Synthesis and characterization of tris(β-diketonato)technetium(III) and -(IV) complexes

The preparations and properties of tris(dipivaloylmethanato)technetium(III), tris(trifluoroacetylacetonato)technetium(III), and tris(hexafluoroacetonato)technetium(III) are described. The oxidation of the dipivaloyl derivative to tris(dipivaloyl)technetium(IV) hexafluorophosphate was shown to take place readily. Voltammetric studies and magnetic resonance results on the new complexes are reported. The large shifts observed for the complexes seem to be due to a contact interaction.     

Syntheses of (±)-Epoformin (Desoxyepoxydon) and (±)-Epiepoformin (Desoxyepiepoxydon)

Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice.     

Synthesis of (±)-Homosarkomycin and (±)-Rosaprostol

(±)-Homosarkomycin (2) and (±)-rosaprostol (3) were synthesized from (±)-methyl 2-oxo-bicyclo[3.1.0]hexane-1-carboxylate (1) by using the nucleophilic ring opening reaction on the double-activated cyclopropane ring as the key step.     

Synthesis of (±)-Lamprolobine and (±)-Epilamprolobine

(±)-Lamprolobine, the (+)-enatiomer of which was isolated from the leaves of Lamprolobium fruticosum, and (±)-epilamprolobine were synthesized from δ-valerolactam.     

Synthesis and characterization of β-diketiminate germanium(II) and tin(II) bromides

The equimolar reaction of a β-diketiminate lithium salt LLi(OEt₂) [L = HC(CMeNAr)₂; Ar = 2,6-iPr₂C₆H₃] with either GeBr₂ or SnBr₂ in diethyl ether affords the synthetically useful monomeric β-diketiminate-element halides LGeBr (1) and LSnBr (2), respectively. Both are soluble in hydrocarbon solvents, stable in inert atmosphere, and have been characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction analysis.     

Schistosomicidal and trypanocidal structure-activity relationships for (±)-licarin A and its (-)- and (+)-enantiomers

(±)-Licarin A (1) was obtained by oxidative coupling, and its enantiomers, (?)-licarin A (2) and (+)-licarin A (3), were resolved by chiral HPLC. Schistosomicidal and trypanocidal activities of these compounds were evaluated in vitro against Schistosoma mansoni adult worms and trypomastigote forms of Trypanosoma cruzi. The racemic mixture (1) displayed significant schistosomicidal activity with an LC₅₀ value of 53.57 μM and moderate trypanocidal activity with an IC₅₀ value of 127.17 μM. On the other hand, the (?)-enantiomer (2), displaying a LC₅₀ value of 91.71 μM, was more active against S. mansoni than the (+)-enantiomer (3), which did not show activity. For the trypanocidal assay, enantiomer 2 showed more significant activity (IC₅₀ of 23.46 μM) than enantiomer 3, which showed an IC₅₀ value of 87.73 μM. Therefore, these results suggest that (±)-licarin A (1) and (?)-licarin A (2) are promising compounds that could be used for the development of schistosomicidal and trypanocidal agents.     

Synthesis and properties of (2-pyridyl)alkylamine- and (2-pyridyl)alkylamine–amide-coordinated copper(II) complexes: Structures and non-covalent interactions

Reaction of the ligand N-methyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylethyl)amine (mpppa) with equimolar amounts of [Cu(H₂O)₆][ClO₄]₂ or CuCl₂ · 2H₂O in MeCN afforded mononuclear copper(II) complexes [Cu(mpppa)][ClO₄]₂ (1) and [Cu(mpppa)Cl₂] (2). Crystal structure analysis reveals CuN₃O (two pyridyl, an aliphatic amine, and an amide oxygen) coordination in 1 and CuN₃Cl₂ (two pyridyl, an aliphatic amine, and two chlorides) coordination in 2. Crystal packing diagram of 1 reveals that one of the perchlorate counteranions provides weak coordination to copper(II) centers and in turn the copper(II) centers assume pseudo-six-coordination, generating 1D chain. Notably, one of the copper(II)-coordinated chloride ions in 2 participates in an intramolecular N–H?Cl interaction. Intermolecular C–H?Cl interactions in the solid state generate helical structure. Spectroscopic (IR, UV–Vis, and EPR) and redox properties of the two complexes have been investigated and compared.     

