Length-Dependent Enantioselectivity of Carbon Nanotubes by Gel Chromatography.

High-purity enantiomer separation of chiral single-wall carbon nanotubes (SWCNTs) remains a challenge compared with electrical type and chirality separations due to the limited selectivities for both chirality and handedness, which is important for an exploration of their properties and practical applications. Here, we performed length fractionation for enantiomer-purified SWCNTs and found a phenomenon in which the enantioselectivities were higher for longer nanotubes than for shorter nanotubes due to length-dependent interactions with the gel medium, which provided an effective strategy of controlling nanotube length for high-purity enantiomer separation. Furthermore, we employed a gentler pulsed ultrasonication instead of traditional vigorous ultrasonication for preparation of a low-defect long SWCNT dispersion and achieved the enantiomer separation of single-chirality (6,5) SWCNTs with an ultrahigh enantiomeric purity of up to 98%, which was determined by using the linear relationship between the normalized circular dichroism intensity and the enantiomeric purity. Compared with all results reported previously, the present enantiomeric purity was significantly higher and reached the highest level reported to date. Due to the ultrahigh selectivity in both chirality and handedness, the two obtained enantiomers exhibited perfect symmetry in their circular dichroism spectra, which offers standardization for characterizations and evaluations of SWCNT enantiomers.

Caracterización del polirribosilribitol fosfato por cromatografía de exclusión molecular de alta eficacia con detección ultravioleta / Characterization of polyribosylribitol phosphate by high efficiency size exclusion chromatography with ultraviolet detection

Haemophilus influenzae tipo b es un importante patógeno del hombre causante de varias de las enfermedades invasivas en niños menores de cinco años, contra el cual fueron autorizadas las vacunas glicoconjugadas a partir del polirribosilribitol fosfato. Quimi-Hib® es la primera y única vacuna contra este patógeno que utiliza el polisacárido obtenido por síntesis química. El Ingrediente Farmacéutico Activo es producido por el Centro de Ingeniería Genética y Biotecnología y se obtiene a partir de su conjugación al toxoide tetánico. En el presente reporte se hizo una caracterización del polirribosilribitol fosfato mediante la técnica de cromatografía de exclusión molecular de alta eficacia con detección ultravioleta a 215 nm. En el estudio se evaluaron tres lotes y se determinó el perfil de elución en una columna SuperdexTM 75 10/300 GL Increase con un porciento de pureza de 77,42 ± 8,97 y una masa molar promedio de 7.381 Da ± 210,93. La principal impureza presente en el polirribosilribitol fosfato es el dimetilsulfóxido, disolvente utilizado en la reacción de activación con el éster N-hidroxisuccinimidilo del ácido β-maleimidopropiónico. El polirribosilribitol fosfato se purificó por filtración con un Amicon Ultra-15 de 2.000 Da hasta una pureza de 99,1 por ciento y se conjugó al toxoide tetánico. El rendimiento de la reacción de conjugación con el polisacárido purificado fue de 30,0 por ciento 1,77 el cual no muestra diferencias significativas con el control que fue 33,7 por ciento ± 3,57 demostrándose que el dimetilsulfóxido no afecta el desempeño de la reacción de conjugación(AU)

Haemophilus influenzae type b is an important human pathogen causing some invasive diseases in children less than five years of age. Glycoconjugate vaccines based on polyribosylribitol phosphate have been licensed against this bacterium. Quimi-Hib® is the first and only vaccine against this pathogen using the chemically synthesized polysaccharide. The Active Pharmaceutical Ingredient is produced by the Center for Genetic Engineering and Biotechnology and is obtained from its conjugation to tetanus toxoid. In the present report a characterization of polyribosylribitol phosphate was performed by high performance molecular exclusion chromatography with ultraviolet detection at 215 nm. Three batches were evaluated in the study and the elution profile was determined on a SuperdexTM 75 10/300 GL Increase column with a purity percentage of 77.42 ± 8.97 and an average molecular weight of 7,381 Da ± 210.93. The main impurity present in polyribosylribitol phosphate was dimethylsulfoxide, the solvent used in the activation reaction with N-hydroxysuccinimidyl ester of β-maleimidopropionic acid. Polyribosylribitol phosphate was purified by filtration using a 2,000 Da cut-off Amicon Ultra-15 to a purity of 99.1 percent and conjugated to tetanus toxoid. The yield of the conjugation reaction with the purified polysaccharide was 30.0 percent ± 1.77 which shows no significant difference with the control which was 33.7 percent ± 3.57 demonstrating that dimethylsulfoxide does not affect the performance of the conjugation reaction(AU)

Gel Chromatography for Separation of Single-Walled Carbon Nanotubes.

