Remote control of enzyme selectivity: the case of stevioside and steviolbioside

The remote control of lipase PS site- and regioselectivity by substrate modification has been observed in the acetylation of stevioside (1) and steviolbioside (2): deglucosylation at position C-19 changed the acylation site of the sophorose moiety linked at C-13. In fact, while esterification of 1 gave mainly the corresponding 6″-O-acetylated derivative, acylation of 2 gave exclusively the 6′-O-monoester. A possible rationale has been suggested, based on the conformational behavior of the substrates in different simulated solvents.     

One-pot multi-component synthesis and cytotoxic activity of terpenoid dimers containing azapolycyclic spacers

Novel terpenoid dimers linked through the E–E rings were synthesized by catalytic multicomponent condensation of amino derivatives of methyl maleopimarate with form-aldehyde and dimethyl-tetraazadecalin or tetraazaperhydro- tetracene. Primary screening of the synthesized terpenoid dimers for cytotoxic activity was performed.     

New cytotoxic cembranolides: isolation, biogenetic studies, and synthesis of analogues

Three new diterpene cembranes (1-3) along with eunilode (4) were isolated from the organic extracts of Eunicea mammosa. Biogenetic studies using a cell-free extract demonstrated that hydroxy cembrane 3 is the precursor to the ether-bridged 1. In order to deduce further structure-activity relationships a series of analogues were synthesized and their cytotoxicity against several cancer cell lines was evaluated.     

Novel dimeric amide alkaloids from Piper chaba Hunter: isolation, cytotoxic activity, and their biomimetic synthesis

Chromatographic fractionation of methanol extract from roots of the Piper chaba Hunter resulted in the isolation of four new dimeric alkaloids, chabamide H (1), I (2), J (3), K (4) together with 11 known compounds (5-15). Their chemical structures and relative stereochemistry were determined on the basis of the comprehensive spectroscopic techniques (IR, Mass, and NMR) and further confirmed by comparison of the data with those reported in literature. In addition, cytotoxic activities of all the dimeric amides (1-7) along with their monomers (8-10) were evaluated against cervical (HELA), breast (MCF-7), liver (HEPG2), colon (HT-29), and colon (COLO-205) cancer cell lines. Among the tested isolates, 5 and 7 exhibited potent cytotoxic activity against COLO-205 cell line with IC₅₀ value of 3.10 μg/mL and 0.018 μg/mL, respectively. To prove biogenesis of the newly isolated compounds, biomimetic synthesis has also been carried out via Diels-Alder reaction by using copper(II) salts in aqueous medium.     

查儿酮类似物的合成及抗肿瘤活性研究

<正>查尔酮及其衍生物是芳香醛酮发生交叉羟醛缩合的产物,是合成多种天然化合物重要的有机合成中间体[1]。由于其分子结构具有较大的柔性,能与不同的受体结合,因此具有广泛的生物活性,包括:抗肿瘤、抑制和清除氧自由基、抗菌、抗病毒、抗溃疡和解痉等生物活性[2-7],抗过敏[8],除     

Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH(3))(2)](+) complex cation by four saccharides was performed. Four saccharides were used: two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005-0.20 mol L(-1)) and pH conditions (11.5-13.0) produced a wide range of particle sizes (25-450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH(3))(2)](+) by maltose produced silver particles with a narrow size distribution with an average size of 25 nm, which showed high antimicrobial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly multiresistant strains such as methicillin-resistant Staphylococcus aureus. Antibacterial activity of silver nanoparticles was found to be dependent on the size of silver particles. A very low concentration of silver (as low as 1.69 mug/mL Ag) gave antibacterial performance.     

吡啶联喹唑啉酮衍生物的设计、合成与抗菌活性研究

以靛红酸酐为起始原料,设计并合成了14个结构新颖的吡啶联喹唑啉酮类衍生物.所有化合物经1 H NMR、13 C NMR和高分辨质谱(HRMS)表征确证其结构.初步抗菌活性结果显示,该类化合物对水稻白叶枯病菌(Xanthomonas oryzae pv.Oryzae,Xoo)、猕猴桃溃疡病菌(Pseudomonassyr...     

