Complexing the Marine Sesquiterpene Euplotin C by Means of Cyclodextrin-Based Nanosponges: A Preliminary Investigation

Euplotin C is a sesquiterpene of marine origin endowed with significant anti-microbial and anti-tumor properties. Despite the promising functional profile, its progress as a novel drug candidate has failed so far, due to its scarce solubility and poor stability in aqueous media, such as biological fluids. Therefore, overcoming these limits is an intriguing challenge for the scientific community. In this work, we synthesized β-cyclodextrin-based nanosponges and investigated their use as colloidal carriers for stably complex euplotin C. Results obtained proved the ability of the carrier to include the natural compound, showing remarkable values of both loading efficiency and capacity. Moreover, it also allowed us to preserve the chemical structure of the loaded compound, which was recovered unaltered once extracted from the complex. Therefore, the use of β-cyclodextrin-based nanosponges represents a viable option to vehiculate euplotin C, thus opening up its possible use as pharmacologically active compound.     

1-O-Alkylglycerol Ethers from the Marine Sponge Guitarra abbotti and Their Cytotoxic Activity

The cytotoxicity-bioassay-guided fractionation of the ethanol extract from the marine sponge Guitarra abbotti, whose 1-O-alkyl-sn-glycerol ethers (AGEs) have not been investigated so far, led to the isolation of a complex lipid fraction containing, along with previously known compounds, six new lipids of the AGE type. The composition of the AGE fraction as well as the structures of 6 new and 22 previously known compounds were established using ¹H and ¹³C NMR, GC/MS, and chemical conversion methods. The new AGEs were identified as: 1-O-(Z-docos-15-enyl)-sn-glycerol (1), 1-O-(Z-docos-17-enyl)-sn-glycerol (2), 1-O-(Z-tricos-15-enyl)-sn-glycerol (3), 1-O-(Z-tricos-16-enyl)-sn-glycerol (4), 1-O-(Z-tricos-17-enyl)-sn-glycerol (5), and 1-O-(Z-tetracos-15-enyl)-sn-glycerol (6). The isolated AGEs show weak cytotoxic activity in THP-1, HL-60, HeLa, DLD-1, SNU C4, SK-MEL-28, and MDA-MB-231 human cancer cells. A further cytotoxicity analysis in JB6 P⁺ Cl41 cells bearing mutated MAP kinase genes revealed that ERK2 and JNK1 play a cytoprotective role in the cellular response to the AGE-induced cytotoxic effects.     

IWSF-FA模袋混凝土抗压强度、孔隙结构和物质组成

为优化模袋混凝土衬砌性能,合理利用当地粉煤灰和废弃硅粉代替部分水泥制备模袋混凝土衬砌.通过抗压强度试验、固体紫外试验、核磁共振和热重试验研究双掺粉煤灰-工业废弃硅粉替代适量水泥后对模袋混凝土抗压特性、内部孔隙结构和水化物质组成的影响.结果表明：合理双掺工业废弃硅粉和粉煤灰(如FA15S4)可以提高模袋混凝土的抗压强度;紫外吸收光谱表明其水化产物C-S-H和CH组成优于其他组别;核磁共振T₂谱分布呈现“三峰结构”,左峰信号幅度最高,双掺工业废弃硅粉-粉煤灰有利于改善其内部孔隙结构.并且双掺工业废弃硅粉和粉煤灰后,热学性质良好.建立了基于BP神经网络理论的模袋混凝土早期抗压强度预测模型,预测结果与试验测试值的最大相对误差为2.7%.研究结果可为工业废弃硅粉和粉煤灰混凝土在水工衬砌工程中的应用提供参考依据.     

茯苓硫酸酯化多糖的制备及其核磁共振波谱分析

[目的]用不同方法制备3种茯苓多糖硫酸酯（Pachyman sulfate,PS）,并对其进行核磁共振波谱对比分析,为多糖硫酸化提供基础数据。[方法]以氯磺酸为磺化试剂硫酸化茯苓多糖制备茯苓多糖硫酸酯PS—I和PSII,以氨基磺酸为磺化试剂制备PS-Ⅲ,分析磺化反应前后和不同硫酸根取代度（Degree of sulfation,DS）的多糖碳原子化学位移的变化规律。[结果]PS—I（DS=2．80）分子所有自由羟基均发生取代反应;PS—H（DS=1．55）C-6羟基被全部酯化,C-2和C-4羟基发生部分酯化反应;PS-Ⅲ（DS=0．95）C-6和C-2羟基发生部分硫酸酯化反应。[结论]发生取代反应的碳原子化学位移移动的距离与PS的DS呈正相关,核磁共振技术能够提供多糖结构解析的关键数据。     

亚热带不同林分土壤表层有机碳组成及其稳定性

在浙江临安玲珑山选取了常绿阔叶林、马尾松林、板栗林和雷竹林4种林分,采用传统的化学方法与固态13C核磁共振(NMR)技术研究其土壤有机碳在不同粒径土壤颗粒中的分布规律和结构特征,探讨林分类别和管理措施对土壤有机碳含量及其结构的影响,为亚热带地区森林固碳和土壤碳库管理提供科学依据.结果显示:(1)土壤表层(0-20 cm)有机碳含量按以下次序递减:雷竹林＞常绿阔叶林＞马尾松林＞板栗林,且板栗林以粉黏粒结合态碳为主,其他林分土壤则以粗砂结合态碳为主;(2)13C NMR结果表明,阔叶林和马尾松林土壤有机碳中烷基碳所占比例最大,而雷竹林和板栗林则是烷氧碳比例最大,表明人工经营措施改变了土壤有机碳的成分组成;(3)随着土壤颗粒变细,有机碳中烷基碳比例增加,烷氧碳比例减少,A/O-A值和疏水碳/亲水碳值逐渐增大,表明颗粒越细,其结合的有机碳结构稳定性越高.     

