Correlation between the antitumor activity of a polysaccharide schizophyllan and its triple-helical conformation in dilute aqueous solution

Eight samples of a polysaccharide schizophyllan ranging in weight-average molecular weight Mw (in water) from 5 x 10(3) to 1.3 x 10(5) were prepared and their antitumor activity (expressed in terms of the tumor inhibition ratio) against Sarcoma 180 ascites, intrinsic viscosities [eta], and gel-filtration chromatograms in aqueous solution were determined. The tumor inhibition ratio was essentially unity for samples with Mw higher than 9 x 10(4), but reduced to zero or even to a negative value when Mw was lower than 10(4). The [eta] data combined with the chromatographic data showed that above Mw approximately 9 x 10(4) the predominant species of schizophyllan in aqueous solution is the previously found rigid triple helix, whereas below Mw approximately 9 x 10(4) both triple helices and single chains coexist in the solution and the fraction of triple helices decreases monotonically to zero as Mw is decreased to 5 x 10(3). From these findings it was concluded that the antitumor potency of schizophyllan in water is related to the amount of triple helices relative to that of single chains.     

Structure and chain conformation of beta-glucan isolated from Auricularia auricula-judae

From Auricularia auricula-judae, a water soluble beta-D-glucan, named as AAG, was isolated by extraction with 70% ethanol/water solution. Its chemical structure was analyzed by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), matrix-assisted laser desorption /ionization (MALDI)-time of flight (TOF), and 1D, 2D NMR. AAG was detected, for the first time, to be composed of a main chain of (1-->4)-linked D-glucopyranosyl with glucopyranosyl side groups at O6. With the help of MALDI-TOF-MS, the sequence and the distribution of glucuronic acid were determined and the content of glucuronic acid is about 19%. Five fractions were prepared from the AAG sample in water by ultrasonic degradation method. Their molecular weight, size, and shape (chain conformation) were studied by dynamics light scattering (DLS), static laser light scattering (LLS), size exclusion chromatography combined LLS (SEC-LLS) and viscometry in 0.1M NaCl aqueous solution at 25 degrees C. The dependence of intrinsic viscosity ([eta]) on Mw for this polysaccharide was established to be [eta] = 1.22 x10(-3)Mw (1.00) (cm3 g(-1)) in the range of Mw from 3.40 x 10(4) to 2.88 x 10(5). The conformational parameters of the AAG polysaccharide were found to be 820 nm(-1) for molar mass per unit contour length (ML), 12.3 nm for persistence length (q) and 2.1 for rho (s2(1/2)/Rh). The results suggested that the polysaccharide exists as extended chains in 0.1M NaCl aqueous solution. The chemical structure of AAG containing glucuronic acid and side groups led to steric hindrance, resulting in the increased stiffness of the chains.     

Allowing for polymer polydispersity--an essential condition for determination of aqueous pore diameters in cell walls and membranes using polymers

A method of allowing for polydispersion of polyethylene glycol (PEG) preparations was developed for the use of these preparations for the osmometrical evaluation of pore diameters with aqueous pores of Chara corallina cell walls as an example. The mass share of polyethylene glycol preparation fractions gamma p penetrating through the pores was determined using cellular "shadows", fragments of internodal cell walls tied up at the ends and filled with a 25% solution of nonpenetrating PEG 6000. When immersed into water, such "shadow" acquired a turgor (hydrostatic) pressure close to the cellular pressure and persistent over long time. The determination of gamma p for polyethylene glycols with different average molecular weights Mw was performed from the degree of pressure restoration after water was replaced by a 5-10% polymer solution. The kinetics of pressure changes was recorded using a mechanotronic dynamometer, which measures, in the quasi-isometric mode, the force necessary for partial compression of the "shadow" in its small fragment. By utilizing the dependence of the overall share of fractions with molecular weights Mi < Mk on Mk (data of [1]), we found that gamma p, for these polyethylene glycols corresponds to the threshold value of Mk = 800-1100 D (hydrodynamic radius of molecules rh = 0.85-1.05 nm). Thus, the effective diameter of the pores in the cell wall of Chara does not exceed 2.1 nm. It was shown that the smoothness of the sigmoid shape of the dependence of ionic channel conductivity on the Mw value of the polymer in the media is largely due to the polydispersion of polymer preparations, particularly, to the reduction in the share of fractions penetrating the channels as Mw is increased. The method normally used to estimate pore diameters in ionic channels which ignores the dispersion of polymer preparations, results in overestimated values.     

