Five new isocoumarins from Sonoran desert plant-associated fungal strains Paraphaeosphaeria quadriseptata and Chaetomium chiversii

Five new isocoumarins, paraphaeosphaerins A-C and chaetochiversins A and B, biogenetically related to monocillin I and radicicol, have been isolated from solid agar cultures of Paraphaeosphaeria quadriseptata and Chaetomium chiversii, two fungal strains living in association with the Sonoran desert plants, Opuntia leptocaulis and Ephedra fasciculata, respectively. A new chroman-4-one, aposphaerin C, was also isolated from P. quadriseptata. Their structures and stereochemistry were elucidated using a combination of ¹H and ¹³C homo- and hetero-nuclear 2D NMR techniques, ¹H NMR analysis of Mosher's esters, and chemical correlations.     

Spectrofluorimetric determination of aliphatic amines using a new fluorigenic reagent: 2,6-dimethylquinoline-4-(N-succinimidyl)-formate

A new amino fluorescence probe, 2,6-dimethylquinoline-4-(N-succinimidyl) formate (DMQF-OSu) has been synthesized. Based on the selective reaction of DMQF-OSu with primary and secondary aliphatic amines to yield strong fluorescence, a new spectrofluorimetric method for the determination of total aliphatic amines has been developed. At λ_ex/λ_em=324.4/416 nm, the linear calibration range was 6×10⁻⁸-6×10⁻⁶ mol l⁻¹ with the detection limit (3σ) of 1.94×10⁻¹⁰ mol l⁻¹ for the determination of aliphatic amines in weak basic media. The proposed method has been applied to the determination of aliphatic amines in tap water and lake water with the recoveries of 99-104%. Compared with the reported methods, the method presented here is rapid, simple, sensitive and feasible.     

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.     

Structure and X-ray conformation of pseudodesmins A and B, two new cyclic lipodepsipeptides from Pseudomonas bacteria

Two new cyclic lipodepsipeptides named pseudodesmins A and B have been isolated from Pseudomonas bacteria collected from the mucus layer in the skin of the black belly salamander. Both compounds show moderate antibacterial activity against Gram positive bacteria, including MRSA. Complete ¹H, ¹³C and ¹⁵N NMR assignment of both compounds afforded their covalent structure and served to guide the analysis of LC-MS and X-ray diffraction data from which the final stereochemistry could be established. Both molecules can be categorized as new members of the viscosin group of cyclic lipodepsipeptides.     

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.     

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.     

Isolation,characterization, and NMR spectroscopic data of indole and oxindole alkaloids from Mitragyna speciosa

A new indole alkaloid, 7β-hydroxy-7H-mitraciliatine (1) and a new oxindole alkaloid, isospeciofoleine (2) together with nine known alkaloids were isolated from Mitragyna speciosa and characterized by NMR, CD, and MS spectroscopic data analyses. The ¹H and ¹³C NMR spectroscopic data of isospeciofoline (3), isorotundifoline (4), paynantheine (5), and 3-isopaynantheine (6) were also reported for the first time.     

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.     

Bioreduction of methyl o-chlorobenzoylformate at 500 g L without external cofactors for efficient production of enantiopure clopidogrel intermediate

Biocatalytic reduction of methyl o-chlorobenzoylformate (CBFM) provides a green and direct access to methyl (R)-o-chloromandelate [(R)-CMM], an intermediate for a platelet aggregation inhibitor named clopidogrel. As much as 500 g L⁻¹ of CBFM was stoichiometrically converted into enantiopure (R)-CMM at 20 °C by using a whole-cell catalyst coexpressing an aldo-keto reductase from Bacillus sp. and a glucose dehydrogenase (GDH). In addition to the high productivity of 812 g L⁻¹ d⁻¹, this new whole-cell reduction is attractive by eliminating the need of an added external cofactor.     

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).     

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.     