用核磁共振研究浸种方法对水稻种子吸水量的影响

为寻求较佳浸种方法,该文应用低场核磁共振检测技术,研究了不同的浸种方式及浸种溶剂对水稻种子吸水量的影响。试验利用横向弛豫时间 T2反演谱分析了水稻种子的水分状态变化及吸水特性,发现浸种过程改变了水稻种子内部的水分分布情况,水稻种子吸水量对初始含水率差异不显著(P>0.05),但对各种浸种方法差异显著(P<0.05)。研究表明,采用连续浸种4 h、浸种3 h-晾干1 h-浸种1 h、浸种2 h-晾干1 h-浸种2 h及浸种2 h-晾干2 h-浸种2 h这4种不同的浸种方式时,浸种2 h-晾干1 h-浸种2 h的间歇浸种方式吸水率较高;采用清水、强氯精300倍液、饱和澄清石灰水、质量分数为40%福尔马林的50倍液、100倍液及200倍液6种不同的浸种溶液时,应用质量分数为40%福尔马林50倍液药剂时吸水率较高。低场核磁共振检测技术揭示了水稻种子含水量的影响因素,为浸种过程中吸水量的测定提供了一种有效的方法。     

Kinetic Parameters of Gross N Mineralization of Peat Soils as Related to the Composition of Soil Organic Matter

Peat land has been considered as an alternative type of land for agricultural development especially in the tropics. In the present study, the N-supplying capacity, one of the most important soil properties in terms of crop production, of peat soils was examined. Ten peat soil samples were collected from Indonesia, Malaysia, and Japan. Gross N mineralization in the soil samples was estimated using a zero-order model, and kinetic parameters of mineralization were determined using a simple type model. Soil organic matter composition was investigated using ¹³C CPMAS NMR. Mineralization potential ( N ₀), apparent activation energy ( E _a), and mineralization rate constant ( k ) ranged between 571–2,445 mg kg⁻¹, 281–8,181 J mol⁻¹, and 0.009–0.020 d⁻¹, respectively. Although none of the parameters showed a significant correlation with the soil C/N ratio, a negative correlation was observed between the k value and the ratio of the proportion of alkyl C in total C to that of O -alkyl C estimated by ¹³C CPMAS NMR. The latter suggested that the k values were higher in the peat soils relatively rich in readily decomposable organic matter including carbohydrates.     

NMR-Based Configurational Assignments of Natural Products: Gibbs Sampling and Bayesian Inference Using Floating Chirality Distance Geometry Calculations

Floating chirality restrained distance geometry (fc-rDG) calculations are used to directly evolve structures from NMR data such as NOE-derived intramolecular distances or anisotropic residual dipolar couplings (RDCs). In contrast to evaluating pre-calculated structures against NMR restraints, multiple configurations (diastereomers) and conformations are generated automatically within the experimental limits. In this report, we show that the “unphysical” rDG pseudo energies defined from NMR violations bear statistical significance, which allows assigning probabilities to configurational assignments made that are fully compatible with the method of Bayesian inference. These “diastereomeric differentiabilities” then even become almost independent of the actual values of the force constants used to model the restraints originating from NOE or RDC data.     

Theonellamides J and K and 5-cis-Apoa-theopalauamide,Bicyclic Glycopeptides of the Red Sea Sponge Theonella swinhoei

Theonella swinhoei is a fairly common inhabitant of reefs throughout the Indian and Pacific Oceans. Metabolomic analyses of samples of T. swinhoei collected in different depths in the Gulf of Aqaba revealed two chemotypes differing in the profiles of the theonellamides they produce, some of which seem to be unknown. Driven by this finding, we examined a sample of T. swinhoei collected more than 40 years ago in the southern part of the Gulf of Aqaba. Large-scale extract of this sample yielded four theonellamides, the known theopalauamide (4), as the major component, and three new metabolites, theonellamide J (1), 5-cis-Apoa-theopalauamide (2), and theonellamide K (3), as the minor components. The planar structure of these complex cyclic glycopeptides was elucidated by combination of 1D and 2D NMR techniques and HRESIMS. The absolute configuration of the amino acids was established by Marfey’s and advanced Marfey’s methods, and the absolute configuration of its galactose unit using “Tanaka’s method” for monosaccharides. The biological activity of the pure compounds was tested for antibacterial activity and for cytotoxicity to HTC-116 cell line. The compounds presented significant cytotoxicity against the HTC-116 cell line, illuminating the importance of the Apoa subunit for the activity.     

磺酸基官能化介孔材料MSU的合成及其酸性研究

为解决涉及一些较大分子的反应之固体酸催化问题,以价格便宜的硅酸钠为主要原料合成了磺酸基官能化介孔材料MSU,并采用固体核磁共振(SSNMR)等技术研究了所合成材料(MSU-SO3H)的结构和酸性.结果表明,合成的磺酸基官能化的MSU具有规整的介孔结构,其总体酸性略弱于微孔分子筛HZSM-5.