黄原胶降解菌BIT-BJ001培养条件的优化

黄原胶在采油工程中有重要的应用,但其难降解性质给采油工程带来很多问题。从塔里木油田胡杨木根部样品中分离得到1株黄原胶降解菌BIT-BJ001,对其发酵条件的研究表明,此黄原胶降解菌最适培养条件为:黄原胶0.3%,酵母粉0.5%,Na+浓度0.8%,Mg2+浓度0.8%,初始pH值为10,温度60℃。菌种BIT-BJ001降解黄原胶的能力与发酵时间、发酵液中还原糖浓度有关,发酵96 h,黄原胶降粘率达到最高,发酵液中还原糖浓度过高,将抑制菌株对黄原胶的降解。     

假酸浆子胶与黄原胶混胶流变性研究

实验研究了放置温度、时间、冻融、pH、盐以及柠檬酸对黄原胶和假酸浆子胶混胶黏度的影响.结果表明:黄原胶和假酸浆子胶有协效性,当假酸浆子胶与黄原胶的质量比15:85时,二者的协同增效性最高,胶溶液为非牛顿型流体,且变化满足Herschel-Bulkley方程.温度、时间对混胶有一定的影响.进一步对其研究表明:冻融、pH、盐以及柠檬酸都对其影响较小.     

Xanthan gum production by wild-type isolates of Xanthomonas campestris

Five newly-isolated strains of Xanthomonas campestris when compared with the standard strain, NRRL B-1459, showed higher broth viscosity and xanthan gum production. Evaluation of polysaccharide rheology is a very important determinant for selecting new xanthan-producing isolates.     

Use of hydrophilic natural gums in formulation of sustained-release matrix tablets of tramadol hydrochloride

The objective of this work was to develop matrix sustained-release tablets of highly water-soluble tramadol HCl using natural gums (xanthan [X gum] and guar [G gum]) as cost-effective, nontoxic, easily available, and suitable hydrophilic matrix systems compared with the extensively investigated hydrophilic matrices (ie, hydroxypropyl methylcellulose [HPMC]/carboxymethyl cellulose [CMC] with respect to in vitro drug release rate) and hydration rate of the polymers. Matrix tablets of tramadol (dose 100 mg) were produced by direct compression method. Different ratios, of 100∶0, 80∶20, 60∶40, 20∶80, 0∶100 of G gum (or X):HPMC, X gum:G gum, and triple mixture of these polymers (G gum, X gum, HPMC) were applied. After evaluation of physical characteristics of tablets, the dissolution test was, performed in the phosphate buffer media (pH 7.4) up to 8 hours. Tablets with only X had the highest mean dissolution time (MDT), the least dissolution efficiency (DE₈%), and released the drug following a zero-order model via swelling, diffusion, and erosion mechanisms. Guar gum alone could not efficiently control the drug release, while X and all combinations of natural gums with HPMC could retard tramadol HCl release. However, according to the similarity factor (f ₂), pure HPMC and H₈G₂ were the most similar formulations to Topalgic-LP as the reference standard. Published: March 17, 2006     

食药用真菌降血脂作用的研究及应用

综述了食药用真菌降血脂药物的研究方法、食药用真菌降血脂的机制以及应用前景。食药用真菌从抑制胆固醇的生物合成、阻止胆固醇或胆酸的吸收或促进其排出以及促进脂类代谢等方面发挥降血脂的作用。     

白芨多糖胶-瓜尔胶复配溶液的流变性

考察了瓜尔胶溶液和白芨多糖胶-瓜尔胶复配溶液的流变特性。两组溶液呈现典型的假塑性,不同浓度下两组溶液表观黏度(ηa)随剪切速率(τ)的变化可以用Ostwald-Dewaele方程描述。白芨多糖胶和瓜尔胶复配产生协同增效作用,复配溶液的ηa大于单一组分的白芨多糖胶溶液或瓜尔胶溶液的ηa。复配溶液中白芨多糖胶与瓜尔胶的最佳配比是质量比为9∶1。     

