Phenolic profile and biological activities of ultrasound-assisted aqueous-ethanolic extracts of Tamarix hispida Willd

Tamarix hispida Willd. (Tamarisk; locally known as “zhyngyl” in Kazakh) is a halophyte traditionally used for dysentery, rheumatism, and ulcers, with reported antioxidant and prolyl endopeptidase-inhibitory activities. This study investigated the phenolic profiles and biological activities of 10%, 50%, and 70% aqueous-ethanolic extracts (THU-10, THU-50, and THU-70) obtained by ultrasound-assisted extraction (UAE). Phenolic constituents were analyzed by HPLC-DAD, and antioxidant, enzyme inhibitory, anti-inflammatory, and cytotoxic activities were evaluated. Eleven phenolic compounds, including rutin, gallic acid, epicatechin, fisetin, and p-hydroxybenzaldehyde were identified, where rutin was the predominant quantified phenolic compound, reaching 2.78, 3.88, and 4.42 mg/g in THU-10, THU-50, and THU-70, respectively. THU-10 showed the strongest antioxidant activity in the ABTS and DPPH assays (IC50 = 2.13 ± 0.75 and 6.01 ± 0.30 µg/mL, respectively) and the strongest AChE and BChE inhibition (IC50 = 21.90 ± 0.70 and 38.71 ± 0.19 µg/mL, respectively). The extracts also inhibited α-amylase, α-glucosidase, and pancreatic lipase. THU-70 exhibited the strongest anti-inflammatory activity (IC50 = 18.4 ± 0.2 µg/mL). In the BSLA, the tested extracts showed no activity and were considered non-cytotoxic. UAE reduced extraction time from 48 h to 25 min and increased extract yield 3–4-fold. Overall, solvent composition significantly influenced the phenolic profiles and biological activities of T. hispida extracts.