Chemical compositions and bioactivities of crude polysaccharides from tea leaves beyond their useful date

The chemical compositions and bioactivities of crude tea polysaccharides (TPS) from the out-of-date tea leaves (beyond their useful date), namely Xihu Longjing (XTPS), Anxi Tieguanyin (TTPS), Chawentianxia (CTPS) and Huizhoulvcha (HTPS), in market were investigated. These TPS showed similar neutral sugar content and different distribution of molecular weight (1-800 kD). These crude TPS were mainly composed of rhamnose, arabinose, galactose, glucose, xylose, mannose, and galacturonic acid. IR spectra confirmed that these crude TPS were composed of polysaccharide, protein and uronic acids. These TPS showed similar DPPH scavenging activity and exhibited lower DPPH scavenging activities than Vc within 25-200 μg/mL. However, these TPS with higher concentrations (200-400 μg/mL) showed similar DPPH scavenging activity with Vc. HTPS exhibited significant higher superoxide anion scavenging activity than others TPS and gallic acid. XTPS showed significant higher inhibitory effects on α-glucosidase and α-amylase with inhibitory percentages of 64.35% and 82.24% than others TPS. TTPS, XTPS, and HTPS exhibited similar inhibition ability on α-d-glucosidase and α-amylase. The overdue tea leaves can be a resource of tea polysaccharides as function food.     

Characterization and in vitro antioxidant activities of polysaccharides from Pleurotus ostreatus

Two polysaccharide fractions (PSPO-1a and PSPO-4a) were isolated from the fruiting bodies of Pleurotus ostreatus using ethanol precipitation, anion-exchange chromatography and gel permeation chromatography. Both fractions were heteropolysaccharide containing protein and uronic acid. PSPO-1a was composed of mannose, glucose, galactose, xylose and rhamnose with a molar ratio of 2.47:0.91:1.00:1.66:3.87. PSPO-4a was composed of only three monosaccharides: rhamnose, mannose and galactose with a molar ratio of 0.92:2.69:1.00. The average molecular weight of PSPO-1a and PSPO-4a determined by HPLC were estimated to be 1.8 × 10(4)Da and 1.1 × 10(6)Da respectively. The in vitro tests revealed that two polysaccharides were natural potential antioxidant. Both polysaccharides presented stronger DPPH radical and superoxide anion radical scavenging activity with increasing concentrations, but less effective on scavenging hydroxyl radical. Compared with PSPO-4a, PSPO-1a was the more effective free-radical scavenger. In conclusion, the two polysaccharides may be useful as a naturally potential antioxidant agent for application in food and medicinal fields.     

药用真菌灵芝液体培养过程中的抗氧化活性研究

灵芝Ganoderma lingzhi是一种重要的药用真菌,已被《中国药典》正式收录。本研究主要以菌丝体干重、多糖含量、多酚含量、黄酮含量、抗坏血酸（ascorbic acid,AA）含量、总抗氧化能力（total antioxidant capacity,T-AOC）、超氧化物歧化酶（superoxide dismutase,SOD）活性、羟自由基清除能力、超氧阴离子清除能力、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力、2,2′-连氮-双(3-乙基苯并噻唑-6-磺酸)[2,2′-azino-bis(3- ethylbenzthiazoline-6-sulphonic acid),ABTS]自由基清除能力、铁离子还原能力（ferric reducing antioxidant power,FRAP）和亚铁离子螯合能力为测定指标,对灵芝液体培养过程中的抗氧化活性进行了评价。结果显示,该菌具有较高的抗氧化活性,体现在液体培养过程中生长代谢旺盛,可分泌大量多糖、多酚、黄酮、AA等物质和SOD等酶类,对羟自由基、超氧阴离子、DPPH自由基及ABTS自由基等的清除效果显著,且具有较强的铁离子还原能力和亚铁离子螯合作用,这也说明该菌的抗氧化活性与其自身的生长状况、次级代谢产物分泌及还原能力等密切相关。此外,一定的环境胁迫压力也可以激发该菌启动自身的抗氧化系统以保护机体免受氧化损伤。     

