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. 2024 Sep 25;41(3):315-317.
doi: 10.5511/plantbiotechnology.24.0303a.

Tracer experiment revealed that (E)-3″-hydroxygeranylhydroquinone is not an intermediate of the shikonin/alkannin and shikonofuran biosynthetic pathways in Lithospermum erythrorhizon

Misaki Manabe  1 , Bunta Watanabe  2 , Haruka Oshikiri  1 , Kojiro Takanashi  1   3
Affiliations

Tracer experiment revealed that (E)-3″-hydroxygeranylhydroquinone is not an intermediate of the shikonin/alkannin and shikonofuran biosynthetic pathways in Lithospermum erythrorhizon

Misaki Manabe et al. Plant Biotechnol (Tokyo). .

Abstract

Lithospermum erythrorhizon (Boraginaceae) produces shikonin/alkannin, an enantiomeric pair of red naphthoquinone pigments with diverse biological activities. For the industrial production of shikonin/alkannin derivatives, a cell suspension culture system of L. erythrorhizon has been established. To produce shikonin/alkannin derivatives more efficiently in cultured cells, it is essential to understand the shikonin/alkannin biosynthetic pathway, which has not been fully elucidated. A previous study suggested that a conversion of (Z)- to (E)-3″-hydroxygeranylhydroquinone (3″-OH-GHQ) is a branching point of the shikonin/alkannin biosynthetic pathway and the shikonofuran biosynthetic pathway in L. erythrorhizon cell cultures. However, it is not clear whether (E)-3″-OH-GHQ is an intermediate of both pathways. This study performed a feeding assay with three deuterium-labeled compounds including (E)-3″-OH-GHQ and its (Z)-isomer, and showed that (E)-3″-OH-GHQ was not involved in the shikonin/alkannin and shikonofuran biosynthetic pathways.

Keywords: 3″-hydroxygeranylhydroquinone; Lithospermum erythrorhizon; alkannin; shikonin; shikonofuran.

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Conflict of interest statement

Conflict of interestThe authors declare that they have no conflict of interest.

Figures

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Figure 1. Production of acetylshikonin/acetylalkannin by L. erythrorhizon cells treated with labeled compounds. (A) Deuterium-labeled compounds used in this study. The method of synthesis of these compounds is described in Supplementary Protocol S1. (B) Comparison of acetylshikonin/acetylalkannin production and presence of labeled compounds. The labeled compounds were detected when treated with GHQ-d3 or (Z)-3″-OH-GHQ-d. Significant differences (p<0.05) of means±SD (n=3) were determined by Turkey–Kramer test and are indicated by different lowercase letters.
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Figure 2. Production of deoxyshikonofuran. The presence of labeled compounds was shown. The labeled compounds were detected when only GHQ-d3 or (Z)-3″-OH-GHQ-d was treated. Significant differences (p<0.05) of means±SD (n=3) were calculated by Turkey–Kramer test and no significant differences were detected.
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Figure 3. Biosynthetic pathway proposed by this study. (E)-3″-OH-GHQ is not an intermediate of both shikonin/alkannin and shikonofuran biosynthetic pathways.
See this image and copyright information in PMC

References

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