RESUMEN
Peristrophe bivalvis (L.) Merr. (Acanthaceae) is a Vietnamese herb that is rich in anthocyanin, a natural colorant. However, the common extraction methods for this pigment often accompany with the presence of contaminated compounds. This study, therefore, focused on applying the aqueous two-phase system (ATPS), a green method for extracting and purifying anthocyanin in the leaf extract. The obtained results revealed that an ATPS composing from ethanol and ammonium sulfate with the concentrations of 32.5% and 25%, respectively, can recover 80% anthocyanin in leaf while eliminating 80% contaminated nitrogen compounds. Besides, the shelf-life of pigment in the purified extract was also elongated significantly in comparison with that in the crude extract.