Phosphate and Nitrate Removal from Coffee Processing Wastewater Using a Photoelectrochemical Oxidation Process.

Water quality, whether utilized for home, irrigation, or recreational reasons, is crucial for health in both developing and developed countries around the world. For the treatment of nitrate (NO3) and phosphate (PO3) from coffee processing wastewater, photoelectrochemical oxidation was used. This process is mainly used to destroy pollutants through the production and use of powerful oxidized species such as hydroxyl radical (OH). It investigated the effects of Uv/H2O2 on electrochemical processes and the effects of various parameters such as pH, time, current, and electrolytes. The results were calculated and analyzed using response surface methodology and Microsoft Excel. Hybrid photoelectrochemical oxidation (PECO) using UV and hydrogen peroxide (UV/H2O2) methods removed nitrates (99.823%) and phosphates (99.982%). These results were obtained with pH 7, current 0.40 amperes, and 1.5 g calcium chloride after 40 minutes of electrolysis. CaCl2 was more effective in removing organic compounds from coffee processing wastewater. An analysis of variance (ANOVA) with a 95% confidence limit was used to determine the significance of the independent variable.

Changes in Chemical Compositions and Antioxidant Activities from Fresh to Fermented Red Mountain-Cultivated Ginseng.

This study investigated changes in nutrients (fatty acids, amino acids, and minerals), ginsenosides, and volatile flavors, and antioxidant activities during food processing of mountain-cultivated ginseng (MCG) with the cocktail lactic acid bacteria. Fatty acid content increased, but the free amino acid content decreased, and minerals were practically unaffected during processing. Total phenolic and flavonoid contents and maillard reaction products increased markedly according to processing stage. The total ginsenosides levels increased from 31.25 mg/g (DMCG) to 32.36 mg/g (red MCG, RMCG) and then decreased (27.27 mg/g, at fermented RMCG) during processing. Particularly, the contents of F2 (0.31 → 1.02 → 2.27 mg/g), Rg3 (0.36 → 0.77 → 1.93 mg/g), and compound K (0.5 → 1.68 → 4.13 mg/g) of ginsenosides and ß-panasinsene (17.28 → 22.69 → 31.61%), biocycloelemene (0.11 → 0.84 → 0.92%), δ-cadinene (0.39 → 0.5 → 0.94%), and alloaromadendrene (1.64 → 1.39 → 2.6%) of volatile flavor compounds increased during processing, along with to the antioxidant effects (such as DPPH, ABTS, and hydroxyl radical scavenging activities, and FRAP). This study may provide several choices for the use of ginseng in functional foods and functional cosmetics.

Role of the Hydroxyl Radical-Generating System in the Estimation of the Antioxidant Activity of Plant Extracts by Electron Paramagnetic Resonance (EPR).

The scavenging activity of hydroxyl radicals, produced by the Fenton reaction, is commonly used to quantify the antioxidant capacity of plant extracts. In this study, three Fenton systems (Fe/phosphate buffer, Fe/quinolinic acid and Fe/phosphate buffer/quinolinic acid) and the thermal degradation of peroxydisulfate were used to produce hydroxyl radicals; the hydroxyl radical scavenging activity of plant extracts (ginger, blueberry juices and green tea infusion) and chemical compounds (EGCG and GA) was estimated by spin trapping with DMPO (5,5-dimethyl-1-pyrroline N-oxide) and EPR (Electron Paramagnetic Resonance) spectroscopy. Phosphate buffer was used to mimic the physiological pH of cellular systems, while quinolinic acid (pyridine-2,3-dicarboxylic acid) facilitates the experimental procedure by hindering the spontaneous oxidation of Fe(II). The EC50 (the concentration of chemical compounds or plant extracts which halves the intensity of the DMPO-OH adduct) values were determined in all the systems. The results show that, for both the chemical compounds and the plant extracts, there is not a well-defined order for the EC50 values determined in the four hydroxyl radical generating systems. The interactions of phosphate buffer and quinolinic acid with the antioxidants and with potential iron-coordinating ligands present in the plant extracts can justify the observed differences.

The pro-radical hydrogen peroxide as a stable hydroxyl radical distributor: lessons from pancreatic beta cells.