Synthesis and cytokinin activity of (R)-(+)- and (S)-(−)-dihydrozeatins and their ribosides

(R)-(+)- and (S)-(?)-dihydrozeatins [(R)-(+)- and (S)-(?)-6-(4-hydroxy-3-methylbutylamino)purines, 1a and 1b] and their ribosides {(?)-6-[(R)-4-hydroxy-3-methylbutylamino]- and (?)-6-[(S)-4-hydroxy-3-methyl-butylamino]-9-β-D-ribofuranosylpurines, 3a and 3b} were synthesized and tested for their cytokinin activity by four bioassay systems, the growth of tobacco callus, the seed germination of lettuce, the fr. wt increase of excised radish cotyledons and the retardation of chlorophyll degradation in radish cotyledons. In tobacco callus bioassay, 1a was more active than 1b. The ribosides 3a and 3b were not less active than their corresponding aglycones 1a and 1b. In other bioassays used the activity followed the order: 1a >3a >1b >3b. In tobacco callus bioassay and lettuce seed germination, trans-zeatin [6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine] showed stronger cytokinin activity than 1a.     

Synthesis of ( ± )-Methyl Epijasmonate and ( ± )-Methyl Cucurbate

A novel synthesis of ( ± )-methyl epijasomonate (2) and the first synthesis of ( ± )-methyl cucurbate (4) were achieved starting from 2-allylcyclohexane-1,3-dione (8). The synthetic epimer 2 had a stronger jasmin flavor than the trans-isomer 1 with 95% purity.     

Healthcare-associated (HA) and community-associated (CA) methicillin resistant Staphylococcus aureus (MRSA) in Bangladesh – Source,diagnosis and treatment

Methicillin-resistant Staphylococcus aureus (MRSA) has long been a common pathogen in healthcare facilities, but now, it has emerged as a problematic pathogen in the community setting as well. This study reported source, diagnosis and treatment of HA-MRSA and CA-MRSA.A total of sixty-five clinical samples (urine, pus, wound swab) were collected from clinical origin of Dhaka city, Bangladesh. All the isolates were tested phenotypically by conventional methods and genotypically by PCR targeting nuc, pvl and mecA genes. Finally sequencing was carried out for pvl gene to know the mutagenic variation or any amino acid changes in pvl gene. Chi square test was employed for statistical analysis. Patients of age group 51–60?years are more susceptible (46.15%) to MRSA, CA-MRSA or HA-MRSA infection. Female are (32.30%) more susceptible to MRSA infection. Among 65 isolates 53 isolates identified phenotypically as S. aureus. These were positive for amplification of nuc (270?bp) gene of S. aureus. Moreover, among 53 isolates 33 phenotypically considered as MRSA and 38 (72%) showed positive amplification for mecA (162?bp) gene. Among 38 MRSA isolates 22 (57.89%) confirmed as CA-MRSA and 16 (42.10%) as HA-MRSA. Finally, sequence analysis for lukS/F-PV genes from 4 representative isolates detected a new single nucleotide polymorphism in comparison with the control sequence. However, no amino acid changes were found. Statistical analysis showed HA-MRSA isolates were more commonly found in urine sample and CA-MRSA in pus and wound swab. CA-MRSA isolates were more resistant to tested antibiotics than HA-MRSA.     

