Enzymatic degradation of cichoric acid in Echinacea purpurea preparations

Citation
B. Nusslein et al., Enzymatic degradation of cichoric acid in Echinacea purpurea preparations, J NAT PROD, 63(12), 2000, pp. 1615-1618
Citations number
31
Categorie Soggetti
Agricultural Chemistry","Pharmacology & Toxicology
Journal title
JOURNAL OF NATURAL PRODUCTS
ISSN journal
01633864 → ACNP
Volume
63
Issue
12
Year of publication
2000
Pages
1615 - 1618
Database
ISI
SICI code
0163-3864(200012)63:12<1615:EDOCAI>2.0.ZU;2-Y
Abstract
Cichoric acid (2R,3R-O-dicaffeoyltartaric acid) (1) is highly susceptible t o enzymatic degradation during the preparation of Echinacea purpurea produc ts. Degradation of 1 and other caffeic acid derivatives can be inhibited by antioxidants added to the extraction solvent or in buffered protein extrac ts saturated with nitrogen. Inhibitor studies conducted with protein extrac ts prepared from dried overground parts of E. purpurea revealed that polyph enol oxidases (PPO) but not peroxidases are responsible for the oxidative d egradation of exogenous and endogenous caffeic acid derivatives. With a vie w to stabilizing aqueous extracts with respect to their content of 1, the e ffects 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 a nd caffeic acid is still active under PPO inhibitory conditions. Finally, a ddition of 40% ethanol and 50 mM ascorbic acid to aqueous extracts of "Echi naceae purpureae herba" resulted in a constant amount of cichoric acid over four weeks.