A novel acylated quercetin tetraglycoside from oolong tea (Camelia sinensis) extracts

A novel acylated quercetin tetraglycoside, namely quercetin 3-O-(2^G-p-coumaroyl-3^G-O-β-l-arabinosyl-3^R-O-β-d-glucosylrutinoside) was isolated from oolong tea (Camelia sinensis) extracts. Structural analysis of this compound was achieved by NMR, TOF-MS and high-resolution FAB-MS. Triglycosyl flavonols have previously been reported from tea leaves and tea seeds however this is the first report of an aromatic acylated and tetraglycosyl flavonol.     

A novel 3,8-seco-taxane metabolite from the seeds of the Chinese yew, Taxus mairei

The structure of a novel 3,8-seco-bicyclic taxanoid metabolite, isolated from the methanol extract of seeds of the Chinese yew, Taxus mairei, was established as (11αH)-3,8-seco-taxa-3E,7E,12(18)-triene-2α,6α,9β-triol (1) on the basis of spectral analysis including ¹H NMR, ¹³C NMR, HMQC, HMBC, NOESY and HR-FABMS.     

FT-IR measurement of tagitinin C after solvent extraction from Tithonia diversifolia

Tagitinin C, an antiplasmodial compound, identified as one major compound of the subtropical medicinal plant, Tithonia diversifolia, was determined by FT-IR spectroscopy method. The crude ether extracts from aerial parts of the plant were evaporated to dryness and re-dissolved in tetrachloroethylene (C₂Cl₄) before analysis.The magnitude of the absorbance of the very specific CO stretching vibration (ν_CO) at 1664.8 cm⁻¹ was exploited in order to quantify tagitinin C. The determination coefficient (r²) of the calibration scale was 0.9994, the detection limit was lower than 3 μg ml⁻¹ and the quantification limit was lower than 10 μg ml⁻¹.Recovery values from 100.5 to 101.7% were found for spiked concentration levels from 19.91 to 89.95 μg ml⁻¹. The main characteristics of the curves obtained from the calibration standards and from the standard addition technique were not statistically different (Student t-test) suggesting that matrix effects were negligible.The results obtained for the determination of tagitinin C in the crude ether extract from aerial parts of T. diversifolia by LC and FT-IR spectroscopic method agreed well: 0.76±0.02 and 0.773±0.009, of tagitinin C in dried plant respectively.     

Synthesis and crystal structure of manganese(II) complexes with high-denticity ligands derived from azacrowns

The hepta- and octa-dentate ligands N,N′-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 (L¹) and N,N′-bis(2-aminobenzyl)-1,10-diaza-18-crown-6 (L²), respectively, form stable mononuclear Mn(II) complexes. Spectrophotometric titrations performed in acetonitrile solution indicate the formation of mononuclear Mn(II) complexes with both ligands, and no evidence for the formation of binuclear complexes was obtained. The optimal architecture of L¹ allows it to impose the less usual pentagonal bipyramidal geometry on the Mn(II) guest, and the X-ray crystal structure of [Mn(L¹)](ClO₄)₂ shows that the Mn(II) ion is deeply buried in the receptor cavity, coordinated to the seven available donor atoms, with the perchlorate anions remaining outside the metal coordination sphere. In spite of its higher denticity, the receptor L² is unable to form the expected binuclear complexes. The X-ray crystal structure of [Mn(L²)](NO₃)₂ consists of the [Mn(L²)]²⁺ cation and nitrate anions involved in hydrogen-bonding interactions with the aniline groups. In [Mn(L²)]²⁺ the metal ion is also placed in the crown hole, but as a result of the large size of the macrocyclic cavity only six of the eight available donor atoms of the receptor form part of the Mn(II) coordination sphere, with the Mn(II) ion found in a distorted octahedral coordination environment.     

A rapid method for the detection of foodborne pathogens by extraction of a trace amount of DNA from raw milk based on amino-modified silica-coated magnetic nanoparticles and polymerase chain reaction

A method based on amino-modified silica-coated magnetic nanoparticles (ASMNPs) and polymerase chain reaction (PCR) was developed to rapidly and sensitively detect foodborne pathogens in raw milk. After optimizing parameters such as pH, temperature, and time, a trace amount of genomic DNA of pathogens could be extracted directly from complex matrices such as raw milk using ASMNPs. The magnetically separated complexes of genomic DNA and ASMNPs were directly subjected to single PCR (S-PCR) or multiplex PCR (M-PCR) to detect single or multiple pathogens from raw milk samples. Salmonella Enteritidis (Gram-negative) and Listeria monocytogenes (Gram-positive) were used as model organisms to artificially contaminate raw milk samples. After magnetic separation and S-PCR, the detection sensitivities were 8 CFU mL⁻¹ and 13 CFU mL⁻¹ respectively for these two types of pathogens. Furthermore, this method was successfully used to detect multiple pathogens (S. Enteritidis and L. monocytogenes) from artificially contaminated raw milk using M-PCR at sensitivities of 15 CFU mL⁻¹ and 25 CFU mL⁻¹, respectively. This method has great potential to rapidly and sensitively detect pathogens in raw milk or other complex food matrices.     

