Optimized microwave-assisted extraction of flavonoids from Tamarix chinensis and evaluation of antioxidant activity in vitro

An efficient microwave-assisted extraction (MAE) technique was developed to extract flavonoids from Tamarix chinensis. The operating parameters were optimized using orthogonal array design. The optimum extraction conditions were as follows: microwave power 700 W; extraction time 20 min; solvent to material ratio 30 ml/g; and ethanol concentration 60 %. Under the optimal extraction conditions, flavonoids yield from T. chinensis reached to 2.51 ± 0.37 mg/g. After method development, the extraction flavonoids yield and the antioxidant activity of the extract were compared with those of the extracts obtained from the conventional methods including Soxhlet extraction (SE), heat reflux extraction (HRE) and ultrasound assisted extraction (UAE). MAE showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. The results demonstrated that MAE could be a fast and reliable method for quantitative analysis of flavonoids from T. chinensis. The flavonoids from T. chinensis may be a good source of natural antioxidants and would be used by the food or pharmacy industry.