2020年8月18日
Alcohol dehydrogenase activity converts 3"-hydroxygeranylhydroquinone to an aldehyde intermediate for shikonin and benzoquinone derivatives in Lithospermum erythrorhizon
Plant and Cell Physiology
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- 巻
- 61
- 号
- 10
- 開始ページ
- 1798
- 終了ページ
- 1806
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1093/pcp/pcaa108
- 出版者・発行元
- Oxford University Press (OUP)
<title>Abstract</title>
Shikonin derivatives are red naphthoquinone pigments produced by several boraginaceous plants, such as Lithospermum erythrorhizon. These compounds are biosynthesized from p-hydroxybenzoic acid and geranyl diphosphate. The coupling reaction that yields m-geranyl-p-hydroxybenzoic acid has been actively characterized, but little is known about later biosynthetic reactions. Although 3"-hydroxy-geranylhydroquinone produced from geranylhydroquinone by CYP76B74 has been regarded as an intermediate of shikonin derivatives, the next intermediate has not yet been identified. This study describes a novel alcohol dehydrogenase activity in L. erythrorhizon cell cultures. This enzyme was shown to oxidize the 3"-alcoholic group of (Z)-3"-hydroxy-geranylhydroquinone to an aldehyde moiety concomitant with the isomerization at the C2'-C3' double bond from the Z-form to the E-form. An enzyme oxidizing this substrate was not detected in other plant cell cultures, suggesting that this enzyme is specific to L. erythrorhizon. The reaction product, (E)-3"-oxo-geranylhydroquinone, was further converted to deoxyshikonofuran, another meroterpenoid metabolite produced in L. erythrorhizon cells. Although non-enzymatic cyclization occurred slowly, it was more efficient in the presence of crude enzymes of L. erythrorhizon cells. This activity was detected in both shikonin producing and non-producing cells, suggesting that the aldehyde intermediate at the biosynthetic branch point between naphthalene and benzo/hydroquinone ring formation likely constitutes a key common intermediate in the synthesis of shikonin and benzoquinone products, respectively.
Shikonin derivatives are red naphthoquinone pigments produced by several boraginaceous plants, such as Lithospermum erythrorhizon. These compounds are biosynthesized from p-hydroxybenzoic acid and geranyl diphosphate. The coupling reaction that yields m-geranyl-p-hydroxybenzoic acid has been actively characterized, but little is known about later biosynthetic reactions. Although 3"-hydroxy-geranylhydroquinone produced from geranylhydroquinone by CYP76B74 has been regarded as an intermediate of shikonin derivatives, the next intermediate has not yet been identified. This study describes a novel alcohol dehydrogenase activity in L. erythrorhizon cell cultures. This enzyme was shown to oxidize the 3"-alcoholic group of (Z)-3"-hydroxy-geranylhydroquinone to an aldehyde moiety concomitant with the isomerization at the C2'-C3' double bond from the Z-form to the E-form. An enzyme oxidizing this substrate was not detected in other plant cell cultures, suggesting that this enzyme is specific to L. erythrorhizon. The reaction product, (E)-3"-oxo-geranylhydroquinone, was further converted to deoxyshikonofuran, another meroterpenoid metabolite produced in L. erythrorhizon cells. Although non-enzymatic cyclization occurred slowly, it was more efficient in the presence of crude enzymes of L. erythrorhizon cells. This activity was detected in both shikonin producing and non-producing cells, suggesting that the aldehyde intermediate at the biosynthetic branch point between naphthalene and benzo/hydroquinone ring formation likely constitutes a key common intermediate in the synthesis of shikonin and benzoquinone products, respectively.
- リンク情報
- ID情報
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- DOI : 10.1093/pcp/pcaa108
- ISSN : 0032-0781
- eISSN : 1471-9053