The toxic potential of H2O2 is limited, even if intracellular concentrations of H2O2 under conditions of oxidative stress increase to the micromolar concentration range. Its toxicity is mostly restricted to the oxidation of highly reactive thiol groups, some of which are functionally very important. Subsequently, the HO· radical is generated spontaneously from H2O2 in the Fenton reaction. The HO· radical is extremely toxic and destroys any biological structure. Due to the high reactivity, its action is limited to a locally restricted site of its generation. On the other hand, H2O2 with its stability and long half-life can reach virtually any site and distribute its toxic effect all over the cell. Thereby HO·, in spite of its ultra-short half-life (10-9 s), can execute its extraordinary toxic action at any target of the cell. In this oxidative stress scenario, H2O2 is the pro-radical, that spreads the toxic action of the HO· radical. It is the longevity of the H2O2 molecule allowing it to distribute its toxic action from the site of origin all over the cell and may even mediate intercellular communication. Thus, H2O2 acts as a spreader by transporting it to sites where the extremely short-lived toxic HO· radical can arise in the presence of "free iron". H2O2 and HO· act in concert due to their different complementary chemical properties. They are dependent upon each other while executing the toxic effects in oxidative stress under diabetic metabolic conditions in particular in the highly vulnerable pancreatic beta cell, which in contrast to many other cell types is so badly protected against oxidative stress due to its extremely low H2O2 inactivating enzyme capacity.

Preparation and related properties of melanin iron supplement.

In this study, BM-Fe (black sesame melanin-iron complex) was prepared and characterized. The results showed that the carboxyl hydroxyl group of BSM (black sesame melanin) participated in the chelation of iron ions. EDS (energy dispersive spectroscopy) and XPS (X-ray photoelectron spectroscopy) results confirmed the presence of iron ions in BM-Fe. The results of DLS (dynamic light scattering) showed that the average particle sizes of BSM and BM-Fe were 844.9 nm and 294.3 nm, respectively, indicating that the structure of BM-Fe with a smaller particle size was formed after the binding of iron ions with the active group on BSM. Finally, the in vitro iron dissolution, iron ion identification, in vitro iron ion reduction, antioxidant activity, cytotoxicity and moisture resistance properties of BM-Fe and FST (ferrous sulfate tablets, a commonly used iron supplement) were comprehensively compared. The results showed that BSM combined with iron instead of physically mixing, and BM-Fe was easily reduced in the gastrointestinal environment. BM-Fe had good bioavailability and retained the excellent characteristics (such as oxidation resistance and biocompatibility) of BSM, and had the potential to be applied in the treatment of iron-deficiency-related diseases. In summary, BM-Fe prepared in this study not only retained the excellent characteristics of BSM but also had a good effect on iron supplementation, high bioavailability and low side effects. Comprehensive analysis showed that the performance of BM-Fe prepared in this study was similar to or even better than that of the control (FST). Thus, BM-Fe is expected to become a new comprehensive multi-functional iron supplement and has a broad developmental prospect.

Production of Hydroxyl Radicals from Oxygenation of Simulated Acid Mine Drainage in Presence of Extracellular Polymers Substances.

The reaction mechanisms Fe(II) abiotic oxidation produce ·OH by CaCO3-induced in acid mine drainage (AMD) are well-documented, but little is known about the influence of extracellular polymeric substances (EPS) secreted by microorganisms on Fe(II) oxidation in AMD. In this study, ·OH production was experimently measured from oxygenation of simulated AMD in the presence of EPS. The cumulative ·OH increased from 56.75 to 158.70 µM within 24 h at pH 3 with the increase in EPS concentration from 0 to 12 mg/L. An appropriate pH (about 6) and EPS (6 mg/L) concentration were required for the moderate rate of Fe(II) oxidation. Besides, the yield of ·OH increased remarkably with the addition of Fe3+. In the presence of EPS, ·OH production is attributed mainly the complexation of Fe(II) with EPS, of which is rich of carboxyl and hydroxyl groups. The findings provide fundamental supplement of ·OH production from Fe(II) oxidation by microorganisms in natural AMD.

Antioxidant Activity Evaluation of Oviductus Ranae Protein Hydrolyzed by Different Proteases.

