13C NMR Calculations Research Articles

Chlorinated Cyclopentene Derivatives and Antifungal Activities from Periconia sp. Induced by the One Strain Many Compounds Strategy and Host Plant Culture.

Eleven new chlorinated cyclopentene derivatives, periconsins A-K, and a new diketopiperazine, periconzin, were found from Periconia sp. cultured in three different media by the one strain many compounds strategy. Additionally, the C-1 methyl hydroxylation of chlorinated cyclopentene was found for the first time in the host plant culture. The structures were identified by extensive spectroscopic analyses, electronic circular dichroism (ECD) and 13C NMR calculations, and single-crystal X-ray diffraction. Compounds 3, 5, 7-11, 15, and 17 showed significant antifungal activities against the plant pathogens Periconia sp., Altemaria sp., and Nigrospora oryzae with MICs ≤2 μg/mL. Other compounds had antifungal activities with MICs ≤8 μg/mL. The antifungal structure-activity relationship of these metabolites indicated that the chlorine at C-5 can increase the activity, but the hydroxy group at C-1 lowered the activity.

Reassignment of the structures of pestalopyrones A–D

Pestalopyrones A–D are four unusual tricyclic pyrone derivatives with flexible chiral structures, isolated from the endophytic fungus Pestalotiopsis neglecta S3. The full elucidation of their structures was a challenging task, and remained unsolved in the original article. Herein, the relative configurations of pestalopyrones A and pestalopyrones B were unambiguously assigned by detailed analyses on spectroscopic data and GIAO 13C NMR calculation method with sorted training sets (STS). The planar structures of pestalopyrones C and pestalopyrones D were revised by reinterpretation of their reported spectroscopic data, and then their relative configurations were deduced by STS GIAO 13C NMR calculation and NOE analysis. The absolute configurations of all the mentioned compounds were determined by the comparison of their experimental and calculated ECD curves.

Kiiacylphnols A−H, eight undescribed polycyclic polyprenylated acylphloroglucinols with anticancer activities from Hypericum przewalskii Maxim

Kiiacylphnols A−H, eight previously undescribed polycyclic polyprenylated acylphloroglucinols (PPAPs), along with two known congeners (hyperforcinol F and oxepahyperforin), were obtained from Hypericum przewalskii Maxim. The structures of these metabolites were confirmed by spectroscopic analyses, quantum-chemical 1H and 13C NMR calculations with DP4+ analyses, electronic circular dichroism (ECD) comparisons and calculations. Kiiacylphnols A and B were the first [3.3.1]-type PPAPs with an unusual octahydrooxireno[2,3-i]chromene scaffold bearing a rare 6/6/6/3 ring system. More significantly, kiiacylphnol A and oxepahyperforin displayed cytotoxicity against acute myeloid leukemia and diffuse large B-cell lymphoma cell lines by inducing cell apoptosis.

Chemical structure characteristics and multidimensional model construction of Fushun oil shale kerogen: An experimental and simulation study

Solid state 13C nuclear magnetic resonance (13C NMR), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) were carried out to characterize the chemical structure characteristics and to establish the average molecular structure of kerogen extracted from Fushun oil shale. NMR predictor was used to calculate the chemical shift of carbon atoms to verify the rationality of the constructed model. And the stability of 3D model was studied by molecular dynamics (MD) simulations. 13C NMR results demonstrate that Fushun kerogen consists of 76.98% of aliphatic structure dominated by long linear methylene and 21.6% of aromatic structure (mainly protonated aromatic carbon). Functional groups observed in 13C NMR spectra were also detected in FT-IR spectra at wavenumber range of 1800-1000 cm−1. XPS analysis indicates that nitrogen-containing groups were pyrrole, pyridine and primary amines, and sulfur existed as sulfoxides, thiophenes and mercaptans. By comparing the calculated 13C NMR and experimental 13C NMR, it was found that the aromatic structure condensed in two aromatic rings and the aliphatic structure without alicyclic and epoxy ether were more rational for the chemical structure model of Fushun kerogen. A new method to evaluate the average methylene chain length was proposed. Finally, a relatively rational 2D molecular structure with a molecular formula of C228H350O10N6S3 was constructed. The most stable 3D periodic structure (20 optimized molecules, 48.44 × 49.63 × 50.28 Å3) with the lowest total potential energy was obtained by MD simulation and density of it was 0.943 g/cm3.

A Dual Approach on Experimental, Theoretical Insight of Structural Elucidation, Hirshfeld Surface Analysis, Optical and Electrochemical Properties of Acyl Thiourea-Ethynyl Hybrid Derivatives.

