High-efficiency separation of rosmarinic acid from perilla leaves by aqueous two-phase flotation using a protein carrier

Rosmarinic acid (RA), a prominent phytochemical, is abundant in perilla leaves and is sought after for its beneficial properties. A highly effective, economically applicable and environmentally safe method has been successfully developed for extracting and separating RA from RA extract. Response surface methodology (RSM) was used to optimize the ultrasound-assisted extraction conditions of Perilla leaves. The optimum extraction conditions for the ultrasound-assisted extraction of RA were obtained as liquid to material ratio of 49 mL/g, a temperature of 44 °C, and an extraction time of 31 min. Under these conditions, the yield of RA was 0.87 %. Aqueous two-phase flotation (ATPF) is an innovative method that demonstrates exceptional efficiency in isolating biomolecules characterized by surface-active properties. Our research innovates by employing perilla seed meal protein (PSMP) as an environmentally sustainable carrier for the ATPF process to isolate RA, overcoming its deficiency in surface activity. Utilizing a dual-phase system consisting of polyethylene glycol and (NH₄)₂SO₄, we conducted a comprehensive analysis of various factors influencing the separation efficiency. Under the optimized conditions comprising 30 % (NH₄)₂SO₄, 8 % PEG-800, pH 4.0, PSMP carrier concentration 101 mg/L, gas velocity 54 mL/min, and operation time 7 min, we attained outstanding results with an E% of 97.89 % and a K_p of 98.45. The RA obtained through this method displayed potent antioxidant activity, suggesting its utility in various applications. This research delineates an efficient ATPF protocol for RA isolation and offers valuable insights for the extraction of other botanical compounds.