Synthesis of chitosan oligosaccharide selenium and its antitumor activity

Background:Polysaccharides have various biological activities;the complexation of polysaccharides with trace element ions can produce synergistic effects,improving the original biological activities of sugars and trace elements.Methods:The preparation process of chitosan oligosaccharide selenium(COSSe)was optimized by the response surface method,followed by a detailed analysis of the resultant compound’s characteristics.The anti-cancer activity of COSSe was studied using the human ovarian cancer cell line SKOV3 as a cell model.Results:The prepared COSSe response surface was well predicted,indicating successful chitosan oligosaccharide binding with selenium.Response surface method analyses identified the optimal synthesis conditions for COSSe:the reaction time of 5.08 h,the reaction temperature of 71.8°C,and mass ratio(Na2SeO3:chitosan oligosaccharide)of 1.02.Under the optimal conditions,the final product,the selenium content,reached 1.302%.The results of cell experiments showed that COSSe significantly inhibited SKOV3 proliferation in a concentration-dependent manner.RNA-seq results showed that chitosan oligosaccharide and COSSe significantly modulated the expression of genes’DNA metabolic processes and cell cycle in SKOV3 cells.Gene enrichment analysis showed the inhibition of the cell cycle,and the results of flow cytometry showed that SKOV3 cells increased in the S phase and decreased in the G2/M phase,with a noted suppression in the protein expression of cyclin-dependent kinase 2(CDK2)and cyclin A1(CCNA1).Conclusion:COSSe has a stronger effect than chitosan oligosaccharide,leading to the arrest of the cell cycle in the S phase.Thus,COSSe may be an effective candidate for the treatment of ovarian cancer.

Effects of Five Chitosan Oligosaccharides on Nuclear Factor-kappa B Signaling Pathway

The effects of five chito-oligomers, from dimer to hexamer （chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose） separated from chitosan oligosaccharides, on nuclear factor -kappaB （NF-rd3） signaling pathway were investigated by using luciferase assay and laser scanning microscopy. The expression of NF-rd3 downstream genes （cyclin DI, TNFa and IL-6） were tested by real time PCR. We found that all five chitosan oligosaccharides increased NF-KB-dependent luciferase gene expression and NF-KB downstream genes transcription, and the most significant were chitotetraose and chitohexaose. In addition, laser scanning microscopy experiments showed that chitotetraose and chitohexaose also activated the p65 subunite of NF-kB translocating from cytoplasm to nucleus, which suggested that they were the most potent activators of NF-kB signaling pathway.

UV irradiation-H2O2 system as an effective combined depolymerization technique to produce oligosaccharides from chitosan

UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.UV irradiation hydrogen peroxide （H202） system is used as an effective, easy and low-cost combined depolymerization technique to produce oligosaccharides from chitosan. UV-Vis spectroscopic studies explained that with increasing treatment time, the absorption of the depolymerized chitosan solution has increased, indicating the increase in the carbonyl and amino groups in their structure. Fourier transform infrared spectroscopy and nuclear magnetic resonance （1H NMR） analysis showed that the 1,4-β-D-glucoside linkages of chitosan are degraded without important changes in chemical structure of decomposed samples. X-ray diffraction patterns verified the polymerization of chitosan to produce oligomers, changing in structure from crystalline to amorphous. Viscosity-average molecular weight measurements of fragmented chitosan samples and MarkHouwink equation are used to demonstrate the efficiency of this depolymerization method. Finally, the obtained results ascertained that this combined method could produce water soluble chitosan with significant efficiency and no essential change in its chemical structure.