Bacillamide, a novel algicide from the marine bacterium, Bacillus sp. SY-1, against the harmful dinoflagellate, Cochlodinium polykrikoides

Bacillamide (1) was isolated as a new algicide against the harmful dinoflagellate, Cochlodinium polykrikoides, from the marine bacterium, Bacillus sp. SY-1, and its structure was elucidated by extensive two-dimensional NMR techniques including ¹H-¹⁵N HMBC analysis and mass analysis. Bacillamide showed algicidal activity against C. polykrikoides with LC₅₀ of 3.2 μg/ml.     

High-speed counter-current chromatographic isolation of ricinine,an insecticide from Ricinus communis

The alkaloid ricinine, an insecticide for leaf-cutting ant (Atta sexdens rubropilosa), was obtained from Ricinus communis. A two-phase solvent system composed of CH₂Cl₂/EtOH/H₂O (93:35:72, v/v/v) was used for high-speed counter-current chromatographic (HSCCC) isolation of ricinine in high yield and with over 96% purity, as determined by liquid and gas chromatography–mass spectrometry (LC–MS and GC–MS). Identification of ricinine was performed by comparison of ¹H NMR, ¹³C NMR and LC–MS/MS data.     

Cyclorhenated compounds derived from 1,4-diaryl-1-azabutadienes: preparation, structures and reactions

PhCH₂Re(CO)₅ reacted with 1,4-diaryl-1-azabutadienes to give cyclometallated (η²-(C,N)-azabutadiene)Re(CO)₄ (4) together with the substituted derivatives (η¹-(N)-azabutadiene)(η²-(C,N)-azabutadiene)Re(CO)₃ (6 and 7) The substituted product was shown by NMR and X-ray crystal structure analysis to be an inseparable mixture of isomers differing in the conformation of the η¹-ligand about the NC bond—trans for (6) and cis for (7). Reaction of the mixture of 6 and 7 from 1,4-diphenyl-1-azabutadiene with phenyl acetylene gave η⁵-(1,2,4-triphenyl-1-aza-cyclohexadienyl)Re(CO)₃.     

Characterization and identification of isomeric flavonoid O-diglycosides from genus Citrus in negative electrospray ionization by ion trap mass spectrometry and time-of-flight mass spectrometry

Flavonoid O-diglycosides are important bioactive compounds from genus Citrus. They often occur as isomers, which makes the structural elucidation difficult. In the present study, the fragmentation behavior of six flavonoid O-diglycosides from genus Citrus was investigated using ion trap mass spectrometry in negative electrospray ionization (ESI) with loop injection. For the flavonoid O-rutinosides, [M − H − 308]⁻ ion was typically observed in the MS² spectrum, suggesting the loss of a rutinose. The fragmentation patterns of flavonoid O-neohesperidosides were more complicated in comparison with their rutinoside analogues. A major difference was found in the [M − H − 120]⁻ ion in the MS² spectrum, which was a common feature of all the flavonoid O-neohesperidosides. The previous literature for naringin located the loss of 120 Da to the glycan part, whereas the present study for naringin had shown that the [M − H − 120]⁻ ion was produced by a retro-Diels-Alder reaction in ring C, and this fragmentation pattern was confirmed by the accurate mass measurement using an orthogonal time-of-flight mass spectrometer. Combined with high performance liquid chromatography (HPLC) and diode array detection (DAD), the established approach to the structural identification of flavonoid O-diglycosides by ion trap mass spectrometry was applied to the analysis of extracts of two Chinese medicines derived from genus Citrus, namely Fructus aurantii and F. aurantii immaturus. According to the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by multistage mass spectrometry (MSⁿ) spectra, 13 flavonoid O-glycosides in F. aurantii and 12 flavonoid O-glycosides in F. a. immaturus were identified rapidly.     

