Optimisation of pressurised water extraction of polysaccharides from blackcurrant and its antioxidant activity

Preparation, characterization, antioxidant and antiglycation activities of selenized polysaccharides from blackcurrant

An ultrasound-assisted enzymatic method was used to extract the polysaccharides from blackcurrant fruits (BP), and then a nitric acid-sodium selenite method was employed to prepare twelve kinds of selenized blackcurrant polysaccharides (SBPs). Among them, SBP-1, SBP-2 and SBP-3 with different selenium contents of 250 ± 11, 312 ± 15 and 643 ± 24 μg g⁻¹, displayed relatively higher 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙) scavenging activities than the others. After treating with a Sepharose-6B chromatography column, the purified blackcurrant polysaccharide (PBP) and three selenized polysaccharides (PSBP-1, PSBP-2, PSBP-3) with high purity were obtained. Compared with PBP, PSBPs possessed a larger absolute value of zeta potential (ZP) and smaller particle size, indicating the positive influence of selenized modification on physical stability of polysaccharides. Ultraviolet (UV), Fourier transform infrared (FT-IR) and circular dichroism (CD) spectra confirmed that selenium had been introduced onto the polysaccharide structure. X-ray diffraction (XRD) and I₂–KI reaction results indicated that selenized modification did not cause an obvious change in crystal form and branch structure of blackcurrant polysaccharides. In addition, PSBPs were superior to PBP in antioxidant and antiglycation capacities, and the bioactivities of PSBPs were significantly improved in positive correlation with selenium content. This study suggested that PSBPs may be a potential selenium source and serve as functional food and medicine.

An ultrasound-assisted enzymatic method was used to extract the polysaccharides from blackcurrant fruits (BP), and then a nitric acid-sodium selenite method was employed to prepare twelve kinds of selenized blackcurrant polysaccharides (SBPs).

Optimization of ultrasonic-assisted enzymatic extraction of polysaccharides from thick-shell mussel (Mytilus coruscus) and their antioxidant activities

This study aimed to obtain the purified fractions of Mytilus coruscus polysaccharides (MCPs) and investigate their antioxidant activities. MCPs were prepared through ultrasonic-assisted enzymatic extraction optimized by employing the response surface methodology. A single-factor experiment was conducted using the Box-Behnken design to determine the optimum extraction conditions of MCPs. The ultrasonic power was 60 W, liquid-to-material ratio was 30 mL/g, extraction time was 36 min, extraction temperature was 64 °C, enzyme concentration was 3.2%, and polysaccharide extraction yield was 12.86% ± 0.12%. A novel polysaccharide (MCP1-2) was obtained after the purification with AB-8 macroporous resin, DEAE Sepharose Fast Flow, and Sepharose CL-6B column. The molecular weight of MCP1-2 was estimated to be 134.9 kDa according to high-performance gel permeation chromatography. High-pressure liquid-phase chromatography results showed that MCP1-2 contained mannose, rhamnose, glucuronic acid, glucose, galactose, and L-Fuc at a molar ratio of 1.53:1:4.83:81.82:2.36:1.51. Infrared and NMR spectroscopies confirmed that MCP1-2 possessed α- and β- configurations. The antioxidant activities of MCP1-2 were investigated in vitro, and the results showed that MCP1-2 had good antioxidant activity and can be used as a natural antioxidant in food.

Physicochemical properties and laxative effects of polysaccharides from Anemarrhena asphodeloides Bge. in loperamide-induced rats

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese herbal medicine, Anemarrhena asphodeloides Bge. possesses the effects of nourishing yin, moistening dryness, clearing lungs and relieving fire. Simultaneously, it has been used to treat constipation for more than one thousand years in China. However, modern medical studies are limited and lacking on its therapeutic mechanism.

AIM OF THE STUDY

This current study was aimed to investigate the laxative activities and explore the potential mechanism of Anemarrhena asphodeloides Bge. polysaccharides (AABP) in loperamide-induced constipation rats.

