Polysaccharides from Nitraria retusa Fruit: Extraction, Purification, Structural Characterization, and Antioxidant...

Area of Science:

• Plant biochemistry
• Natural product chemistry
• Food science

Background:

• Polysaccharides are key bioactive compounds in Nitraria retusa fruit (NRF).
• Understanding NRF polysaccharide structure and function is crucial for potential applications.
• Extraction optimization is necessary to maximize yield and isolate active components.

Purpose of the Study:

• To optimize ultrasonic-assisted extraction (UAE) conditions for Nitraria retusa fruit polysaccharides (NRFPs).
• To characterize the structural properties of isolated NRFPs.
• To evaluate the antioxidant activities of NRFPs.

Main Methods:

• Response surface methodology (RSM) was employed to optimize UAE parameters.
• Polysaccharide fractions (NRFP-1, NRFP-2, NRFP-3) were isolated and characterized.
• Structural analysis included FT-IR, NMR, and monosaccharide composition determination.
• Antioxidant activity was assessed using DPPH, ABTS, hydroxyl radical scavenging, and ferric-reducing assays.

Main Results:

• Optimal UAE conditions yielded 3.35% NRFPs at 59.5 °C, 30.5 min, and a 19.5 mL/g liquid-to-solid ratio.
• Three polysaccharide fractions with distinct molecular weights (20.01–67.45 kDa) were obtained.
• Glucose, galactose, and arabinose were identified as primary monosaccharides; α- and β-glycosidic bonds were confirmed.
• NRFP-3 demonstrated superior scavenging activity against DPPH, ABTS, and hydroxyl radicals, along with high Fe+3 reducing power.

Conclusions:

• Optimized UAE effectively extracts NRFPs with high yield.
• NRFPs possess diverse structural characteristics and significant antioxidant properties.
• The NRFP-3 fraction shows promising potential as a natural antioxidant agent.