Optimization of polysaccharides from Zagros oak leaf using RSM: Antioxidant and antimicrobial activities

•Extraction of QBLP by ultrasonic extraction technique for the first time.•RSM with BBD was applied to optimize the extraction conditions for QBLP.•The optimum conditions were X1 205.8 W, X2 81.9 °C, X3 55.6 min, and X4 23.4.•QBLP showed good antioxidant and antimicrobial activities at 2.5–2.8 mg/mL.

Ultrasonic assisted-extraction technique was applied to extract the polysaccharide from Zagros oak (Quercus brantii Lindl). The effects of four independent factors (ultrasonic power (X1: 150–300 W), extraction temperature (X2: 50–90 °C), extraction time (X3: 30–90 min), and the ratio of water to raw material (X4: 15–45)) on the extraction yield of polysaccharide from the leaves of Q. brantii Lindl (QBLP) were optimized using response surface methodology. The experimental data obtained were fitted to a second-order polynomial equation. The optimal extraction conditions for QBLP were determined as follows: X1: 205.8 W, X2: 81.9 °C, X3: 55.6 min and X4: 23.4. Under these optimal conditions, the experimental yield was 19.42 ± 0.53%, which was well matched with the value predicted by the model 19.61%. The results indicated that polysaccharide has strong scavenging activities in vitro on DPPH and hydroxyl radicals. In addition, the QBLP showed good antimicrobial activity at 1.5–2.5 mg/mL.