Category:TP3

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==Triterpene (C30) Biosynthesis==
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==Triterpene (C30)==
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{{Twocolumn|
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Triterpenes are formed by joining two FPPs tail-to-tail.  The precursor compound of cholesterol (C27) is lanosterol (C30) for animals.  For plants, fungi and algae, it is almost cycloartenol with a trace of lanosterol-derived sterols<ref>Ohyama K, Suzuki M, Kikuchi J, Saito K, Muranaka T “Dual biosynthetic pathways to phytosterol via cycloartenol and lanosterol in Arabidopsis” Proc Natl Acad Sci USA 106(3):725-730, 2009</ref>.
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}}
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==Steroid==
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=={{Bilingual|環の構造|Ring configuration}}==
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===Ring configuration===
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==={{Bilingual|ステロイド|Steroid}}===
 
{{Twocolumn|
 
{{Twocolumn|
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The basic steroid structure is 4 carbon rings, cyclopenta[a]phenanthrene, gonane, or sterane.
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The basic structure is 4 carbon rings, cyclopenta[a]phenanthrene, gonane, or sterane.
 
The rings B/C are always ''trans'' in all natural steroids. If the rings C/D are ''trans'', it is called gonane.  If its stereochemistry is unspecified, it is called sterane.
 
The rings B/C are always ''trans'' in all natural steroids. If the rings C/D are ''trans'', it is called gonane.  If its stereochemistry is unspecified, it is called sterane.
 
Most steroids take gonane form, but in cardenolides and bufanolides, the rings C/D are ''cis''.
 
Most steroids take gonane form, but in cardenolides and bufanolides, the rings C/D are ''cis''.
 
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ステロイドの基本骨格は4つの環状構造で、シクロペンタ[a]フェナンスレン、ゴナン、ステランなどと呼ばれる。
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基本骨格は4つの環構造で、シクロペンタ[a]フェナンスレン、ゴナン、ステランなどと呼ばれます。
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天然のステロイドでは環 B/C は常にトランスの位置にある。環 C/D がトランスの場合をゴナンと呼び、立体配置が指定されていないときをステランと呼ぶ。
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天然のステロイドでは環 B/C は常にトランスの位置にあります。
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ほとんどのステロイドはゴナンの形をとるが、カルデノライドとブファノライドは環 C/D がシスになる。
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環 C/D がトランスの場合をゴナン、立体配置が指定されていないときをステランと呼びます。
 +
ほとんどのステロイドはゴナンの形をとりますが、カルデノライドとブファノライドは環 C/D がシスになります。
 
}}
 
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8&beta;, 9&alpha;, 10&beta;, 13&beta;, and 14&alpha; configurations. C-5 is a special position, because there are as many 5&alpha; steroids as 5&beta; are.
 
8&beta;, 9&alpha;, 10&beta;, 13&beta;, and 14&alpha; configurations. C-5 is a special position, because there are as many 5&alpha; steroids as 5&beta; are.
 
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大多数のステロイドは橋頭位のC-10, C-13からメチル基が出ている。
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大多数のステロイドは橋頭位のC-10, C-13からメチル基が出ます。
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これらのメチル基 (または水素など) が平面より上に出ているときを、ベータ配置とする。平面より下の場合をアルファ配置とする。
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これらのメチル基 (または水素など) が平面より上に出ているときを、ベータ配置とします。平面より下の場合がアルファ配置です。
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また、配置が不明な場合は、&xi; (ギリシャ語の Xi)で表す。
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配置が不明な場合は、&xi; (ギリシャ語の Xi)で表します。
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原則として、C-8, 9, 10, 13, 14位にある水素や置換基はそれぞれ8&beta;, 9&alpha;, 10&beta;, 13&beta;, 14&alpha; 配置である。
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C-5位は特別であり、5&alpha; のステロイドと 5&beta; のものが同じくらい存在する。
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原則として、C-8, 9, 10, 13, 14位にある水素や置換基はそれぞれ8&beta;, 9&alpha;, 10&beta;, 13&beta;, 14&alpha; 配置です。
 +
C-5位だけは特別で、5&alpha; のステロイドと 5&beta; のものが同じくらい存在するので指定が必要です。
 
}}
 
}}
  
 
<center>
 
<center>
 
{| style="text-align:center"
 
{| style="text-align:center"
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| [[Image:5alpha-steroid.png]] || [[Image:5beta-steroid.png]]
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| [[Image:cholestane.png]] || [[Image:5alpha-steroid.png]] || [[Image:5beta-steroid.png]]
 
|-
 
|-
 +
| cholestane backbone
 
| 5&alpha;-configuration
 
| 5&alpha;-configuration
 
| 5&beta;-configuration
 
| 5&beta;-configuration
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</center>
 
</center>
  
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===Hormonal Classes===
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==={{Bilingual|トリテルペン|Triterpenes}}===
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====Estranes (C18)====
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{{Twocolumn|
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The backbone of estrogens, the hormones responsible for female reproductive organs and secondary sex characteristics. The original spelling was 'oestrogen'. Major namings are:
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* estrogen ... estra-1,3,5(10)-triene
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* estrone ... 3-hydroxyestra-1,3,5(10)-triene-17-one
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* estradiol ... estra-1,3,5(10)-triene-3,17&beta;-diol
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* estriol  ... estra-1,3,5(10)-triene-3,16&alpha;,17&beta;-triol
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* equine estrogens ... estra-1,3,5(10),7-tetraene and estra-1,3,5,7,9-pentaene series
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}}
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====Androstanes (C19)====
 
 
{{Twocolumn|
 
{{Twocolumn|
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The backbone of male hormone testosterones. Major namings are:
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In almost all pentacyclic triterpenes in angiosperms, the methyl group at the DE-ring fusion is &beta;-configuration. Some triterpenes in ferns, mosses, gymnosperms have &alpha;-methyl group at the DE-ring fusion.
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* etianic acids (C20) ... androstane-17-carboxylic acids and their derivatives
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* D-homoandrostanes (C20) ... ring D is expanded by including C-17a carbon.
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被子植物におけるほとんどの５環テルペンではDE環の継ぎ目にあるメチル基が&beta;-配置を取ります。シダ類、コケ類、裸子植物における一部の５環テルペンではDE環に&alpha;-配置のメチル基がみられます。
 
}}
 
}}
  
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====Pregnanes (C21)====
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=={{Bilingual|生合成|Biosynthesis}}==
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==={{Bilingual|概要|Overview}}===
 
{{Twocolumn|
 
{{Twocolumn|
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The backbone of pregnancy hormone progesterone and the majority of corticosteroids.
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The starting point is squalene, which is formed by joining two FPPs tail-to-tail.
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It is the largest single group of steroids.
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Bacterial cyclases use squalene directly<ref>Bacterial squalene cyclases can accept oxidosqualene as their substrates, but oxidosqualene usually does not exist in bacteria</ref>, but those of the other species use
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Major namings are:
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2,3-oxidosqualene for cyclization.
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* progesterone ... pregn-4-ene-3,20-dione
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* 17&alpha;-ethynylandrostane ... 17&alpha;-pregn-20-yne
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* 19-norpregnane (C20) ... 17&alpha;-ethynylestrane, 19-nor-17&alpha;-pregn-20-yne
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17&alpha;-pregnanes are sometimes called 17&alpha;-vinyl- and 17&alpha;-ethyl-androstanes.
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始まりとなる物質はスクアレンで、二分子のファルネシル二リン酸が末尾どうしで結合して作られます。バクテリアの環化酵素はスクアレンをそのまま利用しますが<ref>バクテリアのスクアレン環化酵素はオキシドスクアレンも基質として利用できますが、バクテリアはオキシドスクアレンを合成しません。</ref>、それ以外の生物種では2,3-オキシドスクアレンを利用します。
 