Carbon nanotubes (CNTs), having either metallic or semiconducting properties depending on their chirality, are advanced materials that can be used for different devices and materials (e.g., fuel cells, transistors, solar cells, reinforced materials, and medical materials) due to their excellent electrical conductivity, mechanical strength, and thermal conductivity. Single-walled CNTs (SWNTs) have received special attention due to their outstanding electrical and optical properties; however, the inability to selectively synthesize specific types of CNTs has been a major obstacle for their commercialization. Therefore, researchers have studied different methods for the separation of SWNTs based on their electrical and optical properties. Gel chromatography methods enable the large-scale separation of metallic/semiconducting (m/s) SWNTs and single-chirality SWNTs with specific bandgaps. The core principle of gel chromatography-based SWNT separation is the interaction between the SWNTs and gels, which depends on the unique electrical properties of the former. Controlled pore glass, silica gel, agarose-based gel, and allyl dextran-based gel have been exploited as mediums for gel chromatography. In this paper, the interaction between SWNTs and gels and the different gel chromatography-based SWNT separation technologies are introduced. This paper can serve as a reference for researchers who plan to separate SWNTs with gel chromatography.

Fractional analysis of dichloromethane extract of Scutellaria araxensis Grossh root and shoot by HPLC-PDA-ESI-MSn.

Scutellaria araxensis is a well-known ethnobotanical herb for the treatment of various diseases in Iranian traditional medicine. In this study, dichloromethanolic fraction of partitioned methanol root and shoot extract was analysed by silica gel column chromatography, thin layer chromatography and high-performance liquid chromatography combined with photodiode-array detector, and coupled to electrospray ionization with Q-Exactive Orbitrap mass spectrometry (HPLC-PDA-ESI-MSn) in positive ion mode. Metabolites were tentatively characterized by comparing their mass spectrometry spectra with those of bibliographic data. A total of 11 flavonoids were identified from different fractions. Results showed that root and shoot produced very similar flavone patterns characterized by the presence of baicalein, tricin, tenaxin I, tenaxin II, skullcapflavon II, chrysin, wogonin and isorhamnetin. Norwogonin and apigenin-7-glucoside were identified only from shoot. Remarkably, Tenaxin I, II, tricin, apigenin-7-glucoside and norwogonin were tentatively profiled as new compounds for the first time from S. araxensis formula.

Single-step extraction of small-diameter single-walled carbon nanotubes in the presence of riboflavin.

We propose a novel approach to disperse and extract small-diameter single-walled carbon nanotubes (SWCNTs) using an aqueous solution of riboflavin and Sephacryl gel. The extraction of small-diameter semiconducting SWCNTs was observed, regardless of the initial diameter distribution of the SWCNTs. Dispersion of SWCNTs occurs due to the adsorption of π-conjugated isoalloxazine moieties on the surface of small-diameter nanotubes and interactions between hydroxy groups of ribityl chains with water. During the SWCNT extraction, specific adsorption of riboflavin to SWCNTs leads to the minimization of interactions between the SWCNTs and gel media. Our experimental findings are supported by ab initio calculations demonstrating the impact of the riboflavin wrapping pattern around the SWCNTs on their interaction with the allyl dextran gel.

Research on polymer impurities in cefazolin sodium raw materials and products / 药学学报

Research on polymer impurities has always been important in the quality control of cephalosporins. Research on polymers in cephalosporins that lack active amino groups on the C-7 side chain has not been reported. Therefore, our study used cefazolin sodium, which is widely used in the clinic, as an example. The polymer in cefazolin sodium and its product "cefazolin sodium pentahydrate for injection" was analyzed by column switching liquid chromatography-high resolution mass spectrometry. Two polymer impurity peaks were detected and the possible structures of these polymers were suggested. Through two-dimensional liquid chromatography, the chromatographic peaks following Sephadex gel chromatography and high-performance gel chromatography were compared to those obtained by reverse high-performance liquid chromatography (HPLC) for cefazolin sodium as reported in the Chinese Pharmacopoeia. The HPLC method proves more suitable for polymer detection than Sephadex gel chromatography and high-performance gel chromatography. The method of polymer detection for cefazolin sodium was established using the method of related substances HPLC as described in the Chinese Pharmacopoeia.

