Thermosensitive hydrogels for modified release of ellagic acid obtained from Alchemilla vulgaris L. extract

Stimulus-sensitive hydrogels are used as carriers for modified release of pharmaceuticals. The synthesis of thermosensitive hydrogels poly(N-isopropylacrylamide), p(NIPAM), and poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate), p(NIPAM-HPMet), is performed. The synthesized hydrogels are characterized using FTIR and scanning electron microscope methods and swelling properties, and applied for modified release of ellagic acid (EA). This work presents the selective extraction of EA, as a natural antioxidant, from the aerial parts of Alchemilla vulgaris L. EA and A. vulgaris extract are incorporated into p(NIPAM) and p(NIPAM-HPMet) hydrogels and characterized by FTIR method. The EA content in the extract by the UHPLC–DAD–HESI–MS/MS method is determined (0.64?mg?cm^?3). The total flavonoids content in the A. vulgaris extract was determined by the spectrophotometric method. Antioxidant activity of the A. vulgaris extract and EA is examined using the 2,2-diphenyl-1-picrylhydrazyl assay. The p(NIPAM-HPMet) shows a better incorporation and release at 37°C of EA standard and A. vulgaris extract (98.87 and 96.45% respectively), compared with p(NIPAM).