植物乳杆菌胞外多糖包覆的高稳定性硒纳米颗粒的制备及其抗氧化活性的研究*

目的:以植物乳杆菌胞外多糖(EPS)作为稳定剂和包覆剂,安全、简便地制备高稳定性胞外多糖-纳米硒复合物(E-SeNPs),并研究其稳定性和抗氧化活性。方法:将植物乳杆菌胞外多糖引入亚硒酸钠与抗坏血酸的反应体系中,室温合成E-SeNPs。采用透射电子显微镜(TEM)、动态光散射(DLS)、紫外可见光谱(UV-vis)和傅里叶变换红外光谱(FT-IR)等技术对E-SeNPs的尺寸、形貌、结构及稳定性进行研究。此外,通过检测E-SeNPs的还原能力、ABTS⁺的清除率评估其体外抗氧化活性。结果:制备了具有良好分散性、稳定性的E-SeNPs,其平均粒径为(45.17±11.9)nm,带负电荷(-31.3mV)。同时,由于包覆作用,该E-SeNPs在水溶液中可稳定存在20天。最后,相同浓度下,E-SeNPs的还原力、ABTS⁺清除率都明显高于EPS和硒纳米颗粒(SeNPs),表现出了良好的抗氧化活性。结论:获得了一种新型的SeNPs稳定剂和包覆剂,简便、安全地制备了高稳定性、水分散性良好且具有良好抗氧化活性的SeNPs。     

季也蒙假丝酵母胞外多糖的分离纯化及抗氧化活性研究

对一株源于海参肠道的季也蒙假丝酵母产胞外多糖进行分离纯化并对其抗氧化活性进行研究.采用乙醇沉淀、Sevag除蛋白等方法得到胞外粗多糖EPS.EPS经Sepharose强阴离子交换层析分离后,分别得到3个组分EPS1、EPS2和EPS3,对抗氧化活性较高的EPS2采用Sephacryal凝胶过滤层析进行纯化,得到1个单一组分EPS2-1,采用气相色谱法分析其单糖组成,并验证其抗氧化活性.结果表明:EPS2-1是由木糖、甘露糖、葡萄糖和半乳糖组成的;它具有较强的抗氧化活性,当其浓度为0.36 mg/mL时,对羟基自由基的清除率可达100％,明显高于同浓度下Vc对羟基自由基的清除率14.42％;当EPS2-1浓度为0.60 mg/mL时,对超氧阴离子自由基的清除率可达53.22％;同时EPS2-1表现出一定的还原力.研究证明该活性多糖具有很好的应用潜力,值得进一步研究开发.     

植物乳杆菌JLK0142胞外多糖对RAW264.7巨噬细胞和免疫抑制小鼠的免疫调节作用

【目的】研究植物乳杆菌JLK0142胞外多糖(EPS)对RAW264.7巨噬细胞和免疫抑制小鼠免疫活性的影响。【方法】从植物乳杆菌JLK0142培养液中分离纯化EPS,采用体外细胞培养,测定EPS对巨噬细胞增殖、吞噬活性和一氧化氮(NO)分泌的影响;采用环磷酰胺构建免疫抑制小鼠模型,灌胃不同剂量的EPS,分别测定小鼠脾脏指数、T淋巴细胞增殖活力及血清中IL-2和TNF-α水平。【结果】植物乳杆菌JLK0142胞外多糖在50–800μg/m L浓度范围内能促进正常状态RAW264.7巨噬细胞的增殖,显著提高巨噬细胞的吞噬活性及NO的分泌量;与模型组相比,EPS中、高剂量组小鼠脾脏指数和T淋巴细胞增殖活力显著提高;EPS高剂量组小鼠血清中IL-2和TNF-α含量显著提高。【结论】植物乳杆菌JLK0142胞外多糖能有效提高RAW264.7巨噬细胞的免疫活力,并拮抗环磷酰胺对小鼠免疫功能的抑制作用。     

乳杆菌胞外多糖合成基因簇及构效关系

肠道菌群稳态对维护人体的健康具有至关重要的作用。作为肠道天然微生物群“守卫兵”,益生菌参与改善体内微生态平衡。乳杆菌(Lactobacillus)是一种肠道益生菌的代表,其合成的胞外多糖(exopolysaccharide, EPS)既可通过增益肠道内其他益生菌的生长来优化肠道微生态,还具有抗肿瘤、抗氧化、降胆固醇、降血压和增强机体免疫力等益生功能。本文对近年来乳杆菌胞外多糖的遗传、生物学活性、构效关系等方面的研究进展,进行综述和展望。     