Assessment of in vitro and in vivo antimalarial efficacy and GC-fingerprints of selected medicinal plant extracts.

A hallmark of mortality and morbidity, malaria is affecting nearly half of the world's population. Emergence of drug-resistant strains of malarial parasite prompts identification and evaluation of medicinal plants and their constituents that may hold the key to a new and effective anti-malarial drug. In this context, nineteen methanolic extracts from seventeen medicinal plants were evaluated for anti-plasmodial potential against Plasmodium falciparum strain 3D7 (Chloroquine (CQ) sensitive) and INDO (CQ resistant) using fluorescence based SYBR-Green assay and for cytotoxic effects against mammalian cell lines. Leaf extract of two plants showed promising in vitro anti-malarial activity (Pf3D7 IC50 ≤ 10 µg/ml); one plant extract showed good activity (Pf3D7 IC50 = 10.1-20 µg/ml); seven were moderately active (IC50 = 20.1-50 µg/ml), four plant extracts showed poor activity (PfD7 IC50 = 50.1-100 µg/ml) and five extracts showed no activity up to IC50 = 100 µg/ml. Further, six extracts were found equipotent to PfINDO (resistance index ranging 0.4-2) and relatively nontoxic to mammalian cell lines HEK293 (cytotoxicity index ranging 1.4-12.5). Based on good resistance and selectivity indices, three extracts were evaluated for in vivo activity in Plasmodium berghei ANKA infected mice at a dose of 500 mg/kg and they showed significant suppression of P. berghei parasitemia. Further, these active plant extracts were fractionated using silica-gel chromatography and their fractions were evaluated for anti-plasmodial action. Obtained fractions showed enrichment in antimalarial activity. Active fractions were analyzed by gas chromatography and mass-spectrometery. Results suggests that the three active plant extracts could serve as potent source of anti-malarial agent and therefore require further analysis.

Cholera Toxin Subunit B for Sensitive and Rapid Determination of Exosomes by Gel Filtration.

We developed a sensitive fluorescence-based assay for determination of exosome concentration. In our assay, Cholera toxin subunit B (CTB) conjugated to a fluorescence probe and a gel filtration technique (size-exclusion chromatography) are used. Exosomal membranes are particularly enriched in raft-forming lipids (cholesterol, sphingolipids, and saturated phospholipids) and in GM1 ganglioside. CTB binds specifically and with high affinity to exosomal GM1 ganglioside residing in rafts only, and it has long been the probe of choice for membrane rafts. The CTB-gel filtration assay allows for detection of as little as 3 × 108 isolated exosomes/mL in a standard fluorometer, which has a sensitivity comparable to other methods using advanced instrumentation. The linear quantitation range for CTB-gel filtration assay extends over one order of magnitude in exosome concentration. Using 80 nM fluorescence-labeled CTB, we quantitated 3 × 108 to 6 × 109 exosomes/mL. The assay ranges exhibited linear fluorescence increases versus exosome concentration (r2 = 0.987). The assay was verified for exosomal liposomes. The assay is easy to use, rapid, and does not require any expensive or sophisticated instrumentation.

HPLC-ELSD Detection of Macromolecular Substances in Compound Kushen Injection / 中国药学杂志

OBJECTIVE: To establish a high-performance liquid gel chromatography (HPLC-ELSD) method for the detection of macromolecular substances in Compound Kushen injection. METHODS: TSKgel G2000SWXL (7.8 mm×300 mm, 5 μm) chromatographic column was used. A 20 mmol•L-1 ammonium acetate aqueous solution was used as the mobile phase. The column temperature was maintained at 25℃, the flow rate was 0.8 mL•min-1, and the parameters of the evaporative light detector (drift tube temperature 55℃, atomization temperature 55℃, nitrogen flow rate, 1.8 L•min-1), a method for detecting macromolecular substances was established, and eleven batches of Compound Kushen injection were tested for macromolecular substances. RESULTS: No macromolecular substances was detected in the eleven batches of Compound Kushen injection, indicating that after the step-by-step removal of impurities, macromolecular substances have been removed from the finished Compound Kushen injection products. CONCLUSION: This method is simple and fast, which can be used for the detection of macromolecular substances in Compound Kushen injection, it provides a basis for improving the quality standards of Compound Kushen injection.

