微波辐射快速制备水溶性壳聚糖

目的快速制备水溶性壳聚糖。方法利用微波辐射 ,用过氧化氢作氧化剂 ,非均相降解高分子量壳聚糖。设计了正交试验法 ,得到最优化反应条件。结果最优反应条件为 5 %过氧化氢、5 %壳聚糖 ,微波辐射功率约40 0W ,辐射 3min ,所得水溶性壳聚糖分子量为 1 .1× 1 0 4 D ,收率可达 60 %。结论微波法制备低聚壳聚糖效果理想 ,可进一步扩展到壳聚糖的其它化学修饰     

低分子量及寡聚玻璃酸

低分子量及寡聚玻璃酸具有与玻璃酸不同甚至相反的生物活性 ,可采用化学降解法、酶降解法和物理降解法进行制备     

壳聚糖的超声波降解

目的 利用超声波将非水溶性的大分子壳聚糖降解为水溶性低分子量壳聚糖，优选降解的条件。方法 在稀醋酸溶液中，超声波的辐射作用下使壳聚糖发生降解，采用粘度测定法，探讨了超声波辐射时间与壳聚糖粘度的关系以及壳聚糖的浓度，醋酸的浓度对降解速度的影响。结果 壳聚糖浓度为1%左右，醋酸浓度为5-10%，降解速度最快，辐射7小时后粘度下降了73%，产物经高效液相色谱分析得知，随着超声波作用时间的延长低聚糖的含量逐渐增大，分子量也随之降低。结论 溶液中超声波降解壳聚糖是一种理想的有效降解方法。     

壳聚糖制备工艺及其在医药领域的研究进展

壳聚糖是一种可降解的高分子物质,具有良好的生物相容性和生物活性.该文阐述利用化学降解法、微生物发酵法、酶降解法制备高分子物质壳聚糖及其在医药领域的应用研究进展.     

低分子量壳聚糖的研制

研究了在酸性条件下过氧化氢对壳聚糖的氧化降解反应，讨论了过氧化氢浓度、温度及反应时间对氧化降解反应的影响。结果表明，用过氧化氢使壳聚糖氧化降解是制备药用低分子量壳聚糖的一种简便易行的方法。     

肝素降解和低分子量肝素的制备

综述了化学法和酶法制备低分子量肝素的研究进展。化学法包括亚硝酸降解法、β 消去降解法、过氧化氢降解法、高碘酸降解法、硫酸 氯磺酸降解法、次氯酸降解法。酶法主要是肝素酶降解法。对各种制备低分子量肝素方法的特点进行比较 ,并对分子量测定方法和特点进行了讨论。     

水溶性壳聚糖的制备及其降血脂作用

目的研究水溶性壳聚糖的制备工艺,并考察其降血脂效果.方法采用H2O2氧化法制备水溶性壳聚糖,采用灌胃给药方式考察相对黏度为1.1、1.8和3.0(50℃条件)的水溶性壳聚糖对小白鼠降血脂药效.结果平均分子量1000壳聚糖的制备工艺条件为1%HAc为溶剂、壳聚糖浓度20 g/L、3%H2O2∶壳聚糖为0.5∶1、反应温度为60℃、反应时间为20 min.相对黏度为1.1、1.8和3.0的三种水溶性壳聚糖均能显著降低小鼠血浆的TCH水平,降幅可达26～30%.相对黏度1.1和3.0的壳聚糖能显著降低小鼠血浆的TG水平及MDA含量,降幅可分别达24～34%和38～40%.结论本工艺制备的三种不同黏度的壳聚糖具有较强的降脂药效,其降脂和抗氧化效果接近市售降脂良药软脉灵口服液.     