MATERIALS AND METHODS

The structure of AABP was determined by using infrared spectrum, high performance gel permeation chromatography (HPGPC), and high performance liquid chromatography (HPLC). Real-time quantitative polymerase chain reaction (PCR), multitudinous methods were adopted to explore the underlining therapeutic mechanism of AABP in treating constipation, including enzyme-linked immunosorbent assay (ELISA), histopathological, immunohistochemistry and western blotting.

RESULTS

In the present study, the average molecular weight of AABP was determined as 1.11 × 10³ kDa. The primary monosaccharide compositions were analyzed including D-mannose, L-rhamnose, D-galacturonic acid, D-glucose, D-galactose and L-arabinose (1, 0.04, 0.53, 0.11, 0.33, 0.25, respectively) by high-performance liquid chromatography (HPLC). AABP significantly increased the levels of gastrin (Gas), motilin (MTL), substance P (SP), 5-hydroxytryptamine (5-HT) and vasoactive intestinal peptide (VIP), and decreased the NO content of loperamide-induced rats to ameliorate constipation in the rats. Whilst, AABP repaired the damaged colons by regulating PCNA and ICAM-1 protein expressions. Additionally, AABP up-regulated the levels of SCF, c-Kit, AQP3 and VIP as well as down-regulated the expressions of AQP8, AQP4 and PGE2.

CONCLUSION

The present findings suggested that AABP were the laxative active ingredients isolated from Anemarrhena asphodeloides Bge., which could treat constipation through regulating the gastrointestinal hormones and neurotransmitters to improve the intestinal motility and water metabolism.

Optimization of Alkali Extraction and Properties of Polysaccharides from Ziziphus jujuba cv. Residue

Ziziphus jujuba cv. Muzao is a plant widely cultivated in the Yellow River Basin of China. It has nutritional and healthcare functions, in which polysaccharides are the main components of its bio-functions. In order to make effective use of Ziziphus jujuba cv. Muzao residue resources and explore new functional food ingredients, the polysaccharide (ZJRP) from Ziziphus jujuba cv. Muzao residues were extracted by sodium hydroxide, and the optimal extraction conditions of ZJRP were obtained by the response surface method. The basic composition and antioxidant effects of ZJRP were determined. The results showed that ZJRP has significant antioxidant activity, mainly reflected in the high DPPH radical scavenging rate, which may be related to their high content of galacturonic acid and the extraction method. In addition, the rheological and thermal properties of ZJRP were respectively determined by a rheometer and differential scanning calorimetry (DSC), indicating that they have shear thinning properties and good thermal stability. Results showed that the alkaline extraction method can be used as a potential technique for extracting ZJRP with high antioxidant activity, and ZJRP can be further explored as a functional food ingredient.

Optimization of Microwave-Assisted Extraction of Polysaccharides from Ulva pertusa and Evaluation of Their Antioxidant Activity

The use of green marine seaweed Ulva spp. as foods, feed supplements, and functional ingredients has gained increasing interest. Microwave-assisted extraction technology was employed to improve the extraction yield and composition of Ulva pertusa polysaccharides. The antioxidant activity of ulvan was also evaluated. The impacts of four independent variables, i.e., extraction time (X₁, 30 to 60 min), power (X₂, 500 to 700 W), water-to-raw-material ratio (X₃, 40 to 70), and pH (X₄, 5 to 7) were evaluated. The chemical structure of different polysaccharides fractions was investigated via FT-IR and the determination of their antioxidant activities. A response surface methodology based on a Box–Behnken design (BBD) was used to optimize the extraction conditions as follows: extraction time of 43.63 min, power level of 600 W, water-to-raw-material ratio of 55.45, pH of 6.57, and maximum yield of 41.91%, with a desired value of 0.381. Ulvan exerted a strong antioxidant effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and showed reducing power in vitro. Ulvan protected RAW 264.7 cells against H₂O₂-induced oxidative stress by upregulating the expression and enhancing the activity of oxidative enzymes such as superoxide dismutase (SOD) and superoxide dismutase (CAT). The results suggest that the polysaccharides from U. pertusa might be promising bioactive compounds for commercial use.