富硒黄山贡菊多糖的提取及其抗氧化活性研究

目的：探究富硒黄山贡菊多糖的超声辅助提取工艺优化及其抗氧化活性。方法：采用单因素和响应面试验研究最佳提取工艺,测定其体外抗氧化活性(DPPH·、·OH、ABTS⁺清除能力与Fe³⁺还原能力)。结果：料液比为25 mL/g时,最佳提取工艺条件：超声时间30 min,温度70℃,超声功率60 W;与水提法相比,超声辅助提取法和水提法的提取率分别为15.83%与13.46%,且硒含量分别为1.276 mg/kg和0.408 mg/kg;体外抗氧化活性实验表明超声辅助提取法优于水提法。结论：为富硒黄山贡菊多糖的纯化、结构鉴定及食药类产品开发应用提供研究基础。     

Enterobacter cloacae Z0206细菌胞外多糖的体外抗氧化活性研究

本实验旨在对Enterobacter cloacae Z0206菌进行发酵培养,以制备胞外多糖,并对其体外抗氧化活性进行初步研究。通过产多糖菌E.cloacaeZ0206的深层发酵制备细菌胞外多糖,在此基础上对其清除DPPH自由基、超氧阴离子、抑制羟自由基的能力以及还原力等四个方面进行实验,评价其抗氧化活性。结果表明,深层发酵制备的E.cloacaeZ0206胞外多糖产量为6.62g/L,其在5mg/mL时对DPPH自由基和羟自由基的清除率分别达到61.57%和40.08%。提示E.cloacaeZ0206细菌胞外多糖具有显著的抗氧化能力,具有开发为抗氧化类食品或药品的潜力。     

耐高盐枯草芽孢杆菌XP合成球形纳米硒及其抑制草莓病原真菌生物活性

生物方法合成纳米材料具有低能耗、高安全性以及环境友好等优良特点,因而备受人们关注。利用细菌将硒酸盐或亚硒酸盐还原为单质硒,不仅可以降低硒毒性,而且还能获得价值更高的生物纳米材料。文中选用可耐受高盐环境胁迫的枯草芽孢杆菌亚种Bacillus subtilis subspecies stercoris strain XP构建生物模型,分别以LB液体培养基和亚硒酸钠为介质和底物 (电子受体),解析菌株XP合成纳米硒的基本规律。通过扫描电镜 (Scanning electron microscope,SEM) 观察、X射线能谱分析 (X-ray energy dispersive spectral analysis,EDAX)、X射线衍射 (X-ray diffraction,XRD) 分析、傅里叶红外变换光谱 (Fourier transform infrared spectroscopy,FTIR) 技术对合成的纳米硒进行物理化学表征分析,同时选用草莓枯萎、红叶、紫斑病病原真菌对其抗菌活性进行分析。结果表明,菌株XP介导合成的单质硒为球形纳米颗粒 (Selenium nanoparticles,SeNPs),其生成量与反应时间呈正相关 (0–48 h),且细胞形态未发生褶皱或破损等变化 (耐受力强);SeNPs为非晶态,粒径范围在135–165 nm,表面元素组成以Se为主,同时存在C、O、N、S等有机元素;颗粒表面包裹生物大分子物质,-OH、C=O、N-H、C-H等官能团与SeNPs稳定性和生物活性密切相关;高浓度纳米硒对枯萎、红叶、紫斑病病原真菌均有显著抑制活性 (P<0.05),其中对草莓红叶病与枯萎病病原真菌的抑制活性明显优于对紫斑病病原真菌的抑制活性。总而言之,菌株XP不仅耐受高盐胁迫能力强,同时还可介导合成生物SeNPs,其合成的纳米硒颗粒具有良好的稳定性和生物活性,在草莓病害防治以及绿色富硒草莓种植等领域具有潜在的应用价值。     

植物乳杆菌的功能评价

从实验室自制泡菜中分离得到6株乳酸菌,经生理生化试验和分子生物学鉴定为植物乳杆菌(Lactobacillus plantarum)。对6株植物乳杆菌进行评价,发现1株环境耐受能力较强、益生效果较好的植物乳杆菌Z22,其在人工胃液和肠液中的存活率分别为95.45%和45.24%,胆固醇脱除率为65.80%。植物乳杆菌Z22胞外多糖的抗氧化试验结果表明:酸性多糖EPS-S对1,1-二苯基-2-三硝基苯肼自由基(·DPPH)、·OH、超氧阴离子自由基(·O-2)均有较好的清除能力,分别达到27.75%、66.16%和58.00%;中性多糖EPS-Z对这3种自由基清除率分别为24.02%、59.03%和45.20%,且EPS-S的抗氧化能力要高于EPS-Z。     