水溶性壳聚糖固体分散体的制备及质量研究

壳聚糖具有降低胆固醇、降血糖、提高机体免疫功能、抑制肿瘤、活化人体细胞等诸多生理活性,在医疗保健方面具有很大的潜在价值。但壳聚糖的分子量大,水溶性极差,较难被人体吸收,是制约壳聚糖在医药保健产品中应用的关键因素。本研究在保留壳聚糖高分子长链结构的基础上,采用固体分散技术制备具有较高水溶性的壳聚糖固体分散体,并考察其理化性质和化学稳定性,以期拓展壳聚糖在医药保健产品中的应用范围。1试验材料壳聚糖(福州市工业科学研究所),PEG4000、PEG6000(上海联试福州分公司)。2方法与结果2.1制备方法的选择:(1)熔融法,取载体PE…     

青霉菌产壳聚糖酶制备低分子量壳聚糖的研究

利用Penicilliumsp.ZD-Z1发酵培养生产壳聚糖酶,研究其降解特性,并制备特定低分子量的壳聚糖。结果表明,在30℃、pH5、加内切酶ChA0.01u/ml的条件下降解4%壳聚糖,通过MHS方程η=1.02×10-4Mw1.27控制反应时间,可以得到低分子量的壳聚糖。     

水溶性壳聚糖的制备及其降血脂作用

目的研究水溶性壳聚糖的制备工艺，并考察其降血脂效果。方法采用H₂O₂氧化法制备水溶性壳聚糖，采用灌胃给药方式考察相对黏度为1.1、1.8和3.0（50℃条件）的水溶性壳聚糖对小白鼠降血脂药效。结果平均分子量1000壳聚糖的制备工艺条件为：1%Hac为溶剂、壳聚糖浓度20 g/L、3%H₂O₂∶壳聚糖为0.5∶1、反应温度为60℃、反应时间为20 min。相对黏度为1.1、1.8和3.0的三种水溶性壳聚糖均能显著降低小鼠血浆的TCH水平，降幅可达26～30%。相对黏度1.1和3.0的壳聚糖能显著降低小鼠血浆的TG水平及MDA含量，降幅可分别达24～34%和38～40％。结论本工艺制备的三种不同黏度的壳聚糖具有较强的降脂药效，其降脂和抗氧化效果接近市售降脂良药软脉灵口服液。     

甲壳低聚糖的制备和分析

解决壳聚精的水不溶性,拓宽壳聚精的应用范围。方法：直接用过氧化氢对高分子量、高脱乙酸化度的壳聚糖进行非均相降解、制备了水溶性甲壳低聚糖产品,对产品进行红外光谱结构表征,并用高效毛细管电泳测定了寡糖的聚合度。探讨了温度、过氧化氢浓度对降解所需时间、产品得率及甲壳低聚糖聚合度的影响。结果：选择降解温度 ８０℃～９０℃,过氧化氢浓度 ８％～１０％时,水解时间０．５ ～１．０ ｈ,水溶性产品得率为 ４０％～４５％,聚合度为３～７的寡糖占水解产物的３６％～５０％。结论：该方法制备甲壳低聚糖是可行的。如进一步研究工艺条件,有望进行工业化生产。     

Novel technique of insulin loading into porous carriers for oral delivery

The increasing demand for oral macromolecule delivery encouraged the development of microencapsulation technologies to protect such drugs against gastric and enzymatic degradation. However, microencapsulation often requires harsh conditions that may jeopardize their biological activity. Accordingly, many trials attempted to load macromolecules into porous drug carriers to bypass any formulation induced instability. In this study, we prepared chitosan coated porous poly (d, l-lactide-co-glycolide) (PLGA) microparticles (MPs) loaded with insulin using a novel loading technique; double freeze-drying. The results showed a significant increase in drug loading using only 5 mg/ml initial insulin concentration and conveyed a sustained drug release over uncoated MPs. Furthermore, SEM and confocal microscopy confirmed pore blocking and insulin accumulation within the MPs respectively. The oral pharmacodynamic data on rats also proved the preservation of insulin bioactivity after formulation. Finally, the new coating technique proved to be efficient in producing robust layer of chitosan with higher insulin loading while maintaining insulin activity.     

