Effects of Ultrasound Modification with Different Frequency Modes on the Structure, Chain Conformation, and Immune Activity of Polysaccharides from Lentinus edodes

Abstract

The aim of this study was to investigate the effects of ultrasound with different frequency modes on the chemical structure, chain conformation, and immune activity of lentinan from Lentinus edodes; the structure–activity relationship of lentinan was also discussed. The results showed that, compared with original lentinan (extracted using hot water), although ultrasonic treatment did not change the monosaccharide composition and main functional groups of lentinan, it significantly changed its chain conformation. Especially at 60, 40/60, and 20/40/60 kHz, according to atomic force microscopy and solution chain conformation parameters, lentinan transformed from a rigid triple-helix chain to a flexible single-helix chain, and the side-chain was severely broken. Under this condition, lentinan had the worst immune activity. However, at 20/40 and 20/60 kHz, the rigid triple-helix chain transformed into a loose and flexible triple-helix chain, showing the strongest immune activity. These results indicated that dual-frequency ultrasound had significant effects on the conformation of lentinan, and the conformation characteristics of polysaccharide chain such as spiral number, stiffness and flexibility, and side-chain played an important role in immune activity. This study shows the great potential of ultrasound with different frequency modes in carbohydrate food processing, which may have important reference value and practical significance.

Study of Brewer’s Spent Grain Environmentally Friendly Processing Ways

“…For hexose (glucose and fructose), only ultrasonic extraction in the aqueous solution within 30 min is effective. There are data in the literature confirming the destructive ultrasound effect on polysaccharide structure [44,45]. The authors found that at frequencies of 20/40 and 20/60 kHz, the conformation of the triple spiral of the polysaccharide into a loose, flexible triple spiral takes place.…”

Slit dual-frequency ultrasound-assisted pulping of Lycium barbarum fresh fruit to improve the dissolution of polysaccharides and in situ real-time monitoring

“…The particle size can indirectly reflect the aggregation and solution behavior of polysaccharide molecules [30] . The smaller the distance between particles, the more concentrated the distribution of particles, and the higher the degree of polysaccharides size homogenization.…”

“…The number of bubbles generated by multi-frequency ultrasound is five times that of single-frequency ultrasound, thus resulting in much stronger cavitation effect [25] , [26] . Studies show that dual frequency ultrasound can effectively overcome cavitation shielding [27] , avoid the problems of large standing wave area and uneven sound field existing in single frequency ultrasound [28] , [29] , so as to significantly improve the yield of plysaccharides from Lycium barbarum [23] , Lentinus edodes [30] and Fructus aurantii [31] , and enhance their physicochemical properties, antioxidant, anti-tumor and immune activities, which is better than that of single/triple frequency ultrasound and hot water treatment. However, the specific situation of the physical field in the ultrasonic process needs to be verified by finite element coupling simulation [32] , [33] , [34] .…”

Structural characterization and immunostimulant activities of polysaccharides fractionated by gradient ethanol precipitation method from Panax ginseng C. A. Meyer

“…In a solution, polysaccharides may exhibit different conformations, such as helical, including single and triple helix, and random coils, these structural characteristics can affect the direct contact between polysaccharides and immune cells, resulting in immune stimulating activity ( Ferreira et al, 2015 ). In general, the triple-helix polysaccharide is considered to have multiple biological activities ( Zhang et al, 2019 ; Meng et al, 2020 ; Hua et al, 2022 ). However, Li et al, 2020 found that two polysaccharides, MOP-2 and MOP-3, from M. oleifera leaves have similar monosaccharide composition and glycosidic bond types.…”