香菇蛋白的分级纯化和结构分析

香菇粉经10℃pH 10的水提取制备香菇蛋白,得率13.1%,其蛋白含量47.5%,多糖含量24.2%.香菇蛋白经DEAE Sepharose CL-6B柱层析分级得5个级分,收集级分F1、F2、F3、F4,它们都是由蛋白和多糖构成的复合物.Sepharose CL-6B凝胶色谱显示,F2和F4的分子量分布较为均匀,且以蛋白为主,多糖含量很低;F3主要由两个分子量不同的蛋白级分构成,含有一定的多糖;F1中多糖含量较高,蛋白含量较少,且多糖分子量分布均匀.香菇蛋白的分子量主要集中在20 kDa～40 kDa之间.F1、F3、F4都属于酸性蛋白质,含有除色氨酸之外的7种必需氨基酸,除蛋氨酸含量较低外,其余必需氮基酸含量接近,且赖氨酸含量较高.红外光谱分析表明,香菇蛋白的二级结构主要为α-螺旋和无规卷曲.     

Chain conformation of water-insoluble hyperbranched polysaccharide from fungus

Water-insoluble polysaccharide (TM3a), extracted from sclerotia of Pleurotus tuber-regium, was identified as a hyperbranched beta-d-glucan from the results of one- and two-dimensional NMR and GC-MS analysis. The degree of branching of TM3a is 65.5%. TM3a was fractionated by using a non-solvent addition method into 14 fractions, and its solution properties in 0.25 M LiCl/dimethylsulfoxide (DMSO) solution were studied systematically by using static laser light scattering, dynamic light scattering, and viscometry at 25 degrees C. The dependences among the values of intrinsic viscosity ([eta]), radius of gyration (z 1/2), and hydradynamic radius (Rh) on weight-average molecular weight (Mw) were found as the following: [eta] = 0.46Mw0.30+/-0.01, z 1/2 = 4.79 x 10-2Mw0.43+/-0.04, and Rh = 5.01 x 10-2Mw0.41+/-0.02 in the Mw range from 1.94 x 105 to 2.06 x 107 for TM3a in a 0.25 M LiCl/DMSO solution at 25 degrees C. The current theory of polymer solution was applied to explain the relationship among the fractal dimension, ratio of geometric to hydrodynamic radius (rho = z 1/2/Rh), and MwA2/[eta] of TM3a. The results indicated that TM3a existed as a compact chain conformation with a sphere-like structure in LiCl/DMSO solution. Furthermore, by using transmission electron microscopy, we observed directly the spherical molecules with an average diameter of 23.0 +/- 1.8 nm.     

Alignment of absolute and relative molecular size specifications for a polyvalent pneumococcal polysaccharide vaccine (PNEUMOVAX 23).

An approach was developed to align release and end-expiry specifications for molecular size for the polyvalent pneumococcal polysaccharide vaccine (PNEUMOVAX 23). Each of the 23 polysaccharide components of the vaccine was separately subjected to ultrasonication to produce a series of preparations of decreasing weight-average molecular mass (Mw). These size-reduced polysaccharides were analysed as monovalent solutions by high-performance size exclusion chromatography (HPSEC) with multi-angle laser light scattering (MALLS) and refractive index (RI) detection to measure their Mw. These samples were also analysed by HPSEC with rate nephelometry (RN) detection to measure their relative molecular size (r-MS). The data from the two molecular size measurements established a correlation between Mw and r-MS. For each polysaccharide component of the vaccine, this correlation permits the direct alignment of the r-MS specification in the final formulated product with the Mw specification for the monovalent polysaccharide preparation. The alignment of specifications provides a high level of assurance that the quality control of the final vaccine product is consistent with that of the polysaccharide starting materials.     