香茅精油的抑菌和抗氧化活性研究

选用产自福建厦门的香茅(Cymbopogon nardus),测定香茅精油对白色粘性沙雷氏菌、红色粘性沙雷氏菌、大肠杆菌、金黄葡萄球菌、铜绿假单胞菌和紫色杆菌等6种菌的抑菌活性,并利用ABTS^.+自由基清除法以及超氧阴离子清除法研究香茅精油的抗氧化活性。结果表明,新鲜香茅精油的平均提取率为0.29,对6种供试菌种都有较高的抑制作用,其中对紫色杆菌的抑制活性最强,且香茅精油有极高的清除ABTS^.+自由基以及超氧阴离子自由基的能力,证明香茅精油具有广谱抑菌活性及强抗氧化活性。     

棘豆蠕孢菌多糖抗氧化活性研究

以总还原力、羟自由基(.OH)抑制活性、超氧阴离子自由基O 2的清除率、亚硝酸根离子(NO2-)的清除率为评价指标,探明内生真菌棘豆蠕孢菌(Embellisia oxytropis Q.Wang,Nagao&Kakish)次级代谢产物多糖的抗氧化作用。结果表明:棘豆蠕孢菌多糖的抗氧化活性随着多糖浓度的增加而增大,呈量效关系,其中胞内多糖对自由基和亚硝酸根离子具有较好的清除作用,清除率高达80%以上,与维生素C对照组接近。     

Biomedical potential of actinobacterially synthesized selenium nanoparticles with special reference to anti-biofilm,anti-oxidant,wound healing,cytotoxic and anti-viral activities

Currently, there is an ever-increasing need to develop environmentally benign processes in place of synthetic protocols. As a result, researchers in the field of nanoparticle synthesis are focusing their attention on microbes from rare biological ecosystems. One potential actinobacterium, Streptomyces minutiscleroticus M10A62 isolated from a magnesite mine had the ability to synthesize selenium nanoparticles (SeNPs), extracellularly. Actinobacteria mediated SeNP synthesis were characterized by UV–visible, Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and high resolution transmission electron microscopy (HR-TEM) analysis. The UV-spectral analysis of SeNPs indicated the maximum absorption at 510 nm, FT-IR spectral analysis confirms the presence of capping protein, peptide, amine and amide groups. The selenium signals confirm the presence of SeNPs. All the diffraction peaks in the XRD pattern and HR-TEM confirm the size of SeNPs in the range of 10–250 nm. Further, the anti-biofilm and antioxidant activity of the SeNPs increased proportionally with rise in concentration, and the test strains reduced to 75% at concentration of 3.2 μg. Selenium showed significant anti-proliferative activity against HeLa and HepG2 cell lines. The wound healing activity of SeNPs reveals that 5% selenium oinment heals the excision wound of Wistar rats up to 85% within 18 days compared to the standard ointment. The biosynthesized SeNPs exhibited good antiviral activity against Dengue virus. The present study concludes that extremophilic actinobacterial strain was a novel source for SeNPs with versatile biomedical applications and larger studies are needed to quantify these observed effects of SeNPs.     

