Enzymatic Synthesis of Polyol- and Masked Polyol- Glycosides using β-Glycosidase of Sulfolobus Solfataricus

The use of commercially available mesophilic glycosidases in the enzymatic synthesis of glycosides of different types is a well established method suffering from some drawbacks such as a poor yield. Substrates with three or four hydroxyl groups have been subjected to enzymatic glucosylation using crude homogenate of the thermophilic archaeon Sulfolobus solfataricus containing a β-glycosidase activity able to transfer glucose, galactose and fucose from different donors. The stereochemistry of this reaction was interpreted in terms of interaction with a possible “glucose” active site of the enzyme. In addition masked or protected derivatives of tetritols and some simple unsaturated alcohols were glycosylated yielding glycosides in yields very competitive with those obtained using mesophilic enzymes, examples of further chemical manipulation of these compounds were reported. When using a scarce amount of acceptor, a reasonable amount of products could be obtained by adding different aliquots of donor at time intervals.     

Lactones 26 : Stereoselective microbial epoxidation of unsaturated bicyclic γ-lactones with the alkylsubstituted cyclohexane system

The strain Absidia cylindrospora was chosen among eight fungal strains for the biotransformation of unsaturated lactones 1a–c. The processes were carried out by means of shaken cultures. The compounds 1a and 1b were efficiently converted into the corresponding trans-epoxylactones (2a and 2b), whereas the transformation of 1c gave the unsaturated hydroxylactone 3, with the tertiary hydroxy group introduced in the allylic position. The compound 2b was obtained with 100% ee. The structures of compounds 2a and 2b were fully confirmed by the X-ray analysis, which showed the half boat and half chair conformation of cyclohexane ring in these molecules, respectively. All the products were not reported previously in the literature.     

Oxidation of 1,4-alkanediols into γ-lactones via γ-lactols using Rhodococcus erythropolis as biocatalyst

Whole cells of Rhodococcus erythropolis DSM 44534 grown on ethanol, (R)- and (S)-1,2-propanediol were used for biotransformation of racemic 1,4-alkanediols into γ-lactones. The cells oxidized 1,4-decanediol (1a) and 1,4-nonanediol (2a) into the corresponding γ-lactones 5-hexyl-dihydro-2(3H)-furanone (γ-decalactone, 1c) and 5-pentyl-dihydro-2(3H)-furanone (γ-nonalactone, 2c), respectively, with an EE(R) of 40–75%. The transient formation of the γ-lactols 5-hexyl-tetrahydro-2-furanol (γ-decalactol, 1b) and 5-pentyl-tetrahydro-2-furanol (γ-nonalactol, 2b) as intermediates was observed by GC–MS. 1,4-Pentanediol (3a) was transformed into 5-methyl-dihydro-2(3H)-furanone (γ-valerolactone, 3c) whereas (R)- and (S)-2-methyl-1,4-butanediol (4a) was converted to the methyl-substituted γ-butyrolactones 4-methyl-dihydro-2(3H)-furanone (4c₁) and 3-methyl-dihydro-2(3H)-furanone (4c₂) in a ratio of 80:20 with a yield of 55%. Also cis-2-buten-1,4-diol (5a) was transformed resulting in the formation of 2(5H)-furanone (γ-crotonolactone, 5c). At the higher pH values of 8.8 the yield of lactone formed was improved; however, the enatiomeric excesses were slightly higher at the lower pH of 5.2.     

Efficient synthesis, spectral analysis and antimicrobial studies of nitrogen and sulfur containing spiro heterocycles from 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-ones

Acetyl and propionyl group substituted thiadiazole derivatives (4a-4h, 5a-5h, 6a, 6b, 7a and 7b) have been synthesized by the cyclization of 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-one thiosemicarbazones (2a-2h, 3a and 3b) with acetic anhydride/propionic anhydride and were characterized by Elemental analysis, IR, (1)H NMR and (13)C NMR spectral analysis. Single crystal X-ray diffraction has also been recorded for compounds 4c and 5a. From the NMR and Single crystal X-ray diffraction analysis, compounds 4b-4d, 4f-4h, 5b, 5c, 5f-5h, 6a, 7a and 7b were found to adopt twin-chair conformations whereas compounds 4a, 4e, 5a, 5d, 5e and 6b adopt chair and boat conformation of cyclohexane and piperidine rings, respectively. Besides, the synthesized compounds were screened for antibacterial and antifungal activities using serial dilution method. The microbiological analysis showed that the electron withdrawing function substituted phenyl group at C-2 and C-4 of azabicyclononane based thiadiazoles 4c/4h and 5c/5h exposed significant antimicrobial activity against Salmonella typhi, Escherichia coli, Klebsiella pneumoniae, Aspergillus flavus, Aspergillus niger and Candida albicans at MIC of 6.25 μg/ml.     