稀土芦丁配合物的合成、表征及荧光性质和抑菌活性的研究

以稀土金属(Ⅲ)氯化物和芦丁为原料,在乙醇溶液中(pH=7~8)合成了六种稀土芦丁配合物,通过元素分析、IR、UV、热重-差热分析、摩尔电导率的测定对配合物进行了表征,确定了配合物的组成,分析了配合物的热稳定性和热分解行为。同时初步研究了配合物在室温下的荧光性质,结果显示配合物Na5SmLCl7.6H2O(L=C27H29O16)表现出相应的Sm(Ⅲ)离子的特征发射。并研究了配合物的抑菌活性,抑菌活性试验表明六种配合物具有选择性抑菌性能。     

手性单双糖Schiff碱的合成及抑菌活性研究

多糖、寡糖、Schifr碱及其配合物具有抗癌、抗病毒、杀菌等生物活性。酰肼类化合物可与生物体中的微量元素作用达到抗结核和抗肿瘤效果。在酰肼Schiff碱分子中引入单双糖分子,不仅可增加水溶性,降低毒性,引入手性源,     

无C环青蒿素类似物的合成研究

以天然的(-)-香芹酮为原料,设计、合成了四种环状烯醇醚,它们是标题化合物的关键中间体,然而这些化合物出乎意料地与单线态氧不发生反应,仅为光氧化反应提供了有参考价值的经验积累,以(-)-薄荷醇为原料用同样方法则可合成得到化合物4的骨架化合物的混合物。     

Asymmetric synthesis of the cytotoxic lactone (+)-cardiobutanolide and two novel analogues

A new asymmetric synthesis of the naturally occurring styryl lactone cardiobutanolide and two novel analogues have been achieved starting from d-xylose. The key steps of the synthesis included an initial zinc mediated reductive THF-ring opening, stereoselective olefination and Sharpless asymmetric dihydroxylation. It was shown that cardiobutanolide (1) exhibits promising in vitro antitumour properties against certain human neoplastic cell lines. It was more potent than the commercial anticancer agent doxorubicin against three cell lines (K562, HL-60 and Raji).     

Synthesis and cytotoxic activity of benzopyranoxanthone analogues of benz.

Condensation of 3-hydroxy-2-naphthalenecarboxylic acid with phloroglucinol afforded 1,3-dihydroxy-12H-benzo[b]xanthen-12-one. Construction of an additional dimethylpyran ring onto this skeleton, by alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement, gave access to a series of benzo[b]pyrano[2,3-i]xanthen-6-ones and benzo[b]pyrano[3,2-h]xanthen-7-ones related to psorospermine and benzo[b]acronycine. In contrast with what is observed in the pyridoacridone and benzopyridoacridone series, the linear benzo[b]-pyrano[2,3-i]xanthen-6-one derivatives were more potent than their angular benzo[b]pyrano[3,2-h]xanthen-7-one isomers. cis-3,4-Diacetoxy-5-methoxy-2,2-dimethyl-3,4-dihydro-2H,6H-benzo[b]pyrano[2,3-i]xanthen-6-one, the most active among the new compounds, was more potent than acronycine in inhibiting the proliferation of L1210 murine leukemia cells.     