Fabrication of Triple-Layer Matrix Tablets of Venlafaxine Hydrochloride Using Xanthan Gum

The objective of present investigation was to develop venlafaxine hydrochloride-layered tablets for obtaining sustained drug release. The tablets containing venlafaxine hydrochloride 150 mg were prepared by wet granulation technique using xanthan gum in the middle layer and barrier layers. The granules and tablets were characterized. The in vitro drug dissolution study was conducted in distilled water. The tablets containing two lower strengths were also developed using the same percentage composition of the middle layer. Kinetics of drug release was studied. The optimized batches were tested for water uptake study. Radar diagrams are provided to compare the performance of formulated tablets with the reference products, Effexor XR capsules. The granules ready for compression exhibited good flow and compressibility when xanthan gum was used in the intragranular and extragranular fractions. Monolayer tablets failed to give the release pattern similar to that of the reference product. The drug release was best explained by Weibull model. A unified Weibull equation was evolved to express drug release from the formulated tablets. Lactose facilitated drug release from barrier layers. Substantial water uptake and gelling of xanthan gum appears to be responsible for sustained drug release. The present study underlines the importance of formulation factors in achieving same drug release pattern from three strengths of venlafaxine hydrochloride tablets.     

海蜇胶原蛋白肽的降血脂及抗氧化作用的研究

本研究以海蜇胶原蛋白为原料,经酶解得到海蜇胶原蛋白肽,探讨海蜇胶原蛋白肽对小鼠血脂的影响及抗氧化作用。以高脂饲料喂养ICR小鼠,建立高脂血症模型,研究胶原蛋白肽对小鼠肝系数和脂肪系数的变化情况及小鼠血脂水平、肝组织抗氧化功能的影响。结果表明海蜇胶原蛋白肽能显著降低小鼠肝系数和脂肪系数,能显著降低高脂血症小鼠血清总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、动脉硬化指数(LDL-C/HDL-C)水平,升高高密度脂蛋白胆固醇(HDL-C)和抗动脉粥样硬化因子(HDL-C/TC);能提高肝组织超氧化物歧化酶(SOD)谷胱甘肽过氧化物酶(GSH-Px)的活力,并能减低丙二醛(MDA)的含量。海蜇胶原蛋白肽具有辅助减低血脂水平和增强抗氧化功能的作用。     

Xanthan gum and ethanol production by Xanthomonas campestris and Zymomonas mobilis from peach pulp

The wild type of Xanthomonas campestris and a mutant strain of Zymomonas mobilis CP4, tolerant to sucrose up to 40% (w/v), were used to produce either xanthan gum or ethanol, respectively, from peach pulp supplemented with different salts. Both bacteria grew well (2.7 mg/ml for X. campestris and 1.45 mg/ml for Z. mobilis) in fine peach pulp and the production of xanthan gum or ethanol was 0.1–0.2 g/l or 110 g/l, respectively.     

Colon Specific Delivery of Indomethacin: Effect of Incorporating pH Sensitive Polymers in Xanthan Gum Matrix Bases

In the present study, an attempt has been made to design controlled release colon-specific formulations of indomethacin by employing pH responsive polymers Eudragit (L100 or S100) in matrix bases comprised of xanthan gum. The prepared tablets were found to be of acceptable quality with low-weight variation and uniform drug content. In vitro release studies indicated rapid swelling and release of significant percentage of drug in the initial period from matrix tablets composed of xanthan gum alone. Addition of pH responsive polymers Eudragit (L100 or S100) to xanthan gum matrix resulted in negligible to very low drug release in the initial period in acidic to weakly acidic medium. Furthermore, with increase in pH of the dissolution medium due to dissolution of Eudragit L100/Eudragit S100 that resulted in the formation of a porous matrix, faster but controlled drug release pattern was observed. Thus, a sigmoidal release pattern was observed from the designed formulations suitable for colonic delivery. Drug release mechanism in all cases was found to be of super case II type, indicating erosion to be the primary cause of drug release. Since the drug release from almost all the matrix bases in the initial phase was negligibly low and followed with controlled release for about 14–16 h, it was concluded that a matrix design of this composition could have potential applications as a colon-specific drug delivery device with additional advantage of easy scale-up and avoidance of all-or-none phenomenon associated with coated colon-specific systems.     

