Optimization of Ultrasound-Assisted Deep Eutectic Solvent Extraction, Characterization, and Antioxidant,...

This study focuses on the resource utilization of Ficus pumila Linn. (FPL) by valorizing its often-discarded hulls, aiming to reduce waste and enhance material value. An ultrasonic-assisted deep eutectic solvent (DES) extraction method was optimized using response surface methodology to obtain polysaccharides (FPLP). The optimal DES system was choline chloride:oxalic acid at a molar ratio of 1.5:1, DES water content of 54%, ultrasonication time of 55 min, extraction temperature of 69°C, liquid-to-solid ratio of 21:1 mL/g, and ultrasonic power of 240 W. Under these conditions, the extraction yield of FPLP reached 0.9524%. This yield was 4.44- and 1.45-fold higher than those achieved by conventional hot-water and ultrasonic-water extraction, respectively. The crude FPLP was further purified by DEAE and Sephadex G-75 chromatography to obtain a refined polysaccharide, FPLP-1. Bioactivity evaluations demonstrated that FPLP-1 exhibits in vitro antioxidant activity (ABTS·⁺ scavenging IC₅₀ = 2.587 mg/mL) and hypoglycemic potential (α-amylase inhibition IC₅₀ = 1.560 mg/mL). Moreover, FPLP-1 showed potent in vivo antioxidant effects by protecting zebrafish keratinocytes from metronidazole-induced apoptosis, along with broad in vitro immunomodulatory functions, including promoting splenocyte proliferation, enhancing macrophage phagocytosis, and stimulating the secretion of NO, TNF-α, and IL-6 in a concentration-dependent manner. These findings highlight the promising potential of FPLP-1 as a multifunctional bioactive compound.