As nutrition and a health tonic for both medicine and food, the protein content of Oviductus Ranae is more than 40%, making it an ideal source to produce antioxidant peptides. This work evaluated the effects of six different proteases (pepsin, trypsin, papain, flavourzyme, neutral protease and alcalase) on the antioxidant activity of Oviductus Ranae protein, and analyzed the relationship between the hydrolysis time, the degree of hydrolysis (DH) and the antioxidant activity of the enzymatic hydrolysates. The results showed that the antioxidant activity of Oviductus Ranae protein was significantly improved and the optimal hydrolysis time was maintained between 3-4 h under the action of different proteases. Among them, the protein hydrolysate which was hydrolyzed by pepsin for 180 min had the strongest comprehensive antioxidant activity and was most suitable for the production of antioxidant peptides. At this time, the DH, the DPPH radical scavenging activity, the absorbance value of reducing power determination and the hydroxyl radical scavenging activity corresponding to the enzymatic hydrolysate were 13.32 ± 0.24%, 70.63 ± 1.53%, 0.376 ± 0.009 and 31.96 ± 0.78%, respectively. Correlation analysis showed that there was a significant positive correlation between the hydrolysis time, the DH and the antioxidant activity of the enzymatic hydrolysates, further indicating that the hydrolysates of Oviductus Ranae protein had great antioxidant potential. The traditional anti-aging efficacy of Oviductus Ranae is closely related to the scavenging of reactive oxygen species, and its hydrolysates have better antioxidant capacity, which also provides support for further development of its traditional anti-aging efficacy.

Eradication of solid tumors by chemodynamic theranostics with H2O2-catalyzed hydroxyl radical burst.

Activatable theranostics, integrating high diagnostic accuracy and significant therapeutic effect, holds great potential for personalized cancer treatments; however, their chemodynamic modality is rarely exploited. Herein, we report a new in situ activatable chemodynamic theranostics PAsc/Fe@Cy7QB to specifically recognize and eradicate cancer cells with H2O2-catalyzed hydroxyl radical (•OH) burst cascade. Methods: The nanomicelles PAsc/Fe@Cy7QB were constructed by self-assembly of acid-responsive copolymers incorporating ascorbates and acid-sensitive Schiff base-Fe2+ complexes as well as H2O2-responsive adjuvant Cy7QB. Results: Upon systematic delivery of PAsc/Fe@Cy7QB into cancer cells, the acidic microenvironment triggered disassembly of the nanomicelles. The released Fe2+ catalyzed the oxidation of ascorbate monoanion (AscH-) to efficiently produce H2O2. The released H2O2, together with the endogenous H2O2, could be converted into highly active •OH via the Fenton reaction, resulting in enhanced Fe-mediated T1 magnetic resonance imaging (MRI). The synchronously released Cy7QB was activated by H2O2 to produce a glutathione (GSH)-scavenger quinone methide to boost the •OH yield and recover the Cy7 dye for fluorescence and photoacoustic imaging. Conclusion: The biodegradable PAsc/Fe@Cy7QB designed for tumor-selective multimodal imaging and high therapeutic effect provides an exemplary paradigm for precise chemodynamic theranostic.

A Novel Optimization of Water-Soluble Compound Polysaccharides from Chinese Herbal Medicines by Quantitative Theory and Study on Its Characterization and Antioxidant Activities.

The present study optimized the extraction characterization and antioxidant activities of water-soluble compound polysaccharides (CPs) from hawthorn, lotus leaf, Fagopyrum tataricum, semen cassiae, Lycium barbarum, and Poria cocos Chinese herbal medicines that have mass ratios of 4 : 2 : 2 : 1.5 : 1 : 1. The CPs yield equation was predicted using quantitative theory, to which a maximum CPs yield of 7.18±0.24 % under the following optimal extraction conditions: a water-to-raw material ratio of 30 mL/g, an extraction temperature of 65 °C, an extraction time of 45 min, and extraction mode ultrasonic-assistant extraction. CPs were consisted of Ara, Gal, Glc, Xyl, Man, GalA and GlcA in a molar ratio of 3.1 : 2.6 : 50.6 : 1.7 : 20.4 : 17.2 : 4.2. The HPGPC profiles and FT-IR spectra implied that CPs were heterogeneous acidic polysaccharides and possessed the ß-d-pyranose configuration. Congo red test, CD spectrum and SEM revealed that CPs with three helix conformation showed a flocculent, granulous or sheet-like appearance. Furthermore, the relationships between antioxidant activity and concentration of CPs displayed significant positive correlation, and the scavenging abilities for DPPH, hydroxyl radical, ABTS, superoxide-anion radical and reducing power of CPs were 93.56±2.51 %, 84.03±1.69 %, 83.29±1.93 %, 37.49±1.93 % and 0.467±0.006 at a concentration of 4.0 mg/mL. Therefore, CPs could be applied as a potential natural antioxidant in pharmaceutical or functional food fields.