Comparison in antioxidant action between α-chitosan and β-chitosan at a wide range of molecular weight and chitosan concentration

Antioxidant activity in α- and β-chitosan at a wide range of molecular weight (Mw) and chitosan concentration (CS) was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, reducing ability, chelating ability, and hydroxyl radical scavenging activity. The form of chitosan (FC) had significant (P <0.05) effect on all measurements except DPPH radical scavenging activity, and antioxidant activity was dependent on Mw and CS. High Mw (280–300 kDa) of β-chitosan had extremely lower half maximal effective concentrations (EC₅₀) than α-chitosan in DPPH radical scavenging activity and reducing ability. The 22–30 kDa of α- and β-chitosan showed significantly (P <0.05) higher activities in DPPH radical scavenging, reducing ability, and hydroxyl radical scavenging than samples at other Mw, while chelating ability was the highest in 4–5 kDa chitosan. CS had significant effect on all measurements and the effect was related to Mw. The antioxidant activity of 280–300 kDa chitosan was affected by coil-overlap concentrations (C¹) in the CS range of 4–10 mg/mL, forming entanglements. Reducing ability and hydroxyl radical scavenging activity were more predominant action in antioxidant activity of chitosan as shown by the lower EC₅₀ values than those in other antioxidant measurements.     

四种野生食用菌粗多糖的抗氧化活性

利用DPPH自由基清除法、羟基自由基(OH.)清除法、铁离子鳌合能力及测定还原能力等方法对鸡油菌Cantharellus cibarius、变绿红菇Russula virescens、蜜环菌Armillaria mellea和棕灰口蘑Tricholoma myomyces等4种食用菌的粗多糖进行了抗氧化活性评价。结果显示,4种真菌粗多糖均不同程度地具有抗氧化活性。在DPPH自由基清除试验中,棕灰口蘑和蜜环菌表现出很强的活性,其EC50值分别为1.35 g/L、1.53 g/L;棕灰口蘑和蜜环菌对羟基自由基的清除能力也要优于其他2种食用菌,其EC50值分别为0.65 g/L、0.78 g/L;棕灰口蘑的铁离子螯合能力明显优于其他3种测试菌,其EC50值为1.69 g/L;在还原力方面同样是棕灰口蘑活性最强,蜜环菌次之,其EC50值为1.05 g/L、1.37 g/L。     

Antioxidant activity of sulfated polysaccharide fractions extracted from Laminaria japonica

Fucoidan, a group of sulfated heteropolysaccharide, was extracted from Laminaria japonica, an important economic alga species in China. Three sulfated polysaccharide fractions (F1, F2, and F3) were successfully isolated through anion-exchange column chromatography and had their antioxidant activities investigated employing various established in vitro systems, including superoxide and hydroxyl radical scavenging activity, chelating ability, and reducing power. Chemical analysis suggested that F1 and F3 were heteropolysaccharide in which galactose was the major component, while F2 was a typical fucoidan. All fractions possessed considerable antioxidant activity, and F1, F2 and F3 had stronger antioxidant ability than fucoidan in certain tests. The correlation between the sulfate content and scavenging superoxide radical ability was positive. Available data obtained with in vitro models suggested that the ratio of sulfate content/fucose was an effective indicator to antioxidant activity of the samples.     

