甲壳单糖、寡糖、低聚糖制备方法的优化与比较研究

该文通过大量实验,确定了制备单糖、寡糖及低聚糖的最佳生产工艺,并对几种制备方法做了比较研究.该文采用氧化降解和微波降解等不同技术对甲壳低聚糖的制备工艺进行了研究.H<,2>O<,2>作为氧化剂,在酸性条件下,采用4因素3水平进行正交实验,得到了制备分子量2000以下的寡糖的最佳条件.微波降解制备低聚糖目前尚未见报道,经过该实验证明此方法可降低能耗,减小污染,节省时间和原料,是一个具有产业化前景和市场潜力的好方法.通过以不同的壳聚糖为原料,探讨了在微波场作用下纯溶剂及盐效应对分子量变化的影响,最终产物的分子量均在1×10<'5>～10×10<'5>之间.根据IR光谱,壳聚糖降解前后主要峰的位置都无变化,只是随壳聚糖相对分子质量的降低各峰峰强有所变化,证明了壳聚糖氧化降解及微波降解制备寡糖、低聚糖是以开裂壳聚糖的β-1.4糖苷键来进行.该项研究对更好的开发利用甲壳质资源,促进中国海洋生物制品的发展具有十分重要的意义.

不同分子量坛紫菜多糖的制备及其抗衰老活性研究

坛紫菜（Porphyra haitanensis），属红藻门（Rhodophyta），红毛菜科（Bangiacease）紫菜属（Porphyra），是我国大规模养殖的重要经济海藻之一，主要产于我国南方沿海如福建、广东、浙江等地。紫菜作为中药，具有“补肾养心，利水消肿”的功效，实验室前期所作的工作表明，坛紫菜多糖具有良好的抗衰老作用。分子量对多糖生物活性有重大影响，本文以福建沿海的坛紫菜为原料，对坛紫菜多糖（P）的降解方法和该紫菜多糖的抗衰老活性与分子量的关系展开了研究。 本论文首次将植物生长发育过程中发生的抗坏血酸和过氧化氢反应体系应用于坛紫菜多糖的降解。抗坏血酸和过氧化氢的浓度及两者的比例是该降解方法的主要影响因素。采用该法制备了分子量分别为50、30、13、8.2和2.7 kD 的P1、P2、 P3、P4和P5五种产品。其中P1、P2和P3产品的红外图谱与原料多糖的红外图谱一致，表明这两种多糖的化学结构在降解过程中并未发生改变，而P4和P5样品的红外图谱显示该样品中出现了少量的羧基。 本论文还首次对各产物进行了抗氧化、免疫调节、抗疲劳、延长寿命、抗老年痴呆等活性的筛选与研究，具体结果如下： 采用化学法对五种降解多糖和原料多糖的抗氧化活性进行研究。结果表明分子量对坛紫菜多糖清除各种自由基能力的影响是不同的。降解之后，坛紫菜多糖清除超氧阴离子的能力有所下降，与金属离子的螯合能力几乎全部丧失，但是多糖清除羟基自由基的能力变化甚微。降解之后，坛紫菜多糖清除有机自由基的能力和还原能力显著提高，随分子量的降低这两种能力明显加强，其中P4样品清除有机自由基能力最强，而分子量最小的P5样品还原能力最突出。 通过测定T、B淋巴细胞增殖率考察了五种降解多糖和原料多糖的免疫调节作用。研究表明：不同分子量坛紫菜多糖均具有免疫调节作用，可显著促进小鼠脾脏T淋巴细胞增殖，显著抑制小鼠脾脏B淋巴细胞增殖。P2和P4样品效果强于其它降解产品和原料。 通过测定小鼠游泳和爬杆时间考察了三种降解多糖P1、P2、P4和原料多糖的耐疲劳作用。研究表明：坛紫菜多糖降解产品耐疲劳作用要优于原料多糖P。P1、P2和P4通过提高小鼠肝糖原储备从而达到显著延长小鼠爬杆时间和负重游泳时间的功效。 通过测定D. melanogaster果蝇寿命、热耐受时间和性活力考察了三种降解多糖P1、P2、P4和原料多糖对寿命及生命活力的影响。研究表明：分子量对坛紫菜多糖对果蝇的寿命和生命活力有很大影响。降解使坛紫菜原料多糖P对果蝇的延长寿命和提高生命活力作用得到加强。在果蝇正常代谢状态下，降解产品中分子量较大的P1和P2作用更显著，而在热应激状态下，降解产品中分子量较小的P4作用更突出。 采用小鼠侧脑室注射Aβ1-40致痴呆模型考察了样品P1改善认知功能的作用。研究表明：P1通过降低皮层和海马组织乙酰胆碱酯酶活性，显著提高乙酰胆碱转移酶的活性，有效改善痴呆小鼠的认知能力，使之水迷宫游泳时间缩短，使避暗潜伏期延长。 为探讨P1样品改善小鼠认知功能的作用机制，本文采用Aβ25-35损伤神经母细胞瘤株SH-SY5Y模型对P1样品的神经细胞的保护作用进行了研究。结果显示低浓度下P1对该损伤模型具有显著保护作用，高浓度下表现出显著的抑制作用。 本文的研究表明坛紫菜多糖在降解之后生物活性得到显著改善。分子量对坛紫菜多糖活性影响很大。总的看来，在体外实验中，分子量越低其体外抗氧化活性和免疫调节作用越显著，但是，在体内实验中，降解产品中分子量最大的P1样品能更有效地改善小鼠疲劳程度、延长果蝇的寿命及热耐受时间，P1样品还能显著改善痴呆小鼠记忆功能。不同分子量坛紫菜多糖体内和体外生物活性的这种差异还需要进行深入研究。