Fabrication of Modified Release Tablet Formulation of Metoprolol Succinate using Hydroxypropyl Methylcellulose and Xanthan Gum

The present investigation was undertaken to fabricate modified release tablet of metoprolol succinate using hydroxypropyl methylcellulose (HPMC) and xanthan gum as a matrixing agent. A 3² full factorial design was employed for the optimization of formulation. The percentage drug released at a given time (Y ₆₀, Y ₂₄₀ and Y ₇₂₀) and the time required for a given percentage of drug to be released (t _50%) were selected as dependent variables. The in vitro drug dissolution study was carried out in pH 6.8 phosphate buffer employing paddle rotated at 50 rpm. The similarity factor (f ₂) was calculated for selection of best batch considering mean in vitro dissolution data of Seloken® XL as a reference profile. It is concluded that the desired drug release pattern can be obtained by using a proper combination of HPMC (high gelling ability) and xanthan gum (quick gelling tendency). The economy of xanthan gum and faster hydration rate favors its use in modified release tablets. The matrix integrity during dissolution testing was maintained by using hydroxypropyl methylcellulose.     

Effect of dietary fibres on constituents of complex carbohydrates in streptozotocin induced diabetic rat tissues

The effect of dietary fibres on constituents of complex carbohydrates in various tissues of streptozotocin induced diabetic rats is presented by analysing different constituents of complex carbohydrates in presence and absence of dietary fibre. Wheat bran was effective in preventing the decrease (14%) in total sugars in spleen and an increase in total sugars in stomach (33%) during diabetes. Decrease in uronic acid content during diabetes in spleen was prevented to the extent of 25% by the presence of wheat bran in the diet. The other parameters which were affected by the presence of wheat bran in the diet during diabetes are amino sugar (brain and stomach), sulphates (liver) and protein (lungs and stomach). Guar gum was effective in preventing the decrease in total sugar content in spleen by 28% and sulphate content in liver by 14% during diabetes. Variation in protein content in lungs was observed in diabetes. The results indicated beneficial role of dietary fibres like wheat bran and guar gum on complex carbohydrates to varying extents in different tissues.     

培养基的组成对黄原胶发酵产量与质量的影响研究

本文着重研究了培养基各组分对胶产量与质量的影响。结果表明:氮源是极显著因素,碳源是显著因素,无机盐与柠檬酸对质量与产量的影响各有主次;以蔗糖代替葡萄糖可使产量与质量有较大提高。此外还分析了培养基中CaCO_3的加入、消泡剂的选择、H_2O_2水的添加等各因素对产胶的影响。     

黄原胶降解及其抗氧化性能研究

酸性条件下对黄原胶进行氧化降解,透析得到两种黄原胶寡糖,对产物进行FT-IR表征,GPC法测定两种寡糖的分子量分别为7500、10100。考察两种产物对超氧阴离子自由基O2-.和过氧化氢的清除活性以及还原能力,结果表明10100-XG较7500-XG具有更强的抗氧化性能。这可能与黄原胶寡糖活性羟基数目有关。     

Hypolipidemic effect and antioxidant activity of glycoprotein isolated from Ulmus davidiana Nakai in Triton WR-1339-treated mouse