利用扁桃斑鸠菊叶发酵高产粗毛纤孔菌胞外多糖的条件优化及其抗氧化活性研究

粗毛纤孔菌胞外多糖是粗毛纤孔菌液体发酵的重要活性代谢产物,但采用常规的发酵方法,粗毛纤孔菌胞外多糖的产量较低。为更好地获取粗毛纤孔菌胞外多糖,本文采用双向液体发酵的方法,通过向发酵培养基中添加适量的扁桃斑鸠菊叶粉末,来提高粗毛纤孔菌胞外多糖的产量,并对优化得到的胞外多糖抗氧化活性进行了研究。以发酵液中胞外多糖含量为指标,采用单因素实验和正交实验优化发酵条件;采用红外光谱对胞外多糖的结构特征进行分析;通过测定胞外多糖对ABTS、DPPH和羟基自由基的清除率来了解其抗氧化活性。结果表明,最优发酵条件为:扁桃斑鸠菊叶粉末添加量0.5g/L、发酵时间10d、pH 6.5、接种量5.0mL,在此条件下,粗毛纤孔菌胞外多糖的产量达到(2.34±0.25)mg/mL,与未添加扁桃斑鸠菊叶的空白组相比,其胞外多糖产量提高了约216.22%;红外分析与抗氧化活性实验结果表明,添加扁桃斑鸠菊叶后的胞外多糖与未添加扁桃斑鸠菊叶的胞外多糖红外主要吸收峰一致,并且对ABTS、DPPH以及羟基自由基清除能力相近。本研究结果表明扁桃斑鸠菊叶能够有效地提高粗毛纤孔菌胞外多糖的产量,为其他珍稀食药用菌胞外多糖的高效生产提供了新思路。     

Production, characterization and antioxidant activity of exopolysaccharides from submerged culture of Morchella crassipes

The aim of this work was to investigate the fermentation optimization, molecular characterization, and antioxidant activity in vitro of exopolysaccharides (EPS) from Morchella crassipes in submerged culture. Firstly, an optimal medium for EPS production was obtained by single-factor experiment and central composite design as follows: maltose 44.79?g/L and tryptone 4.21?g/L. Then, one fraction of EPS was obtained from the culture filtrates by size exclusion chromatography and the molecular characteristics were examined by a multi-angle laser light scattering and refractive index detector system. The weight-average molar mass and the polydispersity ratio of the EPS fraction were revealed to be 1.961?×?10(4)?g/mol and 1.838, respectively. FT-IR spectroscopy was used for obtaining vibrational spectra of the purified EPS fraction. Finally, the antioxidant activity of EPS was investigated and the relationship with molecular properties was discussed as well.     

Characterization and antioxidant activity of an exopolysaccharide produced by Leuconostoc pseudomesenteroides JF17 from juçara fruits (Euterpe edulis Martius)

Juçara palm tree is considered an important species in the Atlantic forest ecosystem and the exploitation of its fruits is a main sustainable strategy adopted to its maintenance. Among several microorganisms in the juçara fruits, were found lactic acid bacteria (LAB) highly capable of synthesizing exopolysaccharides (EPS). Thus, the EPS synthesized by Leuconostoc pseudomesenteroides JF17 was characterized according to its chemical structure, physicochemical properties and antioxidant activity. HPLC analysis showed that the EPS consisted of a homopolysaccharide composed of glucose units, FT-IR spectroscopy revealed a dextran, confirmed by ¹H and ¹³C NMR spectra which showed the composition of the polysaccharide, d-glucose units bound by α-(1→6). The EPS showed high water retention capacity, 507.812 ± 47.471 %, and may be related to the porous structure revealed by SEM images. Thermal analysis indicated that the EPS had excellent thermal stability with degradation temperature of 320.8 °C and melting point at 279.81 °C, with the enthalpy of 106.557 J/g. The EPS also presented sequestration ability on different free radicals tested, indicating high antioxidant activity. The results suggest that L. pseudomesenteroides JF17 might be widely used in the production of dextran which has potential qualities for applications in the food industry.     

盐穗木金属硫蛋白HcMT的体外自由基清除活性及抗氧化能力*

目的: 原核表达盐穗木(Halostachys caspica C. A. Mey.)金属硫蛋白HcMT并探究其抗氧化活性。方法: 构建原核表达载体pET-32a-HcMT,转化至大肠杆菌Escherichia coli BL21,加入Zn²⁺胁迫培养(终浓度为200 μmol/L),分离纯化得到Zn-HcMT,测定Zn-HcMT自由基清除活性和总抗氧化能力,制备复合物Zn-HcMT/TiO₂并做FTIR表征。结果: 通过原核表达获得融合蛋白Zn-HcMT,对·OH、O₂·^-、DPPH自由基具有较强的清除活性,对·OH、O₂·^-的IC₅₀分别为0.386 mg/mL、0.038 mg/mL。融合蛋白浓度为0.01 mg/mL时,对DPPH清除率达(37.43 ± 0.006 8)%,浓度为0.3mg/mL时TEAC(trolox-equivalent antioxidant capacity)值为(1.023 ± 0.01)mmol/L,融合蛋白还原力A₇₀₀为0.142 ± 0.055,FTIR图谱同时表现了Zn-HcMT和TiO₂吸收特性。结论: Zn-HcMT具有良好的清除ROS活性及较强的抗氧化能力,在化妆品领域有潜在应用前景。     