}}
 
}}
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<center>
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====Cholanes (C24)====
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{| style="text-align:center"
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| [[Image:squalene.png]]
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| [[Image:2,3-oxidosqualene.png]]
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|-
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| squalene
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| 2,3-oxidosqualene
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|}
 +
</center>
 
{{Twocolumn|
 
{{Twocolumn|
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The backbone of bile acids, i.e., 5&beta;-cholan-24-oic acids with hydroxyl substitution at C-3.
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* In bacteria, squalene is cyclized via the 17&alpha;-deoxydammarenyl cation to hopene and other triterpenes.
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* primary bile acids ... cholic acid and chenodeoxycholic acid are biosynthesized directly from cholesterol.
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* In eukaryotes, 2,3-oxidosqualene is cyclized via the protosteryl cation to lanosterol (animals and fungi), cycloartenol (plants) or parkeol (sea cucumbers) by a series of 1,2-hydride and methyl shifts (Wagner-Meerwein shifts).
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* secondary bile acids ... deoxycholic acid and lithocholic acid are generated by intestinal bacteria.
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* In plants, a trace amount of phytosterols comes from lanosterol <ref>Ohyama K, Suzuki M, Kikuchi J, Saito K, Muranaka T (2009) Dual biosynthetic pathways to phytosterol via cycloartenol and lanosterol in Arabidopsis ''Proc Natl Acad Sci USA'' 106(3):725-730</ref> '''At3g45130''' is lanosterol synthase in ''Arabidopsis'' and its orthologs exist in asterids [[Species:Taraxacum|''Taraxacum officinale'']] and [[Species:Panax|''Panax ginseng]] and eurosid [[Species:Luffa|''Luffa cylindrica]].  Lanosterol synthase exists broadly among eudicots <ref>Kolesnikova MD, Xiong Q, Lodeiro S, Hua L, Matsuda SPT (2006) Lanosterol biosynthesis in plants ''Arch Biochem Biophys'' 447:87-95</ref>. Parkeol is also widespread in plants.
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* 24-norcholan-23-oic acids ... loss of one carbon side chain
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* In plants, various triterpenes arise from the 17&beta;-dammarenyl cation.
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* 23,24-dinorcholan-22-oic acids ... loss of two carbon side chains
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* バクテリアでは、スクアレンが環化して17&alpha;-ダンマラン型カチオンとなり、最終的にホペン等のトリテルペンになります。
 +
* 真核生物では、2,3-オキシドスクアレンが環化してプロトステロール型カチオンを作り、プロトンとメチル基の転移 (Wagner-Meerweinシフト) を経て1,2-ラノステロール (動物や真菌類)、シクロアルテノール (植物)や、パルケオール（ナマコ） になります。
 +
* 植物ではラノステロールからも一部の植物ステロールが合成されます。シロイヌナズナの '''At3g45130''' はラノステロール合成遺伝子であり、オーソログが菊類の [[Species:Taraxacum|''Taraxacum officinale'']] や [[Species:Panax|''Panax ginseng'']]、 真正バラ類の [[Species:Luffa|''Luffa cylindrica'']] にあることから、真正双子葉類に幅広く見られると考えられます。パーケオールも幅広い植物に見られます。
 +
* 更に植物の場合、17&beta;-ダンマラン型のカチオンから様々なトリテルペンが生成されます。
 
}}
 
}}
  
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===C/D ''cis'' Classes===
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;References
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<references/>
 +
<br/>
  
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====Cardenolides (C23)====
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==={{Bilingual|真核生物のオキシドスクアレン環化酵素|Oxidosqualene Cyclase in Eukaryotes}}===
 
{{Twocolumn|
 
{{Twocolumn|
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The backbone of ''Digitalis'' glycosides with the androstane skeleton with a &gamma;-lactone ring at C-17. Notable characters are its 14&beta;-configuration in opposition to other steroids (the rings C/D are ''cis''), and the 20(22)-double bond. Their cardiac activity is well known.
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Any path of reactions from the root (2,3-oxidosqualene) to any triterpene backbone with a colored background is catalyzed by a single enzyme called ''oxidosqualene cyclase'' (OSC) or ''terpene synthase h'' (tpsh).<ref>Terpene synthases a-f are responsible for mono-, sesquie- and diterpenes. Tps g is the squalene cyclase.</ref>
 
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この図の最上段 (2,3-オキシドスクアレン) から背景色のついたテルペン骨格までの任意の経路を、オキシドスクアレン環化酵素
 +
(OSC)　またはテルペンシンターゼ h (Tps h) と呼ばれる単一の酵素が触媒します。<ref>テルペンシンターゼ a-f は、モノ、セスキ、ジテルペンを合成します。 Tps g はスクアレン環化酵素です。</ref>
 
}}
 
}}
  
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====Bufanolides (C24)====
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{|
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{{Twocolumn|
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|-
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The backbone of toad skin secretions and the sea onion or squill (''Scilla maritima'') with a &delta;-lactone ring at C-17.
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! {{Bilingual|骨格色分け:|Backbone Color Code:}}
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As for cardenolides, 14&beta;, 17&beta;, and 20''R''-configurations are assumed (the rings C/D are ''cis''). They naturally occur as glycosides or conjugates of suberylarginine.
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! style="background-color:#fdd"| Animals, fungi, and yeast
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! style="background-color:#dfd"| Plants only
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}}
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!
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|-
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! {{Bilingual|6員環表記:|Six-membered rings:}}
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! colspan="2" | chair (C), or boat (B)
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|}
  