Optimization of the extraction, preliminary characterization, and anti-inflammatory activity of crude polysaccharides from the stems of Trapa quadrispinosa

A novel method was developed using pressurized-assisted extraction (PAE) to efficiently extract crude Trapa quadrispinosa polysaccharides (TQCPS) from plant stems, and the extraction process was optimized using response surface methodology (RSM). At a water-to-material fixed ratio of 30 mL g⁻¹, the highest yield of 3.72 ± 0.13% was obtained under the optimum conditions of extraction time of 32 min, extraction temperature at 47 °C, and extraction pressure at 1.87 Mpa, which were in agreement with the predicted value of 3.683%. Compared with conventional hot water extraction (HWE), the PAE method remarkably enhanced the extraction yield with the further advantages of short extraction time and low extraction temperature. The preliminary characteristics of TQCPS were analyzed through UV-vis, FT-IR, and chemical composition analysis. In subsequent anti-inflammatory studies, when RAW 264.7 mouse macrophage cells were treated with TQCPS, satisfactory anti-inflammatory activity was observed, and TQCPS significantly suppressed the release of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) and synchronously restrained the expression levels of inducible nitric oxide synthase (iNOS), TNF-α, and IL-6 mRNA induced by lipopolysaccharide (LPS) in a dose-dependent manner. These results indicate that PAE is a technology that can be used for efficient extraction of polysaccharides from medicinal plants, and TQCPS can be explored as a potential anti-inflammatory agent in medicine.

The high-yield TQCPS extracted by PAE presented good anti-inflammatory activity.

The impacts of natural polysaccharides on intestinal microbiota and immune responses – a review

This paper presents a comprehensive review of the impacts of natural polysaccharides on gut microbiota and immune responses as well as their interactions.

Enrichment and separation of steroidal saponins from the fibrous roots of Ophiopogon japonicus using macroporous adsorption resins

In this study, a simple and effective strategy for the enrichment of total steroidal saponins (TSS) from the fibrous roots of Ophiopogon japonicus (L. f.) Ker-Gawl. (FROJ) using macroporous adsorption resin was systematically developed. XAD-7HP resin was selected from six macroporous resins for further study because of the highest static adsorption and desorption capacities. The static adsorption of TSS on XAD-7HP resin fitted well to the Langmuir isotherm model and pseudo second-order kinetic model; the thermodynamics test showed that the adsorption process was spontaneous and exothermic. The dynamic tests on XAD-7HP resin columns demonstrated that the breakthrough volume was 16 bed volume (BV), and 6 BV of 80% ethanol was suitable for dynamic desorption. In a lab scale-up separation under optimal dynamic conditions, the content of TSS in the resin-enrichment fraction increased from 1.83% in the crude extracts to 13.86% by 7.59-fold with a recovery yield of 82.68%. Three steroidal saponins were obtained from the resin-enrichment fraction, and showed protective effects against oxidized low-density lipoprotein (ox-LDL) induced human umbilical vein endothelial cell (HUVEC) injury. Overall, these results suggested that XAD-7HP resin chromatography was an effective strategy for the large scale enrichment of TSS from FROJ, which showed the potential for functional food and pharmaceutical application.

In this study, a simple and effective strategy for the enrichment of total steroidal saponins (TSS) from the fibrous roots of Ophiopogon japonicus (L. f.) Ker-Gawl. (FROJ) using macroporous adsorption resin was systematically developed.

Effects of ultrasound irradiation on the characterization and bioactivities of the polysaccharide from blackcurrant fruits

