High-pressure ultrasonic-assisted extraction of polysaccharides from Hovenia dulcis: Extraction, structure, antioxidant activity and hypoglycemic.

In this study, high-pressure ultrasonic-assisted extraction (HUE) technology was used for polysaccharide extraction from Hovenia dulcis (HDPS). A maximal extraction yield (11.81 ± 0.26%) was obtained using the response surface method (RSM) with optimized HUE conditions (Ultrasound power 330 W, 68 °C, and 22 min). Results showed that HDPS mainly contained neutral sugar (47.81 ± 1.56%), uronic acid (12.52 ± 0.15%), and protein (3.64 ± 0.24%), specifically. HDPS was comprised of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose in a molar ratio of 3.20%, 20.40%, 4.81%, 11.14%, 27.37% and 33.08%, respectively. And with an average molecular weight of 185.22 kDa for its major component (accounting for 90.13% for HDPS). The result obtained from the X-ray diffraction pattern confirmed a semi-crystalline nature of the sample. HUE-HDPS suggested typical shear thinning behavior and non-Newtonian properties. Additionally, HUE-HDPS exhibited better chemical antioxidant activities in DPPH, ABTS, hydroxyl radical scavenging and Fe2+ chelation activity. The in-vitro and in-vivo experiments indicated that HUE-HDPS had obviously hypoglycemic effects. Accordingly, the polysaccharides from Hovenia dulcis might serve as a natural antioxidant and hypoglycemic agent.

Yang B ，Wu Q ，Luo Y ，Yang Q ，Wei X ，Kan J ... -  《-》

Hovenia dulcis polysaccharides: Influence of multi-frequency ultrasonic extraction on structure, functional properties, and biological activities.

The directional effect of single-frequency ultrasonic was the cause of the low extraction yield of polysaccharide macromolecule. Thus, a possible solution was to use multi-frequency ultrasonic technology to improve the yield of polysaccharide. Single-frequency (SF), dual-frequency (DF), and three-frequency (TF) ultrasonic extraction were applied to extract polysaccharides of Hovenia dulcis (HDPs). A maximal polysaccharide extraction yield (9.02 ± 0.29%) was gat using the dual-frequency ultrasonic with optimized DF conditions comprising 58.00 °C, 33.00 min, 28&40 kHz. The three HDPs were compared for their physicochemical, rheological, and functional properties, and their antioxidant activities. DF-HDPs contain higher uronic acid than SF-HDPs and TF-HDPs. Rheological tests indicated that the HDPs had excellent colloid properties and a promising potential to serve as a thickener, gelatinizer, and stabilizing agent in the food industry. Moreover, the DF-HDPs exhibited a notable oil holding capacity (3.92 ± 0.04 g oil/g), foaming capacity (35.26 ± 0.47%), and emulsion capacity (43.96 ± 0.67%). Compared to the SF- and TF-HDPs, the DF-HDPs had superior antioxidant activities. In conclusion, a better extraction method (dual-frequency ultrasonic extraction) was achieved.

Yang B ，Luo Y ，Wu Q ，Yang Q ，Kan J ... -  《-》

Japanese grape (Hovenia dulcis) polysaccharides: New insight into extraction, characterization, rheological properties, and bioactivities.

In this study, accelerated solvent extraction (ASE) technology was applied to extract Hovenia dulcis polysaccharides (HDPs). The polysaccharide yields, physicochemical properties, rheological properties, antioxidant activities, and hypoglycemic effects were compared between ASE-HDPs and hot water extracted polysaccharides (HWE-HDPs). The maximum ASE-HDPs yield was obtained using a response surface method (RSM) with optimized ASE conditions comprising 2 cycles at 130 °C for 23 min. The maximum ASE-HDPs yield of 8.62 ± 0.29% is significantly higher than the maximum HWE-HDP yield of 6.89 ± 0.21%. The chemical compositions, molecular weight (Mw) distributions, rheological properties, antioxidant activities, and hypoglycemic effects of polysaccharides varied with each extraction method, while the primary structure remained the same. Both HDPs exhibited typical shear thinning behavior and non-Newtonian properties. The storage modulus (G') and loss modulus (G″) of the HDPs solutions were enhanced with increasing oscillation frequency, and displayed gelatinous behavior (G' > G″). ASE-HDPs displayed better antioxidant activities in DPPH and ABTS, as well as superior reducing power and hydroxyl and superoxide anion scavenging ability, whereas HWE-HDPs exhibited higher Fe2+ chelating activity. The in vitro experiments indicated that HDPs have a decidedly hypoglycemic effect.

Yang B ，Wu Q ，Luo Y ，Yang Q ，Chen G ，Wei X ，Kan J ... -  《-》

Optimization of ultrasonic extraction of polysaccharides from Hovenia dulcis peduncles and their antioxidant potential.

An ultrasonic-assisted extraction of polysaccharides from the ripe peduncles of Hovenia dulcis (HDPs) was investigated. Response surface methodology along with a Box-Behnken design based on single-factor experiments was employed to optimize and model the extraction conditions of HDPs, namely extraction temperature (40-60 °C), ultrasonic power (320-480 W) and extraction time (35-65 min). The optimized conditions were extraction temperature 60 °C, ultrasonic power 362 W and extraction time 65 min. Under these conditions, the maximal yield of crude HDPs was 25.12±0.145 mg/g DW, which is consistent with the predictive yield of 25.33 mg/g DW. The polysaccharides were graded by an ethanol precipitation method and three fractions (HDPs1, HDPs2 and HDPs3) were harvested. These had final ethanol concentrations of 40%, 60% and 80%, respectively and were acidic polysaccharides. The preliminary characterization was mainly composed of Ara, Rha, Glu and Gal, and exhibited an almost similar characteristic absorption peak by gas chromatograph and infrared spectra analysis. The antioxidant activity assays in vitro revealed that HDPs can be used as natural antioxidants in functional foods and pharmaceutical industries.

Liu Y ，Qiang M ，Sun Z ，Du Y ... -  《-》

Isolation, purification, structural characterization, and hypoglycemic activity assessment of polysaccharides from Hovenia dulcis (Guai Zao).

Hovenia dulcis polysaccharides (HDPs) have a variety of important biological activities associated with potential applications in food engineering, pharmacy science, and health care. Herein, we isolated and purified polysaccharides from H. dulcis. Chemical composition analysis revealed that the purified polysaccharides (HDPs-2A) were composed of different molar ratios of mannose, Rha, GalA, GlcA, Glc, Gal, and Ara and had a molecular weight of 372.91 kDa. The structure of HDPs-2A was assessed by FT-IR, periodate oxidation, Smith degradation, methylation analysis, and NMR, allowing us to determine that the backbone of HDPs-2A is composed primarily of →5)-α-L-Araf-(1→, →5)-α-L-Araf-(1→, →3,5)-α-L-Araf-(1→, →6)-β-D-Galp-(1→, →3,6)-β-D-Galp-(1→, T-β-D-Galp, →3)-β-D-Galp-(1→, and T-α-D-Glcp. The results of atomic force microscopy (AFM) showed that HDPs-2A present an irregular polymer particle morphology in water. X-ray diffraction (XRD) results showed that HDPs-2A have a single crystal structure. Finally, we demonstrated that HDPs-2A have a good therapeutic effect on a rat model of type 2 diabetes.

Yang B ，Luo Y ，Sang Y ，Kan J ... -  《-》