One century record of contamination by polycyclic aromatic hydrocarbons and polychlorinated biphenyls in core sediments from the southern Yellow Sea

Sixteen polycyclic aromatic hydrocarbons (PAHs) and 28 polychlorinated biphenyls (PCBs) were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical variations in inflow and sources. The chronology was obtained using the Pb-210 method. PAHs concentrations decreased generally with depth and two climax values occurred in 14-16 cm and 20-22 cm layers, demonstrating that the production and usage of PAHs might reach peaks in the periods of 1956-1962 and 1938-1944. The booming economy and the navy battles of the Second World War might explain why the higher levels were detected in the two layers. The result of principal component analysis (PCA) revealed that PAHs were primarily owing to the combustion product. Down-cored variation of PCB concentrations was complex. Higher concentrations besides the two peaks being the same as PAHs were detected from 4 to 8 cm, depositing from 1980 to 1992, which probably resulted from the disposal of the out-dated PCB-containing equipment. The average Cl percentage of PCBs detected was similar to that of the mixture of Aroclor 1254 and 1242, suggesting they might origin from the dielectrical and heat-transfer fluid. The total organic carbon (TOC) content played a prevalent role in the adsorption of high molecular weight PAHs (>= 4-ring), while no obvious relationship among total PCBs, the concentration of congeners, and TOC was found.

Three-dimensional fluorescence characteristics of dissolved organic matter produced by Prorocentrum donghaiense Lu

Filtration and cross-flow ultrafiltration techniques were used to separate culture media of Prorocentrum donghaiense at the exponential growth, stationary and decline stages into < 0.45 mu m filtrate, 100 kDa-0.45 mu m, 10-100 kDa and 1-10 kDa retentate and < 1 kDa ultrafiltrate fractions. The fluorescence. properties of different molecular weights of dissolved organic matter (DOM) were measured by excitation-emission matrix spectra. Protein-like and humic-like fluorophores were observed in the DOM produced by P. donghaiense. The central positions of protein-like fluorophores showed a red shift with prolonged growth duration, shifting from tyrosine-like properties at the exponential growth stage to tryptophan-like properties at the stationary and decline stages. The excitation wavelengths of protein-like fluorophores exhibited some change in the exponential growth and stationary stages with increased molecular size, but showed little change in the decline stage. However, the emission wavelengths in the decline stage exhibited a blue shift. Very distinct C type and A type peaks in humic-like fluorophores were observed. With a prolonged culture time, the intensities of both of the peaks became strong and the excitation wavelengths of peak A showed a red shift, while the A:C ratios fell. More than 94% of fluorescent DOM was in the lower than 1 kDa molecular weight fraction.

