| Summary: | Astaxanthin (AST) characteristics and pigment productivity of <i>Adonis amurensis</i>, one of the few AST-producing higher plants, have not yet been studied extensively. In this study, the geometrical and optical isomers of AST in different parts of the <i>A. amurensis</i> flower were determined in detail, followed by a separation of the all-<i>trans</i> AST using HPLC chromatography. AST extracted from the flower accounted for 1.31% of the dry weight (dw) and mainly existed in the di-esterified form (>86.5%). The highest concentration was found in the upper red part of the petal (3.31% dw). One optical isomer (3<i>S</i>, 3′<i>S</i>) of AST, with five geometrical isomers (all-<i>trans</i>, 9-<i>cis</i>, 13-<i>cis</i>, 15-<i>cis</i>, and di-<i>cis</i>) were observed in all parts of the flower. All-<i>trans</i> AST was the predominant geometrical isomer accounting for 72.5% of the total content of geometric isomers in total flower, followed by the 13-<i>cis</i>, and 9-<i>cis</i> isomers. The all-<i>trans</i> AST isomer was also isolated, and then purified by HPLC from the crude oily flower extract, with a 21.5% recovery yield. The <i>cis</i>-AST extracted from the combined androecium and gynoecium gives a very strong absorption in the UVA region due to a high level of <i>cis</i>, especially di-<i>cis</i>, isomers, suggesting a prospective use in the preparation of anti-ultraviolet agents. The production cost of AST from <i>Adonis</i> flowers can be as low as €388–393/kg. These observations together with other factors such as the low technology requirement for plant culturing and harvesting suggest <i>Adonis</i> has great potential as a resource for natural esterified (3<i>S</i>,3′<i>S</i>)-AST production when compared with <i>Haematococcus</i> culturing.
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