Chain conformation of sulfated derivatives of beta-glucan from sclerotia of Pleurotus tuber-regium

Six water-insoluble (1-->3)-beta-D-glucan fractions TM8-1 to TM8-6 with weight-average molecular mass Mw ranging from 5.76 to 77.4x10(4) obtained from the sclerotia of Pleurotus tuber-regium were sulfated to produce the water-soluble fractions S-TM8-1 to S-TM8-6 with Mw from 6.0 to 64.8x10(4). The degree of substitution (DS) of S-TM8 fractions was analyzed by elemental analysis (EA) to be 1.14-1.74. The 13C NMR results indicated that the C-6 was fully substituted, and C-2, C-4 were partially substituted by the sulfo-groups. The Mw and the intrinsic viscosity [eta] of the S-TM8 fractions were measured, respectively, by size-exclusion chromatography combined with laser light scattering (SEC-LLS), LLS and viscometry in phosphate buffer solution (PBS) at 37 degrees C. The dependences of [eta] and radius of gyration z(1/2) on Mw for the S-TM8 samples were found to be [eta]=1.89x10(-2) Mw(0.70) (cm3/g) and z(1/2)=1.12x10(-4) Mw(0.81) (nm) in the Mw range tested. Based on current theories for a wormlike chain model, the molar mass per unit contour length ML and persistence length q of the S-TM8 were calculated to be 990 nm(-1) and 8.5 nm, respectively. The relatively higher q value suggested a more expanded flexible chain of S-TM8 in PBS. The water-solubility and relatively expanded chain conformation of the STM8 fractions were considered to be significant to their antiviral activity.     

Water-soluble polysaccharides from Salvia officinalis L. possessing immunomodulatory activity

A water-soluble polysaccharide complex (A) composed of galactose (17.9%), 3-O-methyl-galactose (3.0%), glucose (15.5%), mannose (8.3%), arabinose (30.4%), xylose (7.6%), fucose (2.6%), rhamnose (6.7%), and uronic acids (8.0%) has been isolated from the aerial parts of sage (Salvia officinalis L.) by cold water extraction. It showed a broad molecular-mass distribution pattern (Mw approximately 2000-93,000) with a predominance of polymers with Mw< 10,000. Ion-exchange chromatography of A afforded six polymeric fractions (A1-A6) in which arabinogalactans associated with galacturonan and/or rhamnogalacturonan backbones prevail. Sage polysaccharides were examined for their immunomodulatory activity in the comitogenic thymocyte test which is interpreted as being an in vitro correlate of adjuvant activity. The acidic polysaccharide fractions A2, A3 and A4 exhibited the highest mitogenic and comitogenic activities of all fractions tested, and relatively high SI(comit)/SI(mit) ratios approximately 3 indicate potential adjuvant properties of these polysaccharides.     

Effects of urea and sodium hydroxide on the molecular weight and conformation of alpha-(1-->3)-D-glucan from Lentinus edodes in aqueous solution

The weight-average molecular weight (Mw) and intrinsic viscosity ([eta]) of the alpha-(1-->3)-D-glucan (L-FV-II) from Lentinus edodes in 0.5 and 1.0 M NaOH aqueous solution containing urea, were studied by light scattering and viscometry. The Mw value of the glucan decreased with increase of the urea and NaOH concentration. A strong intermolecular hydrogen bonding confers water-insolubility on the glucan, but NaOH and especially urea, broke this hydrogen bonding leading to enhanced water-solubility. Use of 1.0 M urea-1.0 M NaOH as solvent broke not only intermolecular hydrogen bonds but also partial covalent bonds of the alpha-glucan in aqueous solution, resulting in a decrease of Mw and [eta]. The urea and NaOH concentrations, storage time with stirring, and mode of preparation of the polysaccharide in aqueous solution significantly affected the determination of Mw and [eta]. The dependences of specific rotation and fluorescence emission ratio of a probe on urea concentration showed that a change in the molecular conformation of the alpha-glucan in 0.5 M NaOH aqueous solution containing urea occurred in the range 0.4-0.6 M urea. The 0.5 M urea-0.5 M NaOH aqueous solution is a suitable solvent for the glucan, and the Mw and [eta] values obtained were 5.21 x 10(5) and 148 cm3 g(-1), respectively. Degradation of the glucan was obvious after storage for 15 months.     

Bacterial polysaccharides of polymyxan 88A. Basic characteristics and extent of possible uses]

A new high-viscous polysaccharide polymyxan from Bacillus polymyxa 88A is described. Polymyxan consists of an acid high-viscous polysaccharide (Mw 1-10 MD) and a neutral low-viscous polysaccharide (Mw 100-300 kD), which is a glucomannan containing equal amounts of monosaccharides and traces of uronic acids. The acid high-viscous polysaccharide consists of 36% glucose, 36% mannose, 7% galactose and 21% glucuronic acid. Data are presented on the application of polymyxan in baking industry and for preparation of drilling muds.     