Preparation and in vitro antioxidant activity of kappa-carrageenan oligosaccharides and their oversulfated, acetylated, and phosphorylated derivatives

In order to study the relationship between chemical structure and properties of modified carrageenans versus antioxidant activity in vitro, K-carrageenan oligosaccharides were prepared through mild hydrochloric acid hydrolysis of the polysaccharide, and these were used as starting materials for the partial synthesis of their oversulfated, acetylated, and phosphorylated derivatives. The structure and substitution pattern of the oligosaccharides and their derivatives were Studied using FTIR and C-13 NMR spectroscopy, and their in vitro antioxidant activities were investigated. Certain derivatives of the carrageenan oligosaccharides exhibited higher antioxidant activity than the polysaccharides and oligosaccharides in certain antioxidant systems. The oversulfated and acetylated derivatives, which scavenge superoxide radicals, the phosphorylated and low-DS acetylated derivatives, which scavenge hydroxyl radicals, and the phosphorylated derivatives, which scavenge DPPH radicals, all exhibited significant antioxidant activities it, the systems examined. The effect of the molecular weight of the carrageenan on antioxidant activities, however, is not obvious from these studies. (c) 2005 Elsevier Ltd. All rights reserved.

Antimicrobial activity of hydroxylbenzenesulfonailides derivatives of chitosan, chitosan sulfates and carboxymethyl chitosan

Chitosan, carboxymethyl chitosan (CIVICS) and chitosan sulfates (CSS) with different molecular weight were modified by reacting with 4-hydroxyl-5-chloride-1,3-benzene-disulfo-chloride or 2-hydroxyl-5-chloride-1,3 -benzene-disulfo-chloride to give 12 kinds of new hydroxylbenzenesulfonailides derivatives of them. The preparation conditions of the derivatives were discussed in this paper, and their structures were characterized by FT-IR and C-13 NMR spectroscopy. The solubility of the derivatives was measured in the experiment. In addition, their antimicrobial activities against four bacteria and five crop-threatening pathogenic fungi were tested in the experiment. Besides, the rule and mechanism of their antibacterial activities were discussed in this paper. (C) 2009 Published by Elsevier B.V.

Preparation, characterization and antifungal properties of 2-(alpha-arylamino phosphonate)-chitosan

In this paper, 20 kinds of different 2-(alpha-arylamino phosphonate)-chitosan (2-alpha-AAPCS) were prepared by different Schiff bases of chitosan (CS) reacted with di-alkyl phosphite in benzene solution. The structures of the derivatives (2-alpha-AAPCS) were characterized by FT-IR spectroscopy and elemental analysis. In addition, the antifungal activities of the derivatives against four kinds of fungi were evaluated in the experiment. The results indicated that all the prepared 2-alpha-AAPCS had a significant inhibiting effect on the investigated fungi when the derivatives concentration ranged from 50 to 500 mu g mL(-1). Furthermore, the antifungal activities of the derivatives increased with increasing the molecular weight and concentration. And the antifungal activities of the derivatives were affected by their dimensional effect and charge density. Besides, the rule and mechanism of the antifungal activities of them were discussed in this paper. (C) 2009 Elsevier B.V. All rights reserved.

Salt-assisted acid hydrolysis of chitosan to oligomers under microwave irradiation

The effect of inorganic salts such as sodium chloride on the hydrolysis of chitosan in a microwave field was investigated. While it is known that microwave heating is a convenient way to obtain a wide range of products of different molecular weights only by changing the reaction time and/or the radiation power, the addition of some inorganic salts was shown to effectively accelerate the degradation of chitosan under microwave irradiation. The molecular weight of the degraded chitosan obtained by microwave irradiation was considerably lower than that obtained by traditional heating. Moreover, the molecular weight of degraded chitosan obtained by microwave irradiation assisted under the conditions of added salt was considerably lower than that obtained by microwave irradiation without added salt. Furthermore, the effect of ionic strength of the added salts was not linked with the change of molecular weight. FTIR spectral analyses demonstrated that a significantly shorter time was required to obtain a satisfactory molecular weight by the microwave irradiation-assisted inorganic salt method than by microwave irradiation without inorganic salts and conventional technology. (C) 2005 Elsevier Ltd. All rights reserved.