In this study, the influence of ultrasound irradiation on the characterization and bioactivities of the polysaccharide from blackcurrant fruits (BCP, molecular weight: M_w = 3.26 × 10⁴ kDa) was investigated. Two degraded polysaccharides (U-400, M_w = 1.89 × 10⁴ kDa, and U-600, M_w = 1.32 × 10⁴ kDa) were obtained by different ultrasound powers of 400 W and 600 W, respectively. Compared with BCP, U-400 and U-600 showed 63.52% and 68.85% reductions in the particle size (Z_avg), respectively; moreover, the dynamic viscosity of BCP was reduced by 27.88%, and 33.63%, separately. The reducing sugar content and thermal stability increased with the increase of ultrasound intensity. The degraded polysaccharides contained the same monosaccharide species as those of BCP but at different molar ratios. Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic analysis confirmed that the degraded polysaccharides and BCP exhibited the similar structural features, which were mainly composed of six glycosidic bonds. A reduction in surface area of the flake-like structure was observed in the degraded polysaccharides compared to that of BCP, and they had no triple helix structure. Furthermore, the precise structural characteristics of U-600 were identified by 2D NMR analysis. The results of the bioactivity assays indicated that the ultrasound irradiation could evidently enhance the antioxidant (hydroxyl and superoxide radicals scavenging, lipid peroxidation inhibition, and DNA damage protection activities), α-amylase and α-glucosidase inhibition activities of BCP. These activities increased in the order of U-600 > U-400 > BCP. In particular, the DNA protection and α-amylase inhibition activities for U-600 were 52.19 ± 1.34% and 75.98 ± 0.77%, respectively, which were 2 times higher than those of BCP. U-600 prepared with the higher-intensity ultrasound exhibited the best physicochemical properties and bioactivities among the three polysaccharides. These results suggested that ultrasound irradiation was an efficient, green method to produce value-added polysaccharide for use in functional food or medicine.

Physicochemical properties and activities of comfrey polysaccharides extracted by different techniques

The effects of extraction techniques on the physicochemical properties, antioxidant activity and antihyperglycemic activity of comfrey polysaccharides (CPs) were evaluated. Four techniques were used to extract CPs: hot water extraction (HW), ultrasonic-assisted extraction (UA), enzyme-assisted extraction (EA) and enzyme-ultrasonic-assisted extraction (EUA). Experimental results indicated that CPs extracted by the UA (UA-CPs) and EUA methods (EUA-CPs) had higher extraction yields. The four CPs showed the same monosaccharide composition but a significant difference in monosaccharide content. CPs showed antioxidant activities and antihyperglycemic activities in a concentration-dependent manner. UA-CPs exhibited better antioxidant capacity, which might have been related to its smaller molecular weight and higher uronic acid content. In addition, UA-CPs showed notable α-glucosidase inhibition activity. These results suggested that ultrasonic-assisted extraction technology was more beneficial to enhance the extraction yields of the polysaccharides, and obtain higher bioactive polysaccharides from comfrey.

Composition characterization, antioxidant capacities and anti-proliferative effects of the polysaccharides isolated from Trametes lactinea (Berk.) Pat

This study was designed to investigate the chemical characterization and bioactivity of the Trametes lactinea (Berk.) Pat polysaccharides (TLP). The crude TLP was fractionated into two fractions, namely TLP-1 and TLP-2 with Cellulose DEAE-52 and Sephadex G-150. HPLC and FT-IR analysis showed that TLP-1 and TLP-2 were heteropolysaccharides mainly composed of glucose with the average molecular weights of 443.19kDa and 388.83kDa, respectively. TLP-1 from water elution possessed of higher reducing power and scavenging activities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, superoxide radical and hydroxyl radical than TLP-2 eluted by 0.1M of NaCl. In comparison with TLP-2, TLP-1 showed stronger growth inhibition against human hepatoblastoma HepG-2 cells and caused higher LDH leakage. However, TLP-1 showed lower growth inhibition against normal hepatocyte L-02 cells and lower LDH leakage than TLP-2. Flow cytometric analysis showed that TLP-1 had a stimulatory effect on apoptosis of HepG-2 cells. These findings suggested that the polysaccharides, especially TLP-1 could contribute to the potential anticancer effects of T. lactinea (Berk.) Pat, which might be valuable as a natural antioxidant source applied in both healthy medicine and food industry for health benefits.