Structure and biosynthetic implication of (S)-NHAB, a novel shunt product, from a disruptant of the actVI-ORFA gene for actinorhodin biosynthesis in Streptomyces coelicolor A3(2)

A novel shunt product was isolated from a disruptant of the actVI-ORFA gene involved in the biosynthesis of actinorhodin (ACT) in Streptomyces coelicolor A3(2). Its structure was elucidated as 1,4-naphthoquinone-8-hydroxy-3-[3(S)-acetoxy-butyric acid], (S)-NHAB, based on NMR, MS, and CD spectroscopic data as well as a single crystal X-ray crystallographic analysis. The formation of (S)-NHAB involves a retro-Claisen type C-C bond cleavage of an ACT biosynthetic intermediate. Feeding experiments with [1-¹³C] and [2-¹³C] acetates indicated its biosynthetic origin as a single octaketide chain. The relevant gene product, Act-ORFA, which is a functionally unknown protein, is proposed to play a regulatory role related to the multi-enzymatic steps to ACT production, based on the metabolic profile of its disruptant and the wide distribution of actVI-ORFA homologues in the gene clusters for Streptomyces aromatic polyketides.     

Structures of new alkaloids sessilifoliamides A-D from Stemona sessilifolia

Four new Stemona alkaloids, sessilifoliamides A-D (1-4), were isolated from the roots of Stemona sessilifolia, along with five known alkaloids, stenine (5), 2-oxostenine (6), stemoninoamide (7), tuberostemonone (8), and neotuberostemonol (9). The structures and absolute configurations of the new alkaloids were determined by the spectral studies (HRMS, IR, ¹H, ¹³C, and 2D NMR), single-crystal X-ray analyses, and chemical correlations. The absolute configuration of 7 was also determined by the modified Mosher's method.     

Molecular beacons: a real-time polymerase chain reaction assay for detecting Escherichia coli from fresh produce and water

Molecular beacons (MBs) are oligonucleotide probes that fluoresce upon hybridization. The development of a real-time polymerase chain reaction (PCR) assay to detect the presence of Escherichia coli using these fluorogenic reporter molecules is reported. MBs were designed to recognize a 19-bp region of the uid A gene, coding for an enzyme β-glucuronidase. The specificity of the MB-based PCR assay was evaluated for various E. coli strains as well as bacteria species that are present in nature. The capability of the assay to detect E. coli in drinking water and produce was demonstrated. Positive detection of E. coli was demonstrated when >10¹ CFU mL⁻¹ (colony forming unit) was present in the water samples and fresh produce after 18 h of enrichment. These assays could be carried out entirely in sealed PCR tubes, enabling rapid and semiautomated detection of E. coli in food and environmental samples.     

Marine bacterial inhibitors from the sponge-derived fungus Aspergillus sp.

Chromatographic separation of a crude extract obtained from the fungus Aspergillus sp., isolated from the Mediterranean sponge Tethya aurantium, yielded a new tryptophan derived alkaloid, 3-((1-hydroxy-3-(2-methylbut-3-en-2-yl)-2-oxoindolin-3-yl)methyl)-1-methyl-3,4-dihydrobenzo[e][1,4]diazepine-2,5-dione (1), and a new meroterpenoid, austalide R (2), together with three known compounds (3–5). The structures of the new compounds were unambiguously elucidated on the basis of extensive one and two-dimensional NMR (¹H, ¹³C, COSY, HMBC, and ROESY) and mass spectral analysis. Interestingly, the compounds exhibited antibacterial activity when tested against a panel of marine bacteria, with 1 selectively inhibiting Vibrio species and 2 showing a broad spectrum of activity. In contrast, no significant activity was observed against terrestrial bacterial strains and the murine cancer cell line L5178Y.     

A xanthone and a polyketide derivative from the leaves of Cassia obtusifolia (Leguminosae)

A new xanthone, 1,8-dihydroxy-3-methoxy-6-methylxantone and a new polyketide derivative, (4R^∗,5S^∗,6E,8Z)-ethyl-4-((E)-but-1-enyl)-5-hydroxypentdeca-6,8-dienoate, together with 20 known secondary metabolites, including 2 steroids, 4 xanthones, 10 anthraquinones, 2 triterpenoids, 1 fatty ester, and (E)-eicos-14-enoic acid, were isolated from the leaves of Cassia obtusifolia. To the best of our knowledge, the last compound was isolated from a natural source for the first time. The structures of all the compounds were elucidated on the basis of 1D and 2D NMR experiments. Some of the compounds were tested against Salmonella typhi, Staphylococcus aureus, Candida albicans ATCC 9002, and Candida tropicalis, they did not show any activity.     