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===Steroidal Classes===
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<center>
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{|style="text-align:center"
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====Sterols (C27)====
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|-
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{{Twocolumn|
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|colspan="2"|
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The sterol backbone contains a &beta; hydroxyl group at C-3 and side chains of 8-10 carbons at C-17. They are important membrane constituents in addition to their biologically activity.
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|colspan="2"| 2,3-oxidosqualene
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<br/>
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|-
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Major categories are:
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|colspan="2"|
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* cholestane ... androstane structure with a branched C8 chain at the 17&beta;-position
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|colspan="2"|[[Image:2,3-oxidosqualene.png]]
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* norcholestane ... cholestane lacking one of 27 carbons
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|-
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* ergostane and campestane ... 24&beta;- and 24&alpha;-methylcholestane
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|colspan="2" align="right"|
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* poriferastane and stigmastane ... 24&beta;- and 24&alpha;-ethylcholestane
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{|
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* vitamin D2 ... 9,10-secoergonstane derivatives
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|lanosterol/<br/>cycloartenol<br/>syntase<ref>Lanosterol synthase is the most accessible enzyme among oxidosqualene cyclases, e.g. from mammalian liver or yeast. Cycloartenol synthase is the basic OSC in plants, although lanosterol synthase is also found. For the grouping of cyclases, check the review by Xiong Q et al. (2005) in this page.<br/>''References.''
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* vitamin D3 ... 9,10-secocholestane derivatives
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* Corey EJ, Russey WE, Ortiz-de-Montellano PR (1966) 2,3-Oxidosqualene, an intermediate in the biological synthesis of sterols from squalene ''J Am Chem Soc'' 88:4750-1
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* lumistane ... 9&beta;,10&alpha;-ergosta-5,7-diene
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* Kolesnikova MD, Xiong Q, Lodeiro S, Hua L, Matsuda SPT (2006) Lanosterol biosynthesis in plants ''Arch Biochem Biophys'' 447:87-95<br/>
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In ''Arabidopsis'', cycloartenol synthase can be converted to lanosterol synthase with only two amino acid substitutions: His477 to Asn and Ile481 to Val. Tyr410 is also important for specificity.
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* Lodeiro S, Schulz-Gasch T, Matsuda SPT (2005) Enzyme redesign: two mutations cooperate to convert cycloartenol synthase into an accurate lanosterol synthase ''J Am Chem Soc'' 127:14132-14133
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</ref>
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|[[Image:Arrow00dl35.png]]
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|stepwise<br/>cyclization<ref>The cyclization process is stepwise, not concerted as previously thought. As one clue, squalene is not fully folded in the cyclase active site.<br/>''Ref.'' Reinert DJ, Balliano G, Schulz GE (2004) Conversion of squalene to the pentacarbocyclic hopene. ''Chem Biol'' 11:121-6</ref>
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|}
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|colspan="2"|
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|align="left"|
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{|
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|lupeol/<br/>&beta;-amyrin<br/>synthase<ref>Lupeol synthases are found in [[Species:Glycyrrhiza|''Glycyrrhiza glabra'']], [[Species:Betula|''Betula'' platyphylla]], [[Species:Taraxacum|''Taraxacum officinale'']], and [[Species:Olea|''Olea europea'']]. They form a clade (74-81% identical) that is distinct from other OSCs. Lupeol synthase evolved before the divergence of asterids and eurosids. On the other hand, &beta;-amyrin synthases are considerably more distant (48-50% identical) than are the CAS enzymes (70-79% identical). &beta;-amyrin synthases in eudicotsa nd monocots may have independent origins.<ul><li>Haralampidis K, Bryan G, Qi X, Papadopoulou K, Bakht S, Melton R, Osbourn A (2001) A new class of oxidosqualene cyclases directs synthesis of antimicrobial phytoprotectants in monocots ''Proc Natl Acad Sci U S A'' 98(23):13431-6 <li>Qi X, Bakht S, Leggett M, Maxwell C, Melton R, Osbourn A (2004) A gene cluster for secondary metabolism in oat: implications for the evolution of metabolic diversity in plants ''Proc Natl Acad Sci U S A'' 101(21):8233-8</ul></ref>
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|[[Image:Arrow00dr35.png]]
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|stepwise<br/>cyclization
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|}
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|-
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| 17&beta;-protosteryl cation <small>(C-B-C)</small><ref>The C-17 chain of rotosteryl cation is &beta;-configuration, not &alpha;.<br/> ''Ref.'' Corey EJ, Virgil SC (1991) An experimental demonstration of the stereochemistry of enzymic cyclization of 2,3-oxidosqualene to the protosterol system, forerunner of lanosterol and cholesterol. [http://pubs.acs.org/doi/abs/10.1021/ja00010a073 ''J Am Chem Soc'' 113:4025-6]</ref> <br/>[[Image:Protosteryl cation.png|150px]]
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| 1,2-shift<br/>[[Image:Arrow00r.png]]
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| colspan="2" align="left"|lanosteryl cation <small>(C-B-C)</small><br/>[[Image:Lanosteryl cation.png|150px]]
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| 17&beta;-dammarenyl cation <small>(C-C-C)</small><ref>The C-17 chain of dammarenyl cation is &beta;-configuration.<br/> ''Ref.'' Xiong Q, Rocco F, Wilson WK, Xu R, Ceruti M, Matsuda SPT (2005) Structure and reactivity of the dammarenyl cation: configuration transmission in triterpene synthesis. ''J Org. Chem. 70:5362-75</ref> <br/>[[Image:Dammarenyl cation.png|150px]]
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|-
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|colspan="2"|
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{|
 
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}}
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{|
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|-
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====Ecdysteroid (C27)====
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|D-ring<br/>expansion
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{{Twocolumn|
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|[[Image:Arrow00d.png]]
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Ecdysteroids (or ecdysones) are moulting hormones of insects and crustaceans, but also present in many plants.
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|}
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The basic skeleton is highly oxygenated cholestane: 2&beta;,3&beta;,14&alpha;,20,22-pentahydroxy-5&beta;-cholest-7-en-6-one.
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The first ecdysteroid to be isolated was &alpha;-ecdysone from teh silkworm (''Bombyx mori'').
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}}
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{|
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| [[Image:Arrow00dr35.png]]
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====Spirostans and furostans (C27)====
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| fungus<br/>only<ref>Oxygenated protostane are known in ''Cephalosporium caerulens'', ''Fusidium coccineum'', and ''Aspergillus fumigatus'' (Ascomycota). <br/>''Ref.'' Hattori H, Igarashi H, Iwasaki S, Okuda S, (1969) Isolation of 3bhydroxy- 4b-methylfusida-17(20)[16,21-cis],24 diene (3b-hydroxyprotosta-
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{{Twocolumn|
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17(20)[16,21-cis],24 diene) and a related triterpene alcohol ''Tetrahedron Lett'' 13, 1023–1026<br/>Tiwari KP, Choudhary RN (1981) Chemical examination of ''Wisteria sinensis'' ''Proc Natl Acad Sci India A'' 51, 263–271</ref>  
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Furostan has the additional epoxy ring E. Spirostan has another epoxy ring F, which is perpendicular to the planar orientation of rings A-E. The omission of a terminal 'e' from spirostans and furostans indicates that they are not hydrocarbons.
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|-
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(However, the last 'e' is needed if a consonant follows.)
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|
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<br/>
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|style="background-color:#fdd" align="right"| protostane
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Major categories are:
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|}
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* furostan ... 16&beta;,22-epoxycholestane
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|}
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* spirostan ... 22,26-epoxyfurostan
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| colspan="2"|
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{|
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|1,2-shifts [[Image:Arrow00d.png]] all eukaryotes
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|}
 