Extraction Optimization, Purification, Antioxidant Activity, and Preliminary Structural Characterization of Crude Polysaccharide from an Arctic Chlorella sp

The arctic strain of Chlorella sp. (Chlorella-Arc) exists in the coldest and driest arctic ecosystems, and it is a new resource of active polysaccharides. The extraction of crude polysaccharide from Chlorella-Arc was optimized using the response surface methodology. A crude polysaccharide yield of approximately 9.62 ± 0.11% dry weight was obtained under these optimized conditions. Three fractions (P-I, P-II, and P-III) were present after purification by 2-diethylaminoethanol Sepharose Fast Flow and Sephadex G-100 chromatography. The P-IIa fraction demonstrated significant antioxidant activities. Moreover, P-IIa was an α- and β-type heteropolysaccharide with a pyran group and contained variable amounts of rhamnose, arabinose, glucose, and galactose based on fourier-transform infrared spectroscopy, high-performance liquid chromatography, and ¹H and 13C nuclear magnetic resonance imaging. Production of high amounts of polysaccharide may allow further exploration of the microalgae Chlorella-Arc as a natural antioxidant.

Extraction and physicochemical properties of polysaccharides from Ziziphus Jujuba cv. Muzao by ultrasound-assisted aqueous two-phase extraction

In this paper, ultrasound-assisted aqueous two-phase extraction (UAATPE) performed via a one-step procedure was applied to extract polysaccharides from Ziziphus Jujuba cv. Muzao. Using an ethanol/ammonium sulfate system as a multiphase solvent, effects of UAATPE on extraction of ZMP, such as solvent-to-material ratio, composition of aqueous two-phase system, and extraction time and temperature, were investigated using response surface methodology on basis of results of single-factor experiment. The final optimal conditions were ATPS composition: 29% ethanol and 15% (NH₄)₂SO₄, extraction time: 38min, extraction temperature: 48°C, solvent-to-material ratio: 30, and microwave power: 70W. Under these conditions, the experimental extraction yield was 8.18%. Chemical analysis revealed that ZMP were composed of rhamnose, arabinose, xylose, mannose, glucose, galactose, and galacturonic acid, at a ratio of 1.46:2.47:2.27:1.12:1.00:1.57:5.40, respectively. The structures were also characterized with UV, FTIR, and SEM. The DPPH and ABTS radical scavenging activities showed ZMP had moderately antioxidant activity.

Antitumor effect and molecular mechanism of antioxidant polysaccharides from Salvia miltiorrhiza Bunge in human colorectal carcinoma LoVo cells

Salvia miltiorrhiza Bunge polysaccharides (SMP) was comprehensively investigated in this study. The polysaccharides were extracted by the method of water boiling and ethanol precipitation with high purity. The monosaccharide composition of SMP was characterized using the established HPLC-UV protocol with PMP precolumn derivatization, and the results indicate that the polysaccharides are mainly composed of d-galactose (Gal), d-glucose (Glc) and d-galacturonic acid (GalUA), and their mole percentages are 64.5%, 31.1% and 4.4%, respectively. In addition, the antioxidant potential of SMP was evaluated in terms of reducing power, scavenging ability against DPPH, superoxide and hydroxyl free radicals. The results indicate that polysaccharides from S. miltiorrhiza Bunge possess versatile antioxidant activities in a dose-dependent manner. Furthermore, SMP is observed with high inhibition ratio against LoVo cells (typical tumor cells) in both dose- and time-dependent manners. FCM analysis demonstrates that SMP is able to induce apoptosis of LoVo cells, arrest the cell cycle at S phase, as well as elevate the intracellular reactive oxygen pressure. These findings for the first time reveal the potential anti-tumor mechanism of SMP, suggesting that SMP may serve a natural anticancer agent with lower cost and cytotoxicity, as well as a bioactive factor for functional food development.

Structural features of a new water-soluble polysaccharide from the gum exudates of Amygdalus scoparia Spach (Zedo gum)

A new water-soluble polysaccharide (CZGS-1) with molecular weight of 4860kDa and a specific optical rotation of +31.5° (c 1.0, H₂O), was extracted from the gum exudate of Amygdalus scoparia Spach by hot water, following by purification with DEAE-cellulose A52 and Sephacryl S-400 HR columns. Monosaccharide composition analysis indicates that CZGS-1 was an arabino galactan including Rha, Ara, Xyl, and Gal with a relative molar ratio of 1.1:20:5.2:17.9. The uronic acid content of CZGS-1 was about 6%. Structural features of CZGS-1 was investigated by a combination of partial acid hydrolysis, methylation and GC-MS analysis, periodic acid oxidation and Smith degradation, FT-IR and NMR spectroscopy. The results indicated that CZGS-1 possesses a backbone of →3,6)-β-d-Galp-(1→, →3)-β-d-Galp-(1→, and →3)-α-l-Araf-(1→ residues with side chains attached to O-3 and O-6 positions of 1,3,6-linked β-d-Galp. The side chains are consisted of β-d-Xylp-(1→3)-α-l-Araf-(1→3)-α-l-Araf-(1→), α-l-Rhap-(1→6)-β-d-Galp-(1→), and β-d-GlcAp-(1→6)-β-d-Galp-(1→).

