Tuber is widely used in the field of traditional Chinese medicine, and its extract has various biological activities, but there is no research on polysaccharide of tuber. Ultrasonic-assisted extraction has significant advantages in the extraction of natural products. In order to optimize the ultrasonic-assisted extraction conditions of tuber polysaccharides of Angustifolia unicornis, the differences between ultrasonic-assisted extraction and traditional hot water extraction were compared and analyzed, providing a basis for the development and utilization of tuber polysaccharides of Angustifolia unicornis.
The effects of liquid-solid ratio, extraction time, ultrasonic power and extraction temperature on the yield of polysaccharide U were investigated.
The total sugar content of polysaccharide -U and polysaccharide -H were determined by various techniques, including molecular weight, monosaccharide composition and Fourier transform infrared spectroscopy. Its biological activity was analyzed by antioxidant test and α-glucosidase inhibition rate in vitro.
When the liquid-solid ratio was 30mL/g, the extraction time was 30min, the ultrasonic power was 440W, and the extraction time P was 70°C, the polysaccharide-U yield was higher, and the yield would decrease beyond the suitable range.
The polysaccharide yield and total sugar content of tuber were higher in ultrasonic-assisted extraction. There were three main components of tuber polysaccharide and four components of tuber polysaccharide . Ultrasound-assisted extraction reduced the average molecular weight of tuber polysaccharide. The monosaccharide composition was the same, but the molar ratio of monosaccharide was different. Fourier transform infrared spectroscopy analysis shows that the two spectra are similar. The results of Congo red and circular dichroic chromatography showed that they had no trihelix structure. Scanning electron microscope showed that the morphology of polysaccharide from tuber was affected by ultrasound. The thermal stability analysis showed that polysaccharide -H was slightly superior to polysaccharide -U.
The ultrasound-assisted extraction of polysaccharide from tuber was established and the optimal extraction conditions were determined. Compared with the hot water extraction method, ultrasonic assisted extraction method can increase the polysaccharide yield and total sugar content, reduce the average molecular weight and change the molar ratio of monosaccharides. Tuber polysaccharide -U and tuber polysaccharide -H had no triple helix structure, and the thermal stability of tuber polysaccharide -U was poor, but the antioxidant and hypoglycemic activities were stronger.
