602–4 | year = 1999}}. {{citation | title = ''Ent''-kaurane Diterpenoid Glycosides from the Leaves of ''Cussonia racemosa'', a Malagasy Endemic Plant | first1 = Liva Rakotondraibe Romuald | last1 = Harinantenaina | first2 = Ryoji | last2 = Kasai | first3 = Kazuo | last3 = Yamasaki | journal = Chem. Pharm. Bull. | year = 2002 | volume = 50 | issue = 2 | pages = 268–71 | doi = 10.1248/cpb.50.268}}. {{citation | title = Three New Cytotoxic ''ent''-Kaurane Diterpenoids from ''Isodon weisiensis'' C. Y. Wu | first1 = Lan | last1 = Ding | first2 = Zhang-Jing | last2 = Zhang | first3 = Guo-An | last3 = Liu | first4 = Dong-Juan | last4 = Yang | first5 = Guo-Cong | last5 = Guo | first6 = Han | last6 = Wang | first7 = Kun | last7 = Sun | journal = Helv. Chim. Acta | volume = 88 | issue = 9 | year = 2005 | pages = 2502–7 | doi = 10.1002/hlca.200590185}}. {{citation | first1 = Ronan | last1 = Batista | first2 = Pablo A. | last2 = García | first3 = Maria A. | last3 = Castro | first4 = José M. Miguel | last4 = del Corral | first5 = Arturo | last5 = San Feliciano | first6 = Alaíde B. | last6 = de Oliveira | title = New oxidized ''ent''-kaurane and ''ent''-norkaurane derivatives from kaurenoic acid | journal = J. Braz. Chem. Soc. | volume = 18 | issue = 3 | year = 2007 | pages = 622–27 | doi =  10.1590/S0103-50532007000300020}}. {{citation | last1 = Zhao | first1 = Yong | last2 = Pu | first2 = Jian-Xin | last3 = Huang | first3 = Sheng-Xiong | last4 = Ding | first4 = Li-Sheng | last5 = Wu | first5 = Ying-Li | last6 = Li | first6 = Xian | last7 = Yang | first7 = Li-Bin | last8 = Xiao | first8 = Wei-Lie | last9 = Chen | first9 = Guo-Qiang | last10 = Sun | first10 = Han-Dong | title = ''ent''-Kaurane diterpenoids from ''Isodon pharicus'' | journal = J. Nat. Prod. | year = 2009 | volume = 72 | issue = 6 | pages = 988–93 | doi = 10.1021/np9000366 | pmid = 19425589}}.</ref> and so to distinguish it from the IUPAC stereochemistry, in particular by the [[International Union of Biochemistry and Molecular Biology]] (IUBMB).<ref name="EC">{{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC4/2/3/19.html | contribution = EC&nbsp;4.2.3.19 – ''ent''-kaurene synthase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-18}}. {{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/78.html | contribution = EC&nbsp;1.14.13.78 – ''ent''-kaurene oxidase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-05}}. {{citation | url = http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/14/13/79.html | contribution = EC&nbsp;1.14.13.79 – ''ent''-kaurenoic acid oxidase | title = IUBMB Enzyme Nomenclature | accessdate = 2009-09-05}}.</ref> This is the structure of the cyclic skeleton of all naturally occurring kaurane terpenes. However, the numbering system is distinct between CAS nomenclature and IUBMB nomenclature: the metabolic intermediate [[kaurenoic acid]], which has the (4''S'')-configuration, is kaur-16-en-18-oic acid in CAS nomenclature but ''ent''-kaur-16-en-19-oic acid in IUBMB nomenclature.<ref name="CAS"/><ref name="EC"/><ref group="note">The reason for this difference is that the ''ent'' nomenclature operation reverses the configuration of every chiral centre in the molecule, and so maps C-19 onto C-18 and vice versa.</ref>