Ultrafiltration isolation, physicochemical characterization, and antidiabetic activities analysis of polysaccharides from green tea, oolong tea, and black tea.

Both fermentation degree and preparation method of polysaccharides could influence the bioactivity of tea polysaccharides. The aim of this study was to compare the physicochemical characterization and biological activities of the polysaccharides isolated by ultrafiltration method from three kinds of tea (green tea, oolong tea, and black tea). The bioactivities of tea polysaccharide fractions were compared from four aspects, including antioxidant activities, antiglycation activities, α-glucosidase inhibitory capability, and hypoglycemic effects on L6 myotubes. Results showed that six polysaccharides (GTPS1, GTPS2, OTPS1, OTPS2, BTPS1, and BTPS2) had different contents of neutral sugar and uronic acid, and they showed different morphologies. Six polysaccharides were composed of the seven monosaccharides with different molar ratios. BTPS1 exhibited the highest DPPH scavenging activity and hydroxyl radical scavenging activity (P < 0.05), and BTPS1 also showed the strongest antiglycation inhibitory effects (P < 0.05). BTPS1 and BTPS2 showed strong inhibitory capacity on α-glucosidase and hypoglycemic effects in L6 skeletal muscle cells. The result suggested that the degree of fermentation of tea could improve their bioactivities (BTPS > OTPS >GTPS), and TPS1 with smaller molecular weight distribution showed higher bioactivities than TPS2. This study can provide a scientific foundation for the application of tea polysaccharides and related functional products.

Redox Interactions of Vitamin C and Iron: Inhibition of the Pro-Oxidant Activity by Deferiprone.

Ascorbic acid (AscH2) is one of the most important vitamins found in the human diet, with many biological functions including antioxidant, chelating, and coenzyme activities. Ascorbic acid is also widely used in a medical practice especially for increasing the iron absorption and as an adjuvant therapeutic in the iron chelation therapy, but its mode of action and implications in the iron metabolism and toxicity are not yet clear. In this study, we used UV-Vis spectrophotometry, NMR spectroscopy, and EPR spin trapping spectroscopy to investigate the antioxidant/pro-oxidant effects of ascorbic acid in reactions involving iron and the iron chelator deferiprone (L1). The experiments were carried out in a weak acidic (pH from 3 to 5) and neutral (pH 7.4) medium. Ascorbic acid exhibits predominantly pro-oxidant activity by reducing Fe3+ to Fe2+, followed by the formation of dehydroascorbic acid. As a result, ascorbic acid accelerates the redox cycle Fe3+ ↔ Fe2+ in the Fenton reaction, which leads to a significant increase in the yield of toxic hydroxyl radicals. The analysis of the experimental data suggests that despite a much lower stability constant of the iron-ascorbate complex compared to the FeL13 complex, ascorbic acid at high concentrations is able to substitute L1 in the FeL13 chelate complex resulting in the formation of mixed L12AscFe complex. This mixed chelate complex is redox stable at neutral pH = 7.4, but decomposes at pH = 4-5 during several minutes at sub-millimolar concentrations of ascorbic acid. The proposed mechanisms play a significant role in understanding the mechanism of action, pharmacological, therapeutic, and toxic effects of the interaction of ascorbic acid, iron, and L1.

Alumina-mediated photocatalytic degradation of hexachlorobenzene in aqueous system: Kinetics and mechanism.

Five kinds of Al2O3 were characterized by SEM, TEM, FT-IR and BET surface area, and then used as carriers to investigate the photochemical removal of hexachlorobenzene (HCB) in aqueous system. The results showed that HCB coated on the surfaces of all Al2O3 could be photodegraded rapidly, and Neutral-Al2O3 presented the best performance. Meanwhile, the efficient removal of HCB in real water matrices, including tap water, river water and secondary clarifier effluent showed the potential practical application of Al2O3. EPR and theoretical calculation revealed the generation of hydroxyl radicals on Al2O3 surface under 500 W Xe lamp irradiation. Nine intermediates and a small amount of Cl- were identified by GC/MS, LC/MS and IC analysis, which was further verified by transition state calculations. These results can provide a new technique for HCB removal in water and wastewaters, and give more insights into the environmental ecological risk assessment of this pollutant.

Influence of sodium pyrophosphate on the physicochemical and gelling properties of myofibrillar proteins under hydroxyl radical-induced oxidative stress.