A strategy for fast screening and identification of sulfur derivatives in medicinal Pueraria species based on the fine isotopic pattern filtering method using ultra-high-resolution mass spectrometry

Sulfurous compounds are commonly present in plants, fungi, and animals. Most of them were reported to possess various bioactivities. Isotopic pattern filter (IPF) is a powerful tool for screening compounds with distinct isotope pattern. Over the past decades, the IPF was used mainly to study Cl- and Br-containing compounds. To our knowledge, the algorithm was scarcely used to screen S-containing compounds, especially when combined with chromatography analyses, because the ³⁴S isotopic ion is drastically affected by ¹³C₂ and ¹⁸O. Thus, we present a new method for a fine isotopic pattern filter (FIPF) based on the separated M + 2 ions (¹²C_x¹H_y¹⁶O_z³²S¹³C₂¹⁸O, ¹²C_x+2¹H_y¹⁶O_z+1³⁴S, tentatively named M + 2OC and M + 2S) with an ultra-high-resolution mass (100,000 FWHM @ 400 m/z) to screen sulfur derivatives in traditional Chinese medicines (TCM).This finer algorithm operates through convenient filters, including an accurate mass shift of M + 2OC and M + 2S from M and their relative intensity compared to M. The method was validated at various mass resolutions, mass accuracies, and screening thresholds of flexible elemental compositions. Using the established FIPF method, twelve S-derivatives were found in the popular medicinal used Pueraria species, and 9 of them were tentatively identified by high-resolution multiple stage mass spectrometry (HRMSⁿ). The compounds were used to evaluate the sulfurous compounds' situation in commercially purchased Pueraria products. The strategy presented here provides a promising application of the IPF method in a new field.     

Determination of quinolizidine alkaloids in Sophora medicinal plants by capillary electrophoresis

A new capillary electrophoresis (CE) method for the determination of quinolizidine alkaloids in Sophora medicinal plants was developed. A total of seven alkaloid components (cytisine, sophocarpine, matrine, lehmannine, sophoranol, oxymatrine and oxysophocarpine) were separated within 15 min. The running buffer was a 50 mM phosphate buffer containing 1%HP-β-CD and 3.3% isopropanol. The linear calibration ranges were 5.50-88.0 μg ml⁻¹ for cytisine and lehmannine, 5.00-88.0 μg ml⁻¹ for sophocarpine and sophoranol, 5.60-89.6 μg ml⁻¹ for matrine and oxysophocarpine, and 24.0-384 μg ml⁻¹ for oxymatrine. The recoveries of the seven alkaloids were 96.0-102.9% with relative standard deviations from 1.50 to 3.00% (n = 5). The method was successfully applied to different Sophora medicinal plants including Sophora flavescens, Sophora tonkinensis and Sophora alopecuroides.     

Polyfluorinated arylnitrosamines

N-Methyl-, N-n-butyl-, N-t-butylperfluoroarylamines undergo nitrosation with nitrous acid to give the corresponding N-nitroso derivatives. Perfluoroaryl groups were selected from the benzene, indane, biphenyl, naphthalene and pyridine series. According to ¹H and ¹⁹F NMR spectra, N-nitroso-N-methyl derivatives of polyfluoroarenes consist of E and Z isomers with the former prevailing. The more bulky n-butyl group promotes an increase in the formation of Z isomers. Only Z isomers have been obtained from N-t-butyl derivatives of perfluorinated 4-toluidine and 4-aminopyridine. The structure of the Z isomer of N-nitroso-N-methylperfluoro-4-toluidine is confirmed by X-ray data.     

Zwitterionic hydrophilic interaction chromatography coupled with post-column derivatization for the analysis of glutathione in wine samples

In this study the development, validation and application of a new chromatographic method for the determination of glutathione (GSH) in wine samples is presented. The separation of the GSH was carried out using a sulfobetaine-based hydrophilic interaction chromatography (HILIC) analytical column whereas its detection was carried out spectrofluorimetrically (λ_ext/λ_em = 340/455 nm) after post-column derivatization with o-phthalaldehyde. GSH was separated efficiently from matrix endogenous compounds of wines by using a mobile phase of 15 mmol L⁻¹ CH₃COONH₄ (pH = 2.5)/CH₃CN, 35/65% (v/v). The parameters of the post-column reaction (pH, amount concentration of the reagent and buffer solution, flow rate, length of the reaction coil) were investigated. The linear determination range for GSH was 0.25–5.0 μmol L⁻¹ and the LOD was 19 nmol L⁻¹. No matrix effect was observed, while the accuracy was evaluated with recovery experiments and was ranged between 89% and 108%.     