Lactones 27 [1]: Transformations of γ-lactones fused to a dimethylcyclohexane ring in Absidia cylindrospora cultures

Two saturated (4a,b) and one unsaturated (5) bicyclic γ-lactones containing a dimethylcyclohexane ring were subjected to biotransformation using the fungal strain Absidia cylindrospora. Six new compounds (6–11) and one known (12) [K.W. Rosenmund, H. Herzberg, H. Schutt, Chem. Ber. 87 (1954) 1258] [2] were isolated. All substrates were stereoselectively hydroxylated by the microorganism at either the C-4 (in the case of 4a and 5) or C-2 position (in case of 4a and 4b) giving the corresponding hydroxylactones with tertiary (6 and 9) or secondary (8 and 10) hydroxy groups, respectively.

The hydroxy group was also introduced into C-3 (in the case of 4a) and C-6 (in the case of 4b) positions. The structures of all obtained products were established on the basis of their spectral data. In the case of lactones 8–10 these structures were undoubtedly confirmed by their X-ray analysis.     

Diamino benzo[b]thiophene derivatives as a novel class of active site directed thrombin inhibitors: 3. Enhancing activity by imposing conformational restriction in the C-4" side chain

The preparation and biological evaluation of a series of benzo[b]thiophene diamine thrombin inhibitors possessing conformationally restricted C-4" linkers are reported. Compared to the parent compounds 1a/b, the unsaturated derivatives 3a/b exhibited a modest twofold increase in thrombin inhibitory activity, while the more lipophilic carbocyclic ring containing analogs 4a/b affected an eightfold enhancement in potency.     

The copolymeric structure of pig skin dermatan sulphate. Characterization of d-glucuronic acid-containing oligosaccharides isolated after controlled degradation of oxydermatan sulphate

Selective periodate oxidation of unsubstituted l-iduronic acid residues in copolymeric dermatan sulphate chains was followed by reduction-hydrolysis or alkaline elimination. By this procedure the glucuronic acid-containing periods were isolated in oligosaccharide form; general formula: [Formula: see text] Further degradation of these oligosaccharides with chondroitinase-AC yielded three types of products: (a) sulphated trisaccharide containing an unsaturated uronosyl moiety in the non-reducing terminal and a C(4) fragment in the reducing terminal, DeltaUA-GalNAc-(-SO(4))-R; (b) monosulphated, unsaturated disaccharide, DeltaUA-GalNAc-SO(4) when n is greater than or equal to 2; and (c) N-acetylgalactosamine with or without sulphate. Oligosaccharides containing a single glucuronic acid residue (n=1) comprised more than half of the glucuronic acid-containing oligosaccharides. The terminal N-acetylgalactosamine moiety of the shortest oligosaccharide was largely 4-sulphated, whereas higher oligosaccharides primarily contained 6-sulphated or unsulphated hexosamine moieties in the same position. Moreover, IdUA-SO(4)-containing oligosaccharides were encountered. These oligosaccharides were resistant to the action of chondroitinase-ABC.     

Synthesis and affinity studies of himbacine derived muscarinic receptor antagonists

A series of himbacine (1)-related analogues has been prepared featuring three different isomeric configurations with respect to the B-ring (a, b and natural c) and three different interconnecting two-carbon unsaturated units [natural (E)-ene, (Z)-ene, and yne]. The study of the binding affinities of the nine resulting compounds, including synthetic (+)-himbacine (3c), towards the M(1)-M(4) muscarine receptor subtypes revealed that analogues 3a and 5c display a promising 10-fold selectivity for the M(2) receptor as compared to the M(1) receptor.     

