枸杞功能性成分的提取及其组成的液相色谱分析

对枸杞子中的水溶性多糖成分进行了分离提取及组成分析。采用水提、醇沉等方法提取枸杞子中的多糖成分,用Sevage法除去蛋白质后,用凝胶色谱法进行多糖的纯化,制备3-甲基-1-苯基-2-吡唑啉酮（PMP）衍生物进行液相色谱分析。结果表明,枸杞多糖由鼠李糖、阿拉伯糖、木糖、葡萄糖、半乳糖5种单糖组成,其含量分别为5．28％,17．87％,38．29％,17．82％,20．74％。     

活性炭负载TiO2-Fe3O4磁性光催化剂的制备及性能

采用溶胶-凝胶法制备了易于固液分离的活性炭（AC）负载磁性光催化剂（TiO2-Fe3O4／AC）．样品通过SEM-EDX和X射线衍射法进行表征．通过在紫外光照射下降解亚甲基蓝评价其光催化降解能力．结果表明：负载22％Fe3O4的光催化剂（含20％TiO2和58％AC）的光催化活性最强（120min时亚甲基蓝的降解率达到87％,是纯TiO2的2．7倍）;磁性光催化剂可实现磁分离回收．     

芦荟多糖的分离纯化及结构分析

以库拉索芦荟(Aloebarbadensismiller)为材料,经热水抽提,乙醇分级沉淀得2种酸性多糖PSA1和PSA2,用酶法和Seveg法去除蛋白质.经纸层析和Sephadex凝胶柱层析,证实均为单一组分.经薄层层析和乙酰化GC/MS分析表明,多糖PSA1由甘露糖和葡萄糖组成,摩尔比为1:1.3.多糖PSA2主要由甘露糖组成,经红外光谱及核磁共振证明了PSA2为部分乙酰化的甘露聚糖.经过改良的Hakomori甲基化,高碘酸氧化和Smith降解分析表明均为1→4连接,有少量的1→6连接,是分支较少的直链多糖.     

氮离子和稀土离子共掺杂纳米TiO2光催化性能的研究

以钛酸丁酯为原料,以尿素和稀土离子的硝酸盐溶液为掺杂物质,用溶胶．凝胶法制备了氮离子和稀土离子共掺杂的纳米TiO2样品。采用TEM,BET,UV．VIS等方法对样品进行了表征,通过可见光下降解硝基苯对样品的光催化活性进行了研究。结果表明,氮和稀土离子（Y,Nd）共掺杂可增大光催化剂的光吸收范围,并提高其催化活性;当N,Y和Nd离子以7％,2．0％和1．5％（摩尔分数）共掺杂时,制备的样品具有最佳的光催化性能。     

柱前衍生化高效液相色谱法分析当归多糖的单糖组成

采用1-苯基-3-甲基-5-吡唑啉酮（PMP）柱前衍生化反相高效液相色谱（HPLC）法,建立了9种常见单糖的分离模式,并成功地用于当归多糖的单糖组成分析,具有良好的重复性。结果表明,当归多糖由甘露糖、鼠李糖、葡萄糖醛酸、半乳糖醛酸、葡萄糖、半乳糖及阿拉伯糖7种单糖组成,其摩尔比为0．57：1．00：0．13：3．06：8．16：7．17：12．69。该HPLC方法是简单、快速、灵敏、方便的分析技术,可用于当归多糖的质量控制。     

灵芝多糖的结构特征分析

采用沸水回流法从灵芝子实体中提取多糖,经Sevage法除蛋白,乙醇沉淀,离心、透析、膜分离,浓缩、冻干后得灵芝多糖。经HIO4氧化、Smith降解及甲基化反应,并利用多糖及刚果红混合液在碱性溶液中的波长的红移变化,通过UV-VIS,IR,GC,GC-MS,NMR对灵芝水提多糖的结构特征及三螺旋体结构进行分析研究。结果表明:灵芝多糖含有三螺旋体构型,GC-MS分析灵芝多糖的主要单糖组分为葡萄糖,还有少量的半乳糖、甘露糖、木糖和艾杜糖,IR及1HNMR分析多糖为β-构型,HIO4氧化、Smith降解和甲基化分析表明:多糖主要为(1→3)糖苷键连接构型,并伴有少量的1→6位支链键连接的结构,灵芝多糖是由D-葡萄糖单元通过β-(1→3)糖苷键连接葡聚多糖,其主要构型特征为(1→3)β-D-线性连接的骨架结构。     