喇咕来源水溶性壳聚糖抗肿瘤作用及其免疫调节活性研究

目的从喇咕中提取制备水溶性壳聚糖 ,并研究其抗肿瘤作用及免疫活性。方法按 2 0 0mg (kg·d)剂量灌胃给药 ,观察其对荷瘤小鼠的抑瘤作用和免疫学指标。结果水溶性壳聚糖对S180 和艾氏腹水癌的抑瘤率分别为 58.6%和 54.85% ,与环磷酰胺伍用 ,能增强荷瘤小鼠抑瘤率 ;并能拮抗环磷酰胺所致的副作用。结论喇咕来源水溶性壳聚糖对荷瘤小鼠有显著的抗肿瘤作用 ,并能调节机体免疫功能 ,降低化疗药物的毒副作用。     

Production and on-line acetylcholinesterase bioactivity profiling of chemical and biological degradation products of tacrine

The present paper describes a methodology for rapid assessment of chemical and biological degradation products of tacrine and their bioactivity for acetylcholinesterase (AChE). Analysis was achieved by utilizing liquid chromatography coupled to parallel high resolution mass spectrometry and an on-line continuous-flow AChE bioassay for biochemical detection. Key advantage of the strategy described involves the straightforward chemical production of large quantities of products of which many were the same as formed during the biological degradation by cytochromes P450 (CYPs). For this, chemical degradation of tacrine was evaluated under acidic, basic and oxidative conditions as well as elevated temperatures and light exposure. Chemical degradation products were only formed after 2 h under reflux with 3% hydrogen peroxide, where more than 50% of tacrine was converted to degradation products. Many of these products showed bioactivity. Mostly, mono-, di- or tri-oxygenated compounds were observed. This study demonstrated that the combination of chemical and biological degradation provides valuable information indicating that assessment of biological activity is important not only for biological degradation products, but also for chemical degradation products when formed. Furthermore, chemical degradation can be used to produce conveniently and in relatively large quantities clean mixtures of compounds that are also produced during metabolic incubations.     

Marine polysaccharides: therapeutic efficacy and biomedical applications

The ocean contains numerous marine organisms, including algae, animals, and plants, from which diverse marine polysaccharides with useful physicochemical and biological properties can be extracted. In particular, fucoidan, carrageenan, alginate, and chitosan have been extensively investigated in pharmaceutical and biomedical fields owing to their desirable characteristics, such as biocompatibility, biodegradability, and bioactivity. Various therapeutic efficacies of marine polysaccharides have been elucidated, including the inhibition of cancer, inflammation, and viral infection. The therapeutic activities of these polysaccharides have been demonstrated in various settings, from in vitro laboratory-scale experiments to clinical trials. In addition, marine polysaccharides have been exploited for tissue engineering, the immobilization of biomolecules, and stent coating. Their ability to detect and respond to external stimuli, such as pH, temperature, and electric fields, has enabled their use in the design of novel drug delivery systems. Thus, along with the promising characteristics of marine polysaccharides, this review will comprehensively detail their various therapeutic, biomedical, and miscellaneous applications.     

Low molecular weight chitosan inhibits obesity induced by feeding a high-fat diet long-term in mice

Three low molecular weight chitosans (molecular weight: 21, 46 and 130 kDa) obtained by enzymatic hydrolysis of a high molecular weight chitosan (average molecular weight: 650 kDa) had low viscosity and were water-soluble. The effects of these water-soluble chitosans on pancreatic lipase (in-vitro) and the elevation of plasma triacylglycerol concentration after the oral lipid tolerance test were examined in mice. The water-soluble 46-kDa chitosan was the most effective at inhibiting pancreatic lipase activity (in-vitro) and plasma triacylglycerol elevation after the oral lipid tolerance test. Based on this result, the effects of the 46-kDa chitosan on increases in bodyweight, various white adipose tissue weights, and plasma and liver lipids were examined in mice fed a high-fat diet for 20 weeks. Water-soluble 46-kDa chitosan (300 mg kg(-1), twice daily) prevented increases in bodyweight, various white adipose tissue weights and liver lipids (cholesterol and triacylglycerol) in mice fed a high-fat diet, and further increased the faecal bile acid and fat. The results suggest that the lipid-lowering effects of the 46-kDa chitosan may be mediated by increases in faecal fat and/or bile acid excretion resulting from the binding of bile acids, and by a decrease in the absorption of dietary lipids (triacylglycerol and cholesterol) from the small intestine as a result of the inhibition of pancreatic lipase activity. Water-soluble 46-kDa chitosan (100 and 300 mg kg(-1), twice daily) did not cause liver damage with the elevation of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase, or kidney damage with the elevation of blood nitrogen urea. It was concluded that water-soluble 46-kDa chitosan is a safe functional food.     