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|
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{|
 +
|-
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| D-ring<br/>expansion
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|[[Image:Arrow00d.png]]
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|[[Image:Arrow00dr35.png]]<br/><br/>
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|style="background-color:#dfd" align="center"| dammarane<br/>euphane<br/>tirucalane etc.<ref>Dammarane derivatives are unusually prevalent in the genus [[Species:Euphorbia|Euphorbia]].</ref>
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|}
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|- valign="top"
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|colspan="2"| cation with the chain at C18 or C17 position<br/>[[Image:CBCC cation.png|150px]]or [[Image:CBCC cation2.png|100px]]
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|
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{|
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|style="background-color:#fdd"| all steroids<br/>lanostane<br/>cycloartane<br/>cucurbitane<br/>ergostane etc.
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|}
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|style="vertical-align:bottom"|
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{| style="margin-left:auto;margin-right:0;"
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|style="background-color:#dfd"| baccharane<br/>shionane
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| [[Image:Arrow00l35.png]]
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|}
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| baccarenyl cation <small>(C-C-C-C)</small><br/>[[Image:Baccarenyl cation.png|150px]]
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|-
 +
|
 +
{|
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| E-ring<br/>cyclization<br/>(from 17&beta;)
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| [[Image:Arrow00d.png]]
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| No 17&alpha; known<br/>in nature <ref name="JOC">No 17&alpha; cyclization for the ring-B boat form. Also no squalene cyclase is known for the ring-B boat form.<br/>''Ref''. Xiong Q, Rocco F, Wilson WK, Xu R, Ceruti M, Matsuda SPT (2005) Structure and reactivity of the dammarenyl cation: configurational transmission in triterpene synthesis. ''J Org Chem'' 70:5362-75</ref>
 +
|}
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|
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{|
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| E-ring<br/>cyclization<br/>(from 18&alpha;)
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| [[Image:Arrow00d.png]]
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|}
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|
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|
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{| style="margin-left:auto;margin-right:0;"
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| E-ring cyclization<br/>(from 17&alpha;/&beta;)
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| [[Image:Arrow00dl.png]]
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|}
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|
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{|
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|E-ring cyclization<br/>(from 18&alpha;/&beta;)
 +
|[[Image:Arrow00d.png]]
 +
|}
 +
|- valign="top"
 +
| arborinyl cation <small>(C-B-C-C)</small><br/>[[Image:Arborinyl cation.png|150px]]
 +
| colspan="2" align="left"| unnamed cation <small>(C-B-C-C)</small><br/>[[Image:Hanco cation.png|150px]]
 +
| 21&alpha;-hopyl cation <small>(C-C-C-C)</small><br/>21&beta;-moretyl cation <small>(C-C-C-C)</small><ref>The 21''R'' stereocenter is usually lost in hydride shift.</ref><br/>[[Image:Hopyl cation.png|150px]]
 +
| H18&alpha;-lupyl cation <small>(C-C-C-C)</small><br/>H18&beta;-lupyl cation <small>(C-C-C-B)</small><br/>[[Image:Lupyl cation.png|150px]]
 +
|-
 +
|align="left"|
 +
{|
 +
|1,2-shifts
 +
|[[Image:Arrow00d35.png]]
 +
|E-ring expansion
 +
|}
 +
|
 +
{|
 +
|1,2-shifts
 +
|[[Image:Arrow00d35.png]]
 +
|E-ring expansion
 +
|}
 +
|
 +
|
 +
{|
 +
|1,2-shifts
 +
|[[Image:Arrow00d35.png]]
 +
|E-ring expansion
 +
|}
 +
|
 +
{|
 +
|1,2-shifts
 +
|[[Image:Arrow00d35.png]]
 +
|E-ring expansion
 +
|}
 +
|-
 +
|style="background-color:#dfd"| arborinane (C-B-C-C)<br/>stictane (C-B-C-C-C)<ref>C-B-C-C-C rings are very rare and stictanediol from Ascomycota [[Species:Sticta|''Sticta'']] genus is the sole example.<br/>''Ref.'' Chin WJ, Corbett RE, Heng CK, Wilkins AL (1973) Lichens and fungi. XI. Isolation and structural elucidation of a new group of triterpenes from ''Sticta coronata, S. colensoi'', and ''S. flavicans''. ''J Chem Soc Perkin Trans'' 1:1437–46</ref>
 +
|style="background-color:#dfd"| hancokinane (C-B-C-C)
 +
|
 +
|style="background-color:#dfd" align="left"| hopane (C-C-C-C)<br/> gammacerane (C-C-C-C-C)<br/> fernane (C-C-C-C)<br/> swertane (C-C-C-C-C)<br/>
 +
|style="background-color:#dfd" align="left"| oleanane<ref>&beta;-amyrin has the oleanane skeleton</ref> (C-C-C-C-C)<br/> lupane (C-C-C-C)<br/> germanicane<br/> taraxastane (C-C-C-C-C)<br/> ursane (C-C-C-C-C/B)<br/> friedomadeirane (C-C-C-C)<ref>E-ring cyclization precedes D-ring expansion.</ref><br/>
 +
|}
  
−
}}
+
</center>
  
−
====Withanolides (C28)====
+
{| class="wikitable collapsible" style="width:100%"
−
{{Twocolumn|
+
! References
−
Withanolides were found in the root of [[Species:Withania|Withania Somnifera]], also known as Indian ginseng.  Its backbone is a highly oxygenated ergostane with a &gamma;-lactone ring linking C-22 and C-26 <ref>Iida, T et al. (1985) J. Lipid Res. 26,874</ref>. The configuration of C-22 is usually ''R''.
+
|-
 +
| <references/>
 +
|-
 +
! Reviews
 +
|-
 
|
 
|
−
}}
+
* Xu R, Fazio GC, Matsuda SPT (2004) On the origins of triterpenoid skeletal diversity. ''Phytochemstry'' 65:261-291 PMID 14751299
 +
* Philips DR, Rasbery JM, Bartel B, Matuda SPT (2006) Biosynthetic diversity in plant triterpene cyclization ''Curr Opin Plant Biol'' 9:305-314
 +
|}
  
−
====Brassinolides (C28)====
+
==={{Bilingual|バクテリア・シダ類のスクアレン環化酵素|Squalene Cyclase in Bacteria and Ferns}}===
−
{{Twocolumn|
+
−
Brassinolides are plant growth-promoting hormones isolated originally from [[Species:Brassica|''Brassica napus'']] (rape).  Its backbone is a highly oxygenated ergostane with the oxygen-expanded B-ring (&epsilon;-lactone). This lactone is not essential for plant growth activity (e.g. castasterone) but the 22''R'', 23''R''-diol are.
+
−
The configurations of C-2,3 and 5 are &alpha; in brassinolides whereas they are &beta; in ecdysteroids.
+
−
|
+
  
−
}}
 
−
 
−
====Gorgostane (C30)====
 
 
{{Twocolumn|
 
{{Twocolumn|
−
Gorgostanes occur in marine organisms.  Its backbone is ergostane with an additional metyl group at C-23 and ana methylene bridge between C-22 and C-23.
+
Squalene cyclase (SC) or terpene synthase g (tpsg) are found in prokaryotes, ciliates, and lower plants (mosses and ferns) and can convert squalene, which is symmetric, as well as 2,3-oxidosqualene.
−
|
+
Main products are hopanol and tetrahymanol, and only generate all-chair cations.
  