Chitosan Oligosaccharide-Ca Complex Accelerates the Depuration of Cadmium from Chlamys ferrari

This study investigated the effect of a chitosan oligosaccharide-Ca complex (COS-Ca) on the depuration of cadmium (Cd) from Chlamys ferrari. After exposure to 0.5 mg L-1 CdCl2 for 3 or 7 d, the scallops were treated by COS-Ca prior to determina-tion of Cd, calcium (Ca) and zinc (Zn) contents, Cd distribution in organs, malondialdehyde (MDA) content and antioxidant variables. Results showed that COS-Ca reduced Cd content in the viscera of the scallops, with highest Cd depuration rate (47%) observed on day 3. The COS-Ca concentration substantially affected Cd depuration, and the exposure to 8.75 mg L-1 COS-Ca led to significantly higher Cd depuration rate compared with those of lower COS-Ca concentrations (1.75, 3.5, 5.25, and 7.00 mg L-1). Distribution analysis of Cd in scallop organs indicated that COS-Ca significantly reduced Cd content in the kidney throughout the 5-d experiment, as well as in the gill during the early stage of Cd depuration. In addition, COS-Ca treatment decreased glutathione peroxidase (GSH-Px) activity and MDA content while increasing superoxide dismutase (SOD) and catalase (CAT) activities on different days. Our work suggested COS-Ca complex treatment as an effective method for acceleration of Cd depuration from Cd-contaminated bivalves.

Specific Targeting MRI of Chitosan Oligosaccharide Modified Fe_(3)O_(4) Nanoprobe on Macrophage and the Inhibition of Macrophage Foam­ing Induced by ox-LDL

Atherosclerosis(AS)is a primary cause of morbidity and mortality all over the world.Molecular imaging techniques can enable early localization and diagnosis of atherosclerosis plaques.Recent newly developed chitooligosaccharides(CSO)is considered to be capable of target mannose receptors on the surface of macrophages and to inhibit foam cell formation.Here we present a targeting magnetic resonance imaging(MRI)nanoprobe,which was successfully constructed with polyacrylic acid(PAA)modified nanometer iron oxide(Fe_(3)O_(4))as the core,and coating with CSO molecules,possessing the abilities of targeted MRI and specifically inhibition of the formation of foamy macrophages in the atherosclerotic process.The experimental results showed that the distributions of PAA-Fe_(3)O_(4) and CSO-PAA-Fe_(3)O_(4) were uniform and the corresponding sizes were about 5.93 nm and 8.15 nm,respectively.The Fourier transform infrared spectra(FTIR)testified the CSO was coupled with PAA-Fe_(3)O_(4) successfully.After coupled with CSO,the r1 of PAA-Fe_(3)O_(4) was increased from 5.317 mM s-1 to 6.147 mM s-1,indicating their potential as MRI contrast agent.Oil Red O staining and total cholesterols(TC)determination showed that CSO-PAA-Fe_(3)O_(4) could significantly inhibit the foaming process of RAW264.7 cells induced by oxidatively modified low density lipoprotein(ox-LDL).In vitro cellular MRI displayed that,compared with PAA-Fe_(3)O_(4),CSO-PAA-Fe_(3)O_(4) could lower the T1 relaxation time of RAW264.7 cells better.In summary,construction of CSO-PAA-Fe_(3)O_(4) nanoprobe in this study could realize the targeted MRI of macrophages and inhibition of ox-LDL induced macrophage foaming process.This will provide a new avenue in the diagnosis and treatment of AS.

壳寡糖对乙醇诱导的炎症反应的保护作用

为研究壳寡糖对酒精损伤海马组织的保护作用,将39只新生SD大鼠随机分为3组,分别是空白对照组(CON组)、模型组(ETOH组)和壳寡糖干预组(COS组)。建立新生SD大鼠酒精损伤模型,对COS组进行壳寡糖干预,在出生后第9天(PD9)干预结束,在PD9到PD24之间不再进行干预,分别检测PD9和PD24的磷脂酰肌醇3-激酶(PI3K)/蛋白激酶B(Akt)、胶质纤维酸性蛋白(GFAP)和凋亡诱导因子(AIF1)的表达,炎症因子白细胞介素6(IL-6)、白细胞介素10(IL-10)、肿瘤坏死因子α(TNF-α)的表达量,在PD24进行新物体识别试验。结果表明:在PD9时,COS组中PI3K和Akt及其磷酸化水平、GFAP和AIF1蛋白水平与ETOH组相比无显著差异,IL-10显著增加,IL-6和TNF-α显著降低。在PD24时,与ETOH组相比,COS组中PI3K、Akt蛋白的磷酸化水平显著上升,GFAP表达下降,IL-10显著增加,IL-6和TNF-α显著降低。壳寡糖可以在PD24缓解PI3K/Akt通路的抑制,抑制星形胶质细胞标志物GFAP的过表达,在PD9和PD24抑制IL-6和TNF-α的过表达,缓解IL-10的抑制。