Structure elucidation and antioxidant activity of a novel polysaccharide isolated from Boletus speciosus Forst

In this study, a novel heteropolysaccharide was isolated from the fruiting bodies of Boletus speciosus Forst through DEAE-cellulose column and Sephadex G-200 column. The Boletus speciosus Forst polysaccharide (BSFP-1) had a molecular weight of 1.33×10(4) Da and was mainly composed of l-Man and d-Gal which ratios were 2:1. Structural features of Boletus speciosus Forst polysaccharide (BSFP-1) were investigated by a combination of total hydrolysis, methylation analysis, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectra and nuclear magnetic resonance (NMR) spectroscopy. The results indicated that Boletus speciosus Forst polysaccharide (BSFP-1) had a backbone of (1→4)-α-l-mannopyranose residues which branches at O-6 based on the experimental results. The branches were mainly composed of one with →1)-α-d-galactopyranose residue. The antioxidant activity of BSFP-1 was evaluated with two biochemical methods, including 1,1-diphenyl-2-picrylhydrazyl (DPPH(-)) radical scavenging, scavenging activity of 2,2'-azino-bis(3-ethylbenzthiazoline-6-suphonic acid)diammonium (ABTS(+)) radical. The results indicated that BSFP-1 showed strong antioxidant.     

Physico-chemical characterization, antioxidant and anticancer activities in vitro of a novel polysaccharide from Melia toosendan Sieb. Et Zucc fruit

A novel water-soluble polysaccharide pMTPS-3, obtained from Melia toosendan Sieb. Et Zucc fruit by hot-water extraction and ethanol precipitation, was fractionated by DEAE-52 cellulose anion-exchange and Sephadex G-100 gel filtration chromatography. Its primary structural features and molecular weight were characterized by Fourier infrared spectrometry (FTIR), gel permeation chromatography (GPC) and gas chromatography (GC). And the antioxidant activities of pMTPS-3 in vitro were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay, superoxide radical scavenging assay and hydroxyl radical scavenging assay. The results suggested that pMTPS-3 was a heteropolysaccharide, composed of arabinose, glucose, mannose, and galactose in the molar ratio of 17.3:28.3:41.6:12.6 with molecular weight 26 100 Da. The purified pMTPS-3 was revealed to have notable scavenging activity against DPPH radical in a concentration-dependent manner and present a moderate inhibition of superoxide radicals with an IC₅₀ (5.6 mg/ml), and potent inhibiting power for hydroxyl radical compared with crude polysaccharide. Further, it exhibited strong inhibition effect in vitro on the growth of human gastric cancer BGC-823 cells. It is strongly evidenced that pMTPS-3 purified from the crude polysaccharides of Melia toosendan Sieb. Et Zucc could be explored as a potential antioxidant and therapeutics.     

Improvement of antioxidant activity of chitosan by chemical treatment and ionizing radiation

Modification of chitosan (CS) to N-maleoylchitosan (NMCS), N-phthaloylchitosan (NPhCS) and sulfonated-chitosan (SCS) was done using maleic anhydride, phthalic anhydride and chlorosulfonic acid, respectively followed by exposing them to γ-rays at different doses. The molecular weights and structural changes of irradiated chitosan derivatives were determined by GPC, FT-IR and UV-vis spectrophotometer. The molecular weights decreased with increasing irradiation dose. Results revealed that the main polysaccharide structure remained after irradiation. To investigate the enhancement of antioxidant activity of chitosan and its derivatives of different molecular weights, radical mediated lipid peroxidation inhibition, scavenging effect of DPPH radicals, reducing power and ferrous ion chelating activity assays were used. Chitosan derivatives with different molecular weights exhibit antioxidant activity. The lower the molecular weights of chitosan and its derivatives, the higher the antioxidant activity. NMCS possessed high scavenging effect on DPPH radicals compared with NPhCS, SCS and ascorbic acid. The irradiated chitosan and its derivatives could be used as natural antioxidants.     

