Ultrasound-assisted extraction (UAE) of antioxidant phenolics from Corchorusolitorius leaves: a response surface optimization

Background Besides fibre production, Corchorus olitorius is considered a nutritional and medicinal plant in traditional medicine. Its leaves possess different antioxidant compounds and display various biological properties. This study optimized the ultrasound-assisted extraction (UAE) parameters like temperature, time, solvent concentration, and liquid-solid ratio for total flavonoids ( TFC) and total polyphenols content (TPC) from leaves employing response surface methodology (RSM). Results Findings demonstrated that under the optimized conditions, the highest extraction yield of total flavonoids (7.17 mg QE/g DW) and total polyphenol content (13.92 mg GAE/g DW) were recorded with the ethanol concentration 70.92%, temperature 68.06 degrees C, liquid-solid ratio 48.80 mL/mg, and ultrasound irradiation time 37.20 min. The optimum value of TFC (6.96 mg QE/g DW) and TPC (13.38 mg GAE/g DW) from the experiment of verification of optimized conditions was close to the predicted value and significantly superior to the conventional heat reflux extraction (HRE). LC-MS and HPLC analysis of the optimized extract from UAE demonstrated the existence of six major phenolic compounds, including chlorogenic acid, isoquercetin, hyperoside, adhyperforin, 1,3-di-O- caffeoylquinic acid, and 3,4-di-O-caffeoylquinic acid. Furthermore, the antioxidant test of the UAE leaves extract revealed an excellent 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot), 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+)center dot) and hydroxyl radical scavenging with IC50 values of 226.29, 199.53 and 402.02 mu g/mL, respectively, compared to HRE with 336.31 mu g/ mL, 253.86 mu g/mL, 520.08 mu g/mL. Conclusions The developed optimization method could contribute to the good recovery of natural antioxidants from C. olitorius in the pharmaceuticals and food industries.