壳三糖和壳五糖对睡眠剥夺小鼠学习记忆障碍的影响

各种原因引起的睡眠时间减少已成为生活常态,睡眠剥夺会降低机体的学习记忆能力,影响生活质量。该研究对C57BL/6J小鼠进行21 d睡眠剥夺,同时每天对小鼠灌胃壳三糖(chitotriose,COS3)和壳五糖(chitopentaose,COS5),通过体重、新物体识别实验、病理学染色、氧化应激和凋亡相关蛋白表达评估COS3和COS5的保护作用。结果显示,COS3和COS5干预能够缓解小鼠体重下降和海马神经细胞坏死变形,显著提高海马组织中超氧化物歧化酶水平和总抗氧化能力,显著降低海马丙二醛含量。COS3和COS5干预能够显著提升海马p-PI3K(phospho-phosphotylinosital 3 kinase)和p-Akt(phospho-protein kinase B)蛋白的相对表达量,激活PI3K/Akt信号通路,缓解神经细胞凋亡。研究表明,COS3和COS5能够明显改善睡眠剥夺引起的学习记忆能力下降,其机制可能与COS3和COS5能够缓解海马组织氧化应激和神经细胞凋亡有关,其中COS3的效果优于COS5。

玉米糖肽抗氧化活性的稳定性研究

为研究玉米糖肽在食品加工条件下抗氧化活性的稳定性,以转谷氨酰胺酶(TGase)为催化剂,利用生物安全、多伯氨基团的壳寡糖(COS)对玉米醇溶蛋白源活性肽进行糖基化修饰制备玉米糖肽,以DPPH自由基清除率和亚铁离子螯合率为指标,探究冻融次数、温度、pH、食品辅料(NaCl、葡萄糖和柠檬酸)和体外模拟胃肠消化对玉米糖肽抗氧化活性的影响。结果表明,玉米糖肽具有良好的冻融稳定性(4次)和热稳定性(60~100℃),弱碱(pH 8.0)条件下稳定,NaCl(0.5~5.0 g/100 mL)的添加对玉米糖肽的抗氧化活性无显著影响,葡萄糖(1~8 g/100 mL)的添加对DPPH自由基清除活性无显著影响,对亚铁离子螯合能力有促进作用,柠檬酸(0.04~0.20 g/100 mL)的添加及体外模拟胃肠消化对DPPH自由基清除活性有促进作用,对亚铁离子螯合能力有抑制作用。因此玉米糖肽具有一定的抗氧化活性稳定性,选择合理的加工及储藏条件有利于维持玉米糖肽的抗氧化活性。

壳寡糖通过调控SOCS3/STAT3信号通路改善脂多糖诱导的小鼠神经炎症

目的探讨壳寡糖(chitosan oligosaccharide,COS)对脂多糖(lipopolysaccharide,LPS)诱导小鼠神经炎症的改善作用及机制。方法通过对10周龄C57BL/6N小鼠腹腔注射LPS建立神经炎症模型。动物随机分为5组,分别是:对照(CON)组、LPS组、LPS+COS低剂量(LPS+COS 50 mg/kg)组、LPS+COS中剂量(LPS+COS 100 mg/kg)组、LPS+COS高剂量(LPS+COS 200 mg/kg)组。LPS注射完毕后进行旷场实验、新物体识别、Morris水迷宫等行为学实验。处死动物后,收集脑组织,酶联免疫吸附实验(enzyme linked immunosorbent assay,ELISA)分析脑内促炎因子白细胞介素-2(interleukin-2,IL-2)、白细胞介素-6(interleukin-6,IL-6)和抗炎因子白细胞介素-4(interleukin-4,IL-4)的表达;Western blot分析脑内信号传导及转录激活蛋白(STAT3)、细胞因子信号抑制物(SOCS3)蛋白的表达水平。结果行为学实验结果表明,COS可以改善LPS诱发的小鼠认知障碍下降等表现。ELISA结果表明,LPS组小鼠的促炎细胞因子的释放量显著增加,抗炎细胞因子的释放量显著降低;而COS灌胃可逆转这一变化趋势。Western blot结果提示,与CON组相比,LPS的STAT3磷酸化水平显著升高,同时也促进SOCS3的蛋白表达升高;而COS则显著下调这两个蛋白的表达。结论COS可能通过抑制SOCS3/STAT3信号通路改善LPS引起的小鼠神经炎症。