1,1-Organoboration of tri-1-alkynyltin compounds: novel triorganotin cations, stannoles, 3-stannolenes and 1-stanna-4-bora-2,5-cyclohexadienes

Tri-1-alkynyltin compounds [R²Sn(CCR¹)₃ (1), R² = Me, R¹ = Me (a), ⁿBu (b), ^tBu (c), Me₃Si (d), 1-(1-cyclohexenyl) (e); R² = Et, R¹ = Me (a(Et)), ⁿBu (b(Et)), ^tBu (c(Et)), SiMe₃ (d(Et)); R² = ⁿBu, R¹ = Me (a(Bu)), ⁿBu (b(Bu))] were prepared, and their reactivity towards trialkylboranes Et₃B (2) and ⁱPr₃B (3) in 1,1-organoboration reactions was studied. The first step in each reaction is an intermolecular 1,1-alkytoboration. Afterwards, intramolecular 1,1-vinyloboration or 1,1-alkyloboration compete with further intermolecular 1,1-alkyloboration. Various triorganotin cations (4-7), stabilized by intramolecular side-on coordination to the CC bond of an alkynylborate moiety, were detected as highly fluxional intermediates prior to rearrangement into heterocyclic systems such as stannoles (9-11), 1-stanna-4-bora-2, 5-cyclohexadienes (8, 12). The reactions between 1a or 1a(Bu) and an excess of Et₃B (2) afford the tris(alkenyl)tin compounds 13 via threefold intermolecular 1, 1-ethyloboration. 13 rearrange to the 3-stannolenes (14a or 14a(Bu)). The intermediates and final products were characterized by multinuclear one- and two-dimensional ¹H, ¹¹B, ¹³C, ²⁹Si and ¹¹⁹Sn NMR.     

Synthesis, antimicrobial activity and conformational analysis of novel substituted pyridines: BF(3)-promoted reaction of hydrazine with 2-alkoxy pyridines

Some new 2-alkoxy-3-cyano-4,6-diarylpyridines 3,4 were synthesized by condensation of different alpha,beta-unsaturated ketones 1 with malononitrile 2, followed by cyclization in sodium alkoxide/alcohol system. Lewis acid-catalyzed reaction of 4 with hydrazine afforded the corresponding 1H-pyrazolo[3,4-b]pyridines 5. The potency of the results as antimicrobial agents has been evaluated. The structure of the newly prepared compounds was assessed by microanalysis, IR and NMR spectra. Molecular mechanics (MM2) and semiemperical (AM1) molecular orbital calculations have been performed for the most biologically active compounds 5b and c to get insight into their molecular structures and to learn more about their stable molecular conformations.     

Synthesis, biological evaluation, and docking studies of 3-(substituted)-aryl-5-(9-methyl-3-carbazole)-1H-2-pyrazolines as potent anti-inflammatory and antioxidant agents

A novel series of 3-(substituted)-aryl-5-(9-methyl-3-carbazole)-1H-2-pyrazolines (5a-o) has been synthesized and the structures of newly synthesized compounds were characterized by IR, (1)H NMR and mass spectral analysis. All the synthesized compounds were evaluated for their in vitro and in vivo anti-inflammatory activity, and also for their antioxidant activity. Compounds 5b, 5c, 5d and 5n were found to be selective COX-2 inhibitors. Compound 5c was found to potent inhibitor of the carrageenin induced paw edema in rats. Most of the compounds exhibited good DPPH and superoxide radical scavenging activity, while compounds 5c, 5d, 5i and 5k exhibited good hydroxyl radical scavenging activity. Molecular docking result, along with the biological assay data, suggested that compound 5c was a potential anti-inflammatory agent.     

Enantiospecificity of kappa receptors: comparison of racemic compounds and active enantiomers in two novel series of kappa agonist analgesics.

Two novel series, Ia,b and IIa,b, of kappa opioid antinociceptive agents have recently been described. 2a,b,3a,b,c The biological activities of 16 racemic compounds and their corresponding (-) enantiomers are now compared in a battery of tests. Enantiomers of unsubstituted piperidines Ia were synthesized starting from S(-) pipecolic acid, whereas the enantiomerically pure substituted piperidines (Ib), tetrahydroisoquinolines (IIa), and thienopiperidines (IIb) were, in general, obtained after diastereomeric crystallization of the corresponding tartrate salts. The absolute stereochemistry of one representative enantiomer from series IIa was determined to be (1S) by X-ray crystallographic analysis. Antinociceptive activity in the mouse abdominal constriction and tail-flick tests following subcutaneous administration, and binding affinity for kappa and mu receptors, were found to reside predominantly in the (-) enantiomers. Consequently, racemic compounds showed approximately half potency of the corresponding enantiomers. This potency difference was less clear after oral administration presumably due to small differences in bioavailability of the two corresponding enantiomers. For compounds with some affinity also for mu receptors (Ki less than 1,000 nM), the kappa/mu selectivity was maintained within each enantiomeric pair, in contrast to results found for other kappa agonists.     