Porcine myofibrillar proteins (MP) with or without sodium pyrophosphate (PP) were oxidatively stressed in hydroxyl radical (˙OH)-generating systems (10 µM FeCl3, 100 µM ascorbic acid, and 0, 0.5, 3, 10 mM H2O2) at 4 °C for 12 h. The results showed significant protein oxidation under the ˙OH stress, indicated by the modification of amino acid side chain groups and the aggregation of MP, which led to losses in gelling properties of MP especially at high dosages of H2O2 (3-10 mM). The PP addition effectively suppressed ˙OH induced lipid oxidation (as evidenced by TBARS values) in MP, but the inhibitory effect on protein oxidation was limited. In fact, the PP treatment with a high level of H2O2 (10 mM) tended to promote protein unfolding and aggregation in the tested systems. However, a significantly (P < 0.05) improved protein solubility was found in all tested systems with added PP. The PP treated MP gels exhibited a more compact and orderly microstructure, which may explain the reduced cooking loss and improved gel strength.

Characterization and Antioxidant Activity Determination of Neutral and Acidic Polysaccharides from Panax Ginseng C. A. Meyer.

Panax ginseng (P. ginseng) is the most widely consumed herbal plant in Asia and is well-known for its various pharmacological properties. Many studies have been devoted to this natural product. However, polysaccharide's components of ginseng and their biological effects have not been widely studied. In this study, white ginseng neutral polysaccharide (WGNP) and white ginseng acidic polysaccharide (WGAP) fractions were purified from P. ginseng roots. The chemical properties of WGNP and WGAP were investigated using various chromatography and spectroscopy techniques, including high-performance gel permeation chromatography, Fourier-transform infrared spectroscopy, and high-performance liquid chromatography with an ultra-violet detector. The antioxidant, anti-radical, and hydrogen peroxide scavenging activities were evaluated in vitro and in vivo using Caenorhabditis elegans as the model organism. Our in vitro data by ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), reducing power, ferrous ion chelating, and hydroxyl radical scavenging activity suggested that the WGAP with significantly higher uronic acid content and higher molecular weight exhibits a much stronger antioxidant effect as compared to that of WGNP. Similar antioxidant activity of WGAP was also confirmed in vivo by evaluating internal reactive oxygen species (ROS) concentration and lipid peroxidation. In conclusion, WGAP may be used as a natural antioxidant with potent scavenging and metal chelation properties.

The antioxidant activities of garlic polysaccharide and its derivatives.

Garlic was used as raw material to extract garlic polysaccharide (P) with hot water extraction method. IR and NMR spectra showed that the preparation of sulfated garlic polysaccharide (SP), phosphorylated garlic polysaccharide (PP) and carboxymethylated garlic polysaccharide (CMP) was successful. The sugar content of P, SP, PP and CMP was determined, and their degree of substitution was measured. Hydroxyl radical scavenging ability, superoxide anion scavenging ability, significant reduction capacity, and anti-lipid peroxidation ability of P, SP, PP, CMP and VC were determined. It showed that the introduction of substituents had different effects on the antioxidant activities of P.

Decolorization affects the structural characteristics and antioxidant activity of polysaccharides from Thesium chinense Turcz: Comparison of activated carbon and hydrogen peroxide decolorization.

Different decolorization methods have different effects on the properties of polysaccharides. In this study, polysaccharides extracted from Thesium chinense Turcz (T. chinense) were decolorized using either hydrogen peroxide (H2O2), which has been previously reported, or activated carbon. To begin, the conditions for decolorization by activated carbon were optimized through single factor experiments and orthogonal modeling and were predicted to be best at 0.5% (w/w) activated carbon, pH 5.0 and 40 °C in a water bath for 60 min. Following treatment by the two methods, the structures of the decolorized polysaccharides were compared. The samples treated by activated carbon (CTP) had higher molecular weight (Mw: 3.064 × 105 g/mol) and more sulfate groups (14.33%, w/w), whereas the samples treated by H2O2 (HTP) had lower Mw (8.349 × 104 g/mol) and more uronic acid (35.02%, w/w). The antioxidant capacities of the two samples were analyzed by free radical scavenging (DPPH, hydroxyl and ABTS) and cell antioxidant activity (CAA). The HTP showed a better scavenging effect on free radicals and a higher CAA. Together, the results showed that various decolorization methods differentially influence the characteristics of the polysaccharides extracted from T. chinense.