Association between carbonyl sulfide uptake and (18)Δ during gas exchange in C(3) and C(4) leaves

Carbonyl sulfide (COS) and C(18)OO exchange by leaves provide potentially powerful tracers of biosphere-atmosphere CO(2) exchange, and both are assumed to depend on carbonic anhydrase (CA) activity and conductance along the diffusive pathway in leaves. We investigated these links using C(3) and C(4) plants, hypothesizing that the rates of COS and C(18)OO exchange by leaves respond in parallel to environmental and biological drivers. Using CA-deficient antisense lines of C(4) and C(3) plants, COS uptake was essentially eliminated and discrimination against C(18)OO exchange ((18)Δ) greatly reduced, demonstrating CA's key role in both processes. (18)Δ showed a positive linear correlation with leaf relative uptake (LRU; ratio of COS to CO(2) assimilation rates, A(s)/A(c), normalized to their respective ambient concentrations), which reflected the effects of stomatal conductance on both COS and C(18)OO exchange. Unexpectedly, a decoupling between A(s) and (18)Δ was observed in comparing C(4) and C(3) plants, with a large decrease in (18)Δ but no parallel reduction in A(s) in the former. This could be explained by C(4) plants having higher COS concentrations at the CA site (maintaining high A(s) with reduced CA) and a high phosphoenolpyruvate carboxylase/CA activity ratio (reducing (18)O exchange efficiency between CO(2) and water, but not A(s)). Similar A(s) but higher A(c) in C(4) versus C(3) plants resulted in lower LRU values in the former (1.16 ± 0.20 and 1.82 ± 0.18 for C(4) and C(3), respectively). LRU was, however, relatively constant in both plant types across a wide range of conditions, except low light (<191 μmol photon m(-2) s(-1)).     

Comparison Between poly(dG-dC)·poly(dG-dC) and DNA Modified by cis-diamminedichloroplatinum (II): Immunological and Spectroscopic Studies

Abstract

The importance of the base composition and of the conformation of nucleic acids in the reaction with the drug cis-diamminedichloroplatinum(II) has been studied by competition experiments between the drug and several double-stranded polydeoxyribonucleotides. Binding to poly(dG)·poly(dC) is larger than to poly (dG-dC)·poly(dG-dC). There is no preferential binding in the competition between poly(dG-dC) ·poly(dG-dC), poly(dA-dC) ·poly(dG-dT) and poly(dA-dG)·poly(dC-dT). In the competition between poly(dG-dC) ·poly (dG-dC) (B conformation) and poly(dG-br⁵dC) ·poly(dG-br⁵dC) (Z conformation), the drug binds equally well to both polynucleotides. In natural DNA, modification of guanine residues in (GC)_n·(GC)_nsequences by the drug has been revealed by the inhibition of cleavage of these sequences by the restriction enzyme BssHII. By means of antibodies to platinated poly(dG-dC), it is shown that some of the adducts formed in platinated poly(dG-dC) are also formed in platinated pBR322 DNA. The type of adducts recognized by the antibodies is not known. Thin layer chromatography of the products after chemical and enzymatic hydrolysis of platinated poly(dG-dC) suggests that interstrand cross-links are formed. Finally, the conformations of poly(dG-m⁵dC) modified either by cis-diamminedichloroplatinum(II) or by trans-diammine- dichloroplatinum(II) have been compared by circular dichroism. Both the cis-isomer and the trans-isomer stabilize the Z conformation when they bind to poly(dG-m⁵dC) in the Z conformation. When they bind to poly(dG-m⁵dC) in the B conformation, the conformations of poly(dG-m⁵dC) modified by the cis or the trans-isomer are different. Moreover, the cis-isomer facilitates the B form-Z form transition of the unplatinated regions while the trans-isomer makes it more difficult.     

α(2)-adrenoceptor agonist-induced inhibition of gastric motor activity is mediated by α(2A)-adrenoceptor subtype in the mouse

