A new natural nucleotide and other antibacterial metabolites from an endophytic Nocardia sp.

Nine compounds were isolated from Nocardia sp. YIM 64630, and their structures were elucidated as 5′-O-acetyl-2′-deoxyuridine (1), 22E,24R-5α,6α-epoxyergosta-8(14),22-diene-3β,7α-diol (2), 22E,24R-5α,6α-epoxyergosta-8,22-diene-3β,7α-diol (3), 22E,24R-ergosta-7,22-diene-3β,5α,6β-triol (4), 5α,8α-epidioxyergosta-6,22-dien-3β-ol (5), 4′,5,6-trihydroxy-7-methoxyisoflavone (6), 2,4,4′-trihydroxy-deoxybenzoin (7), methyl [4-hydroxyphenyl]acetate (8) and daidzein by extensive spectroscopic analyses. Compound 1 was isolated from natural resources for the first time. The antimicrobial and antioxidant activities of compounds 1–8 were investigated.     

A new triterpenoid from the fruits of Gardenia jasminoides var. radicans Makino

A novel triterpenoid 3α,16β,23,24-tetrahydroxy-28-nor-ursane-12,17,19,21-tetraen (1) was isolated from the fruits of Gardenia jasminoides var. radicans Makino. The structure of the new compounds was elucidated on the basis of spectroscopic analysis including MS and NMR data. Compound 1 was in vitro tested for cytostatic activity on human throat cancer (Hep-2) cell line by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide method and showed mild anticancer activity with the IC₅₀ of 31.2 μM.     

Tetramic acid derivatives and polyphenols from sponge-derived fungus and their biological evaluation

Fifteen compounds, including two tetramic acid derivatives, penicillenol A₁ (1) and penicillenol A₂ (2), six polyphenols containing both phenolic bisabolane sesquiterpenoid and diphenyl ether units, expansols A–F (3–8), together with six phenolic bisabolane sesquiterpenoids (9–14) and diorcinol (15), were isolated from the fermentation broth of the marine-derived fungus ZSDS1-F11 isolated from the sponge Phakellia fusca Thiele collected in the Yongxing island of Xisha. Their structures were elucidated mainly by using extensive NMR spectroscopic and mass spectrometric analyses. Compounds 3–5, 7 and 8 showed potent COX-1 inhibitory activity with IC₅₀ values of 5.3, 16.2, 30.2, 41.0 and 56.8 μM, respectively. Meanwhile, compounds 3–8 showed potent COX-2 inhibitory activity with IC₅₀ values of 3.1, 5.6, 3.0, 5.1, 3.2 and 3.7 μM, respectively. In addition, compound 1 exhibited antituberculosis activity with 96.1% inhibition at concentration of 10 μM.     

磁性碳纳米管固相萃取-原子荧光光谱法测定水中痕量镉

建立了检测水中痕量镉的磁性固相萃取-原子荧光光谱法。制备磁性碳纳米管,以其作为固相萃取吸附剂用来萃取和富集水中的痕量镉,采用氢化物发生-原子荧光光谱法进行检测。在最佳条件下,镉在0.05~5.0μg·L-1范围内呈线性,检出限(3σ)为1.6 ng·L-1。加标回收率在97.1%~101%之间,测定值的相对标准偏差在1.6%~4.8%之间。方法用于分析标准物质,测定值与认定值相符。     

不同杂环取代(E)-β-Farnesene类似物的合成及生物活性研究

为了寻求新型蚜虫控制剂,以蚜虫报警信息素(E)-β-farnesene(EBF)为先导,引入不同类型的杂环取代EBF结构中不稳定的共轭双键,设计合成了一系列不同杂环取代的EBF类似物.所有化合物结构均通过1H NMR、13C NMR、IR及HRMS确证.对化合物进行了生物活性测试及初步构效关系分析.结果表明,所有化合物均对桃蚜和大豆蚜表现出一定的生物活性,部分化合物的杀虫活性优于先导EBF,酯基的引入则对驱避活性有利.     

Organocatalytic asymmetric chlorinative dearomatization of naphthols

An organocatalytic asymmetric chlorinative dearomatization of naphthols was realized for the first time, providing chiral naphthalenones with a Cl-containing all-substituted stereocenter in excellent yields and enantioselectivity (up to 97% yield and 96% ee). The reaction features mild reaction conditions, good tolerance of diverse functional groups and simple reaction operation.     

High‐Throughput,Label‐Free Isolation of Cancer Stem Cells on the Basis of Cell Adhesion Capacity

Herein we report a microfluidics method that enriches cancer stem cells (CSCs) or tumor‐initiating cells on the basis of cell adhesion properties. In our on‐chip enrichment system, cancer cells were driven by hydrodynamic forces to flow through microchannels coated with basement membrane extract. Highly adhesive cells were captured by the functionalized microchannels, and less adhesive cells were collected from the outlets. Two heterogeneous breast cancer cell lines (SUM‐149 and SUM‐159) were successfully separated into enriched subpopulations according to their adhesive capacity, and the enrichment of the cancer stem cells was confirmed by flow cytometry biomarker analysis and tumor‐formation assays. Our findings show that the less adhesive phenotype is associated with a higher percentage of CSCs, higher cancer‐cell motility, and higher resistance to chemotherapeutic drugs.     

Development and validation of polymerized high internal phase emulsion monoliths coupled with HPLC and fluorescence detection for the determination of trace tetracycline antibiotics in environmental water samples

A polymerized high internal phase emulsion monolith was used as a novel sorbent for solid‐phase extraction coupled with high‐performance liquid chromatography and fluorescence detection for the determination of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline in environmental water samples. The polymerized high internal phase emulsion monolithic column was prepared by the in situ polymerization of the continuous phase of a high internal phase emulsion containing glycidyl methacrylate, styrene, and divinylbenzene in pipette tips, and then functionalized with iminodiacetic acid. The resulting monolith exhibited highly interconnected porosity and large surface areas, making it an excellent candidate as an solid‐phase extraction sorbent for the enrichment of trace tetracycline antibiotics. Several factors affecting the extraction performance of polymerized high internal phase emulsion monoliths, including the pH of sample solution, the eluting solvents, the sample loading flow rate and volume, were investigated, respectively. Under the optimized conditions, the mean recoveries of oxytetracycline, tetracycline, doxycycline, and chlorotetracycline spiked in pond and farm wastewater samples ranged from 78.1 to 119.3% with relative standard deviation less than 15%. The detection limits (S/N = 3) of the proposed method were in the range of 51–137 pg/mL. This study demonstrated that the monolithic polymerized high internal phase emulsion would be promising solid‐phase extraction sorbents in the extraction and proconcentration of trace analytes from complex samples.     

Correlation between electron delocalization and structural planarization in small water rings

The discovery of the covalent‐like character of the hydrogen bonding (H‐bonding) system [Science 342 , 611(2013)] has promoted a renewal of our understanding of the electronic and geometric structures of water clusters. In this work, based on density functional theory calculations, we show that the preferential formation of a stable quasiplanar structure of (H₂O)_n(n = 3–6) is closely related to three kinds of delocalized molecular orbitals (MOs; denoted as MO‐I, II, and III) of water rings. These originate from the 2p lone pair electrons of oxygen (O), the 2p bond electrons of O and the 1s electrons of H and the 2s electrons of O and 1s electrons of H, respectively. To maximize the orbital overlaps of the three MOs, geometric planarization is needed. The contribution of the orbital interaction is more than 30% in all the water rings according to our energy decomposition analysis, highlighting the considerable covalent‐like characters of H‐bonds. © 2015 Wiley Periodicals, Inc.