Synthesis, structure, and bioactivity of N'-substituted benzylidene-3,4,5-trimethoxybenzohydrazide and 3-acetyl-2-substituted phenyl-5-(3,4,5-trimethoxyphenyl)-2,3-dihydro-1,3,4-oxadiazole derivatives

Some 3-acetyl-2-substituted phenyl-5-(3,4,5-trimethoxyphenyl)-2,3-dihydro-1,3,4-oxadiazole derivatives were synthesized by cyclization reaction of N'-substituted benzylidene-3,4,5-trimethoxybenzohydrazide in acetic anhydride. Their structures were verified by elemental analysis, IR, (1)H NMR, and (13)C NMR. Compound 3i was provided with X-ray crystallographic data. The compounds were evaluated for their antiproliferative activities against some cancer cells in vitro by MTT method. Among them, 2a, 2b, 2c, 2f, 3l, and 3m were highly effective against PC3 cells and 2a, 2c, and 2f showed moderate activities against Bcap37 and BGC823 cells. The IC(50) values of high active compounds 2a, 2b, 2c, 2f, 3l, and 3m against PC3 cells were 0.2, 1.8, 0.2, 1.2, 1.7, and 0.3muM, respectively.     

A Dominant Trait Linked to Chromosome 1 in DBA/2 Mice for the Resistance to Autoimmune Gastritis Appears in Bone Marrow Cells

Neonatal thymectomy (NTx) induces autoimmune gastritis (AIG) in BALB/c mice, a model for human type A chronic atrophic gastritis, but not in DBA/2 mice and rarely in CDF1 mice (a hybrid of BALB/c and DBA/2 mice). The aim of this study was to clarify the mechanisms of AIG-resistance in mice bearing the dominant trait of DBA/2. Linkage groups associated with, and cells related to AIG resistance were examined with CDF1-BALB/c backcrosses. Intracellular staining and flow-cytometric bead array for several cytokines were performed on NTx BALB/c mice and NTx DBA/2-chimeric BALB/c mice receiving DBA/2-bone marrow cells. In NTx BALB/c mice, IFN-γ-secreting CD4⁺ T cells were increased, but not in NTx DBA/2 mice. Because Vβ6⁺ T cell-bearing mice of half of their backcrosses developed AIG, but the other half of Vβ6⁺ T cell-negative mice developed scarcely, resistance for AIG generation is associated with the presence of the Mls-1a locus on chromosome 1 in DBA/2 mice, which deletes Vβ6⁺ T cells. NTx DBA/2-chimera BALB/c mice showed dominant production of IL-10 and resistance for AIG, although the deletion of Vβ6⁺ T cells was found not to be a cause of AIG-resistance from Mls-1a locus segregation experiments. Although NTx DBA/2-chimeric BALB/c mice did not suffer from AIG, they brought immediate precursors of T cells for AIG. It is concluded that DBA/2 mice generate bone marrow-derived cells that produce anti-inflammatory cytokines to prevent the activation of AIG-T cells.     

甜菜夜蛾触角结合蛋白Ⅱ的cDNA克隆、 组织分布及配体结合特性分析

触角结合蛋白（antennal binding proteins, ABPs）是气味结合蛋白（odorant binding proteins, OBPs）的一个亚类, 推测其在昆虫嗅觉中起作用。为了探讨这一问题, 本研究通过转录组数据分析并利用RACE技术, 克隆了甜菜夜蛾Spodoptera exigua触角结合蛋白Ⅱ基因（SexigABP2）的全长cDNA序列（GenBank登录号为HQ234486）。序列分析表明, 该基因开放阅读框长444 bp, 编码148个氨基酸, 具有OBPs典型的6个半胱氨酸位点; 其氨基酸序列和烟芽夜蛾Heliothis virescens的HvirABP2的一致性最高, 达72%。实时定量PCR分析显示, 该基因主要在触角中表达, 在喙、 足、 翅等组织中也有少量表达, 且在雌蛾触角及足中的表达量显著高于雄蛾。进一步对该基因进行原核表达和纯化, 利用荧光竞争结合实验测定了SexigABP2对35种气味物质的结合能力, 发现其对甜菜夜蛾性信息素组分(Z)-9-十四碳烯醇和植物挥发物法尼醇的结合能力较强, 结合常数分别为8.24 μmol/L和8.14 μmol/L。结合能力比较表明, SexigABP2对不饱和长碳链化合物较饱和短碳链化合物具有更强的结合能力; 在不饱和长碳链化合物中, 对醇类物质又较乙酸酯类物质具有更强的结合能力。结果提示SexigABP2可能参与了成虫对不饱和长碳链的植物挥发物的感受。     