Auxin-Induced Changes in the Molecular Weight Distribution of Cell Wall Xyloglucans in Avena Coleoptiles

The effect of auxin on the molecular weight (Mw) distributionof cell wall xyloglucans was investigated by gel permeationchromatography using coleoptile segments of Avena sativa L.cv. Victory, and the following results were obtained.

1. The water-insoluble hemicellulose (HC-A) mainly consisted ofxyloglucans. Iodine staining method revealed that relativelylarge amounts of xyloglucans were present in the water-solublehemicellulose (HC-B) and water-soluble polysaccharide (WS) fractions.
2. IAA did not cause remarkable changes in xyloglucan contentsin the hemicellulose, but significantly increased the xyloglucancontent in the WS fraction.
3. IAA substantially decreased theweight-average Mw of HC-A. Thiseffect became apparent within30 min of the incubation period,and was not affected by the0.15 M mannitol or 2% sucrose applied.Hydrogen ions also causeda decrease in the weight-average Mwof HC-A; its effect beingreversible.
4. Neither IAA nor hydrogen ions caused any remarkablechangesin the weightaverage Mw of water-soluble xyloglucansin theHC-B.

These results suggest that cell wall xyloglucans have an importantrole in auxininduced cell wall loosening in oat coleoptile cells. (Received May 10, 1984; Accepted August 20, 1984)     

Physical characteristics and antioxidant effect of polysaccharides extracted by boiling water and enzymolysis from Grifola frondosa

Grifola frondosa has been widely consumed in China and other Asian countries. Recent studies on G. frondosa have focused on the activities of polysaccharides extracted by water, and the activities of polysaccharides extracted by enzymolysis have not been studied. In this work, the relationship between the physical properties and antioxidant activity of polysaccharides extracted from G. frondosa by boiling water and enzymolysis was studied. Five polysaccharide extracts from the fruit body of G. frondosa were prepared by different extracting methods including boiling water, single enzyme enzymolysis with three different single enzymes (cellulose, pectinase, and pancreatin), and combined enzyme enzymolysis (cellulose:pectinase:pancreatin; 2:2:1). Characteristics such as the viscosity, Mw, polysaccharide content, protein content, infrared spectra, and antioxidant activities of the extracts were evaluated. The highest antioxidant activity was exhibited by the extracts prepared by combined enzyme extraction. The correlation analysis between antioxidant activity and polysaccharide content, protein content, Mw or viscosity indicated that the Mw had a more important role in antioxidant activity. Overall, the results indicate that the combined enzyme polysaccharide extracts can be developed as a new potential natural antioxidant.     

Structural properties of polydisperse biopolymer solutions: a light scattering study of bovine alpha-crystallin.

We have measured mean value of RHz, mean value of R2G1/2z, and mean value of Mw for individual fractions of the protein alpha-crystallin obtained by gel filtration of bovine lens nuclear extracts. A strong and monotonic decrease of mean value of RHz and mean value of Mw with increasing elution volume could be observed, indicating a broad size distribution. The experimental results are quantitatively consistent with a polymerization of monomeric units into linear chains, which may have a certain degree of flexibility. Using theoretical expressions for mean value of R2G and mean value of RH originally derived for semiflexible polymers in solution, we can self-consistently analyse the data from static and dynamic light scattering, and from electron microscopy experiments. We thus obtain detailed information on the molecular weight distribution and the quaternary structure of alpha-crystallin in these solutions.     

Physicochemical properties and antitumor activities of water-soluble native and sulfated hyperbranched mushroom polysaccharides