壳寡糖浸种对低温下江西铅山红芽芋脱毒试管芋萌发及生理代谢的影响

江西铅山红芽芋脱毒试管芋一般在1月至2月上旬晴天播种,“倒春寒”等低温胁迫会导致早播的江西铅山红芽芋脱毒试管芋生长缓慢,出苗周期变长,严重时会造成烂种死亡,出苗率降低,影响其产量。为提高播种期江西铅山红芽芋脱毒试管芋抗寒性,该研究利用植物组织培养和植物生理学的方法测定了壳寡糖浸种后低温下江西铅山红芽芋脱毒试管芋的萌发及其相关生理指标。结果表明:200~250 mg/L壳寡糖浸种可显著促进低温下江西铅山红芽芋脱毒试管芋的萌发。与低温对照相比,当浸种浓度为200 mg/L时,在内源激素方面,有利于低温下江西铅山红芽芋脱毒试管芋萌发过程中赤霉素、玉米素核苷、多胺和茉莉酸的积累,而不利于生长素和脱落酸的积累;在抗氧化方面,提高了超氧化物歧化酶、过氧化物酶、过氧化氢酶的活性,降低了丙二醛和过氧化氢的含量;在渗透调节方面,有利于可溶性糖、可溶性蛋白、脯氨酸的积累;在代谢关键酶方面,可提高脂肪酶、蛋白酶和α-淀粉酶活性以及三磷酸腺苷含量。因此,200 mg/L壳寡糖可以调控低温下江西铅山红芽芋脱毒试管芋内源植物激素和渗透调节物质含量、抗氧化酶和代谢关键酶活性,促进其在低温下的萌发。

壳寡糖的生物活性及其在食品添加剂方面的应用进展

壳寡糖(chitosan oligosaccharide,COS)是由壳聚糖通过物理、化学或酶水解等方法脱乙酰解聚得到的多糖,是自然界中唯一具有正电荷的阳离子碱性氨基寡糖,其主要来源于虾壳、贝类等甲壳类水生物。根据分子量、聚合度、脱乙酰度、电荷分布、各单元排列方式不同,COS能表现出不同的物理化学特性,然而,COS的生物活性主要来自于各单元的羟基和氨基。由于COS具有诸多特殊活性(如抗菌、抗氧化、抗炎等),目前已经被广泛应用于医学、化妆和农业等多个领域,但在食品领域的应用相对较少,且对COS的生物活性及在食品添加剂方面的应用缺乏系统总结报道。本文通过对COS的结构、性质以及其生物活性的阐述,总结了COS在食品添加剂中如保鲜剂、功能因子添加剂、风味改善剂中的应用与发展,对COS在食品加工领域未来的发展进行展望,为食品加工方面的应用提供新思路。

氮肥运筹与化学调控对双季稻产量及其抗倒伏特性的影响

以早稻品种陆两优996、株两优819及晚稻品种H优518、盛泰优018为材料,于2020年开展大田试验,设计3种氮肥运筹方式N1、N2、N3(分蘖肥、穗肥、粒肥用量比分别为7∶2∶1、6∶3∶1、5∶4∶1)与2种化学调控剂多效唑(C1)、壳寡糖(C2)双因素试验,研究氮肥运筹方式和化学调控对水稻产量及抗倒伏能力的影响。结果表明:氮肥运筹和化学调控对水稻产量影响显著,早、晚稻各品种产量均以N2C2处理的最高,主要通过提高植株有效穗数而增产;与N1相比,N2和N3降低了茎秆高度、节间长度和重心高度,增加了茎粗、茎壁厚度和节间充实度,茎秆抗倒伏能力增强,且N2优于N3处理;与对照处理(C3,喷施清水)相比,C1和C2均降低了水稻茎秆高度、重心高度和节间长度,增加了茎粗、茎壁厚度和节间充实度,从而提高了水稻抗倒伏能力;从互作效应来看,N2C1、N2C2和N3C1处理的茎粗和茎壁厚度较大,倒3与倒4节节间长度较短,节间充实度和抗折力较高,倒伏指数较低。综合考虑各品种倒伏指数和产量性状,N2C2处理,即分蘖肥、穗肥、粒肥施用比例为6∶3∶1条件下,于拔节初期喷施壳寡糖,可在提高双季稻抗倒伏能力的同时获得最高产量。