银耳菌糠黑色素的理化性质及抗氧化和抑菌活性

银耳菌糠中存在一种银耳的伴生菌——炭团菌(俗称香灰菌),其菌丝生长到一定阶段后会产生大量的黑色素,具有广泛的应用价值。本研究从银耳菌糠中提取黑色素,研究其理化性质、抗氧化活性及抑菌作用。通过紫外-可见光谱、傅里叶红外光谱对提取的黑色素进行鉴定,表明银耳菌糠黑色素具有黑色素的典型特征。通过对银耳菌糠黑色素理化性质的研究,表明银耳菌糠黑色素是一种趋于黑色并略带红色和黄色的粉末;该黑色素易溶于碱性溶液;具有较好的热稳定性和光稳定性,其稳定性受氧化剂和还原剂的影响较小,受Ca²⁺、Cu²⁺的影响较明显。通过总抗氧化能力(FRAP法)、自由基清除能力检测银耳菌糠黑色素的抗氧化活性,研究表明黑色素具有较高的抗氧化活性,羟自由基、ABTS自由基清除的EC₅₀值分别为0.429 mg/mL和0.016 mg/mL。本研究还检测了黑色素对革兰氏阳性、革兰氏阴性细菌的抑菌能力,结果表明该黑色素在浓度为3.2 mg/mL时对供试菌株的抑菌率超过90%,且对革兰氏阳性菌会较敏感。本研究为银耳菌糠的有效利用及其黑色素产品的开发提供了理论基础,具有较高的经济价值。     

鲍姆桑黄五个品种栽培特性及功能成分的比较分析

测定比较了鲍姆桑黄5个品种的菌丝生长速度、原基分化时间、农艺性状和产量,子实体多糖、总黄酮、总三萜和总酚含量,以及其对ABTS+自由基、DPPH自由基和羟自由基的清除能力。结果表明：相同培养条件下,鲍姆桑黄不同品种菌丝生长速度、原基分化时间、农艺性状、产量、活性成分及抗氧化能力均存在差异;鲍姆桑黄HN01菌丝生长速度最快、生长势好、原基分化快、农艺性状佳、产量高,鲍姆桑黄SW次之;鲍姆桑黄SW子实体多糖、总黄酮、总三萜和总酚含量相对较高,其活性成分的抗氧化能力也最强,鲍姆桑黄HN01次之。综合比较有效物质总量(产量×有效成分含量),鲍姆桑黄HN01粗多糖总量高,鲍姆桑黄SW总酚总量高,总黄酮和总三萜总量相近,2个品种都可作为优良的生产菌株。     

Adiantum capillus attained selenium nanoparticles (SeNPs) ameliorate resistive effects in rat model of gentamicin nephrontoxicity via regulation of Interlukin-1β, tumor necrosis factor-α and engagement of Vimentin and Bcl-2 proteins

In this study the green method for synthesizing selenium nanoparticles (SeNPs) is experienced, in which the leaf extract of Adiantum capillus was used as an effective chelating and capping agent for producing SeNPs. The characterization techniques that achieved to confirm the synthesis and the structure details of the SeNPs were: UV–Vis spectroscopy, FT-IR analysis, XRD, EDX and SEM analysis. The biological activity of the synthesized SeNPs were tested and compared to the crude extract of Adiantum capillus on gentamicin model of nephrotoxicity in Wistar rats. Sera were used to test the pro-inflammatory cytokines Tumor necrosis factor alpha (TNF-α) and Interleukin beta (IL-β) levels. Histopathology and immunohistochemistry analysis for the apoptosis regulator protein (Bcl-2) and the interstitial filament protein (Vimentin) were performed. Results revealed that the synthesized SeNPs peak appeared at 400–430 nm wave length with crystallite particle size is around 37 nm. The predominant shape is spherical and cubic at different magnification levels with a narrow size distribution of 22.04–128.43 nm. The synthesized SeNPs showed a strong protective effect against gentamicin induced toxic effects to the rat’s kidneys obtained from the (kidney function parameters, histopathology evaluation, recovery of the pro-inflammatory cytokines IL-β and TNF-α level with retrieval of Bcl-2 and vimentin protein levels proximate to the vehicle control groups). Due to the significant protective effect of SeNPs, it considered much better than the crude extract of Adiantum capillus in the treatment of kidney injury; however, additional studies are necessary to find the precise mechanism of their action.