Ethyl Lactate as a Green Solvent for Aqueous Two-Phase Extraction of Bioactive Compounds from Orthosiphon stamineus

This study evaluates the utilization of ethyl lactate as an environmentally friendly solvent for extracting phenolic compounds from the Orthosiphon stamineus (O. stamineus) by employing aqueous two-phase system (ATPS). Ethyl lactate (EL) was selected as the primary component for the top phase due to its non-toxic attributes and cost-effectiveness. The impact of type of salt, phase compositions, sample loading, pH, equilibration time, and neutral salt’s composition on the partition coefficient, K; yield, Y; and 2,2-diphenyl-1-pircrylhydrazyl (DPPH) scavenging activity of phenolic compounds was evaluated. The EL-salt ATPS contained 41.9% (w/w) EL and 14.6% (w/w) sulfate at 1.4% (w/w) of sample load, 1.5% (w/w) of potassium chloride, and pH 6.0, had the greatest K of 23.28 ± 0.12, Y of 99.03% ± 1.37%, and DPPH scavenging activity of 98.22% ± 0.40%. Therefore, the study underscores the efficiency of EL-based ATPS for extracting phenolic compounds from plants.