氮肥减量配施壳寡糖对棉花根系生长及根际土壤酶活性的影响

改善根际土壤环境以及促进棉花根系发育对棉花健康生长及产量和品质的提高意义重大。为探究氮肥减量配施壳寡糖促进棉花根系生长及调节土壤酶活性的作用,以盆栽试验和田间小区试验为研究方法,设置了不施肥、常规施肥(施N 400 kg/hm^(2)、P_(2)O_(5)140 kg/hm^(2)、K_(2)O 130 kg/hm^(2))、常规减氮20%施肥、常规减氮20%施肥+聚合度2~6型壳寡糖450 g/hm^(2)、常规减氮20%施肥+聚合度2~20型壳寡糖450 g/hm^(2)等5个处理,研究了氮肥减量配施不同聚合度类型壳寡糖对棉花根系生长和根际土壤酶活性的影响。结果表明,除土壤过氧化氢酶外,2个配施壳寡糖的处理均不同程度上降低了土壤脲酶、蔗糖酶、磷酸酶活性,其中酶活性降幅最大的为土壤磷酸酶,常规减氮20%施肥配施聚合度2~6型壳寡糖处理和常规减氮20%施肥配施聚合度2~20型壳寡糖处理分别比常规减氮20%施肥处理降低10.6%和5.5%。常规减氮20%施肥配施聚合度2~6型壳寡糖处理较常规减氮20%施肥处理土壤硝态氮含量增加了38.1%,而常规减氮20%施肥配施聚合度2~20型壳寡糖处理较常规减氮20%施肥处理土壤硝态氮含量降低了43.4%。并且施加聚合度2~6型、聚合度2~20型2种不同聚合度类型壳寡糖后,棉花根长较常规减氮20%施肥处理分别增加64.2%、40.1%,根表面积较常规减氮20%施肥处理增加74.8%、54.4%,根体积较常规减氮20%施肥处理增加106.2%和73.2%。由此可见,聚合度2~6型壳寡糖对促进棉花根系生长效果要优于聚合度2~20型壳寡糖。

Antoioxidant Activity of Carboxymethyl Chitosan with Different Substituted Degrees

[Objective] In order to study the relations among different positions, degrees of substitution and antioxidant ability. [Method] N, O-carboxymethyl chitosan （NOA, NOB and NOC）with various degrees of substitution （DS）were obtained by etherizing chito-oligosacchaside. Their structure and substituted degree were characterized and their antioxldant activity to·OH was evaluated. [ Result] The IC50 s of NOA ,NOB and NOC were 0.15 ,0. 29 ,0. 23 mg/ml while their DSs of -NH2 position（DSN） were 0.51,0.29 and 0.38 and DSo were 0. 74 ,0. 84 ,0. 97respectively.[ Conclusion] With the increase of DSN ,antioxidant activity of N,O-carboxymethyl chitosan oligosaccharide to·OH was up.

超声-微波预处理协同复合酶法制备壳寡糖的工艺优化及其抗氧化活性

为了实现壳寡糖的高效制备,本研究以壳聚糖为原料,利用超声-微波预处理协同复合酶法制备低聚合度壳寡糖。以还原糖含量为指标,通过响应面设计法优化酶解工艺参数,并评估壳寡糖的抗氧化活性。结果表明:α-淀粉酶和壳聚糖酶1:1的复合酶组合效果最佳。最佳制备工艺参数为:微波功率200 W、超声功率200 W、超声-微波预处理时间5 min、底物浓度1%、pH5.8、温度53.5℃、复合酶添加量0.24%,在此条件下酶解5.7 h,还原糖含量达到最大值8.10 mg/mL。所制备的壳寡糖为2~6糖,平均分子量为993.5 Da。抗氧化活性结果表明壳寡糖具有较强的自由基清除活性,其对DPPH自由基和ABTS+自由基的IC50分别为0.274、0.127 mg/mL,铁离子还原能力在1.5 mg/mL时达到最大值24.56 mmol/L。本实验结果表明超声-微波预处理协同复合酶法在壳寡糖制备方向具有较好的应用前景。