印度块菌提取物抗氧化活性的研究

对印度块菌Tuber indicum子实体的提取物,包括55%乙醇粗提物(ECE)、石油醚提取物(PEF)和乙酸乙酯提取物(EAF)的清除DPPH自由基和羟基自由基能力、铁离子鳌合能力以及各提取物的总酚含量等进行了研究和测定,结果显示,3种提取物的清除自由基能力和铁离子鳌合能力具有显著差异(P0.05);ECE对DPPH自由基的清除活性最高,其EC50值为1.61g/L;EAF对羟基自由基及铁离子表现出较强的清除或螯合的能力,其EC50值分别为3.31g/L和0.70g/L;EAF的总酚含量(2.964mg GAE/g提取物)最高,其次是ECE,总酚含量为(2.618mg GAE/g提取物);PEF的清除自由基和铁离子鳌合能力较差,其总酚含量也最低(1.124mg GAE/g提取物);总酚含量与印度块菌提取物清除自由基以及鳌合铁离子的能力密切相关。     

Effect of the chelation of metal cation on the antioxidant activity of chondroitin sulfates

The antioxidant potencies of chondroitin sulfates (CSs) from shark cartilage, salmon cartilage, bovine trachea, and porcine intestinal mucosa were compared by three representative methods for the measurement of the antioxidant activity; DPPH radical scavenging activity, superoxide radical scavenging activity, and hydroxyl radical scavenging activity. CSs from salmon cartilage and bovine trachea showed higher potency in comparison with CSs from shark cartilage and porcine intestinal mucosa. Next, CS from salmon cartilage chelating with Ca²⁺, Mg²⁺, Mn²⁺, or Zn²⁺ were prepared, and their antioxidant potencies were compared. CS chelating with Ca²⁺ or Mg²⁺ ions showed rather decreased DPPH radical scavenging activity in comparison with CS of H⁺ form. In contrast, CS chelating with Ca²⁺ or Mg²⁺ ion showed remarkably enhanced superoxide radical scavenging activity than CS of H⁺ or Na⁺ form. Moreover, CS chelating with divalent metal ions, Ca²⁺, Mg²⁺, Mn²⁺, or Zn²⁺, showed noticeably higher hydroxyl radical scavenging activity than CS of H⁺ or Na⁺ form. The present results revealed that the scavenging activities of, at least, superoxide radical and hydroxyl radical were enhanced by the chelation with divalent metal ions.     

Antioxidant Activity of Purified Protein Hydrolysates from Northern Whiting Fish (Sillago sihama) Muscle

In the present study, northern whiting fish (Sillago sihama) muscle was hydrolyzed with gastrointestinal enzymes (pepsin, trypsin and α-chymotrypsin) separately and the resulted protein hydrolysates were tested for antioxidant activities using DPPH radical scavenging activity and reducing power assays. The protein hydrolysate obtained from trypsin exhibited highest antioxidant activity. Further, it was fractionated by consecutive chromatography using anion exchange and gel filtration chromatography; the separated fractions were collected and evaluated for antioxidant activity. The results showed that fraction 2 exhibited high chelating activity (73.15 % at 0.5 mg/mL) and best radical scavenging activity for DPPH radical (55.16 % at 0.5 mg/mL), ABTS radical (57.98 % at 50 μg/mL), superoxide radical (39.55 % at 200 μg/mL) and hydroxyl radical (51.33 % at 100 μg/mL). In addition, the active fraction showed strong antioxidant activity in the inhibition of linoleic acid autooxidation (60 % at 0.5 mg/mL) and also it exhibited significant protective effect on DNA damage caused by hydroxyl radicals. The size of the active fraction was found to be <360.2 Da using mass spectroscopy. These results demonstrate that muscle protein hydrolysate from northern whiting fish could be a best alternative to produce natural antioxidant peptides.     