气相色谱/气质联用分析食品及环境基质中特丁硫磷残留量

建立在食品及环境样品中特丁硫磷残留量的气相色谱检测及气质联用确证法。样品采用乙酸乙酯提取、活性炭-酸性氧化铝复合小柱净化,丙酮-正己烷混合溶液（体积比为1：9）洗脱,样液浓缩后经GC—FPD检测．外标法定量,GC—MS定性。GC—FPD法分析时,特丁硫磷在不同样品、不同水平的加标回收率为74．5％～103．3％．RSD为2．1％～11．7％（n=5）,方法的检出限为0．001mg／kg.气质联用法确证时,特丁硫磷的SIM离子为186、231（Q,100）、288.     

竹黄多糖的化学研究

竹黄是高等真菌,腐生于箣竹上.子实体经分离后按常规发酵,再分离、纯化得到竹黄多糖SB1及SB2两个组分.物理化学性质测定证明分别为单一的均匀组分.经定性及定量气相层析分析表明SB1含D-葡萄糖、D-半乳糖和L-阿拉伯糖,摩尔比为0.37:1:0.07;SB2含D-葡萄糖、D-半乳糖、D-甘露糖和L-阿拉伯糖,摩尔比为0.25:1:0.47:0.12.经甲基化、过碘酸盐氧化、Smith降解和逐步水解等证明SB1的重复结构中含8种类型的单糖连接方式,非还原末端基团为葡萄糖、半乳糖和阿拉伯糖,主要键的连接方式为1,3-和1,3,6-葡萄糖及1,4-,1,6-和1,3,6-半乳糖.SB2的重复结构中含7种类型的单糖连接方式,非还原末端基团为葡萄糖和阿拉伯糖,主要单糖的连接方式为1,2-和1,3,6-甘露糖及1,4-,1,6-和1,3,6-半乳糖.上述多糖为一种新的杂多糖.     

蒙成药黑木日嘎-13中多糖的组分研究

介绍了提取蒙成药黑木日嘎-13中水溶性多糖的方法,并用硫酸-苯酚法测定了黑木日嘎-13的水溶性多糖的含量。平均回收率为98．9％,RSD为0．95％。用GC测定了黑木日嘎-13中水溶性多糖由阿拉伯糖、木糖、甘露糖、半乳糖、葡萄糖等组成。摩尔比为：1．5：0．7：2．5;2．45：23．0。     

凝胶渗透色谱-气相色谱质谱法测定：花生中6种除草剂农药残留

建立了凝胶渗透色谱一气相色谱质谱（GPC～GC=MS）法测定花生中6种除草剂（氟乐灵、异恶草酮、甲草胺、二甲戊乐灵、乙氧氟草醚、喹禾灵）农药残留的方法。样品经乙腈提取,氨基固相萃取柱和凝胶渗透色谱净化,在选择离子扫描（SIM）模式下进行气相色谱质谱法测定,外标法定量。6种除草剂浓度在0．02-1．00mg／L范围内与色谱峰面积呈良好的线性,线性相关系数为O．9949～0．9998,添加回收率为77．8％-101．6％,测定结果的相对标准偏差为4．4％～11．4％（月=5）,方法的检出限为0．1～1．3μg／kg。     

Biosynthesis of polyhydroxyalkanoate (PHA) copolymer from fructose using wild-type and laboratory-evolved PHA synthases

Eleven laboratory-evolved polyhydroxyalkanoate (PHA) synthases which originated from Pseudomonas sp. 61-3 enzyme (PhaC1(Ps)), together with the wild-type enzyme, were applied for PHA synthesis from fructose using Ralstonia eutropha PHB(-)4 as a host strain. The evolved PhaC1(Ps) mutants had amino acid substitution(s) at position 325 and/or position 481. In these mutants, serine-325 (S325) was replaced by cysteine (C) or threonine (T), while glutamine-481 (Q481) was replaced by lysine (K), methionine (M) or arginine (R). All recombinant strains harboring the genes of the evolved PhaC1(Ps) mutants produced a significantly increased amount of PHA (55-68 wt.-%) compared with the one harboring the wild-type gene (49 wt.-%). Particularly, those evolved PhaC1(Ps) mutants having multiple amino acid substitutions showed higher activities for PHA synthesis. Characterization of the PHA by NMR spectroscopy revealed that they were copolymers consisting of (R)-3-hydroxybutyrate (98-99 mol-%) and medium-chain-length comonomers (1-2 mol-%). This study also confirmed that amino acid substitution at position 481 in PhaC1(Ps) led to an increasing molecular weight of PHA. The number-average molecular weight (Mn) of PHA (Mn = 240,000) synthesized by the evolved PhaC1(Ps) (Q481K) mutant was 4.6-fold greater than that (Mn = 52,000) synthesized by the wild-type enzyme.     