叶面喷施寡糖对花生根区固氮菌群落结构及产量的影响

研究施用壳寡糖和纤维寡糖对花生根区土壤固氮菌群落结构及产量的影响。通过田间试验,以清水处理作为对照(CK),叶面喷施浓度为50 mg/L的壳寡糖(CSOS)和纤维寡糖(COS),利用高通量测序技术,研究土壤中固氮菌群落结构组成及多样性分布特征,分析2种寡糖对土壤理化性质和花生产量指标的影响。(1)与CK相比,CSOS处理慢生根瘤菌属(Bradyrhizobium)、透明颤菌属(Vitreoscilla)、固氮氢自养单胞菌属(Azohydromonas)、固氮螺菌属(Azospirillum)、假单胞菌属(Pseudomonas)、眉藻属(Calothrix)和弗兰克氏菌属(Frankia),相对丰度显著增加分别为10.99%、45.63%、29.88%、23.24%、181.13%、27.75%和36.61%。COS处理固氮螺菌属(Azospirillum)、中华根瘤菌属(Sinorhizobium)和眉藻属(Calothrix)相对丰度显著增加分别为86.12%、664.41%和277.97%。(2)与CK相比,CSOS处理显著提高土壤中全氮和铵态氮含量,平均增幅分别为15.50%和20.19%。COS处理显著增加土壤中全氮、硝态氮和铵态氮,分别为17.05%、18.68%和27.58%;此外,CSOS和COS处理相较于CK,土壤p H均显著下降,分别下降了0.08和0.06。(3)CSOS和COS处理均显著增加花生产量,分别为19.3%和22.0%。因此,叶面喷施壳寡糖和纤维寡糖,可以调节花生根区土壤不同固氮菌属的相对丰度和影响土壤的理化因子(全氮、硝态氮和铵态氮),最终均显著提高花生产量。

不同外源寡糖对设施黄瓜生理特性及产量和品质影响差异

选择壳寡糖(GT)和复合寡糖(KP)为制剂处理,以大棚常规对照(CG)和清水对照(CK)为对比,分析黄瓜叶片叶绿素相对含量(SPAD)、叶绿素荧光参数和超微结构,根系表观形态和根系活力(RV),以及抗氧化酶和内源激素的变化,比较不同类型寡糖制剂对设施黄瓜生长及产量的调控作用。结果表明:与其他处理相比,KP处理能有效促进黄瓜叶片和根系生长,其SPAD、最大光化学量子产量(Fv/Fm)、光化学淬灭系数(qP)、非光化学淬灭系数(NPQ)和RV均显著增加4.15%~15.63%、6.49%~20.03%、33.33%~152.63%、10.37%~71.62%和8.51%~171.43%;超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性显著提升6.75%~91.49%、3.85%~97.62%和3.00%~28.15%;此外,促使黄瓜生育后期叶片生长素(IAA)含量显著提高5.43%以上,脱落酸(ABA)含量显著降低4.35%~18.63%;黄瓜产量和可溶性糖含量显著增加13.72%和11.52%以上。比较而言,GT处理对黄瓜根冠生长,内源激素和抗氧化酶活性的影响表现出不稳定性,仅坐果期叶片光合生理特性(SPAD、叶绿素荧光参数和叶片超微结构)和RV有所改善。相较于GT处理,KP处理在促进黄瓜根冠生长,调控抗氧化酶活性和内源激素平衡方面具有明显优势。结合相关性分析发现,黄瓜产量与NPQ、RV、SOD和POD活性呈极显著正相关(P<0.01),与Fv/Fm显著正相关(P<0.05);且SOD和POD活性均与ABA含量显著负相关(P<0.05)。综上,外源复合寡糖主要通过促进黄瓜根冠协调生长,维持生育后期高光合效率、根系活力和叶片功能结构稳定,调节抗氧化酶活性,促进生长激素和抑制生长激素间的平衡,保障生育后期细胞膜功能稳定,延缓叶片自然衰老,实现黄瓜的提质增产。