Antioxidant and free radical scavenging properties of N-acetylcysteine amide (NACA) and comparison with N-acetylcysteine (NAC)

The antioxidant potential of N-acetylcysteine amide (NACA), also known as AD4, was assessed by employing different in vitro assays. These included reducing power, free radical scavenging capacities, peroxidation inhibiting activity through linoleic acid emulsion system and metal chelating capacity, as compared to NAC and three widely used antioxidants, alpha-tocopherol, ascorbic acid and butylated hydroxytoluene (BHT). Of the antioxidant properties that were investigated, NACA was shown to possess higher 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging ability and reducing power than NAC, at all the concentrations, whereas the scavenging ability of H(2)O(2) differed with concentration. While NACA had greater H(2)O(2) scavenging capacity at the highest concentration, NAC was better than NACA at lower concentrations. NAC and NACA had a 60% and 55% higher ability to prevent beta-carotene bleaching, respectively, as compared to control. The chelating activity of NACA was more than 50% that of the metal chelating capacity of EDTA and four and nine times that of BHT and alpha-tocopherol, respectively. When compared to NACA and NAC; alpha-tocopherol had higher DPPH scavenging abilities and BHT and alpha-tocopherol had better beta-carotene bleaching power. These findings provide evidence that the novel antioxidant, NACA, has indeed enhanced the antioxidant properties of NAC.     

Purification and identification of antioxidant peptides from egg white protein hydrolysate

Egg white proteins were hydrolysed separately using five different proteases to obtain antioxidant peptides. The antioxidant activity of egg white protein hydrolysates was influenced by the time of hydrolysis and the type of enzyme. Of the various hydrolysates produced, papain hydrolysate obtained by 3-h hydrolysis (PEWPH) displayed the highest DPPH radical scavenging activity. PEWPH could also quench the superoxide anion and hydroxyl radicals, effectively inhibit lipid peroxidation and exhibit reducing power. Then, PEWPH was purified sequentially by ultrafiltration, gel filtration, RP-HPLC and two fractions with relatively strong antioxidant activity were subsequently subjected to LC-MS/MS for peptide sequence identification. The sequences of the two antioxidant peptides were identified to be Tyr-Leu-Gly-Ala-Lys (551.54?Da) and Gly-Gly-Leu-Glu-Pro-Ile-Asn-Phe-Gln (974.55?Da), and they were identified for the first time from food-derived protein hydrolysates. Last, the two purified peptides were synthesized and they showed 7.48- and 6.02-fold higher DPPH radical scavenging activity compared with the crude PEWPH, respectively. These results indicate that PEWPH and/or its isolated peptides may be useful ingredients in food and nutraceutical applications.     

Purification, chemical characterization and radical scavenging activities of alkali-extracted polysaccharide fractions isolated from the fruit bodies of Tricholoma matsutake

Tricholoma matsutake, a high-class edible mushroom in China, has been regarded as famous foods and biopharmaceutical materials with a great deal of interest. In the previous investigations, researchers believe the water-soluble polysaccharide β-glucan is the major active component of T. matsutake, which displays various biological activities. In the present study, two novel alkali-extracted polysaccharide fractions, TM-APS-1 and TM-APS-2, were isolated from the fruit bodies of T. matsutake by DEAE-cellulose and Sepharose CL-6B columns on ÄTKA explorer chromatography system. Their chemical and physical characteristics and radical scavenging capacity were valuated, including chemical methods, GC, HPLC, scavenging activity against DPPH radicals, superoxide radicals, hydroxyl radicals, and chelating ability. The results showed that TM-APS-1 and TM-APS-2 exhibited significantly antioxidant activity at a concentration-dependent manner. The alkali-extracted polysaccharide fractions from T. matsutake can be developed to be novel functional food or pharmaceutical products with antioxidant effects.     