Identification of squamous cell carcinoma antigen-2 in tumor tissue by two-dimensional electrophoresis

The aim of this study was to identify two homologous serine proteinase inhibitor (serpin) molecules, squamous cell carcinoma (SCC) antigen-1 and -2, by two-dimensional electrophoresis (2-DE), combined with immunoblotting, and examine their expression in tumor tissue. The recombinant SCC (rSCC) antigen-1 showed four spots with p/ 6.5, 6.4, 6.3 and 6.0, whereas rSCC antigen-2 showed a more acidic spot with p/5.95. SCC antigen in tumor tissue appeared in three new acidic spots (p/5.7-5.5, M(r) 44 500), numbered 5, 6 and 7, besides the previously reported four spots numbered 1 to 4. These new acidic spots of SCC antigen apparently increased in SCC tissue. Treatment of tissue extract by carboxymethyl (CM)-papain agarose matrix extinguished spots 1 to 4 encoded on the SCCA1 gene, but not 5 to 7 on the SCCA2 gene. Overexpression of the SCCA2 gene may play an important role in the malignant behavior of tumor cells.     

Mutation effects of a conserved alanine (Ala510) in type I polyhydroxyalkanoate synthase from Ralstonia eutropha on polyester biosynthesis

Type I polyhydroxyalkanoate (PHA) synthases, as represented by Ralstonia eutropha enzyme (PhaC(Re)), have narrow substrate specificity toward (R)-3-hydroxyacyl-coenzyme A with acyl chain length of C3-C5 to yield PHA polyesters. In this study, saturation point mutagenesis of a highly conserved alanine at position 510 (A510) in PhaC(Re) was carried out to investigate the effects on the polymerization activity and the substrate specificity for in vivo PHA biosynthesis in bacterial cells. A series of saturation mutants were first applied for poly[(R)-3-hydroxybutyrate] homopolymer synthesis in Escherichia coli and R. eutropha PHB(-)4 (PHA negative mutant) cells to assess the polymerization activity. All mutants showed quantitatively similar polymerization activities when R. eutropha PHB(-)4 was used for assay, whereas several mutants such as A510P showed low activities in E. coli. Further analysis has revealed that majority of mutants synthesize polyesters with higher molecular weights than the wild-type. In particular, substitution by acidic amino acids, A510D(E), led to remarkable increases in molecular weights. Subsequently, PHA copolymer synthesis from dodecanoate (C12 fatty acid) was examined. The copolymer compositions were varied depending on the mutants used. Significant increased fractions of long monomer units (C6 and C8) in PHA copolymers were observed for three mutants [A510M(Q,C)]. From these results, the mutations at this potion are beneficial to change the molecular weight of polyesters and the substrate specificity of PhaC(Re). Molecular weight distributions of PHA polymers synthesized by the wild-type enzyme (PhaC(Re)) and its mutants.     

Modification of iodometric determination of total and reactive sulfide in environmental samples

In iodometric determination of sulfide two reactions are taking place when alkaline solution is added to HCl acid-iodine. The main oxidation reaction (1), H(2)S+I(2)=2HI+S; and side reaction of sulfide (2), S(-2)+4I(2)+8OH(-)=SO(4)(2-)+8I(-)+4H(2)O. Preference of reaction (2) over (1) is dependent on pH increasing to >7. When sulfide solution of pH 9 was mixed with HCl acid-iodine, the recovery exceeded 120%, but the recovery of a solution with a pH of 13 exceeded 200%. To eliminate the side reaction in iodometric titration, the sulfide solution must be acidic when it is mixed with HCl-iodine. To avoid the side reaction (2), the pH of sulfide solutions were adjusted with acetic acid to pH 5.5, mixed with HCl-iodine solution and then titrated with standard thiosulfate with precision and accuracy <+/-3%.     