A water-soluble hyperbranched beta-glucan, coded as TM3b, extracted from sclerotia of an edible fungus (Pleurotus tuber-regium) was fractioned into eight fractions coded as F1-F8 by a nonsolvent addition method. Five fractions were treated with chlorosulfonic acid at 35 degrees C to synthesize successfully sulfated derivatives coded as S-F2, S-F3, S-F4, S-F5, and S-F8 with degree of substitution of 0.28-0.54. The 13C NMR results of these sulfated beta-glucans indicated that while the C-6 position was fully substituted, C-2, C-3, and C-4 were only partially substituted by the sulfate groups. The weight-average molecular weights (Mw) and intrinsic viscosities ([eta]) of the native and sulfated TM3b fractions were determined using multi-angle laser light scattering and viscometry in 0.15M aq NaCl at 25 degrees C, respectively. The dependences of [eta] on Mw for TM3b and sulfated TM3b were found to be [eta]=0.18Mw(0.28+/-0.03) (Mw range from 3.30 x 10(4) to 3.90 x 10(7)) and [eta]=2.24 x 10(-2)Mw(0.52+/-0.06) (Mw range from 3.24 x 10(4) to 3.15 x 10(5)) in 0.15M aq NaCl at 25 degrees C, respectively. It revealed that both the native TM3b and its sulfated derivatives exist in a spherical chain conformation in 0.15M aq NaCl. Furthermore, the native and sulfated TM3b fractions showed potent antitumor activities in vivo and in vitro. The sulfated derivatives exhibited relatively higher in vitro antitumor activity against human hepatic cancer cell line HepG2 than the native TM3b. Water solubility and introduction of sulfate groups were the main factors in enhancing the antitumor activities.     

Dextran retention in the rat brain following release from a polymer implant.

Intracranial controlled release polymers may improve drug administration to the brain, where therapy is frequently limited due to the low permeability of brain capillaries to therapeutic agents. On the basis of drug transport and elimination rates, we proposed that high molecular weight, water-soluble molecules would be retained in the brain space following release from an intracranial implant. To test this hypothesis, solid particles of different molecular weight fractions of fluorescein isothiocyanate labeled dextran (FITC-dextran; 4 x 10(3) Da (4 kDa) < weight-averaged molecular weight (Mw) < 150 kDa) or fluorescein were uniformly dispersed in matrices of a polyanhydride copolymer synthesized from a fatty acid dimer and sebacic acid in a 50:50 ratio, P(FAD:SA). When incubated in buffered saline, FITC-dextran fractions of 70 kDa Mw were released from the polymer within 48 h; 4 kDa Mw FITC-dextran and fluorescein were released more slowly. Following implantation of P(FAD:SA) matrices containing either 70 kDa Mw FITC-dextran, 4 kDa Mw FITC-dextran, or fluorescein into the brains of normal rats, fluorescent tracers were continuously released into the brain tissue for 30 days. Tracer concentrations within the brain were significantly higher for large molecular weight tracers (70 kDa Mw FITC-dextran > 4 kDa Mw FITC-dextran > fluorescein). The rate of elimination, kapp, of each tracer from the brain was determined by comparing experimental data with a model describing tracer diffusion/elimination in the brain extracellular space; kapp decreased with increasing molecular weight (fluorescein > 4 kDa Mw FITC-dextran > 70 kDa Mw FITC-dextran).     

Solution properties of antitumor sulfated derivative of alpha-(1-->3)-D-glucan from Ganoderma lucidum

Four fractions of a water-insoluble alpha-(1-->3)-D-glucan GL extracted from fruiting bodies of Ganoderma lucidum were dissolved in 0.25 M LiCl/DMSO, and then reacted with sulfur trioxide-pyridine complex at 80 degrees C to synthesize a series of water-soluble sulfated derivatives S-GL. The degree of substitution of DS was measured by using IR infrared spectra, elemental analysis, and 13C NMR to be 1.2-1.6 in the non-selective sulfation. Weight-average molecular weight Mw and intrinsic viscosity [eta] of the sulfated derivatives S-GL were measured by multi-angle laser light scattering and viscometry. The Mw value (2.4 x 10(4)) of sulfated glucan S-GL-1 was much lower than that (44.5 x 10(4)) of original alpha-(1-->3)-D-glucan GL-1. The Mark-Houwink equation and average value of characteristic ratio C(infinity) for the S-GL in 0.2 M NaCl aqueous solution at 25 degrees C were found to be: [eta] = 1.32 x 10(-3) Mw(1.06) (cm3 g(-1)) and 16, respectively, in the Mw range from 1.1 x 10(4) to 2.4 x 10(4). It indicated that the sulfated derivatives of the alpha-(1-->3)-D-glucan in the aqueous solution behave as an expanded chain, owing to intramolecular hydrogen bonding or interaction between charge groups. Interestingly, two sulfated derivatives synthesized from the alpha-(1-->3)-D-glucan and curdlan, a beta-(1-->3)-D-glucan, all had significant higher antitumor activity against Ehrlich ascites carcinoma (EAC) than the originals. The effect of expanded chains of the sulfated glucan in the aqueous solution on the improvement of the antitumor activity could not be negligible.     