Microwave-assisted extraction and pharmacological evaluation of polysaccharides from Posidonia oceanica

Microwave-assisted extraction was employed for the isolation of polysaccharides from Posidonia oceanica (PPO). The extracting parameters were optimized adopting response surface methodology. The highest polysaccharide yield (2.55 ± 0.09%), which is in concordance with the predicted value (2.76%), was obtained under the following conditions: extraction time 60 s, liquid–solid ratio of 50:1 (mL/g) and power of 800 W. This polysaccharide, with molecular weight of 524 KDa, characterized by gas chromatography–mass spectrometry showed that PPO was mainly composed of galactose, glucose, and arabinose with molar percentages 25.38, 24.37, and 21.64%, respectively. The pharmacological evaluation of PPO using animal models at the dose of 100 mg/kg indicated a significant anti-inflammatory activity with a percentage of inhibition of edema of 54.65% and a significant antinociceptive activity with 78.91% inhibition of writhing for peripheral analgesic activity and an increase in the hot plate reaction time for central analgesic activity.

Characterization and protective effect of Polygonatum sibiricum polysaccharide against cyclophosphamide-induced immunosuppression in Balb/c mice

In this study, the polysaccharide from Polygonatum sibiricum (PSP) was evaluated for the immunomodulatory activity by the cyclophosphamide (Cy)-induced immunosuppressed-model in vivo. The PSP has been analyzed in order to identify a variety of chemical properties such as monosaccharide compositions and structural confirmation. The results show that the main components of PSP were galactose and rhamnose. The PSP could significantly stimulate neutral red phagocytosis of RAW264.7 macrophages. Compared with the cyclophosphamide group, PSP accelerated recovery of spleen and thymus indexes, and enhanced T cell and B cell proliferation responses as well as peritoneal macrophage phagocytosis. In addition, PSP treatment restored the levels of IL-2, TNF-α, IL-8 and IL-10 in the serum of the Cy-treated mice in a dose-dependent manner. Therefore, PSP played an important role in the protection against immunosuppression in the Cy-treated mice and could be used as a potential immunostimulant agent.

Extraction optimization and influences of drying methods on antioxidant activities of polysaccharide from cup plant (Silphium perfoliatum L.)

Response surface methodology (RSM) was used to investigate the extraction condition of polysaccharide from cup plant (Silphium perfoliatum L.) (named CPP). Water to raw material ratio (10-30 mL/g), extraction time (40-80 min) and extraction temperature (60-100°C) were set as the 3 independent variables, and their effects on the extraction yield of CPP were measured. In addition, the effects of drying methods including hot air drying (HD), vacuum drying (VD) and freeze drying (FD) on the antioxidant activities of CPP were evaluated. The results showed that the optimal condition to extract CPP was: water to raw material ratio (15 mL/g), extraction time (61 min), and extraction temperature (97°C), a maximum CPP yield of 6.49% was obtained under this condition. CPP drying with FD method showed stronger reducing power (0.943 at 6 mg/mL) and radical scavenging capacities against DPPH radical (75.71% at 1.2 mg/mL) and ABTS radical (98.06 at 1.6 mg/mL) than CPP drying with HD and VD methods. Therefore, freeze drying served as a good method for keeping the antioxidant activities of polysaccharide from cup plant. The polysaccharide from cup plant has potential to use as a natural antioxidant.