Determination of Total Polysaccharides in Decoction Pieces of Polyporus with Different Sources and Different Grades / 中国实验方剂学杂志

Objective: To establish a method for determining the content of total polysaccharides in decoction pieces of Polyporus,analyze the content of total polysaccharides in samples with different sources and grades. Method: The relative molecular weight and the polydispersity index of polysaccharides in decoction pieces of Polyporus were measured by a high performance gel chromatography coupled with a multi-angle laser light scattering and refractive index system.Dextran with similar molecular weight as polysaccharides was selected as the reference substance.Orthogonal experiment and single factor tests were used to optimize the pretreatment conditions for the determination of total polysaccharides in Polyporus.Polysaccharides in Polyporus with different areas and grades were determined by anthrone-sulfuric acid colorimetric method at 630 nm. Result: The linearity,stability,precision,repeatability and recovery rate of the established method all reached the standards,respectively.The content of total polysaccharides in samples from different areas ranged from 0.87% to 1.39%.The content of total polysaccharides in samples with different grades was 1.40% for first-grade pieces,1.21% for second-grade pieces, and 1.03% for third-grade pieces. Conclusion: The established method is simple,accurate and reproducible,and it can be used for the determination of polysaccharides in decoction pieces of Polyporus.The content of polysaccharides in samples from different origins varies greatly.The content of polysaccharides in samples with different grades shows a certain regularity.The content of polysaccharides is the highest in the first-grade pieces,followed by the content in the second-grade,and the lowest in the third-grade.The results can provide a reference for formulating limits for the content of total polysaccharides and the grade standard of decoction pieces of Polyporus.

Relative molecular weight determination of astragalus polysaccharides for injection / 药学学报

To determine relative molecular weight of astragalus polysaccharides (APs), we used Shodex GS620 gel permeation chromatographic column and differential refraction detector (GPC-RI) with dextran as a reference. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and GPC combined with multi-angle laser light scattering detection (GPC-MALLS) were also used．GPC-RI measure showed four peaks of APs, with the Mw of 1 380 000, 231 000, 18 000, and 480, respectively. Three main peaks were found by GPC-RI-MALLS with the Mw as 1 148 000, 180 000, and 43 000, respectively. Strong signals in 155 000 and 18 000 were detected by MALDI-TOF-MS, which also indicated the sugar moieties of the APs as hexoses. From our study, we found that the GPC-RI method with universal correction is most suitable for Mw determination of the APs. Nevertheless, the three methods should be combined and contrasted with each other to obtain accurate information in research of polysaccharides from Chinese medicine.

Separation of α-ketoglutaric acid and pyruvic acid from the culture broth of Yarrowia lipolytica WSH-Z06 by chromatographic methods.

Both α-ketoglutaric acid (KGA) and pyruvic acid (PYR) are important keto acids. Efficient co-production of KGA and PYR has been achieved in our previous work, and could significantly decrease the cost of fermentation production. KGA and PYR have similar physical and chemical properties. Hence, finding a way to separate the two keto acids efficiently has become a key challenge. In this study, different chromatographic methods have been investigated, including ion-exchange chromatography, aluminum oxide chromatography and silica gel chromatography. The results show that the two keto acids can be well separated with silica gel chromatography, whereas ion-exchange chromatography and aluminum oxide chromatography could not separate them. Using the pretreated fermentation broth of Yarrowia lipolytica WSH-Z06, the purity and yield of KGA/PYR reached 98.7%/99.1% and 86.7%/70.9%, respectively, with an optimized silica gel chromatography-based procedure. This study provides an efficient method for separating KGA and PYR from fermentation broth, which might be applied on an industrial scale and significantly decrease the cost of biotechnological production of keto acids. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1370-1379, 2018.

Preparative Separation of High-Purity Dihydroartemisinic Acid from Artemisinin Production Waste by Combined Chromatography.