Preparation of 1,3,5-thiadiazine-2-thione derivatives of chitosan and their potential antioxidant activity in vitro

Three new kinds of 1,3,5-thiadiazine-2-thi one derivatives of chitosan with two different molecular weight (SATTCS1, SATTCS2, TITTCS1, TITTCS2, CITTCS1 and CITTCS2) have been prepared. Their structures were characterized by IR spectroscopy. The substitution degree of derivatives calculated by elemental analyses was 0.47, 0.42, 0.41, 0.38, 0.41 and 0.36, respectively. The result shows that substitution degree of derivatives was higher with lower molecular weight. The antioxidant activity was studied using an established system, such as bydroxyl radical scavenging, superoxide radical scavenging and reducing power. Antioxidant activity of the 1,3,5-thiadiazine-2-thione derivatives of chitosan were stronger than that of chitosans and antioxiclant activity of low molecular weight derivatives were stronger than that of high molecular weight derivatives. It is a potential antioxidant in vitro. (c) 2007 Elsevier Ltd. All rights reserved.

Synthesis and antifungal properties of sulfanilamide derivatives of chitosan

Sulfanilamide derivatives of chitosan (2-(4-acetamido-2-sulfanimide)-chitosan (HSACS, LSACS), 2-(4-acetamido-2-sulfanimide)-6-sulfo-chitosan (HSACSS, LSACSS) and 2-(4-acetamido-2-sulfanimide)-6-carboxymethyl-chitosan (HSACMCS, LSACMCS)) were prepared using different molecular weights of chitosan (CS), carboxymethyl chitosan (CMCS) and chitosan sulfates (CSS) reacted with 4-acetamidobenzene sulfonyl chloride in dimethylsulfoxide solution. The structures of the derivatives were characterized by FT-IR spectroscopy and elemental analysis, which showed that the substitution degree of sulfanilamide group of HSACS, HSACSS, HSACMCS, LSACS, LSACSS and LSACMCS were 0.623, 0.492, 0.515, 0.576, 0.463 and 0.477, respectively. The solubility of the derivatives (pH < 7.5) was higher than that of chitosan (pH < 6.5). The antifungal activities of the derivatives against Aiternaria solani and Phomopsis asparagi were evaluated based on the method of Jasso et al. in the experiment. The results indicated that all the prepared sulfanilamide derivatives had a significant inhibiting effect on the investigated fungi in the polymer concentration range from 50 to 500 mu g mL(-1). The antifungal activities of the derivatives increased with increasing the molecular weight, concentration or the substitution degree. The sulfanilamide derivatives of CS, CMCS and CSS show stronger antifungal activities than CS, CMCS and CSS. (C) 2007 Elsevier Ltd. All rights reserved.

The preparation and antioxidant activity of the sulfanilamide derivatives of chitosan and chitosan sulfates

Chitosan (CS) and chitosan sulfates (CSS) with different molecular weight (Mw) were reacted with 4-acetamidobenzene sulfonyl chloride to obtain sulfanilamide derivatives of chitosan and chitosan sulfates (LSACS, HSACS, LSACSS, HSACSS). The preparation conditions such as different reaction time, temperature, solvent, and the molar ratio of reaction materials are discussed in this paper. Their structures were characterized by FTIR spectroscopy and elemental analyses. The antioxidant activities of the derivatives were investigated employing various established in vitro systems, such as hydroxyl-radical (OH) superoxide anion (O-2(center dot-)) scavenging and reducing power. All kinds of the compounds (HCS, LCS, HCSS, LCSS, HSACS, LSACS, HSACSS, LSACSS) showed stronger scavenging activity on hydroxyl radical than ascorbic acid (Vc). The inhibitory activities of the derivatives toward superoxide radical by the PMS-NADH system were obvious. The experiment showed that the superoxide radical scavenging effect of sulfanilamide derivatives of chitosan and chitosan sulfates was stronger than that of original CS and CSS. All of the derivatives were efficient in the reducing power. The results indicated that the sulfanilamide group were grafted on CS and CSS increased the reducing power of them obviously. (c) 2007 Elsevier Ltd. All rights reserved.