Hydrolytic reactions of the phosphorodithioate analogue of uridylyl(3',5')uridine: kinetics and mechanisms for the cleavage, desulfurization, and isomerization of the internucleosidic linkage

The hydrolytic reactions of the phosphorodithioate analogue of uridylyl(3',5')uridine [3',5'-Up(s)2U] were followed by HPLC over a wide pH range at 363.2 K. Under acidic and neutral conditions, three reactions compete: (i) desulfurization to a mixture of the (Rp)- and (Sp)-diastereomers of the corresponding 3',5'- and 2',5'-phosphoromonothioates [3',5'- and 2',5'-Up(s)U], which are subsequently desulfurized to a mixture of uridylyl(3',5')- and -(2',5')uridine [3',5'- and 2',5'-UpU], (ii) isomerization to 2',5'-Up(s)2U, and (iii) cleavage to uridine, in all likelihood via a 2',3'-cyclic phosphorodithioate (2',3'-cUMPS2). Under alkaline conditions (pH > 8), only a hydroxide ion catalyzed hydrolysis to uridine via 2',3'-cUMPS2 takes place. At pH 3-7, all three reactions are pH-independent, the desulfurization being approximately 1 order of magnitude faster than the cleavage and isomerization. At pH < 3, all the reactions are hydronium ion catalyzed. On going to very acidic solutions, the cleavage gradually takes over the desulfurization and isomerization. Accordingly, the cleavage overwhelmingly predominates at pH < 0. The overall hydrolytic stability of 3',5'-Up(s)2U is comparable to that of (Sp)- and (Rp)-3',5'-Up(s)U (and to that of 3',5'-UpU, except at pH < 2). The rate of the hydroxide ion catalyzed hydrolysis of 3',5'-Up(s)2U is 37% and 53% of that of (Sp)- and (Rp)-3',5'-Up(s)U, respectively. The reactions, however, differ with the respect of the product accumulation. While the phosphoromonothioates produce a mixture of 2'- and 3'-thiophosphates as stable products, 3',5'-Up(s)2U is hydrolyzed to uridine without accumulation of the corresponding dithiophosphates. At pH < 3, where the hydrolysis is hydronium ion catalyzed, the kinetic thio-effect of the second thio substitution is small: under very acidic conditions (Ho -0.69), (Sp)-3',5'-Up(s)U reacts 1.6 times as fast as 3',5'-Up(s)2U, but the reactivity difference decreases on going to less acidic solutions. In summary, the hydrolytic stability of 3',5'-Up(s)2U closely resembles that of the corresponding phosphoromonothioate. While replacing one of the nonbridging phosphate oxygens of 3',5'-UpU with sulfur stabilizes the phosphodiester bond under acidic conditions by more than 1 order of magnitude, the replacement of the remaining nonbridging oxygen has only a minor influence on the overall hydrolytic stability.     

Reactions of 3-acetyltropolone and its methyl ethers with hydroxylamine. Formation of 8H-cyclohept[d]isoxazol-8-one and 8H-cyclohept[c]isoxazol-8-one

The reaction of 3-acetyltropolone ( 1 ) with hydroxylamine under the acidic condition gave 3-methyl-8H-cyclohept[d]isoxazol-8-one ( 4 ) and its oxime ( 5 ), and under the neutral condition gave 4 and 3-acetyltropolone oxime ( 6 ). The reaction of 3-acetyl-2-methoxytropone ( 2a ) with hydroxylamine under the acidic condition gave 4, 5 , and 4-methyl-1H-2,3-benzoxazin-1-one ( 7 ), and under the neutral condition gave 4, 7 , 3-methyl-8H-cyclohept[c]isoxazol-8-one ( 8 ), and its oxime ( 9 ). The reaction of 7-acetyl-2-methoxytropone ( 2b ) with hydroxylamine under the acidic condition gave 4 and 5 , and under the neutral condition gave 5, 7 , and 9 .     

Selective destruction of leukaemic cells by photo-activation of 5-aminolaevulinic acid-induced protoporphyrin-IX

The effect of 5-aminolaevulinic acid-based photodynamic therapy (ALA-PDT) on the viability and proliferation of leukaemia/lymphoma cells as well as normal human lymphocytes has been investigated by flow cytometry-propidium iodide assay (FC-PI), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and bromodeoxyuridine (BrdU) incorporation and on clonogenic activity of normal human bone marrow progenitor cells by clonogenic methods. ALA-PDT (1 mM 5-ALA, 4 h, 18 J cm-2) reduces the number and/or suppressed proliferation of leukaemic cells of promyelocytic (HL60), B-cell-derived (DAUDI) and T-cell-derived (JURKAT) cell lines by 2 logs and that of the HEL erythroleukaemia cells by 77%. The effect of ALA-PDT on quiescent human lymphocytes is small (85% viable cells after ALA-PDT). The proliferation of lymphocytes subjected to ALA-PDT and induced with phytohaemagglutinin (PHA) decreases by 75% as compared to the untreated control. For normal human bone marrow progenitors, 58% of colony-forming units-granulocytes-macrophages (CFU-GM) and 55% burst-forming units-erythrocytes (BFU-E) activities are preserved.     