In order to make full use of artemisinin production waste and thus to reduce the production cost of artemisinin, we developed an efficient and scalable method to isolate high-purity dihydroartemisinic acid from artemisinin production waste by combining anion-exchange resin with silica-gel column chromatography. The adsorption and desorption characteristics of dihydroartemisinic acid on 10 types of anion-exchange resin were investigated, and the results showed that the 717 anion-exchange resin exhibited the highest capacity of adsorption and desorption to dihydroartemisinic acid. Adsorption isotherms were established for the 717 anion-exchange resin and they fitted well with both Langmuir and Freundlich model. Dynamic adsorption and desorption properties of 717 anion-exchange resin were characterized to optimize the chromatographic conditions. Subsequently, the silica-gel column chromatography was performed and dihydroartemisinic acid with a purity of up to 98% (w/w) was obtained. Finally, the scale-up experiments validated the preparative separation of high-purity dihydroartemisinic acid from industrial waste developed in the present work. This work presented for the first time an isolation of dihydroartemisinic acid with a purity of 98% from Artemisia annua (A. annua) by-product, which adds more value to this crop and has the potential to lower the prices of anti-malarial drugs.

Stress-Inducible Protein 1 (STI1): Extracellular Vesicle Analysis and Quantification.

This chapter is derived from our experience in the study of stress-Inducible Protein 1 (STI1) in extracellular vesicles. We used different techniques to isolate, explore, and characterize the extracellular vesicles that contained this protein. Ultracentrifugation and gel chromatography were used to isolate extracellular vesicles of different sizes, nanotracking particle analysis (NTA) determined number and size of vesicles, while flow cytometry and ELISA were used to determine the specific protein content of vesicles.

Effect of different doses of nitrogen on protein profiling, pasting and quality attributes of rice from different cultivars.

Effect of different level (60, 120 and 180 kg N/ha) of nitrogen (N) application on protein profiling, pasting and cooking quality characteristics of milled rice from different paddy cultivars was evaluated. N dose showed positive correlation with protein content and negative correlation with L*, whiteness and amylose content. N application significantly affected the protein profile, textural and pasting properties of different cultivars. All the cultivars expect PR120 and PAU201, showed an increase in the amount of accumulation of 60 kDa polypeptide with increase in N application. Accumulation of prolamines (16 and 14 kDa) and polypeptides of 38 and 35 kDa increased in all the cultivars. Size exclusion chromatography revealed decrease in low molecular weight subunits and increase in medium molecular weight subunits in all the cultivars upon N application. However, high molecular weight subunits increased in IET21214 and decreased in PR120 and PAU20 upon N application. N application resulted in increase in glutelins and decrease in peak and breakdown viscosity. PAU201 and PR120 showed lower AAC due to low accumulation of 60 kDa granule-bound starch synthase (GBSS), in response to N application. Gumminess and hardness of cooked rice increased with the increase in N dose and the increase was significant at 60 kg N/ha.

Selective Surface Charge Sign Reversal on Metallic Carbon Nanotubes for Facile Ultrahigh Purity Nanotube Sorting.

Semiconducting (semi-) single-walled carbon nanotubes (SWNTs) must be purified of their metallic (met-) counterparts for most applications including nanoelectronics, solar cells, chemical sensors, and artificial skins. Previous bulk sorting techniques are based on subtle contrasts between properties of different nanotube/dispersing agent complexes. We report here a method which directly exploits the nanotube band structure differences. For the heterogeneous redox reaction of SWNTs with oxygen/water couple, the aqueous pH can be tuned so that the redox kinetics is determined by the availability of nanotube electrons only at/near the Fermi level, as predicted quantitatively by the Marcus-Gerischer (MG) theory. Consequently, met-SWNTs oxidize much faster than semi-SWNTs and only met-SWNTs selectively reverse the sign of their measured surface zeta potential from negative to positive at the optimized acidic pH when suspended with nonionic surfactants. By passing the redox-reacted nanotubes through anionic hydrogel beads, we isolate semi-SWNTs to record high electrically verified purity above 99.94% ± 0.04%. This facile charge sign reversal (CSR)-based sorting technique is robust and can sort SWNTs with a broad diameter range.

