Phytopharmacologic preparations as predictors of plant bioactivity: A particular approach to Echinacea purpurea (L.) Moench antioxidant properties

Abstract

Objective: A large body of evidence has confirmed a multitude of health benefits of plant products and their derived formulations. Echinacea purpurea (L.) Moench is a good example, widely used due to its therapeutic properties. In the present study, the chemical composition of the different samples and antioxidant properties of E. purpurea hydroethanolic and aqueous extracts obtained from dry or fresh raw material were evaluated and compared with dietary supplements based on the same plant (tablets and syrup), to determine the most active phytopharmacologic preparation or formulation.

Methods: Chemical composition of the different samples was assessed through the determination of free sugars, organic acids and tocopherols. The in vitro antioxidant properties were determined using four assays: 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radicals scavenging activity, reducing power, inhibition of b-carotene bleaching and inhibition of lipid peroxidation by thiobarbituric acid reactive substances (TBARS) assay. Total phenolics and flavonoids were also determined.

Results: Overall, the hydroethanolic extract of fresh plant revealed the highest activity, directly related with its higher contents in phenolic (229.22 ± 4.38 mg gallic acid equivalent [GAE]/mL), flavonoids (124.83 ± 7.47 mg GAE/mL), organic acids (8.89 ± 0.10 g/100 g), and tocopherols (4.55 ± 0.02 mg/100 g). Tablets followed by syrup revealed the worst effect, positively correlated with the lowest abundance in bioactive molecules. The weak in vitro antioxidant potential of commercial phytopharmacologic formulations could be related to their chemical composition, including the addition of excipients.

Conclusion: Further studies are necessary to deepen knowledge on this area, namely focusing on in vivo experiments, to establish upcoming guidelines to improve the quality and bioavailability of phytopharmacologic formulations.

Keywords: Antioxidant activity; Aqueous/hydroethanolic extracts; Medicinal plants; Purple cone flower.