Optimization of Ultrasound-Assisted Extraction of Flavonoids from Celastrus hindsii Leaves Using Response Surface Methodology and Evaluation of Their Antioxidant and Antitumor Activities

Table 1

Coded and uncoded values of the variables for RSM optimization.

Variables	Symbols	Variable levels
		−1	0	1
Ultrasonic power (W)	X1	100	150	200
Extraction temperature (°C)	X2	30	40	50
Extraction time (min)	X3	20	30	40
Ethanol concentration (%)	X4	50	70	90