TGase催化的壳寡糖糖基化修饰玉米肽的抗氧化活性

为进一步提高玉米肽的抗氧化活性,以玉米醇溶蛋白源活性肽为原料,利用谷氨酰胺转氨酶(TGase)催化壳寡糖(分子质量1500 Da)与玉米肽共价结合制备玉米糖肽,研究壳寡糖的糖基化修饰对玉米肽抗氧化活性的影响,并对玉米糖肽进行体外模拟胃肠消化,表征玉米糖肽在体内发挥抗氧化活性的潜力。结果表明:TGase催化的壳寡糖共价结合使玉米肽的肽含量和体外消化率显著提高;在质量浓度为2.0 mg/mL时,TGase催化壳寡糖糖基化修饰使玉米肽的DPPH自由基、羟自由基、超氧阴离子自由基清除率,Fe^(2+)螯合率和还原力提高,体外消化使玉米糖肽的DPPH自由基、羟自由基清除率和还原力提高,而Fe^(2+)螯合率和超氧阴离子自由基清除率降低。综上,TGase途径的壳寡糖糖基化反应使玉米肽的抗氧化活性显著提高,且体外消化可以促进玉米糖肽抗氧化活性的释放(Fe^(2+)螯合能力和超氧阴离子自由基清除能力除外)。

光敏功能化载药系统CPTPP-FA-LCOS的制备及性能

通过酰化反应将叶酸(FA)、两亲性亚油酰化壳寡糖(LCOS)连接到羧基取代的四苯基卟啉(TPP)化合物5-(4-羧基苯基)-10,15,20-三苯基卟啉(CPTPP)结构上,得到了潜在光敏功能化载药系统CPTPP-FA-LCOS。利用FTIR、UV-Vis、TEM、FL对CPTPP-FA-LCOS的结构进行了表征,并运用表面张力法测定了其临界胶束质量浓度(CMC)。结果表明:CPTPP-FA-LCOS的CMC=2.5×10^(-3)g/L,其可形成稳定的球形纳米胶束,粒径在70~120 nm。四唑盐(MTT)比色法的初步实验结果表明:在光照条件下,0.4 g/L的CPTPP-FA-LCOS即可使He La细胞存活率降至50%以下,表明CPTPP-FA-LCOS具有明显的光毒性。

壳寡糖水溶液(优力克)的抗菌活性及其影响因素

为探究壳寡糖水溶液(商品名优力克)体外抗菌活性及其影响因素,本研究采用标准微量肉汤稀释联合平板计数法(简称标测法)测定了优力克对4株渔源多重耐药菌的最小抑菌浓度(minimum inhibitory concentration,MIC)和最小杀菌浓度(minimum bactericidal concentration,MBC)、采用微孔板模拟全池泼洒(简称模测法)测定了优力克对MHA可培养水生细菌的MIC和MBC、并评价了标测法的孵育温度、起始细菌浓度、MH浓度、pH和货架期对优力克MIC和MBC的影响。结果显示,标测法下,优力克对大肠杆菌E105、维氏气单胞菌AV040、副炭疽芽孢杆菌BC006和贝莱斯芽孢杆菌B14的MIC和MBC(32~64 g·m^(-3))是其临床推荐使用浓度(0.3~0.5 g·m^(-3))的数百倍;而模测法下,优力克对MHA可培养水生菌的MIC和MBC(4~8 g·m^(-3))是其临床推荐使用浓度的数十倍。标测法体系的温度(5~35℃)越高、细菌浓度(103~108 cfu·mL^(–1))越高、MH浓度(1/256~1×MH)越高、pH(5.5~9.5)越高,优力克对细菌的MIC和MBC越大(最大值是最小值的2~8倍);上述参数范围内优力克对4种测试菌的MIC在16~128 g·m^(-3)之间。优力克货架保质期至少为24个月。本研究结果提示,壳寡糖水溶液(优力克)是非常有前景的渔业水环境细菌载量的调节剂。