The role of α(2)-adrenoceptors in regulation of gastric motility has been well documented. However, only few data are available on the adrenoceptor subtype that mediates this effect. The purpose of the present work was to identify the α(2)-adrenoceptor subtype(s) responsible for the inhibition of gastric motor activity in isolated fundus strip of the mouse. It was shown that (i) the electrically evoked contraction of the gastric fundus strip of the mouse was inhibited by the non-selective α(2)-adrenoceptor stimulant clonidine (EC(50): 0.019±0.001μM), the α(2A)-adrenoceptor subtype selective agonist oxymetazoline (EC(50): 0.004±0.001μM) and the α(2B)-adrenoceptor subtype preferring ST-91 (EC(50): 0.029±0.004μM), (ii) the inhibitory effect of clonidine (1μM), oxymetazoline (0.1μM) and ST-91 (1μM) on the contractions of gastric fundus strip was reversed by the non-selective α(2)-adrenoceptor antagonist idazoxan and α(2A)-adrenoceptor antagonist BRL 44408, but not by the α(2B/2C)-adrenoceptor antagonist ARC-239. (iii) Clonidine and ST-91 inhibited the electrically induced gastric contractions in C57BL/6 wild type mice as well as in α(2B)- and α(2C)-adrenoceptor deficient mice in a concentration-dependent manner; however, neither of them was effective in α(2A)-deficient mice. As a conclusion, it was first demonstrated that the inhibitory effect of α(2)-adrenoceptor agonists on the gastric motor activity of isolated stomach strip of the mouse is mediated purely by α(2A)-adrenoceptors.     

Relationships between unitary motor and sensory activity in the walking legs of cancer pagurus (Decapoda,Brachyura)†

Muscular tension and sensory activity in the flexor apodeme sensory nerve were recorded during stimulation of single motor afferents innervating the M‐C flexor. Muscular tension and unitary sensory activity both varied, depending upon the motor fiber stimulated. Differences in the abililty of individual motor fibers to elicit sensory activity were only partially accounted for by differences in tension development. Some tension afferent units were more readily excited by a muscular contraction elicited by one motor axon than they were by another, even when the tension elicited by the more effective motor fiber was less than that evoked by the less effective efferent.     

He(I) and He(II) photoelectron spectra of Hyprrole-2-CHN′t-Bu and the biscarbonyl Rh(I) and Ir(I) complexes of its anion

The He(I) and He(II) photoelectron spectra of a series of [(LL)M(CO)₂] (LL = pyrrole-2-CHN′ R; R = t-Bu; M = Rh, Ir) complexes are reported. Assignments are proposed based on He(I)/He(II) intensity differences, on molecular orbital calculations of related complexes and of free ligands, and by comparison with the spectra of the free ligands Hpyrrole-2-CHN′t-Bu, Hpyrrole-2-carbaldehyde and Hpyrrole.The electronic structure of the complexes is discussed and conclusions are drawn about the metal-ligand interaction.     

Physicochemical and biological properties of 2-O-α-D-galactosyl-cyclomaltohexaose (α-cyclodexterin) and -cyclomaltoheptaose (β-cyclodextrin)

The physicochemical and biological properties of the new branched cyclomaltooligosaccharides (cyclodextrins; CDs), 2-O-α-D-galactosyl-cyclomaltohexaose (2-O-α-D-galactosyl-α-cyclodextrin, 2-Gal-αCD) and 2-O-α-D-galactosyl-cyclomaltoheptaose (2-O-α-D-galactosyl-β-cyclodextrin, 2-Gal-βCD), were investigated. The formation of inclusion complexes of 2-Gal-CDs with various kinds of guest compounds (clofibrate, cholesterol, cholecalciferol, digitoxin, digitoxigenin, and prostaglandin A(1)) was examined by a solubility method, and the results were compared with those of non-branched CDs and other 6-O-glycosyl-CDs such as 6-O-α-D-galactosyl-CDs, 6-O-α-D-glucosyl-CDs, and 6-O-α-maltosyl-CDs. The inclusion abilities of 2-Gal-αCD for clofibrate and prostaglandin A(1), and 2-Gal-βCD for clofibrate, cholecalciferol, cholesterol, and digitoxigenin were markedly weaker than those of non-branched CD and other 6-O-glycosyl-CDs in each series, probably because of a steric hindrance caused by the α-(1→2)-galactoside linkage. The hemolytic activities of 2-Gal-CDs on human erythrocytes were the lowest among each CD series, and the compounds showed negligible cytotoxicity towards Caco-2 cells up to at least 100mM.