Optimization of ultrasonic-assisted extraction of phenolic compounds from leaves.

A Box-Behnken design (Extraction-time, pulse-cycle, sonication-amplitude) was employed to extract phenolic compounds from leaves by ultrasonic-assisted extraction. The muicle leaves extracts were analyzed measuring total phenolic compounds and antioxidant capacity. According to response surface methodology the optimal conditions of ultrasonic-assisted extraction to obtain the highest soluble phenolic content were 2 min (extraction time) for 0.