Target-based design,synthesis and biological activity of new pyrazole amide derivatives

Based on the similarities in the conformation of VS008 (N-(4-methylphenyl)-3-(tert-butyl)-1-(phenylmethyl)-1H-pyrazole-5-carboxamide) and BYIO6830 (N'-(3,5-dimethylbenzoyl)-N'-tert-butyl-5-methyl-2,3-dihydro-1,4-benzodioxine-6-carbohydrazide) bound to the active site of the EcR subunit of the ecdysone receptor (EcR)-ultraspiracle protein (USP) heterodimeric receptor, a series of new pyrazole amide derivatives were designed and synthesized. Their structures were confirmed by IR, ¹H NMR, ¹³C NMR and elemental analysis. Results from a preliminary bioassay revealed that two of the pyrazole derivatives exhibited promising insecticidal activity. Specifically, compounds 6e and 6i exhibited good activity against Helicoverpa armigera (cotton bollworm) at low concentration. Symptoms displayed by tebufenozide-treated H. armigera were identical with those displayed by its treated counterpart. 6i showed the same poisoning symptoms as those of tebufenozide. In addition, results from molecular docking result indicated that the binding modes of 6e and 6i at the active site of the EcR subunit of the heterodimeric receptor were similar to that of the bound tebufenozide.     

Metalloantibiotics: synthesis and antibacterial activity of cefepime metal complexes

Cefepime interacts with transition metal(II) ions to give [M(cefepime)Cl₂] complexes (M = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) which were characterized by physicochemical and spectroscopic methods. The complexes are insoluble in water and common organic solvents, and probably have polymeric structures. The spectra indicated that the ligand is a multidentate chelating agent. The complexes have been screened for antibacterial activity against several bacteria and showed activity less than that of free cefepime.     

Metalloantibiotics: synthesis and antibacterial activity of ceftazidime metal complexes

Ceftazidime (Hceftaz) interacts with transition metal(II) ions to give octahedral [M(ceftaz)(H₂O)Cl] complexes [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Cd(II)] which were characterized by physicochemical and spectroscopic methods. The spectra indicated that the ligand is a multidentate chelating agent. The complexes are insoluble in water and common organic solvents and probably have polymeric structures. The antibacterial activity of the metal complexes was found to be lower than that of free ceftazidime.     

Synthesis, antibacterial activity and quantum-chemical studies of novel 2-arylidenehydrazinyl-4-arylthiazole analogues

A new series of 2-arylidenehydrazinyl-4-arylthiazole derivatives (2a-k) was designed and synthesized through a rapid, simple, and efficient methodology in excellent isolated yield. These compounds were screened for in vitro antimicrobial activities against eight bacteria, e.g. Bacillus cereus, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, Shigella dysenteriae, Salmonella typhi, Escherichia coli, and three fungi e.g. Aspergillus oryzae, Candida albicans, and Saccharomyces cerevis. The results indicate that some of the compounds exhibit strong antibacterial activity, depending on the bacterial strain, but show virtually no antifungal activity. The structure-antibacterial activity relationships were studied using some physicochemical and quantum-chemical parameters with the ab initio Hartree-Fock model at the RHF/6-31G level of theory. A good qualitative correlation between predicted lipophilic parameters and antibacterial activity has been found.     

Design,synthesis and antibacterial activity of novel 1-oxacephem analogs

A series of l-oxacephem analogs were synthesized and their antibacterial properties against five strains of Gram-positive and Gram-negative bacteria were evaluated in vitro while ceftazidine was selected as control. Some of the tested compounds, compound 2c in narticular,showed more active aeainst three selected strains than the standard.     

砷配合物的固相合成、表征及抑菌活性研究

一些砷、锑的配合物具有抗癌、杀菌等生物功能[1,2],可用于药物研究.近年来,用砷剂(主要是三氧化二砷)治疗急性早幼粒细胞白血病(APL),具有缓解率高而复发率低的优点,引起世人的关注.因砒霜中仅含氧和砷,起药物作用的实际是砷(Ⅲ).因此,选择有生物功能的配体合成新型砷配合物对治疗白血病可能有一定药物作用.由于砷的无机盐易水解,故合成砷的生物配合物很困难,对砷配合物的研究也很少报道 [3-7].本文用异烟肼、L-苯丙氨酸和三碘化砷通过室温固相反应合成了两种未见报道的砷配合物,经元素分析,紫外光谱,X-射线粉末衍射,中、远红外光谱和热重差热分析确定了配合物的化学组成,并对配合物的抑菌活性进行了研究.