Combined extracts of Echinacea angustifolia DC. and Zingiber officinale Roscoe in softgel capsules: Pharmacokinetics and immunomodulatory effects assessed by gene expression profiling

Background and objective: Echinacea angustifolia DC. and Zingiber officinale Roscoe are two natural products with documented immunomodulatory activity, both able to modulate the expression of important immune-related genes. Thus, their use in combination seems to be particularly promising. In this context, we have considered the oral supplementation of a highly standardized lipophilic extract combining both above-mentioned phytocomplexes, formulated in attractive softgel capsules, with two objectives: on the one hand to study oral pharmacokinetic of main active extracts’ components and on the other hand to examine the immunomodulation and anti-inflammatory properties by gene expression profiling. Methods: Softgel capsules containing a combination of E. angustifolia DC. and Z. officinale Roscoe (5 mg and 25 mg, respectively) were given by oral administration to 10 healthy volunteers. The plasma concentrations of dodeca-2E,4E,8Z,10E/Z-tetraenoic isobutylamide (tetraene) for E. angustifolia DC., 6-gingerol and 6-shogaol (free and glucuronide) for Z. officinale Roscoe were determined by LC-MS analysis, and the pharmacokinetic analysis was performed. To understand the functional mechanisms responsible for the documented health benefits, we also examined the overall transcriptional remodeling induced in the peripheral blood mononuclear cells and performed an integrative functional analysis on the generated gene expression. Results: All bioactive components were absorbed very rapidly, and their tmax were detected in plasma from 30 min to 1.40 h. The peak concentrations of tetraene, 6-gingerol, 6-shogaol and their glucuronide metabolites were 14.74, 5.66, 9.25, 29.2 and 22.24 ng/ml, respectively. Integrated analysis performed on the generated gene expression data highlighted immunomodulatory and anti-inflammatory effects similar to those exerted by hydrocortisone. Conclusion: These data demonstrated that the bioactive ingredients are highly and rapidly absorbed from softgel capsules containing the combination of the above-mentioned lipophilic extracts, providing evidence to support their immunomodulatory and anti-inflammatory properties. These data also help in defining the mechanistic pathways underlying the health benefits of these plant-derived bioactive compounds.