Synthesis and antioxidant activities of garlic polysaccharide-Fe(III) complex.

Garlic polysaccharide-Fe(III) complex (FePS) was synthesized by co-thermal synthesis with garlic polysaccharide (PS) and ferric trichloride. The complex was characterized by infrared spectroscopy and thermogravimetric analysis. The scavenging activity of PS and FePS on hydroxyl radicals, superoxide anions and lipid peroxidation were studied. The scavenging hydroxyl radical activity of PS and FePS was similar, that was to say, FePS had not obvious raised compared with PS. The inhibitory effect on lipid peroxidation of FePS was lower than that of PS at low concentration. With the increase of concentration, the inhibitory effect of FePS increased rapidly and exceeded that of PS. The scavenging ability of FePS on superoxide anion radicals was obviously raised than that of PS, which showed a good synergistic effect.

Optimization of polysaccharide process from Fructus corni with box-behnken design and antioxidant capacity.

In the present study, the ultrasound-assisted extraction (UAE) process of polysaccharide from Fructus corni (FCP) was opitimized using the Box-Behnken design (BBD). The main parameters including ultrasound time (min), temperature (oC) and solvent to raw material ratio (mL/g) were chosen as the process variables for the optimization of UAE process. The results of analysis of variance indicated that the equation obtained from the experiments could represent the data and the predicted responses satisfactorily. The optimum conditons obtained by BBD were ultrasonic time (51min), temperature (69oC) and solvent to solid ratio (20mL/g) with actual yield (12.68±0.16%), which was good agreement with value predicted by the model. The antioxidant properties of FCP were assessed in vitro based on scavenging effect of the DPPH radical, hydroxyl radical and super oxide radical tests. The FCP possessed strong antioxidant abilities on DPPH and super oxide radical at the high concentration. The results on hydroxyl radical demonstrated that FCP exhibited high scavenging effect when the concentration was over 3000µg/mL. The findings suggested that the FCP had antioxidant capacities and could be developed as a source of natural antioxidants and functional food material.

Application of surfactant modified montmorillonite with different conformation for photo-treatment of perfluorooctanoic acid by hydrated electrons.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a class of highly persistent contaminants with high bioaccumulation and toxicity. Our previous studies showed that perfluorooctanoic acid (PFOA) can be completely defluorinated under UV irradiation in organo-montmorillonite/indole acetic acid (IAA) system. However, there is still lack of information for the degradation mechanism and the test for wastewater treatment. Here, we systematically investigated the defluorination reaction in the presence of different organo-montmorillonites and found that the degradation process was apparently controlled by the configuration of surfactants. In hexadecyltrimethyl ammonium (HDTMA)-modified montmorillonite, HDTMA exists as a tilt conformation and isolated clay interlayer from the aqueous solution, protecting hydrated electrons generated by photo-irradiation of IAA from quenching by oxygen. Defluorination hydrogenation process was the dominant degradation pathway. While in poly-4-vinylpyridine-co-styrene (PVPcoS)-modified montmorillonite, due to the multiple charges of PVPcoS, a flat conformation parallel to clay surface was expected. Hydroxyl radicals, which were generated by the reaction of hydrated electrons with oxygen molecules diffused into clay interlayer, are also involved in the degradation process. Our results further demonstrate that mixture modified montmorillonite could combine the advantages of both modifications, thus showing superior reactivity even for actual industrial wastewater without any pretreatment. This technique would have great potential for treatment of actual wastewater.

The antioxidant activities of carboxymethylated garlic polysaccharide and its derivatives.

The garlic polysaccharide (P) was extracted with the hot water, and the temperature was 80 °C, solid-liquid ratio was 1:7 (m/v), and extraction time was 150 min. In the experiment, carboxymethylated garlic polysaccharide (CM) was prepared with chloroacetic acid, and carboxymethylated-sulfated garlic polysaccharide (CMS) and carboxymethylated-phosphorylated garlic polysaccharide (CMP) were prepared with CM. The sugar content of CM and its derivatives were determined by the phenol­sulfuric acid method, and the degree of substitution of CM and its derivatives were characterized. Vc was used as a control to determine the four antioxidant activities (hydroxyl radical scavenging ability, superoxide anion scavenging ability, reducing ability, anti-lipid peroxidation ability) of CM and its derivatives. It showed that CM and its derivatives were potential antioxidants.