The isoprostanes - unique products of arachidonate peroxidation: their role as mediators of oxidant stress

The isoprostanes (IsoPs) are a series of novel prostaglandin-like compounds formed in vivo in humans from the free radical-catalyzed peroxidation of arachidonate independent of the cyclooxygenase. While quantification of these compounds is a highly accurate measure of oxidant stress in vivo in humans, IsoPs also possess potent biological activity and likely mediate certain aspects of oxidative injury. The purpose of this review is to summarize selected aspects of our knowledge regarding the bioactivity of the IsoPs. I will first briefly highlight mechanisms involved in IsoP formation. Subsequently, I will discuss the biological activities of certain IsoPs that are formed in abundance in vivo and focus on two compounds, 15-F(2t)-IsoP and 15-E(2t)-IsoP, that have been studied in the greatest detail. This review will then examine, at a molecular level, mechanisms by which IsoPs exert their bioactivity. It has been shown that they are ligands for various eicosanoid receptors, in particular, the thromboxane receptor. In addition, I will discuss the controversial evidence that a unique IsoP receptor(s) exists. Finally, I will offer avenues for future research related to the development of pharmacological approaches to modulate IsoP formation and action in vivo and thus decrease the pathophysiological sequelae of oxidative injury.     

Synthesis and biological activity of glycosylated analogs of the C-terminal hexapeptide and heptapeptide of Substance P

The synthesis of two glycosylated analogs of Substance P is described. The activity of the peptides was assayed on the isolated guinea-pig ileum and their degradation was studied using rat hypothalamus slices. While glycosylation noticeably enhances the solubility of the corresponding compounds, the β-glucopyranosyl moiety only slightly modifies the biological half-life and the bioactivity of the glycopeptides.     

Studies on the degradation of chitosan films by lysozyme and release of loaded chemicals

Chitosan films with or without chemicals of interest were prepared and degradation properties of chitosan films of themselves by lysozyme and releases of the loaded chemicals from the films were investigated. Enzymatic degradation rate of the films was dependent on the degree of deacetylation of chitosan used and decreased with an increase in its deacetylation. The acidic conditions accelerated the degradation compared to the neutral pH. Most of the water-soluble chemicals used in the present experiments except Coomassie Brilliant Blue with a strong acidic group and pullulan with a high molecular weight (5.8 x 10(4)-38.0 x 10(4], were rapidly released from the films within 1 h. The two chemicals described above were released only in the presence of lysozyme, and their release rates were controlled by the degradation rate of the films.     

Proapoptotic effect of a dietary supplement: water soluble chitosan activates caspase-8 and modulating death receptor expression

The effect of water-soluble chitosan, a natural polymer used as a dietary supplement, on human bladder-tumor cells was investigated. Apoptotic morphological change was demonstrated by nuclear staining. Chitosan-treated cells showed elevation of caspase-8-like activity, but no significant elevation of caspase-9-like activity, which suggest that proapoptotic effect of chitosan is attributable to death receptor activation and not to activation of the mitochondria-cytochrome c pathway. Chitosan increased expression of TNF-R1, but decreased Fas expression. Use of monoclonal antibodies to inhibit death-receptor signal transduction did not attenuate the proapoptotic activity of chitosan. Examination of death-ligands revealed that TNFalpha mRNA expression was markedly increased by chitosan treatment while FasL mRNA was not affected. Although the direct interaction of chitosan with death receptors remains unidentified, the results suggest that its proapoptotic effect might be related to interaction with TNFalpha or TNF-R1.