Caldaphnidines A-F, six new Daphniphyllum alkaloids from Daphniphyllum calycinum

Six new Daphniphyllum alkaloids, namely caldaphnidines A-F (1-6), together with eight known ones, deoxycalyciphylline B, deoxyisocalyciphylline B, bukittiggine, calycicine A, methyl homosecodaphniphyllate, daphnilactone B, and daphnezomines L-M, were isolated from the leaves and the seeds of Daphniphyllum calycinum. The structure of 1 was determined by a single-crystal X-ray diffraction study, and the structures of 2-6 were established by spectral methods, especially two-dimensional NMR techniques (¹H-¹H COSY, HMQC, HMBC, and NOESY).     

Oxirane synthesis from diazocarbonyl compounds via NHC-Ag catalysis

A new method was developed to synthesize oxirane products from the reaction of diazocarbonyl substrates with aryl aldehydes by using Ag(I) N-heterocyclic carbene complex as the catalyst. A combination of N-heterocyclic carbene silver complex (IPrAgCl) with another silver salt (AgOTf) generated the catalytic active IPr-Ag⁺ intermediate, which then catalyzed the epoxidation reaction.     

Three new monoterpene indole alkaloids from Psychotria umbellata Thonn.

Three new psychollatine-derived monoterpene indole alkaloids were obtained from Psychotria umbellata Thonn.: 3,4-Dehydro-18,19-β-epoxy-psychollatine (2), N⁴-[1-((R)-2-hydroxypropyl)]-psychollatine (3), and N⁴-[1-((S)-2-hydroxypropyl)]-psychollatine (4). Their structures were determined by ¹H and ¹³C NMR spectra, 2D correlations (COSY, HMQC, and HMBC), and mass and UV spectra. Compounds 3 and 4 were synthesized for structural confirmation and for the determination of the stereochemistry of the hydroxyl group.     

Identification of polyoxypregnane glycosides from the stems of Marsdenia tenacissima by high-performance liquid chromatography/tandem mass spectrometry

A facile method based on high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/(+)ESI-MSⁿ) has been established for the analysis of polyoxypregnane glycosides in the stems of Marsdenia tenacissima. The data reveals the ability of MSⁿ in the structural elucidation of polyoxypregnane glycosides including the nature of the polyoxypregnane core, the kinds of the substituents and the types of sugar residues. Offline Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is also performed to assign accurate elemental compositions. In this study, eighteen polyoxypregnane glycosides have been investigated. Among these components, five compounds are unambiguously identified as Marsdenoside K, Tencissoside A, B, C and D; two compounds are established as novel compounds based on mass spectral data; and the other eleven compound's structures are tentatively proposed. Furthermore, breakdown curves are constructed to distinguish five pairs of isomers among these eighteen compounds. As far as our knowledge, this is the first report on identification of polyoxypregnane glycosides in the stems of M. tenacissima by HPLC/ESI-MSⁿ directly, which could save time and material consuming efforts in traditional phytochemistry analyses.     

Cytotoxic and novel skeleton compounds from the heartwood of Chamaecyparis obtusa var. formosana

The novel skeleton compounds, chamaecypanone C (3) and obtunorlignan A (4) were isolated from the heartwood of Chamaecyparis obtusa var. formosana. The structure of 3 was elucidated as a dimeric of monoterpene and norlignan with tricyclo[5.2.2.0^2.6]undecane and the structure of 4 was elucidated as a norlignan skeleton by spectroscopic methods. Compound 3 exhibits potent cytotoxic activity against several human cancer cells with IC₅₀ values ranging from 0.19 to 0.52 μM, whereas 4 has no activity.     

Syntheses and structures of zinc and tin(II) compounds with hemilabile N-silyl-tert-butylamido and N-silyl-p-tolylamido ligands that contain pendent tert-butoxy groups

Syntheses and solid-state structures of zinc and tin(II) compounds, containing the N-silyl-amide ligands (O^tBu)(NR)SiMe₂, R = ^tBu (L^tBu), or R = p-tolyl (L^pTol), are reported. The N-silyl amines were synthesized by modified published procedures from commercially available Me₂SiCl₂, ^tBuOH, and ^tBuNH₂, or p-Me-C₆H₄NH₂, respectively. Treatment of SnCl₂ with LiL^pTol furnished Sn(L^pTol)₂, which was X-ray structurally characterized and shown to contain two covalent Sn-N bonds and two asymmetrical O → Sn donor bonds. The single-crystal X-ray structure of Sn(L^tBu)₂ revealed a much more symmetrically-coordinated, pseudo-trigonal-bipyramidal tin atom. Aminolysis of diethylzinc with HL^pTol produced [EtZn(L^pTol)]₂, which crystallized as a centrosymmetric dimer, containing four-coordinate zinc atoms connected by bridging amides. Zinc dichloride, by contrast, reacted with two equivalents of LiL^tBu to produce the homoleptic, pseudo-spirocyclic Zn(L^tBu)₂.