The glycoprotein isolated from Ulmus davidiana Nakai (UDN) (UDN glycoprotein) has a molecular weight of 116 kDa and consists of 78.65% carbohydrate content and 21.35% protein content. In the present study, we investigated the hypolipidemic effect of UDN glycoprotein on Triton WR-1339-induced mice. With pretreatment with UDN glycoprotein, the triacylglycerol (TAG), total cholesterol and low density lipoprotein-cholesterol (LDL-C) concentrations were significantly reduced, whereas high density lipoprotein-cholesterol (HDL-C) concentration was increased in the plasma of Triton WR-1339-induced mice. With respect to antioxidative activity, UDN glycoprotein significantly decreased the level of thiobarbituric acid reactive substances (TBARS) and improved activities of catalase and glutathione peroxidase (GPx), without an apparent change of superoxide dismutase (SOD) activity. Also UDN glycoprotein significantly increased nitric oxide (NO) production in Triton WR-1339-induced mice. These results indicate that UDN glycoprotein has a hypolipidemic effect, possesses antioxidant activity and has an ability to stimulate NO production. Thus, we speculate that UDN glycoprotein is an example of natural compound that lowers plasma lipid level together with having an antioxidant function in Triton WR-1339-induced mice.     

黄原胶寡糖的抗氧化性能和非酶糖基化抑制作用研究

分别在酸性和碱性条件下通过氧化降解制备了两种黄原胶寡糖XG-H和XG-OH.红外光谱法对黄原胶寡糖的结构进行表征,凝胶渗透色谱法测定黄原胶寡糖的分子量,紫外可见分光光度法测定黄原胶寡糖的丙酮酸和还原糖含量,考察了两种黄原胶寡糖的抗氧化性能和非酶糖基化(NEG)的抑制作用.结果表明,XG-H和XG-OH都表现出一定的抗氧化能力且XG-OH强于XG-H; XG-OH促进5-羟甲基糠醛(非酶糖基化中间产物)的生成,但可显著抑制非酶糖基化荧光末端产物的生成.而XG-H表现出非酶糖基化促进作用.这可能与两种黄原胶寡糖的丙酮酸和还原糖含量有关.     

Hypolipidemic effect of an exo-biopolymer produced from submerged mycelial culture of Auricularia polytricha in rats

The hypolipidemic effect of an exo-biopolymer (EBP) produced from a submerged mycelial culture of the mushroom fungus, Auricularia polytricha, was investigated in the dietary-induced hyperlipidemic rats. In a dose-dependent study, the EBP was fed at 50–100 mg kg^–1 body weight and significantly decreased the concentrations of the plasma triacylglycerols, total cholesterol, and low-density lipoprotein (LDL) cholesterol. The plasma LDL cholesterol concentration was decreased up to 70%. Production of A. polytricha biomass and EBP were optimal at pH 4 with maximum growth at 20 °C and EBP production at 30 °C. Gel chromatography of the EBP revealed a single peak of a glycoprotein with a molecular size of 32 kDa. It contained 77.5% carbohydrate and 22.5% protein. The sugar and amino acid compositions of the EBP were analyzed.     

黄原胶降解的研究进展

综述了黄原胶的理化特性、降解意义及降解方法,重点介绍了生物法降解黄原胶的国内外研究进展,并对降解黄原胶的研究方向提出了寻求更多降解途径、开发寡糖产品等建议.     

Improved shake-flask test for the screening of xanthan-producing microorganisms

Baffled 500 ml Erlenmeyer flasks were compared with conventional 2800 ml Fernbach flasks forXanthomonas campestris to produce xanthan. Bacterial growth rates were similar in both types of flask although the Fernbach flasks gave higher biomass concentrations. Xanthan production was similar in both types of flasks but different viscosities were attained. On a weight basis, the xanthan produced in baffled flasks was up to three times more viscous and more pseudoplastic or shear thinning. For screening purposes, baffled flasks are better because the rheological quality of the gum produced in them is more like that obtained in stirred fermentors than the gum from Fernbach flasks and considerably less shaker space is required, thus allowing a larger number of tests to be performed.     

槐豆胶与黄原胶的协效性研究

对槐豆胶与黄原胶的协效性进行了研究,结果表明,槐豆胶和黄原胶有较高的协效性,其最佳配比（重量比）为2：8;当混合液浓度达到0.5%-0.6%时形成凝胶,因此槐豆胶可作为黄原胶的增稠剂和凝胶剂。