 +
|
 +
スクアレン環化酵素 (SC) またはテルペン合成酵素 g (tpsg) は原核生物、せん毛虫、下等な植物（コケ・シダ類）に見られ、スクアレンだけでなく2,3-オキシドスクアレンも触媒します。主な代謝産物はホパノールやテトラヒマノールで、全て椅子型の骨格しか生成しません。
 
}}
 
}}
  
−
===Biosynthesis===
+
{| style="text-align:center"
−
{| style="text-align:center; cellpadding:0"
+
| squalene<br/>[[Image:squalene.png|150px]]
−
|-
+
| [[Image:Arrow00r.png]]<br/>squalene-hopene cyclase<ref>SH cyclase is the most investigated enzyme among squalene cyclases. <br/>''Ref.'' Kannenberg EL, Poralla K (1999) Hopanoid biosyntehsis and function in bacteria. ''Naturwissenschaften'' 86:168-76.</ref>
−
| [[Image:2,3-oxidosqualene.png]]<br/>2,3-Oxidosqualene
+
| 17&alpha;-deoxydammarenyl cation<ref>The C-17 chain of deoxydammarenyl cation is &alpha;-configuration, not &beta; as in eukaryotes.<br/>
−
| [[Image:Arrow00r.png]]
+
''Ref.'' Wendt KU, Schulz GE, Corey EJ, Liu DR (2000) Enzyme mechanisms for polycyclic triterpene formation. [http://www3.interscience.wiley.com/journal/72515653/abstract?CRETRY=1&SRETRY=0 ''Angew Chem, Int Ed'' 39:2812-33]</ref> <br/>[[Image:Deoxydammarenyl cation.png|150px]]
−
| [[Image:Dammarane.png]]<br/>{{Bilingual|Dammarane-type|ダンマラン (dammarane) 型}}
+
−
|-
+
−
| || || [[Image:Arrow00d35.png]]
+
−
|-
+
−
| [[Image:Cholestane.png]]<br/>Cholestane-type
+
−
| [[Image:Arrow00l.png]]
+
−
| [[Image:Lanostane.png]]<br/>Lanostane-type
+
 
|-
 
|-
 +
|
 +
|
 +
|align="center"|
 +
{|
 +
| D-ring<br/>expansion
 
| [[Image:Arrow00d35.png]]
 
| [[Image:Arrow00d35.png]]
 +
| E-ring cyclization<br/> from 17&alpha;
 +
|}
 
|-
 
|-
−
| [[Image:Pregnane.png]]<br/>Pregnane-type
+
|style="background-color:#ddf"| hopene<br/>[[Image:Hopene.png|150px]]
−
| [[Image:Arrow00r.png]]
+
| [[Image:Arrow00l.png]]
−
| [[Image:Androstane.png]][[Image:Estrane.png]]<br/>Androstane- and Estrane-type
+
| hopyl cation (c-c-c-c)<br/>[[Image:Hopyl cation.png|150px]]
 
|}
 
|}
  
−
==Phytosterols==
 
 
{{Twocolumn|
 
{{Twocolumn|
−
Most common phytosterols are campesterol, &beta;-sitosterol, and stigmasterol.  Soybean ([[Species:Glycine|''Glycine max'']], [[:Category:Fabaceae|Fabaceae]]) is a rich source of phytosterols (about 0.1% of its weight), and is used for semi-synthesis of medicinal steroids <ref>Yamaya A, Endo Y, Fujimoto K, Kitamura K. “Effects of genetic variability and planting location on the phytosterol content and composition in soybean seeds” Food Chem 102(4): 1071-1075, 2006</ref>.  Since dietary phytosterols reduce cholesterol levels, they are used as food additives such as for margarine <ref>Schiepers OJ, de Groot RH, van Boxtel MP, Jolles J, de Jong A, Lütjohann D, Plat J, Mensink RP “Consuming functional foods enriched with plant sterol or stanol esters for 85 weeks does not affect neurocognitive functioning or mood in statin-treated hypercholesterolemic individuals” J Nutr 139(7):1368-1373, 2009</ref>.  Vitamin D is a family of sterol metabolites generated photochemically in our skin by UV irradiation.
+
Hopanoids are widespread: they are found in bacteria, ferns, and geological sediments. They are not found, however, in archaea or animals.
 +
 
 
|
 
|
 +
ホパノイドはバクテリアだけでなく、シダ類や地下堆積物からも見つかっています。しかしアーキアや動物からは見つかっていません。
 +
}}
  
 +
{{Twocolumn|
 +
Almost all mono-, di-, tri- and tetracyclic terpenes from squalene are found in ferns: [[Species:Polypodium|Polypodium]], [[Species:Lemmaphyllum|Lemmaphyllum]], and [[Species:Pyrrosia|Pyrrosia]].  Notable exception is ''Z''-Dammara-17(20),24-diene from moss [[Species:Floribundaria|Floribundaria]]<ref>Toyota M, Masuda K, Asakawa Y (1998) Triterpenoid constituents of the moss Floribundaria aurea subsp. nipponica. Phytochemistry 48:297–299</ref>.
 +
Pentacyclic terpenes from squalene, on the other hand, are found also in angiosperms such as [[Species:Achillea|Achillea]], [[Species:Erysimum|Erysimum]], [[Species:Castanopsis|Castanopsis]] and in Ascomycota.
 +
|
 +
スクアレンから生成されるほぼ全ての１，２，３，４環テルペンはシダ類で見つかっています（[[Species:Polypodium|Polypodium]], [[Species:Lemmaphyllum|Lemmaphyllum]], and [[Species:Pyrrosia|Pyrrosia]]）。例外はコケ類[[Species:Floribundaria|Floribundaria]]からの''Z''-Dammara-17(20),24-diene ぐらいです。
 +
それに対して、スクアレン由来の５環のテルペンは被子植物（[[Species:Achillea|Achillea]], [[Species:Erysimum|Erysimum]], [[Species:Castanopsis|Castanopsis]]）や子嚢菌類にも見つかっています。
 
}}
 
}}
  
−
==Saponins==
+
<references/>
 +
 
 +
==={{Bilingual|ビスオキシドスクアレン環化酵素|Bis-oxidosqualene Cyclase}}===
 
{{Twocolumn|
 
{{Twocolumn|
−
Saponins are surfactant glycosides, i.e., they produce foams in aqueous solution and therefore are called ‘sapo’ (a Latin for soap).  Plant-based crude drugs are still actively prescribed in Eastern Asia, and many of their active components are attributed to saponins. Well known examples of saponin and its aglycone include glycyrrhizin from liquorice ([[Species:Glycyrrhiza|''Glycyrrhiza uralensis/glabra'']], [[:Category:Fabaceae]]) used in European confectionery and Asian medicine; ginsenosides from ginseng ([[Species:Panax|''Panax ginseng'']], [[:Category:Araliaceae|Araliaceae]]) for tonic, especially in Korea; diosgenin from wild yam ([[Species:Dioscorea|''Dioscorea spp.'']], [[:Category:Dioscoreaceae|Dioscoreaceae]]) for hormone replacement therapy.
+
Squalene is oxidized by squalene oxidase to become 2,3-oxidosqualene.
 +
Further epoxidation of this symmetric molecule produces 2,3-(''S'')-22,23-(''S'')-bis-oxidosqualene, which is converted to 24,25-epoxylanostan-3-ol or 24,25-epoxycycloartan-3-ol.
 +
Epoxylanosterol is known to negatively regulate sterol biosynthesis<ref>Gardner RG, Shan H, Matsuda SPT, Hampton RY (2001) A positive oxysterol-derived signal for 3-hydroxy-3-methylglutaryl CoA reductase degradation in yeast. ''J Biol Chem'' 276:8681–869</ref>.
 
