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 ... -  《-》

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 ... -  《-》

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 ... -  《-》

Optimization of ultrasonic-assisted extraction of antioxidant polysaccharides from the stem of Trapa quadrispinosa using response surface methodology.

Response surface methodology (RSM) was used to optimize experimental conditions for ultrasonic-assisted extraction (UAE) of antioxidant crude polysaccharides (CPS) from Trapa quadrispinosa stems. Antioxidant capacity of polysaccharides was determined by Ferric-Reducing Antioxidant Capacity (FRAC) assay with the method of 1, 10-phenanthroline. The maximum yield of polysaccharides (2.78±0.16%) was obtained under optimal extraction conditions of extraction time, 41min; ratio of water to material, 31.5mL/g; and extraction temperature, 58°C. The maximum antioxidant capacity (19.02±0.24μmol Fe2+/g) was obtained under the optimal extraction conditions of extraction time, 38min; ratio of water to material, 32mL/g; and extraction temperature, 56°C. These two values were agreed well with predicted yield (2.75%) and antioxidant capacity (18.77μmol Fe2+/g). Antioxidant activities of CPS were investigated by various assays. The results showed that CPSUAE obtained by UAE showed higher 1,1-Diphenyl-2-picrylhydrazxyl (DPPH), 2,2-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activities and stronger reducing power, total antioxidant capacity compared with CPSHWE obtained by hot water extraction (HWE).The results indicated that UAE is an advisable method for extraction of antioxidant polysaccharides from the stem of T. quadrispinosa and polysaccharides could be explored as potential antioxidant to use in medicine or functional food.

Raza A ，Li F ，Xu X ，Tang J ... -  《-》

Preparation, preliminary characterization and immunostimulatory activity of polysaccharide fractions from the peduncles of Hovenia dulcis.

The peduncles of Hovenia dulcis, containing abundant nutrients and having a taste like a combination of raisin, clove, cinnamon and sugar, have been consumed as fruits and used as traditional herbal medicine for a long time in China. Up to date, little information is available about the polysaccharides from peduncles of H. dulcis (HDPS) and their potential bioactivity. In this study, three purified fractions were prepared by sequential purification of crude HDPS through ion-exchange chromatography and gel-filtration chromatography. The three fractions of HDPS-1, HDPS-2 and HDPS-3 were found to be homogeneous heteropolysaccharides mainly composed of rhamnose, arabinose, galactose and galacturonic acid with an average molecular weight of 235, 70 and 53 kDa, respectively. HDPS-3 was quite different from HDPS-1 and HDPS-2, as it contained much higher content of galacturonic acid (40.5%). In vitro immunostimulatory activity evaluation revealed that all the three fractions could significantly stimulate the proliferation of splenocytes and enhance phagocytosis, nitric oxide production and acid phosphatase activity of peritoneal macrophages, which suggested that HDPS had a potent immunostimulatory activity and could be explored as a potential natural immunomodulatory agent.

Wang M ，Jiang C ，Ma L ，Zhang Z ，Cao L ，Liu J ，Zeng X ... -  《-》