RSM-based microwave- and ultrasound-assisted bioactive compounds extraction and isolation from <i>Quercus infectoria</i> and anti-viral docking studies

Quercus infectoria (Q. infectoria) is a medicinal plant renowned for its therapeutic benefits. The current study included optimization of microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) for obtaining bioactive compounds from QI galls, identification of its compounds via GC–MS, and isolation of pyrogallol using chromatography, as well as a molecular docking study of pyrogallol and 10 other compounds containing pyrogallol rings against HCV NS3 serine protease using Maestro 12.5. Response surface methodology (RSM) was used for optimization with total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity, and iron chelating activity (Fe-CA) as responses. Well-fitted models were suggested that were supported by validation studies. In MAE, the optimal TPC, TFC, DPPH radical scavenging activity (DRSA), ABTS radical scavenging activity (ARSA), and Fe-CA were 223.25 mg GAE/g DW, 81.28 mg RE/g DW, 79.21%, 89.75% and 46.28%, respectively and in UAE, 202.14 mg GAE/g DW, 74.06 mg RE/g DW, 69.97%, 79.38% and 41%, respectively. MAE and UAE optimal conditions were power 490 W, time 80 s, and 35 mL/g solvent-to-sample ratio (SSR) and amplitude 37%, time 360 s, and solvent-to-sample ratio 15 mL/g, respectively. Isolated pyrogallol was characterized based on spectral data. The highest docking score of −15.177 kcal/mol was shown by eugeniin, followed by casuarinin (−12.76 kcal/mol) and 1,3,6-tri-O-galloyl-β-d-glucose (−12.17 kcal/mol), respectively. The study has important implications for HCV and related antiviral drug discovery and optimal bioactive compounds recovery from Q. infectoria using green techniques.