Process Engineering for Production of Chiral Hydroxycarboxylic Acids from Bacterial Polyhydroxyalkanoates

An efficient process for the production of (R)‐hydroxycarboxylic acids (RHAs) from polyhydroxyalkanoates (PHAs) was developed. It involved the synthesis of PHA in bacteria, followed by bringing the culture broth directly to a pH optimal for in vivo PHA degradation, thus avoiding cell collection by centrifugation and pellet resuspension. The optimal pH was maintained to allow maximal release of RHAs. Using this process, cells having a dry weight (w) of 1.8 g · L⁻¹ and 45% (w/w) PHA exhibited a linear PHA degradation rate of about 0.059 g · L⁻¹ · h⁻¹ in the first 9 h. Concomitantly, RHAs were released with a rate of 0.057 g · L⁻¹ · h⁻¹. Further incubation of up to 15 h resulted in almost 90% (w/w) degradation of PHA. Based on this approach in combination with chemostat and a plug flow reactor a continuous process for the production of RHAs could be achieved.

     

高效液相色谱-串联质谱法测定可食性包装材料中22种酸性染料

建立了可食性包装材料中酸性黄23、酸性红18、酸性蓝7等22种酸性染料的高效液相色谱-串联质谱(HPLC-MS/MS)分析方法。样品以乙腈-甲醇(5:5, v/v)提取,采用Strata-X-AW固相萃取柱净化。待测物经Zorbax Eclipse Plus C₁₈柱(100 mm×3.0 mm, 1.8 μm)分离,以乙腈-10 mmol/L乙酸铵为流动相梯度洗脱;采用电喷雾负离子源(ESI^-)、多重反应监测(MRM)模式检测;以保留时间和特征离子对(母离子和两个碎片离子)信息比较进行定性,基质匹配外标法定量。22种酸性染料在各自的线性范围内相关系数(r²)均大于0.991;在3种基质(糯米纸、植物胶囊、明胶胶囊)中方法的定量限(以S/N≥10计)为0.1~2.0 mg/kg, 3个加标水平(1、2、10倍定量限)下,回收率为78.4%~109.5%,相对标准偏差(RSD)为4.6%~14.5%。本方法快速简便、准确可靠,适用于可食性包装材料中多种酸性染料的测定。     

Acid-base properties of xanthosine 5'-monophosphate (XMP) and of some related nucleobase derivatives in aqueous solution: micro acidity constant evaluations of the (N1)H versus the (N3)H deprotonation ambiguity

The first acidity constant of fully protonated xanthosine 5'-monophosphate, that is, of H3(XMP)+, was estimated by means of a micro acidity constant scheme and the following three deprotonations of the H2(XMP)+/- (pKa=0.97), H(XMP)- (5.30), and XMP2- (6.45) species were determined by potentiometric pH titrations; further deprotonation of (XMP-H)3- is possible only with pKa>12. The most important results are that the xanthine residue is deprotonated before the P(O)2(OH)- group loses its final proton; that is, twofold negatively charged XMP carries one negative charge in the pyrimidine ring and one at the phosphate group. Micro acidity constant evaluations reveal that this latter mentioned species occurs with a formation degree of 88 %, whereas its tautomer with a neutral xanthine moiety and a PO3(2-) group is formed only to 12 %; this distinguishes XMP from its related nucleoside 5'-monophosphates, like guanosine 5'-monophosphate. At the physiological pH of about 7.5 mainly (XMP-H)3- exists. The question, which of the purine sites, (N1)H or (N3)H, is deprotonated in this species cannot be answered unequivocally, though it appears that the (N3)H site is more acidic. By application of several methylated xanthine species intrinsic micro acidity constants are calculated and it is shown that, for example, for 7-methylxanthine the N1-deprotonated tautomer occurs with a formation degree of about 5 %; a small but significant amount that, as is discussed, may possibly be enhanced by metal ion coordination to N7, which is known to occur preferably to this site.