Study of the fractions and fibrinolytic activity of fungal mannan

Characteristics of the fraction composition of extracellular mannan produced by Rhodotorula rubra are presented. Various lots of the polysaccharide mainly contained two fractions similar by their chemical structures and differing in the solution relative viscosity. HPLC was used for determining the molecular weight of the samples. In the isolated fractions it differed 3-5 fold. Relationship between the fibrinolytic activity of the polysaccharide and its molecular weight was revealed. The samples of mannan with the molecular weight of 400-500 kD had the highest capacity for lowering the fibrinogen blood levels in rats. The polysaccharide with the molecular weight of less than 100 kD had practically no fibrinolytic activity.     

Isolation and physical characterization of an exocellular polysaccharide

The physical properties of a polysaccharide produced by the lactic acid bacterium Lactococcus lactis subsp. cremoris strain NIZO B40 were investigated. Separation of the polysaccharide from most low molar mass compounds in the culture broth was performed by filtration processes. Residual proteins and peptides were removed by washing with a mixture of formic acid, ethanol, and water. Gel permeation chromatography (GPC) was used to size fractionate the polysaccharide. Fractions were analyzed by multiangle static light scattering in aqueous 0.10 M NaNO3 solutions from which a number- (Mn) and weight-averaged (Mw) molar mass of (1.47 +/- 0.06).10(3) and (1.62 +/- 0.07).10(3) kg/mol, respectively, were calculated so that Mw/Mn approximately 1.13. The number-averaged radius of gyration was found to be 86 +/- 2 nm. From dynamic light scattering an apparent z-averaged diffusion coefficient was obtained. Upon correcting for the contributions from intramolecular modes by extrapolating to zero wave vector a hydrodynamic radius of 86 +/- 4 nm was calculated. Theoretical models for random coil polymers show that this z-averaged hydrodynamic radius is consistent with the z-averaged radius of gyration, 97 +/- 3 nm, as found with GPC.     

Purification and structural characterization of a new water-soluble neutral polysaccharide GLP-F1-1 from Ganoderma lucidum

A water-soluble neutral polysaccharide (GLP-F1-1) was isolated from the fruiting bodies of Ganoderma lucidum by DEAE Sepharose Fast Flow and Sephacryl S-500 High Resolution Chromatography. The neutral polysaccharide had an average molecular weight (Mw) of approximately 2.5×10(6) kDa. GC analysis showed that this polysaccharide was mainly composed of glucose and galactose in the molar ratio of 34:1. 1H and 13C NMR spectroscopy in combination with GC-MS technique indicated that the new polysaccharide had a backbone chain of 1,4-disubstituted-β-glucoseopyranose and 1,4,6-trisubstituted-β-glucoseopyranosyl, while the branched chains were mainly composed of 1,6-disubstituted-β-glucopyranosyl and 1,4-disubstituted-β-galactoseopyranosyl residues.     

Antioxidant activities potential of tea polysaccharide fractions obtained by ultra filtration

Three polysaccharide fractions (TPS1, TPS2 and TPS3) with different molecular weights were obtained using ultra filtration membranes from crude tea polysaccharide (CTPS) extracted from abandoned lower grade tea leaves. Each fraction contained different contents of neutral sugar, uronic acid, protein, and total polyphenols. These differences provided basis for the antioxidant and free radical scavenging activity of these polysaccharide fractions. The molecular weights of TPS1, TPS2, and TPS3 were around 2.40×10(5) Da, 2.14×10(4) Da, and 2.46×10(3) Da, respectively. In general, TPS1 and CTPS had stronger antioxidant activity, TPS2 and TPS3 had lower antioxidant activity. TPS1 had higher activity for DPPH and lipid per oxidation inhibition. But it had lower capacity for reducing power and metal chelating. This might be due to its higher content of hexuronic acid and larger molecular weight. The order of inhibition activity of lipid per oxidation of various polysaccharide fractions was the same as DPPH radical scavenging activity, as well as the order of metal chelating activity of various polysaccharide fractions similar to hydroxyl radical scavenging activity, which demonstrated that hydroxyl radical scavenging activity of polysaccharide relied heavily on the Fe(2+) metal chelating to decrease the generation of hydroxyl radical.