Optimizing extraction techniques for enhanced polyphenol yield from Rheum emodi and Urtica dioica: Comparative analysis of solvent systems and methods.

The study optimized polyphenol extraction from Rheum emodi and Urtica dioica , varying solvents (Ethanol, Methanol, Water), concentrations, and extraction methods (CE, MAE, UAE). UAE consistently outperformed, yielding significantly higher phenolics, flavonoids, and antioxidants. In the 60% methanolic extract of U. diocia, the highest antioxidant activities were recorded, with DPPH (69.4 ± 2.2%), ABTS (94.61 ± 2.1%), and FRAP (0.82 ± 0.005 mol Fe2+/g). For Rheum emodi, the 70% ethanolic extract exhibited superior flavonoid content (63.6 ± 2.1 mg RE/g), phenolic content (132.7 ± 2.2 mg E GA/g), and antioxidant activities, including DPPH (69.4 ± 2.2%), ABTS (94.6 ± 2.1%), and FRAP (0.82 ± 0.005 μmol Fe2+/g). HPLC analysis identified eight phenolic acids , five flavonoids, and two anthraquinones in both extracts. These results highlight the potential of Rheum emodi and Urtica dioica as rich sources of phytochemicals for various food and pharmaceutical applications. [Display omitted] • Ultrasound-assisted extraction is an efficient method for extracting polyphenols • Hydroalcoholic solvents yielded highest phenolic content and antioxidant activity. • A positive influence of lyophilization on stability, AoA, and phenolic content. • Urtica dioica and Rheum emodi have nutraceutical and functional food potential. [ABSTRACT FROM AUTHOR]