|
 
|
 +
スクアレンはスクアレン酸化酵素により2,3-オキシドスクアレンになりますが、対称な分子のため酸化が進むと 2,3-(''S'')-22,23-(''S'')-ビスオキシドスクアレンになります。これからエポキシ末端をもつラノステロールやシクロアルテノールが生じます。
  
 +
エポキシラノステロールはHMG-CoA還元酵素の分解を促進してステロール合成の調節をつかさどっていることが酵母で知られています。
 
}}
 
}}
  
−
{| style="text-align:center; cellpadding:0"
+
<center>
 +
{| style="text-align:center"
 +
| [[Image:2,3-oxidosqualene.png]]
 +
| [[Image:2,3-22,23-bis-oxidosqualene.png]]
 
|-
 
|-
−
| [[Image:2,3-oxidosqualene.png]]<br/>2,3-Oxidosqualene
+
| 2,3-oxidosqualene  
−
| [[Image:Arrow00r.png]]
+
| 2,3-22,23-bis-oxidosqualene
−
| [[Image:Dammarane.png]]<br/>{{Bilingual|Dammarane-type|ダンマラン (dammarane) 型}}
+
−
|-
+
−
| || || [[Image:Arrow00d35.png]] ring rearrangement
+
−
|-
+
−
| [[Image:Lupane.png]]<br/>Lupane-type
+
−
| [[Image:Arrow00l.png]]
+
−
| [[Image:Baccharane.png]]<br/>Baccharane-type
+
−
|-
+
−
| [[Image:Arrow00d35.png]]
+
−
|-
+
−
| [[Image:Oleanane.png]]<br/>Oleanane-type
+
−
| [[Image:Arrow00r.png]]
+
−
| [[Image:Taraxastane.png]]<br/>Taraxastane-type
+
 
|}
 
|}
 +
</center>
 +
 +
<references/>
  
−
==Design of Tri-terpene ID numbers ID番号の設計==
+
=={{Bilingual|ID番号の設計|Design of Tri-terpene ID numbers}}==
 
<center>
 
<center>
 
12-DIGIT
 
12-DIGIT
Line 281: Line 388:
  
 
; ''y'' ... backbone structure (母核構造) :
 
; ''y'' ... backbone structure (母核構造) :
−
<table><tr valign="top"><td>
+
 
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
−
! Symbol at ''y'' || Carbons || Steroids
+
! Symbol at ''y'' || Carbons || Steroids || Backbone Structure
 
{{#repeat:TP/Backbone/TableRow|3|
 
{{#repeat:TP/Backbone/TableRow|3|
 
GN
 
GN
Line 316: Line 423:
 
poriferastane
 
poriferastane
 
}}
 
}}
−
|}</td><td>
+
|}
 +
 
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
−
! Symbol at ''y'' || Carbons || (Plant) Triterpenes
+
! Symbol at ''y'' || Carbons || Triterpenoids || Backbone Structure
 
{{#repeat:TP/Backbone/TableRow|3|
 
{{#repeat:TP/Backbone/TableRow|3|
 +
PS
 +
C30
 +
protostane
 +
EU
 +
C30
 +
euphane
 
LN  
 
LN  
−
C30 (4 rings)
+
C30
 
lanostane
 
lanostane
 
CY
 
CY
−
C30 (4 rings)
+
C30
 
cycloartane
 
cycloartane
−
BC
+
FS
−
C30 (4 rings)
+
C29
−
baccharane
+
fusidane
 +
HP
 +
C30 (5 rings)
 +
hopane
 +
FN
 +
C30 (5 rings)
 +
fernane
 
CC
 
CC
−
C30 (4 rings)
+
C30
 
cucurbitane
 
cucurbitane
 
DM
 
DM
−
C30 (4 rings)
+
C30
 
dammarane
 
dammarane
 +
BC
 +
C30
 +
baccharane
 
HL
 
HL
−
C30 (4 rings)
+
C30
−
holostane  
+
holostane
 
PF
 
PF
 
C29 (5 rings)
 
C29 (5 rings)
 
pfaffane
 
pfaffane
−
HP
 
−
C30 (5 rings)
 
−
hopane
 
 
LP
 
LP
 
C30 (5 rings)
 
C30 (5 rings)
Line 350: Line 470:
 
C30 (5 rings)
 
C30 (5 rings)
 
oleanane
 
oleanane
−
SR
+
FD
 
C30 (5 rings)
 
C30 (5 rings)
−
serratane
+
friedelane
 
TR
 
TR
 
C30 (5 rings)
 
C30 (5 rings)
Line 359: Line 479:
 
C30 (5 rings)
 
C30 (5 rings)
 
ursane
 
ursane
 +
SR
 +
C30 (5 rings)
 +
serratane
 
}}
 
}}
 
|}
 
|}
−
</td></tr></table>
+
 
  
 
; ''r'' ... number of major rings (環構造数) :
 
; ''r'' ... number of major rings (環構造数) :

Latest revision as of 11:55, 8 December 2012

Contents

[edit] Triterpene (C30)

[edit] Ring configuration

[edit] Steroid

The basic structure is 4 carbon rings, cyclopenta[a]phenanthrene, gonane, or sterane. The rings B/C are always trans in all natural steroids. If the rings C/D are trans, it is called gonane. If its stereochemistry is unspecified, it is called sterane. Most steroids take gonane form, but in cardenolides and bufanolides, the rings C/D are cis.

Cyclopenta-a-phenanthrene.png Gonane.png
Cyclopenta[a]phenanthrene Gonane

The majority of steroids have methyl groups sticking out from the bridgehead positions C-10 and C-13. When these methyl groups (or hydrogens) stand above the plane, they are called β-configuration. Those below the plane are called α-configuration. If the configuration at any site is unknown, it is indicated as ξ (Greek Xi). By default, hydrogen atoms or substituents at the positions C-8, 9, 10, 13, and 14 are assumed to be 8β, 9α, 10β, 13β, and 14α configurations. C-5 is a special position, because there are as many 5α steroids as 5β are.

Cholestane.png 5alpha-steroid.png 5beta-steroid.png
cholestane backbone 5α-configuration 5β-configuration

[edit] Triterpenes

In almost all pentacyclic triterpenes in angiosperms, the methyl group at the DE-ring fusion is β-configuration. Some triterpenes in ferns, mosses, gymnosperms have α-methyl group at the DE-ring fusion.

[edit] Biosynthesis

[edit] Overview

The starting point is squalene, which is formed by joining two FPPs tail-to-tail. Bacterial cyclases use squalene directly[1], but those of the other species use 2,3-oxidosqualene for cyclization.

Squalene.png 2,3-oxidosqualene.png
squalene 2,3-oxidosqualene

  • In bacteria, squalene is cyclized via the 17α-deoxydammarenyl cation to hopene and other triterpenes.
  • In eukaryotes, 2,3-oxidosqualene is cyclized via the protosteryl cation to lanosterol (animals and fungi), cycloartenol (plants) or parkeol (sea cucumbers) by a series of 1,2-hydride and methyl shifts (Wagner-Meerwein shifts).
  • In plants, a trace amount of phytosterols comes from lanosterol [2] At3g45130 is lanosterol synthase in Arabidopsis and its orthologs exist in asterids Taraxacum officinale and Panax ginseng and eurosid Luffa cylindrica. Lanosterol synthase exists broadly among eudicots [3]. Parkeol is also widespread in plants.
  • In plants, various triterpenes arise from the 17β-dammarenyl cation.

