Nüßlein B, Kurzmann M, Bauer R, Kreis W (2000)
Publication Language: English
Publication Type: Journal article, Original article
Publication year: 2000
Publisher: American Chemical Society
Book Volume: 63
Pages Range: 1615-1618
DOI: 10.1021/np0002839
Cichoric acid (2R,3R-O-dicaffeoyltartaric acid) (1) is highly susceptible to enzymatic degradation during the preparation of Echinacea purpurea products. Degradation of 1 and other caffeic acid derivatives can be inhibited by antioxidants added to the extraction solvent or in buffered protein extracts saturated with nitrogen. Inhibitor studies conducted with protein extracts prepared from dried overground parts of E. purpurea revealed that polyphenol oxidases (PPO) but not peroxidases are responsible for the oxidative degradation of exogenous and endogenous caffeic acid derivatives. With a view to stabilizing aqueous extracts with respect to their content of 1, the effects of ascorbic acid and ethanol were tested. Compound 1 was not stable under conditions where oxidative processes could almost be excluded. It was found that an esterase hydrolyzing the ester bonds between tartaric acid and caffeic acid is still active under PPO inhibitory conditions. Finally, addition of 40% ethanol and 50 mM ascorbic acid to aqueous extracts of "Echinaceae purpureae herba" resulted in a constant amount of cichoric acid over four weeks.
APA:
Nüßlein, B., Kurzmann, M., Bauer, R., & Kreis, W. (2000). Enzymatic Degradation of Cichoric Acid in Echinacea purpurea Preparations. Journal of Natural Products, 63, 1615-1618. https://doi.org/10.1021/np0002839
MLA:
Nüßlein, Birgit, et al. "Enzymatic Degradation of Cichoric Acid in Echinacea purpurea Preparations." Journal of Natural Products 63 (2000): 1615-1618.
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