Shikonin from Lithospermum erythrorhizon

After cells reach a certain population, the modification of the medium may affect product accumulation. Fujita et al. (1981) improved the yield of shikonin derivatives from the suspension cultures of Lithospermum erythrorhizon by using a production medium. The production medium usually contains more sucrose but less inorganic components and vitamins than the growth medium. 

Both cell culture with a lipophilic extraction phase and with a polar extraction phase have been reported to be helpful for the accumulation and detection of secondary substances [7,8]. Plant cell cultures release lipophilic and volatile substances such as ethylene, ethanol, and acetaldehyde. The addition of a lipophilic phase to the culture medium can be used as a means of accumulating and detecting these substances. Maisch et al. [8] found that the addition of XAD-4 resin to Nicotiana tabacum cultures enhanced the production of phenolic secondary metabolites several times compared to the adsorbent-free control. Kim and Chang [9] reported in situ extraction for enhanced shikonin production by Lithospermum erythrorhizon. When n-hexadecane was added to the cultivation, higher specific shikonin productivity was obtained than that from the cultures of free cells without extraction. They also suggested that n-hexadecane addition at an early stage in calcium alginate immobilized cell cultures was effective for shikonin production. Most of the produced shikonin was dissolved in n-hexadecane, so it would reduce the costs for shikonin separation. 

The first plant product commercially produced by plant cell culture was the prenylated anthraquinone shikonin 16, from the boraginaceous plant Lithospermum erythrorhizon Sieb. et Zucc. (Mitsui Petrochemical Industry Company) in 1983.25 Shikonin is used as a dye in cosmetics (lipsticks, soaps and lotions) and its production yield from cell cultures was over ten-fold its isolation yield from the intact plant.25 In practice, eight runs of two weeks each in a 200 L bioreactor could afford the amount of shikonin produced in four years by a 1 ha field of L. erythrorhizon 25 Shikonin has an interesting and pleiotropic biological profile, which includes insulin mimicry and interference with protein-protein interactions, but it has not yet found medicinal application.26... 

Extracts from the root of Ko-shikon (Lithospermum erythrorhizon) have long been used in Japan as dyes and for their anti-bacterial activity in the treatment of wounds, and burns. The active principles, a series of anthraqmnone derivatives known as shikonins, accumulate in the root to a level of 2% (dry wt.). The total supply of Ko-shikon is imported from China and Korea and it takes the plants 5-7 years to grow to commercial size. Pure natural shikonin sells for about 4500/kg. Based on an earlier report showing shikonin production in root derived callus cultures... 

Prenylated naphthoquinones occur in the roots of several genera of the Boraginaceae (Leistner, 1985). The shikonins (55), an important group of prenylated naphthoquinones used in Japan for their anti-inflammatory properties, antibacterial activity, and as dyestuffs, have become one of the most important groups of secondary compounds produced in tissue culture (Ellis, 1988 Flores et al, 1987). These compounds come from the roots of Lithospermum erythrorhizon (Boraginaceae). Although the roots accumulate up to 2% naphthoquinones, several years are required for the plant to reach commercial size. In a 23-day fermentation period, cells in a 750-L tank accumulated 23% of their dry weight as shikonins (Flores et al, 1987). 

Yazaki, K., Kunihisa, M., Fujisaki, T. Sato, F. (2002). Geranyl diphosphate 4-hydroxybenzoate geranyltransferase from Lithospermum erythrorhizon cloning and characterization of a key enzyme in shikonin biosynthesis. Journal of Biological Chemistry, 277, 6240-6246. 

The roots of alkanet, also known as common bugloss Alkanna tinctoria, syn. Anchusa tinctoria, Boraginaceae) growing in the south of Europe, contain the reddish pigment alkannin (alkannet, 9-151) that was used as a textile dye. The (S)-isomer of alkannin is used today as a food colouring E103 to impart colour to ice creams, sweets and other products. The red (R)-isomer called shikonin was isolated from the roots of the medicinal plant Lithospermum erythrorhizon of the same family, which is native to China. 

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