Ultrasound-assisted low-temperature extraction of polysaccharides from Lavandula angustifolia Mill.: optimization,...

Lavandula angustifolia Mill. is a traditional Chinese medicinal herb with high economic and pharmacological value. In this study, we optimized the conditions for low-temperature ultrasound-assisted extraction of L. angustifolia Mill. polysaccharides using response surface methodology (RSM), and two homopolysaccharides LAPW1 (33.6 kDa) and LAPS1 (95.9 kDa) were obtained after isolation and purification by DEAE-650 M and Superdex™ 200 chromatography. The primary structure of LAPS1 was determined using "partial acid hydrolysis, methylation, two-dimensional (2D NMR) spectroscopy" as the core method. The results revealed that LAPS1 is a heteropolysaccharide whose main chain consists of [-1)-β-Galp-(6→1)-α-Araf-(5→]₃-1-α-Araf-(3→1)-α-Araf-(5→[1)-β-Galp-(6→1)-α-Araf-(5→]₃-1-α-Araf-(5→1)-α-Araf-(5→[-1)-β-Galp-(6→1)-α-Araf-(5→]₃. In vitro experiments revealed that LAPW1 and LAPS1 significantly reduced the production of the inflammatory cytokines Interleukin-1β (IL-1β), Interleukin-6 (IL-6), and Tumor Necrosis Factor (TNF), as well as the expression of Nitric Oxide Synthase 2 (NOS2) and release of nitric oxide (^.NO) free radical in the inflammatory model established by lipopolysaccharide (LPS) stimulated RAW264.7. Besides, the zebrafish inflammatory model, stimulated by CuSO₄, was employed to assess the impact of polysaccharides on neutrophil migration, indicating a notable decrease in zebrafish neutrophils and confirming their potential anti-inflammatory activity. These results indicate that polysaccharides from L. angustifolia Mill. be used in the development of functional foods and pharmaceutical products.