Optimization of extraction process of Codonopsis pilosula polysaccharides and study on its composition / 中草药

Objective: To optimize the extraction process of polysaccharide from Codonopsis pilosula and determine the monosaccharide composition and molecular weight distribution, in order to provide the basis for further separation of C. pilosula polysaccharide. Methods: The content of polysaccharide in C. pilosula was determined by phenol sulfuric acid method, the extraction process of polysaccharide was optimized by orthogonal test. C. pilosula polysaccharides were prepared from crude polysaccharides by deproteinization, decoloration, dialysis, and lyophilization, then monosaccharide composition and mean molecular mass of C. pilosula polysaccharides were analyzed by high performance liquid chromatography (HPLC) and high performance gel permeation chromatography (HPGPC). Results: The extraction temperature was 85 ℃, the extraction time was 1.5 h per time, twice, and solid to liquid ratio was 1:12. Under these conditions, the yield of polysaccharides was 22.57%. The polysaccharides were consisted by glucuronic acid, aminogalactose, xylose, and small quantities of mannose, the average molecular mass was 21 498. Conclusion: This study provides a theoretical basis for the classification and activity of polysaccharide from C. pilosula.

Optical isomer separation of single-chirality carbon nanotubes using gel column chromatography.

We report a gel column chromatography method for easily separating the optical isomers (i.e., left- and right-handed structures) of single-chirality carbon nanotubes. This method uses the difference in the interactions of the two isomers of a chiral single-wall carbon nanotube (SWCNT) with an allyl dextran-based gel, which result from the selective interaction of the chiral moieties of the gel with the isomers. Using this technique, we sorted optical isomers of nine distinct (n, m) single-chirality species from HiPco SWCNTs, which is the maximum number of isolable species of SWCNTs reported to date. Because of its advantages of technical simplicity, low cost, and high efficiency, gel column chromatography allows researchers to prepare macroscopic ensembles of single-structure SWCNTs and enables the complete discovery of intrinsic properties of SWCNTs and advances their application.

Chromatographic isolation of nanoparticles from Ma-Xing-Shi-Gan-Tang decoction and their characterization.

ETHNOPHARMACOLOGICAL RELEVANCE: The herbal decoction is a complex dispersion system containing solutes, colloid, aggregates, emulsions and precipitates. In which phase bioactive phytochemicals are dispersed determines their delivery, action and metabolism. This study took ephedrine, a well-studied and widely used phytochemical, as an example to elucidate its exact distribution in the phases of Ma-Xing-Shi-Gan-Tang decoction (MXSGT), which is an Ephedra sinica Stapf. containing traditional Chinese medicinal formula, and the biological meaning of this distribution correspondingly. It may provide an important update to the safety and efficacy assessment of the herbal decoction and its active phytochemicals. MATERIALS AND METHODS: In this study, the decoction was fractionated with size-exclusion chromatography coupled with multi-angle laser light scattering detector. The morphology of fractionated nanoparticles was observed with AFM and SEM. The bioactivities of the decoction, the ephedrine alkaloids loaded NPs (prepared by chromatography isolation) and the synthetic ephedrine were assessed by cell proliferation tests using five cell lines, namely Caco-2, L-02, Hep-G2, NR-8383, and Hela-229. RESULTS: Nanoparticles with radii of gyration ranged from 50 to 150 nm were isolated, in spherical shape. Further analysis of nanoparticles on the subsequent reversed phase chromatography revealed that the majority of ephedrine (99.7%) and pseudoephedrine (95.5%) were associated with these nanoparticles, rather than dispersed freely in the real solution. The addition of both the herbal decoction and the separated ephedrine-loaded nanoparticles reserved higher cell viability/proliferation than that of the sole synthetic ephedrine among the Caco-2, L-02, Hep-G2, and NR-8383 cells. In contrast, the nanoparticles reduced the proliferating power of ephedrine on Hela-229 cells. In general, the ephedrine-loaded NPs conducted the intermediate influences on the cell viability, in either way. CONCLUSIONS: The colloidal nanoparticles were separated from the decoction. The association of ephedrine alkaloids with nanoparticles was demonstrated and may have changed the bioactivity of the alkaloids. The naturally occurred colloidal nanoparticles may play an important role in the pharmacological properties of both the decoction and its active phytochemicals, therefore warrant further studies.

Separation and quantification of neoagaro-oligosaccharides.

Oligosaccharides were obtained from agar by enzymatic hydrolysis. Activated carbon adsorption separation was used to extract oligosaccharides, and gel chromatography separation was applied to further purify oligosaccharides. The result showed that activated carbon adsorption could remove the most salt impurities, and gel column chromatography could give the separation of the two kinds of oligosaccharides. ESI-MS, (13)C-NMR revealed that the molecular weight (Mw) of two oligosaccharides were 630 and 936, which were identified as neoagarotetraose and neoagarohexaose respectively.