7种广西产甜茶抗氧化活性的比较

通过清除二苯代苦味酰基(1,1-diphenyl-2-picrylhydrazyl,DPPH)法、铁离子还原测定(ferric reducing antioxidant power,FRAP)法、亚铁离子螯合(ferrous ion-chelating,FIC)法、β-胡萝卜素-亚油酸法等4种体外抗氧化活性测定方法,首次比较了3种茶科属茶叶和7种广西产甜茶水提物的抗氧化活性,同时用Folin-Ciocalteus法测定了其总多酚的含量。研究结果表明,多穗柯甜茶和藤茶的总多酚含量高于其他供试品。藤茶具有很好的清除DPPH·的能力,高于绿茶及阳性对照水溶性维生素E(Trolox)和人工合成抗氧化剂二丁基羟基甲苯(butylated hydroxytoluene,BHT)。甜叶菊茶和悬钩甜茶的金属离子螯合能力均高于绿茶。其中,黄杞和牛白藤两种植物的抗氧化活性为首次报道。由此可见,广西产甜茶均具有较高的开发利用价值,是治疗和防治慢性代谢性疾病的重要研究对象。对广西产甜茶的研究对于了解和抢救某些少数民族的历史文化具有重要意义,为别样茶的抗氧化研究奠定了基础,值得进一步探索和开发。     

In vitro antioxidant activities of sulfated polysaccharide fractions extracted from Corallina officinalis

Sulfated polysaccharides (F1, F2) from seaweed Corallina officinalis were isolated through anion-exchange column chromatography. Their chemical characteristics were determined by GC, HPLC, FT-IR and UV spectra. F1 and F2 contained only two monosaccharides, namely galactose and xylose. The antioxidant activities of F1, F2 and the de-sulfated polysaccharides (DF-1, DF-2) in vitro were investigated, including hydroxyl radicals scavenging effect, superoxide radical scavenging capacity, DPPH radical activity and reducing power. As expected, antioxidant assay showed that the two sulfated polysaccharide fractions (F1, F2) possessed considerable antioxidant properties and had more excellent abilities than de-sulfated polysaccharides (DF-1, DF-2).     

有柄石韦醇提物抗氧化活性研究

通过DPPH自由基清除测定、还原能力、总抗氧化能力、羟自由基清除测定,评价有柄石韦Pyrrosia petiolosa醇提物的抗氧化活性。结果显示,有柄石韦醇提物清除DPPH·的IC50为75.82 μg·mL-1,清除·OH的IC50为46.30 μg·mL-1。有柄石韦醇提物清除DPPH· 的能力强于抗坏血酸,清除·OH的能力弱于抗坏血酸;同时,其还原能力和总抗氧化能力均强于抗坏血酸。该结果说明有柄石韦醇提物具有较强的抗氧化活性。     

Antioxidant and antiradical activities of L-carnitine

L-carnitine plays an important regulatory role in the mitochondrial transport of long-chain free fatty acids. In this study, the antioxidant activity of L-carnitine was investigated as in vitro. The antioxidant properties of the L-carnitine were evaluated by using different antioxidant assays such as 1, 1-diphenyl-2-picryl-hydrazyl free radical (DPPH.) scavenging, total antioxidant activity, reducing power, superoxide anion radical scavenging, hydrogen peroxide scavenging and metal chelating activities. Total antioxidant activity was measured according to ferric thiocyanate method. alpha-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant compounds. At the concentrations of 15, 30 and 45 microg/mL, l-carnitine showed 94.6%, 95.4% and 97.1% inhibition on lipid peroxidation of linoleic acid emulsion, respectively. On the other hand, 45 microg/mL of standard antioxidant such as alpha-tocopherol and trolox indicated an inhibition of 88.8% and 86.2% on peroxidation of linoleic acid emulsion, respectively. In addition, L-carnitine had an effective DPPH. scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, total reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to alpha-tocopherol and trolox as references antioxidants.     

Antioxidant activity of different molecular weight sulfated polysaccharides from <Emphasis Type="Italic">Ulva pertusa</Emphasis> Kjellm (Chlorophyta)

Polysaccharides extracted from Ulva pertusa Kjellm (Chlorophyta) are a group of sulfated heteropolysaccharides, the ulvans. In this study, different molecular weight ulvans were prepared by H₂O₂ degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U₃ (the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC₅₀ values of 22.1 μ g mL⁻¹ and 2.8 mg mL⁻¹; its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of ulvan with low molecular weight ulvan having stronger antioxidant activity.