Synthesis and biological evaluation of novel fluoro and iodo quinoline carboxamides as potential ligands of NK-3 receptors for in vivo imaging studies

In order to develop radioligands of human NK-3 receptor (hNK-3r) for imaging studies by positron emission tomography (PET) or single photon emission computed tomography (SPECT), a new series of fluoro- and iodo-quinoline carboxamides were synthesized and evaluated in a target receptor binding assay. Compared to the unsubstituted parent compound SB 223 412 (Ki=27 nM +/- 9), affinity was not altered for the analogues 1c and 2c bearing a fluorine in position 8 (Ki approximately 24-27 nM), and was only slightly reduced for compounds 1b, 2b, 1e and 2e fluorinated or iodinated at the position 7 (Ki approximately 49-67 nM). A drastic reduction in binding (Ki > 115 nM) was observed for all other halogenated compounds 1a, 2a, 1d, 2d, 1f and 2f.     

Emollient, humectant, and fluorescent alpha,beta-unsaturated thiol esters for long-acting skin applications

We describe compounds in which an emollient or a humectant bears an α,β-unsaturated thiol ester capable of reacting with nucleophilic amino acids in stratum corneum proteins. These compounds should serve as long-lasting moisturizers for skin. The emollient derivatized was octadecyl propanoate, and the humectant was poly(ethylene glycol). These hydrophobic and hydrophilic compounds, as well as a fluorescent, dansyl-containing thiol ester, were found to react within minutes with the thiol N-acetylcysteamine upon addition of a catalytic amount of an organic base in chloroform. The structures of the products resulting from conjugate addition to the unsaturated thiol esters were determined by NMR spectroscopy. In the case of the α,β,γ,δ-unsaturated (sorboyl) thiol ester, both the 1,4-addition product and the β,γ-unsaturated-1,6-addition product formed, followed by diadduct. An in vivo test of the fluorescent α,β-unsaturated thiol ester showed that this compound persisted on skin for 3 weeks vs. 6 days for the non-bonding control compound.     

Respiratory Development in Saccharomyces cerevisiae Grown at Controlled Oxygen Tension

Saccharomyces cerevisiae was grown in batch culture over a wide range of oxygen concentrations, varying from the anaerobic condition to a maximal dissolved oxygen concentration of 3.5 muM. The development of cells was assayed by measuring amounts of the aerobic cytochromes aa(3), b, c, and c(1), the cellular content of unsaturated fatty acids and ergosterol, and the activity of respiratory enzyme complexes. The half-maximal levels of membrane-bound cytochromes aa(3), b, and c(1), were reached in cells grown in O(2) concentrations around 0.1 muM; this was similar to the oxygen concentration required for half-maximal levels of unsaturated fatty acid and sterol. However, the synthesis of ubiquinone and cytochrome c and the increase in fumarase activity were essentially linear functions of the dissolved oxygen concentration up to 3.5 muM oxygen. The synthesis of the succinate dehydrogenase, succinate cytochrome c reductase, and cytochrome c oxidase complexes showed different responses to changes in O(2) concentration in the growth medium. Cyanide-insensitive respiration and P(450) cytochrome content were maximal at 0.25 muM oxygen and declined in both more anaerobic and aerobic conditions. Cytochrome c peroxidase and catalase activities in cell-free homogenates were high in all but the most strictly anaerobic cells.     

Synthesis and biological evaluation of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thioglycosides

In the present study, the synthesis of 1, 3, 4-thiadiazole-based thioglycosides were accomplished in good yields with employing a convergent synthetic route. The starting material 5-amino-1, 3, 4-thiadiazole-2-thiol and followed by a series of 5-fatty-acylamido-1, 3, 4-thiadiazole-2-thiols (4a–4j) were synthesized with different fatty acid chlorides. The glycosylation of compounds 4a–4j were achieved with trichloroacetimidate methodology. Antimicrobial and cytotoxicity activities of title compounds were evaluated. Among the entire compounds lauric acid and myristic acid derivatives showed good and moderate antimicrobial activity. In case of cytotoxicity results of compounds 8a–8j and 9a–9j, the acetate protected short chain (C6:0, C8:0, C10:0) compounds and the free hydroxyl long chain saturated (C16:0, C18:0) and unsaturated (C18:1, C22:1) compounds exhibited good activity against different cancer cell lines. Further, the free hydroxyl compounds 9a, 9c–9j did not show any toxicity towards normal CHO-K1 cell line whereas acylated compounds 8a–8j exhibited toxicity.