Box-Behnken design (BBD) was performed via ultrasound-assisted system to optimize extraction yield and total antioxidant ability of polysaccharides from Suaeda fruticosa. Three independent variables were studied: temperature, time and pH with optimal settings 90 °C, 37 min and 2.9, respectively. Under these settings, isolation yield and total antioxidant activity were 34.0% and 31.8 mg ascorbic acid equivalent/g material, respectively. Furthermore, preliminary structure study was carried out using UV-vis analysis, Fourier transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (1D (1H, 13C NMR) and 2D (1H, 1H COSY, 1H/13C HSQC)) methods Size exclusion chromatography (SEC) determination revealed that polysaccharide extracted had an average molecular weight of 240 kDa. Chemical composition analyses showed that extracted polysaccharide was a pectin-like polysaccharide with uronic acid content (47.5%) and neutral monosaccharides (52.5%) constituted mainly of arabinose, mannose, galactose, rhamnose, glucose and xylose in the molar percentage of 48.63%, 5.85%, 29.42%, 7.96%, 6.54% and 1.60%, respectively. This sugar composition was typical of that of a galactoarabinan. Importantly, the optimum polysaccharide possesses significant potentials in antioxidant activity effect. Moreover, pharmacological investigation of extracted polysaccharide revealed a good anti-inflammatory effect and interesting peripheral as well as central antinociceptive activities.
Keywords: Antioxidant effect; Citric acid; Pharmacological activities; Physico-chemical characterization; Polysaccharides; Suaeda fruticosa.
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