Optimization of ultrasound-assisted extraction conditions followed by solid phase extraction fractionation from Orthosiphon stamineus benth (Lamiace) leaves for antiproliferative effect on prostate cancer cells

Abstract

Primarily, optimization of ultrasonic-assisted extraction (UAE) conditions of Orthospihon stamineus was evaluated and verified using a central composite design (CCD) based on three factors including extraction time (minutes), ultrasound amplitude (A), and solvent concentration (%). The response surfacemethodology (RSM)was performed to develop an extractionmethodwithmaximum yield and high rosmarinic acid content. The optimal UAE conditions were as follows: extraction time 21min, ultrasound amplitudes 62A, and solvent composition 70%ethanol inwater. The crude extractwas further fractionated using solid-phase extraction (SPE),where six sequential fractions that varied in polarity (0-100% Acetonitrile in water) were obtained. Next, the six fractions were evaluated for their antioxidant and anti-cancer properties. This study found that Fraction 2 (F2) contained the highest rosmarinic acid content and showed the strongest antioxidant activity. Additionally, F2 showed an anti-proliferative effect against prostate cancer (DU145) with no harmful effect on normal cells.