References
  1. ↑ Bacterial squalene cyclases can accept oxidosqualene as their substrates, but oxidosqualene usually does not exist in bacteria
  2. ↑ Ohyama K, Suzuki M, Kikuchi J, Saito K, Muranaka T (2009) Dual biosynthetic pathways to phytosterol via cycloartenol and lanosterol in Arabidopsis Proc Natl Acad Sci USA 106(3):725-730
  3. ↑ Kolesnikova MD, Xiong Q, Lodeiro S, Hua L, Matsuda SPT (2006) Lanosterol biosynthesis in plants Arch Biochem Biophys 447:87-95


[edit] Oxidosqualene Cyclase in Eukaryotes

Any path of reactions from the root (2,3-oxidosqualene) to any triterpene backbone with a colored background is catalyzed by a single enzyme called oxidosqualene cyclase (OSC) or terpene synthase h (tpsh).[1]

Backbone Color Code: Animals, fungi, and yeast Plants only
Six-membered rings: chair (C), or boat (B)
2,3-oxidosqualene
2,3-oxidosqualene.png
lanosterol/
cycloartenol
syntase[2] 		Arrow00dl35.png stepwise
cyclization[3]
lupeol/
β-amyrin
synthase[4] 		Arrow00dr35.png stepwise
cyclization
17β-protosteryl cation (C-B-C)[5]
Protosteryl cation.png 		1,2-shift
Arrow00r.png 		lanosteryl cation (C-B-C)
Lanosteryl cation.png 		17β-dammarenyl cation (C-C-C)[6]
Dammarenyl cation.png
D-ring
expansion 		Arrow00d.png
Arrow00dr35.png fungus
only[7]
protostane
1,2-shifts Arrow00d.png all eukaryotes
D-ring
expansion 		Arrow00d.png Arrow00dr35.png

 dammarane
euphane
tirucalane etc.[8]
cation with the chain at C18 or C17 position
CBCC cation.pngor CBCC cation2.png
all steroids
lanostane
cycloartane
cucurbitane
ergostane etc.
baccharane
shionane 		Arrow00l35.png
baccarenyl cation (C-C-C-C)
Baccarenyl cation.png
E-ring
cyclization
(from 17β) 		Arrow00d.png No 17α known
in nature [9]
E-ring
cyclization
(from 18α) 		Arrow00d.png
E-ring cyclization
(from 17α/β) 		Arrow00dl.png
E-ring cyclization
(from 18α/β) 		Arrow00d.png
arborinyl cation (C-B-C-C)
Arborinyl cation.png 		unnamed cation (C-B-C-C)
Hanco cation.png 		21α-hopyl cation (C-C-C-C)
21β-moretyl cation (C-C-C-C)[10]
Hopyl cation.png 		H18α-lupyl cation (C-C-C-C)
H18β-lupyl cation (C-C-C-B)
Lupyl cation.png
1,2-shifts Arrow00d35.png E-ring expansion
1,2-shifts Arrow00d35.png E-ring expansion
1,2-shifts Arrow00d35.png E-ring expansion
1,2-shifts Arrow00d35.png E-ring expansion
arborinane (C-B-C-C)
stictane (C-B-C-C-C)[11] 		hancokinane (C-B-C-C) hopane (C-C-C-C)
gammacerane (C-C-C-C-C)
fernane (C-C-C-C)
swertane (C-C-C-C-C)
 oleanane[12] (C-C-C-C-C)
lupane (C-C-C-C)
germanicane
taraxastane (C-C-C-C-C)
ursane (C-C-C-C-C/B)
friedomadeirane (C-C-C-C)[13]
References
  1. ↑ Terpene synthases a-f are responsible for mono-, sesquie- and diterpenes. Tps g is the squalene cyclase.
  2. ↑ Lanosterol synthase is the most accessible enzyme among oxidosqualene cyclases, e.g. from mammalian liver or yeast. Cycloartenol synthase is the basic OSC in plants, although lanosterol synthase is also found. For the grouping of cyclases, check the review by Xiong Q et al. (2005) in this page.
    References.
    • Corey EJ, Russey WE, Ortiz-de-Montellano PR (1966) 2,3-Oxidosqualene, an intermediate in the biological synthesis of sterols from squalene J Am Chem Soc 88:4750-1
    • Kolesnikova MD, Xiong Q, Lodeiro S, Hua L, Matsuda SPT (2006) Lanosterol biosynthesis in plants Arch Biochem Biophys 447:87-95
    In Arabidopsis, cycloartenol synthase can be converted to lanosterol synthase with only two amino acid substitutions: His477 to Asn and Ile481 to Val. Tyr410 is also important for specificity.
    • Lodeiro S, Schulz-Gasch T, Matsuda SPT (2005) Enzyme redesign: two mutations cooperate to convert cycloartenol synthase into an accurate lanosterol synthase J Am Chem Soc 127:14132-14133
  3. ↑ The cyclization process is stepwise, not concerted as previously thought. As one clue, squalene is not fully folded in the cyclase active site.
    Ref. Reinert DJ, Balliano G, Schulz GE (2004) Conversion of squalene to the pentacarbocyclic hopene. Chem Biol 11:121-6
  4. ↑ Lupeol synthases are found in Glycyrrhiza glabra, Betula platyphylla, Taraxacum officinale, and Olea europea. They form a clade (74-81% identical) that is distinct from other OSCs. Lupeol synthase evolved before the divergence of asterids and eurosids. On the other hand, β-amyrin synthases are considerably more distant (48-50% identical) than are the CAS enzymes (70-79% identical). β-amyrin synthases in eudicotsa nd monocots may have independent origins.
    • Haralampidis K, Bryan G, Qi X, Papadopoulou K, Bakht S, Melton R, Osbourn A (2001) A new class of oxidosqualene cyclases directs synthesis of antimicrobial phytoprotectants in monocots Proc Natl Acad Sci U S A 98(23):13431-6
    • Qi X, Bakht S, Leggett M, Maxwell C, Melton R, Osbourn A (2004) A gene cluster for secondary metabolism in oat: implications for the evolution of metabolic diversity in plants Proc Natl Acad Sci U S A 101(21):8233-8
  5. ↑ The C-17 chain of rotosteryl cation is β-configuration, not α.
    Ref. Corey EJ, Virgil SC (1991) An experimental demonstration of the stereochemistry of enzymic cyclization of 2,3-oxidosqualene to the protosterol system, forerunner of lanosterol and cholesterol. J Am Chem Soc 113:4025-6
  6. ↑ The C-17 chain of dammarenyl cation is β-configuration.
    Ref. Xiong Q, Rocco F, Wilson WK, Xu R, Ceruti M, Matsuda SPT (2005) Structure and reactivity of the dammarenyl cation: configuration transmission in triterpene synthesis. J Org. Chem. 70:5362-75
  7. ↑ Oxygenated protostane are known in Cephalosporium caerulens, Fusidium coccineum, and Aspergillus fumigatus (Ascomycota).
    Ref. Hattori H, Igarashi H, Iwasaki S, Okuda S, (1969) Isolation of 3bhydroxy- 4b-methylfusida-17(20)[16,21-cis],24 diene (3b-hydroxyprotosta- 17(20)[16,21-cis],24 diene) and a related triterpene alcohol Tetrahedron Lett 13, 1023–1026
    Tiwari KP, Choudhary RN (1981) Chemical examination of Wisteria sinensis Proc Natl Acad Sci India A 51, 263–271
  8. ↑ Dammarane derivatives are unusually prevalent in the genus Euphorbia.
  9. ↑ No 17α cyclization for the ring-B boat form. Also no squalene cyclase is known for the ring-B boat form.
    Ref. Xiong Q, Rocco F, Wilson WK, Xu R, Ceruti M, Matsuda SPT (2005) Structure and reactivity of the dammarenyl cation: configurational transmission in triterpene synthesis. J Org Chem 70:5362-75
  10. ↑ The 21R stereocenter is usually lost in hydride shift.
  11. ↑ C-B-C-C-C rings are very rare and stictanediol from Ascomycota Sticta genus is the sole example.
    Ref. Chin WJ, Corbett RE, Heng CK, Wilkins AL (1973) Lichens and fungi. XI. Isolation and structural elucidation of a new group of triterpenes from Sticta coronata, S. colensoi, and S. flavicans. J Chem Soc Perkin Trans 1:1437–46
  12. ↑ β-amyrin has the oleanane skeleton
  13. ↑ E-ring cyclization precedes D-ring expansion.
Reviews
  • Xu R, Fazio GC, Matsuda SPT (2004) On the origins of triterpenoid skeletal diversity. Phytochemstry 65:261-291 PMID 14751299
  • Philips DR, Rasbery JM, Bartel B, Matuda SPT (2006) Biosynthetic diversity in plant triterpene cyclization Curr Opin Plant Biol 9:305-314