 Kaurane diterpenes have been extracted from a variety of plant species,<ref name="ent"/><ref>{{citation | last1 = Nagashima | first1 = Fumihiro | last2 = Kondoh | first2 = Masuo | last3 = Uematsu | first3 = Toshinari | last4 = Nishiyama | first4 = Akiko | last5 = Saito | first5 = Sayaka | last6 = Sato | first6 = Masao | last7 = Asakawa | first7 = Yoshinori | title = Cytotoxic and apoptosis-inducing ''ent''-kaurane-type diterpenoids from the Japanese liverwort ''Jungermannia truncata'' nees | journal = Chem. Pharm. Bull. | year = 2002 | volume = 50 | issue = 6 | pages = 808–13 | doi = 10.1248/cpb.50.808}}. {{citation | first1 = Maurizio | last1 = Bruno | first2 = Franco | last2 = Piozzi | first3 = Nelly Apostolides | last3 = Arnold | first4 = K. Hüsnü Can | last4 = Başer | first5 = Nurhayat | last5 = Tabanca | first6 = Neşe | last6 = Kirimer | title = Kaurane Diterpenoids from Three ''Sideritis'' Species | url = http://journals.tubitak.gov.tr/chem/issues/kim-05-29-1/kim-29-1-7-0402-1.pdf | journal = Turk. J. Chem. | volume = 29 | issue = 1 | year = 2005 | pages = 61–64}}. {{citation | last1 = Kim | first1 = Ki Hyun | last2 = Choi | first2 = Sang Un | last3 = Lee | first3 = Kang Ro | title = Diterpene glycosides from the seeds of ''Pharbitis nil'' | journal = J. Nat. Prod. | year = 2009 | volume = 72 | issue = 6 | pages = 1121–27 | doi = 10.1021/np900101t | pmid = 19435339}}.</ref> in particular ''Stevia'' sp., the source of the [[steviol glycoside]]s [[stevioside]] and [[rebaudioside-A]] that have been used as [[artificial sweetner]]s.<ref>{{citation | title = An efficient microwave-assisted extraction process of stevioside and rebaudioside-A from ''Stevia rebaudiana'' (Bertoni) | last1 = Jaitak | first1 = Vikas | last2 = Bikram Singh | first2 = Bandna | last3 = Kaul | first3 = V. K. | journal = Phytochem. Anal. | year = 2009 | volume = 20 | issue = 3 | pages = 240–45 | doi = 10.1002/pca.1120 | pmid = 19358287}}.</ref> They are intermediates in [[gibberellin biosynthesis]], leading to a group of important plant hormones ([[gibberellin]]s):<ref>{{citation | last1 = Brandle | first1 = J. E. | last2 = Telmer | first2 = P. G. | title = Steviol glycoside biosynthesis | journal = Phytochemistry | year = 2007 | volume = 68 | issue = 14 | pages = 1855–63 | doi = 10.1016/j.phytochem.2007.02.010}}.</ref> [[Gibberellin A12|gibberellin A<sub>12</sub>]] is [[Biosynthesis|biosynthesized]] from [[Ent-Kaurene|''ent''-kaurene]] by six successive [[oxidation]]s catalyzed by [[Ent-Kaurene oxidase|''ent''-kaurene oxidase]] (EC&nbsp;1.14.13.78) and [[Ent-Kaurenoic acid oxidase|''ent''-kaurenoic acid oxidase]] (EC&nbsp;1.14.13.79).<ref name="EC"/> The ''ent''-kaurane skeleton is also found in [[veatchine]] and other ''Garrya'' [[alkaloid]]s.<ref>{{citation | first1 = S. William | last1 = Pelletier | first2 = Naresh V. | last2 = Mody | contribution = The Chemistry of C<sub>20</sub>-Diterpenoid Alkaloids | title = The Alkaloids: Chemistry and Pharmacology | editor1-first = R. H. F. | editor1-last = Manske | editor2-first = R. G. A. | editor2-last = Rodrigo | volume = 18 | year = 1981 | location = New York | publisher = Academic Press | pages = 102–21 | isbn = 0-12-469518-3}}.</ref>
-==References==
+==Notes and references==
+===Notes===
+{{reflist|group=note}}
+===References===
 {{reflist}}

Difference between revisions of "Kaurane"

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