Structural studies on a novel fucogalactan sulfate extracted from the brown seaweed Laminaria japonica

A low molecular weight fucogalactan, obtained from the brown seaweed Laminaria japonica, was separated into three fractions (LF1, LF2 and LF3) by DEAE-Sepharose FF column chromatography. All three fractions contained predominantly fucose, sulfate group and galactose. The results showed that the main fraction LF2 consisted of L-fucose, D-galactose and sulfate at a molar ratio 6:1:9. Structural study on the LF2 was carried out by NMR spectroscopy. The backbone of LF2 was primarily (1 -> 3)-linked alpha-L-fucopyranose residues (75%) and a few (1 -> 4)-alpha-L-fucopyranose linkages (25%). The branch points were at C-4 of 3-linked alpha-L-fucopyranose residues by beta-D-galactopyranose unites (35%, molar ratio) or at C-2 of 3-linked alpha-L-fucopyranose residues by non-reducing terminal fucose unites (65%, molar ratio). Sulfate groups occupied at position C-4 or C-2, sometimes C-2, 4 to fucose residues, and C-3 and/or C-4 to galactose residues. The structure of LF2 was supposed as following: [GRAPHICS] (C) 2010 Elsevier B.V. All rights reserved.

The preparation and antioxidant activity of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan

Chitosan (CS) with two different molecular weight were modified by reacting with methyl hydrazine-dithiocarboxylate and methyl phenylhydrazine-dithiocarboxylate to give 2-(hydrazine-thiosemicarbazone)-chitosan (2-HTCHCS, 2-HTCLCS) and 2-(phenylhydrazine-thiosemicarbazone)chitosan (2-PHTCHCS, 2-PHTCLCS). The structure of the derivatives was characterized by FT-IR spectroscopy and elemental analysis. The antioxidant activities of the derivatives were investigated employing various established systems, such as hydroxyl radical (*OH)/superoxide anion (O-2(center dot-)) scavenging/reducing power and chelating activity. All of the derivatives showed strong scavenging activity on hydroxyl radical than chitosan and ascorbic acid (Vc), and IC50 of 2-HTCHCS, 2-HTCLCS, 2-PHTCHCS and 2-PHTCLCS was 0.362, 0.263, 0.531 and 0.336 mg/mL respectively. The inhibitory activities of the derivatives toward superoxide radical by the PMS-NADH system were strong. The results showed that the superoxide radical scavenging effect of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan were higher than that of chitosan. The derivatives had obviously reducing power and chelating activity. The data obtained from vitro models clearly establish the antioxidant potency of 2-[phenylhydrazine (or hydrazine)-thiosemicarbazone]-chitosan. (C) 2010 Elsevier B.V. All rights reserved.

Isolation and characterization of a novel variant of HMW glutenin subunit gene from the St genome of Pseudoroegneria stipifolia

The x- and y-type high molecular weight (HMW) glutenin subunits are conserved seed storage proteins in wheat and related species. Here we describe investigations on the HMW glutenin subunits from several Pseudoroegneria accessions. The electrophoretic mobilities of the HMW glutenin subunits from Pd. stipifolia, Pd tauri and Pd strigosa were much faster than those of orthologous wheat subunits, indicating that their protein size may be smaller than that of wheat subunits. The coding sequence of the Glu-1St1 subunit (encoded by the Pseudoroegneria stipifolia accession PI325181) was isolated, and found to represent the native open reading frame (ORF) by in vitro expression. The deduced amino acid sequence of Glu-1St1 matched with that determined from the native subunit by mass spectrometric analysis. The domain organization in Glu-1St1 showed high similarity with that of typical HMW glutenin subunits. However, Glu-1St1 exhibited several distinct characteristics. First, the length of its repetitive domain was substantially smaller than that of conventional subunits, which explains its much faster electrophoretic mobility in SDS-PAGE. Second, although the N-terminal domain of Glu-1St1 resembled that of y-type subunit, its C-terminal domain was more similar to that of x-type subunit. Third, the N- and C-terminat domains of Glu-1St1 shared conserved features with those of barley D-hordein, but the repeat motifs and the organization of its repetitive domain were more similar to those of HMW glutenin subunits than to D-hordein. We conclude that Glu-1St1 is a novel variant of HMW glutenin subunits. The analysis of Glu-1St1 may provide new insight into the evolution of HMW glutenin subunits in Triticeae species. (C) 2007 Elsevier Ltd. All rights reserved.