[edit] Squalene Cyclase in Bacteria and Ferns

Squalene cyclase (SC) or terpene synthase g (tpsg) are found in prokaryotes, ciliates, and lower plants (mosses and ferns) and can convert squalene, which is symmetric, as well as 2,3-oxidosqualene. Main products are hopanol and tetrahymanol, and only generate all-chair cations.

squalene
Squalene.png 		Arrow00r.png
squalene-hopene cyclase[1] 		17α-deoxydammarenyl cation[2]
Deoxydammarenyl cation.png
D-ring
expansion 		Arrow00d35.png E-ring cyclization
from 17α
hopene
Hopene.png 		Arrow00l.png hopyl cation (c-c-c-c)
Hopyl cation.png

Hopanoids are widespread: they are found in bacteria, ferns, and geological sediments. They are not found, however, in archaea or animals.

Almost all mono-, di-, tri- and tetracyclic terpenes from squalene are found in ferns: Polypodium, Lemmaphyllum, and Pyrrosia. Notable exception is Z-Dammara-17(20),24-diene from moss Floribundaria[3]. Pentacyclic terpenes from squalene, on the other hand, are found also in angiosperms such as Achillea, Erysimum, Castanopsis and in Ascomycota.

  1. ↑ SH cyclase is the most investigated enzyme among squalene cyclases.
    Ref. Kannenberg EL, Poralla K (1999) Hopanoid biosyntehsis and function in bacteria. Naturwissenschaften 86:168-76.
  2. ↑ The C-17 chain of deoxydammarenyl cation is α-configuration, not β as in eukaryotes.
    Ref. Wendt KU, Schulz GE, Corey EJ, Liu DR (2000) Enzyme mechanisms for polycyclic triterpene formation. Angew Chem, Int Ed 39:2812-33
  3. ↑ Toyota M, Masuda K, Asakawa Y (1998) Triterpenoid constituents of the moss Floribundaria aurea subsp. nipponica. Phytochemistry 48:297–299

[edit] Bis-oxidosqualene Cyclase

Squalene is oxidized by squalene oxidase to become 2,3-oxidosqualene. Further epoxidation of this symmetric molecule produces 2,3-(S)-22,23-(S)-bis-oxidosqualene, which is converted to 24,25-epoxylanostan-3-ol or 24,25-epoxycycloartan-3-ol. Epoxylanosterol is known to negatively regulate sterol biosynthesis[1].

2,3-oxidosqualene.png 2,3-22,23-bis-oxidosqualene.png
2,3-oxidosqualene 2,3-22,23-bis-oxidosqualene
  1. ↑ Gardner RG, Shan H, Matsuda SPT, Hampton RY (2001) A positive oxysterol-derived signal for 3-hydroxy-3-methylglutaryl CoA reductase degradation in yeast. J Biol Chem 276:8681–869

[edit] Design of Tri-terpene ID numbers

12-DIGIT

T P 3 x y y r h g n c c
x ... species information
Symbol at x Kingdom Phyla Examples
I Animalia Arthropoda (Insects, crabs) ecdysteroids
V Chordate (Vertebrates) sex steroids, corticosteroids, anabolic steroids
O Others marine steroids
P Plantae Phytosterols lanosterols, cholesterols, brassinolides
S Saponins saponins
F Fungi ergosterols ergosterols
B Bacteria bacterial sterols hopanoids
y ... backbone structure (母核構造) 
Symbol at y Carbons Steroids Backbone Structure
GN C17 gonane Gonane.png
ES C18 estrane Estrane.png
AD C19 androstane Androstane.png
PG C21 pregnane Pregnane.png
CA C24 cholane Cholane.png
CL C27 cholestane Cholestane.png
CM C28 campestane Campestane.png
EG C28 ergostane Ergostane.png
SG C29 (4 rings) stigmastane Stigmastane.png
PR C29 (4 rings) poriferastane Poriferastane.png
Symbol at y Carbons Triterpenoids Backbone Structure
PS C30 protostane Protostane.png
EU C30 euphane Euphane.png
LN C30 lanostane Lanostane.png
CY C30 cycloartane Cycloartane.png
FS C29 fusidane Fusidane.png
HP C30 (5 rings) hopane Hopane.png
FN C30 (5 rings) fernane Fernane.png
CC C30 cucurbitane Cucurbitane.png
DM C30 dammarane Dammarane.png
BC C30 baccharane Baccharane.png
HL C30 holostane Holostane.png
PF C29 (5 rings) pfaffane Pfaffane.png
LP C30 (5 rings) lupane Lupane.png
OL C30 (5 rings) oleanane Oleanane.png
FD C30 (5 rings) friedelane Friedelane.png
TR C30 (5 rings) taraxastane Taraxastane.png
UR C30 (5 rings) ursane Ursane.png
SR C30 (5 rings) serratane Serratane.png


r ... number of major rings (環構造数) 

Click above categories to see details.

h ... hydroxylation pattern (水酸基数) 

Click above categories to see details.

g ... glycosylation pattern(糖修飾パターン) 

Click above categories to see details.

n ... number of sugars (修飾糖数) 

Click above categories to see details.

c ... serial number (通し番号)

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