Introduction
Numerous echinacea extracts are available on the market, all intended for the same application—enhancing immune system function—but exhibiting different standardization profiles. The aim of this study is to analyze the most feasible chromatographic technique for the authentication and standardization of Echinacea reference materials and commercial samples. Moreover, a functional evaluation of both is conducted to confirm the standardization process.
Methods
Echinacea raw materials (13) and their corresponding water extracts as reference samples, together with commercial echinacea extracts (15), were analyzed by chromatography (HPLC-DAD/MS, HPTLC-UV/Vis/FLD, and GC-FID/MS). In addition, the organism model of Caenorhabditis elegans was used to evaluate in vivo functionality.
Results
HPLC and GC analyses revealed that the concentrations of chicoric and caffeic acids varied among the commercial samples, ranging from 0.2% to 5.6% and from 0.0% to 2.6%, respectively. The main volatile compounds found in most Echinacea samples were benzaldehyde and hexanal; however, some commercial extracts also contained unexpected organic solvents.
In HPTLC analysis, multiple active compound zones were observed, e.g., caffeic acid exhibited multipotent activity, detectable across several assays. The strongest effect was antioxidant activity. However, highly lipophilic antibacterial compounds and α-amylase inhibitors were also detected. In addition, more polar α-/β-glucosidase and cholinesterase inhibitors were identified, which may be beneficial for supporting metabolic and cognitive health, respectively. Furthermore, tyrosinase and β-glucuronidase inhibitors were present.
The functional effects of an Echinacea extract standardized to chicoric and caffeic acids (4% and 1%, respectively) were demonstrated using the C. elegans model under oxidative stress conditions.
Conclusions
The acquisition of comprehensive data and information on complex Echinacea extracts facilitates more informed decision-making. Besides in vivo assays, effect-directed information is essential. The comparative analysis performed in parallel on the same planar assay plate demonstrates high reliability and represents a significant advantage of planar chromatographic techniques.