天山乌鲁木齐河源1号冰川成冰过程的地球化学研究--以低分子有机酸为主

冰川上的表面雪层是联系大气成分与冰芯记录的重要纽带，对雪－冰现代过程的研究将有助于正确解释保存在冰芯中的古气候和环境信息。山地冰川雪冰中有机酸记录的研究在认识有机酸生物地球化学循环方面占很大的优势，本文依托天山冰川观测试验站开展的冰雪物理、化学现代过程方面的研究，对乌鲁木齐河源1号冰川中低分子有机酸和无机阴离子在成冰作用过程中的迁移转化进行了研究。新雪和保存较好的表层雪主要用来分析采样点低分子有机酸和无机阴离子的季节变化特征，粒雪坑样品主要用于进行低分子有机酸和无机阴离子沉积后过程的研究。 雪冰样品采集于1号冰川东支东经86°49′，北纬43°06′，海拔4 130 m 处，2004年3月至2005年3月期间，共获取了23个连续雪坑剖面的粒雪样品。采用美国Dionex公司的ICS-90型离子色谱仪加RFC-30型淋洗液在线发生器进行测定，检测到的低分子有机酸主要有HCOO-、CH3COO-、C2H5COO- 和(COO)22-，无机阴离子主要有F-、Cl-、NO2-、NO3-、SO42- 和PO43-。 表层雪是研究粒雪化和成冰作用过程中化学组成变化的起点。为配合天山乌鲁木齐河源1号冰川沉积后过程中化学组成变化的研究，我们首先对表层雪样品（雪坑表层5cm的雪样）进行了低分子有机酸和无机阴离子含量的分析。结果显示，除(COO)22- 外，大部分有机酸和高浓度的无机阴离子因受到周围环境和盛行风的影响呈现出明显的季节变化特征，即夏半年离子浓度变化剧烈，最大值和最小值同时出现在夏半年，冬半年的浓度则相对小而稳定；而(COO)22- 和低浓度的无机阴离子随季节变化的特征不明显，在全年均显示出波动性。数据表明，在外界条件不变的情况下，表层雪可以长时间（至少半年时间）保存其中高含量的化学组成不被改变。 通过对高含量低分子有机酸和高含量无机阴离子的沉积后过程的研究，发现它们在沉积后的迁移转化过程受温度和融水的影响较大，在不同时期表现出不同的季节变化特征。雪层消融初期，淋溶作用导致雪层内的大部分离子组分进入初始融水中，并随着融水下渗、聚集，使下部雪层中离子组分的浓度不断增加；当消融进一步加剧，大部分低分子有机酸和无机阴离子随融水径流而流失，雪层中记录的低分子有机酸和无机阴离子含量迅速降低；在消融季节，峰值向雪坑底部移动的速度较快。在冬半年的负温条件下，雪层中记录的低分子有机酸和无机阴离子的含量及其保存在雪坑下部的峰值都相对稳定，这也再次说明如果外界条件不发生改变，雪冰可以长时间（至少半年时间）保存其中的化学组成不被改变这个结论；另外，冬半年雪坑上部记录的峰值在一定程度上可以反映它们在大气中的初始水平。CH3COO- 和(COO)22- 的峰值通常会出现在污化层的附近，与污化层的位置具有较好的一致性，说明污化层对CH3COO- 和(COO)22- 的沉积后过程可能有一定的影响。