New soluble aromatic polyamides containing ether linkages and laterally attached p-terphenyls

Two series of new polyamides containing flexible ether linkages and laterally attached side rods (3a-i and 4a-i) were synthesized from 2^′,5^′-bis(4-aminophenoxy)-[1,1^′;4^′,1^″]terphenyl (1a) and 2^′,5^′-bis(4-amino-2-trifluoromethylphenoxy)-[1,1^′;4^′,1^″]terphenyl (1b), respectively, with various aromatic dicarboxylic acids by the direct phosphorylation polycondensation. The polymers were produced with high yields and moderate to high inherent viscosities (0.41-0.97 dl/g) that corresponded to weight-average molecular weights (by size exclusion chromatography) of 47,000-65,000. Except for some polyamides that derived from rigid diacids, the obtained polyamides were readily soluble in aprotic polar solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc), and could afford flexible and tough films via solvent casting. The polymer films cast from DMAc solutions possessed tensile strengths of 85-106 MPa and initial moduli of 1.82-2.96 GPa. These polyamides showed glass-transition temperatures (T_g) in the range of 206-263 °C (by DSC) and softening temperatures (T_s) in the range of 211-253 °C (by TMA). Decomposition temperatures (T_d) for 10% weight loss all occurred above 400 °C (by TGA) in both nitrogen and air atmospheres. The polyamides 4a-i derived from trifluoromethyl-substituted diamine 1b generally showed a higher solubility, T_g and T_s but lower thermal stability as compared to the analogous polyamides 3a-i based on diamine 1a.     

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.     

Photoluminescent behavior of SrB4O7:RE (RE=Sm and Eu) prepared by Pechini, combustion and ceramic methods

This work reports the preparation of system containing RE²⁺ ions (RE=Sm and Eu)-doped in SrB₄O₇ matrix by ceramic, Pechini and combustion methods. These compounds were prepared by reduction of RE³⁺ to RE²⁺ in air, which exhibit some different features according to the preparation method. Photoluminescent properties of these systems were investigated based on the emission and excitation spectral data. The emission spectra of SrB₄O₇:Eu²⁺ system prepared by combustion and Pechini methods are characterized by a broad band assigned to interconfigurational 4f⁶5d→4f⁷ transition, while SrB₄O₇:Sm²⁺ compound exhibit narrow emission bands arising from intraconfigurational-4f⁶ also shows ⁴G_5/2→⁶H_J′ transitions ( and ) arising from Sm³⁺ ion, transitions. SrB₄O₇:RE system prepared by combustion method presents emission bands from RE³⁺ ions as intense as that arising from RE²⁺, suggesting that the preparation route is not efficient for the reduction RE³⁺→RE²⁺ process. Emission quantum efficiency and radiative emission rates of Sm²⁺ ion are determined and discussed.     

New polyhydroxy sterols from the marine sponge Callyspongia fibrosa (Ridley & Dendly)

Four new polyhydroxylated sterols are isolated from Marine sponge Callyspongia fibrosa collected from the Gulf of Mannar, western Bay of Bengal (India). The structural assignment is based on ¹H and ¹³C NMR spectra. All sterols are based on the known 24S-24-methyl cholesterol 1 which is also isolated, and contain 3β,6β-dihydroxy system and 25-O-acetate as common features (except in the case of sterol 6 that has a Δ²⁵ in the place of 25-OAc). Additional OH substitution is also present at 5α in 4a and at 8β in 5. A further 12β-OH is present in 6 and 7. The hydroxylation pattern is so far known only in coral sterols but is without a precedent in sponge sterols. The major steroid 4a showed antimalarial activity against Plasmodium falciparum on the chloroquine-resistant stain better than on the chloroquine-sensitive strain.     

New cytotoxic halogenated sesquiterpenes from the Egyptian sea hare, Aplysia oculifera

Two new sesquiterpenes, oculiferane (1) and epi-obtusane (2) have been isolated and identified from an acetone extract of the digestive gland of the sea hare, Aplysia oculifera. The structures were elucidated by spectroscopic analysis including HREIMS, ¹H, ¹³C, DEPT, ¹H–¹H COSY, HMQC, and HMBC NMR; the relative configuration was confirmed by X-ray analysis. Compounds 1 and 2 exhibited cytotoxic activity in vitro against several human cancer cell lines with IC₅₀ values in the low μg/ml range.