Extraction of Opuntia dillenii Haw. Polysaccharides and Their Antioxidant Activities

Use of natural polysaccharides in medicine and food has wide interest in research. In this study, we extracted and purified some polysaccharides from cactus Opuntia dillenii Haw. (ODP). Some preliminary functions of these products were characterized. Under the optimal purification conditions, the yield of ODP extracted from the 2–4 month-old Opuntia dillenii Haw. (T-ODP) was 30.60% ± 0.40%, higher than that of ODP from the 5–10 month-old materials (O-ODP) (18.97% ± 0.58%). The extracted ODP was purified by DEAE sepharose fast flow anion exchange and Sephacryl S-400 chromatography with four fractions obtained (ODP-Ia, ODP-Ib, ODP-IIa and ODP-IIb). Analysis with UV-vis chromatography indicated that ODP-Ia and ODP-IIa were relatively homogeneous molecules with a molecular weight of 339 kD and 943 kD, respectively. Results of infrared spectroscopy indicated that ODP, ODP-Ia, and ODP-IIa were acidic polysaccharides. Further, the antioxidant activity against DPPH (1,1-diphenyl-2-picrylhydrazyl) radical, hydroxyl radicals, and superoxide radical in vitro demonstrated that the T-ODP exhibited higher antioxidant activity than the O-ODP, and the purified fraction (ODP-Ia) was superior to the ODP. These results will offer a theoretical basis for further research on the structure-function relationship of ODP and the rational utilization of Opuntia dillenii Haw.

Quantitative Structure Activity Relationship Models for the Antioxidant Activity of Polysaccharides

In this study, quantitative structure activity relationship (QSAR) models for the antioxidant activity of polysaccharides were developed with 50% effective concentration (EC50) as the dependent variable. To establish optimum QSAR models, multiple linear regressions (MLR), support vector machines (SVM) and artificial neural networks (ANN) were used, and 11 molecular descriptors were selected. The optimum QSAR model for predicting EC50 of DPPH-scavenging activity consisted of four major descriptors. MLR model gave EC50 = 0.033Ara-0.041GalA-0.03GlcA-0.025PC+0.484, and MLR fitted the training set with R = 0.807. ANN model gave the improvement of training set (R = 0.96, RMSE = 0.018) and test set (R = 0.933, RMSE = 0.055) which indicated that it was more accurately than SVM and MLR models for predicting the DPPH-scavenging activity of polysaccharides. 67 compounds were used for predicting EC50 of the hydroxyl radicals scavenging activity of polysaccharides. MLR model gave EC50 = 0.12PC+0.083Fuc+0.013Rha-0.02UA+0.372. A comparison of results from models indicated that ANN model (R = 0.944, RMSE = 0.119) was also the best one for predicting the hydroxyl radicals scavenging activity of polysaccharides. MLR and ANN models showed that Ara and GalA appeared critical in determining EC50 of DPPH-scavenging activity, and Fuc, Rha, uronic acid and protein content had a great effect on the hydroxyl radicals scavenging activity of polysaccharides. The antioxidant activity of polysaccharide usually was high in MW range of 4000-100000, and the antioxidant activity could be affected simultaneously by other polysaccharide properties, such as uronic acid and Ara.

Optimization extraction of polysaccharide from Tunisian Zizyphus lotus fruit by response surface methodology: Composition and antioxidant activity

Response surface methodology using a Box-Behnken design was employed to optimize extraction temperature, extraction time and ratio of water to material to obtain a maximum polysaccharide yield with high uronic acid content and antioxidant property from edible Zizyphus lotus fruit. The optimal conditions were: extraction time of 3h 15min, extraction temperature of 91.2°C and water to solid ratio of 39mL/g. Under these conditions, the experimental extraction yield, uronic acid content and 2,2-diphenyl-1-picrylhydrazyl scavenging ability (IC50) were 18.88%, 41.89 and 0.518mg/mL, respectively. Chemical analysis revealed that the extract was composed of 97.92% carbohydrate of which 41.89% is uronic acid. The extracted polysaccharides, with an average molecular weight of 2720kDa, are composed of arabinose, rhamnose, glucose, fructose, galactose and xylose. Moreover, the polysaccharides exhibited a significant reducing power and anti-lipid peroxidation activities.