Hybrid moieties of ethynylated-thiourea, Th1 and Th2 have been synthesised via the addition reaction between ethynyl derivatives and 4-tert-butylbenzoyl isothiocyanate in acetone, and were characterised by selected spectroscopic methods (i.e., 1H and 13C NMR, UV–visible, FT-IR) and elemental analysis. Thermogravimetric analysis indicated that Th1 and Th2 were relatively stable up to ca. 210 °C. Single-crystal X-ray diffraction was used to identify the crystal structure of Th2 in which the centre of 1-acyl thiourea moiety (-C(O)NHC(S)NH) exhibits S conformation. The Hirshfeld surface analysis has allowed visualizing the crystal packing, which is characterised by the prolonged intermolecular N–H⋯O = C and N–H⋯S = C hydrogen-bonding interactions within Th2 molecule. Electrochemical data of both compounds correspondingly exhibit irreversible redox potential processes. Besides, frontier molecular orbitals and Natural Bond Orbital population analysis were computed at the B3LYP/6-31G (d, p) level of approximation, suggesting strong delocalization of the electronic density through a conjugated π-system involving the ethynyl-phenyl and thiourea groups.Graphical Figure of molecular structure for acyl thiourea-ethynyl derivative. Two derivatives of acyl thiourea-ethynyl were synthesised and characterised by selected spectroscopic methods such as 1H and 13C NMR, UV-visible, FT-IR, elemental, thermal, electrochemical, X-ray diffraction, and density functional theory (DFT) calculation for molecular orbitals and natural bond orbital population analysis.

Oligomer-first mechanism in the transformation of biomass derivatives selectively to produce D-lactic acid

Enhancing carbon utilization in biomass conversion makes a big challenge on sustainability. Herein, a novel catalytic system, MgO-D-lactic acid (D-LaA) was adopted, and a new “oligomer-first mechanism” was discovered for xylose transformation to a mixture very rich in D-LaA in a unique way. Supported by 13C NMR and DFT calculation, it was discovered that xylose oligomerized to C10/C15 through coupling of C–C bond via aldol condensation catalyzed by MgO species. The resultant oligomers were further split into C3 intermediates via selective C–C cleavage by Mg(OH)(H2O)3+ catalytic species. Besides, MgO-D-LaA catalytic system could also enable the reutilization of C2 by-product, glycolaldehyde, which was oligomerized to C4/C6 and further contributed to LaA production. These two factors synergistically made a significant breakthrough on carbon utilization for hemicellulose valorization, enabling the outstanding LaA yield up to 70.2 C-mol% with 73.1% ee value for D-LaA. The proposed oligomer mechanism comprehensively explained the origin of “excess” LaA yield beyond 60% via the conventional “3 + 2” pathway. This work made a significant breakthrough for the improvement of carbon utilization in xylose transformation to LaA, and allowed for the sufficient use of carbon atoms in xylose.

Oblongolides from endophytic fungus Phoma bellidis Neerg. harbored in Tricyrtis maculata (D. Don) J.F.Macbr.

Five previously undescribed oblongolides, namely phomaones A-E, along with four known compounds, were isolated from the endophytic fungus Phoma bellidis Neerg.. Their structures and absolute configurations were determined by extensive experimental spectroscopic methods as well as single crystal X-ray diffractions, ECD calculations and GIAO 13C NMR calculations. Phomaone A represent the first example of oblongolides with glycol directly linked by two C–C bonds, and its biosynthetic pathway were proposed. The cytotoxicity of obtained compounds was evaluated against human cancer cell lines MCF-7, DU145, and SW480. All compounds except phomaone A showed the cytotoxicity against MCF-7 with IC50 value ranging from 12.45 to 49.84 μM.

Immunosuppressive Isopimarane Diterpenes From Cultures of the Endophytic Fungus Ilyonectria robusta.

Five new isopimarane diterpenes, robustaditerpene A-E (1–5), which include 19-nor-isopimarane skeleton and isopimarane skeleton, were isolated from the liquid fermentation of the endophytic fungus Ilyonectria robusta collected from Bletilla striata. The structure elucidation and relative configuration assignments of all compounds were accomplished by interpretation of NMR and HRESIMS spectrometric analyses and 13C NMR calculation. And the absolute configuration of 1-5 were identified by single-crystal X-ray diffraction and ECD calculation. Compound 3 inhibited lipopolysaccharide-induced B lymphocytes cell proliferation with an IC50 value at 17.42 ± 1.57 μM while compound 5 inhibited concanavalin A-induced T lymphocytes cell proliferation with an IC50 value at 75.22 ± 6.10 μM. These data suggested that compounds 3 and 5 may possess potential immunosuppressive prospect.

Concise total syntheses of two flavans and structure revision assisted by quantum NMR calculations.

A two-step protecting-group-free protocol for the synthesis of 3'-hydroxy-5,7-dimethoxy-4-O-2'-cycloflavan (1) and concise total synthesis of 4'-hydroxy-5,7-dimethoxy-4-O-2'-cycloflavan (8) enabled by a PTSA triggered bioinspired olefin isomerization/hemiacetalization/dehydration/[3 + 3]-type cycloaddition cascade reaction are reported. The successful synthesis of cycloflavan 8 along with GIAO 13C NMR calculations of flavan-4-ol 9 and cycloflavan 8 indicated the misassignment of the flavonoid isolated previously and realized the revision of its actual structure.

Sesquiterpenoids and Xanthones from the Kiwifruit-Associated Fungus Bipolaris sp. and Their Anti-Pathogenic Microorganism Activity.

Nine previously undescribed sesquiterpenoids, bipolarisorokins A–I (1–9); two new xanthones, bipolarithones A and B (10 and 11); two novel sativene-xanthone adducts, bipolarithones C and D (12 and 13); as well as five known compounds (14–18) were characterized from the kiwifruit-associated fungus Bipolaris sp. Their structures were elucidated by extensive spectroscopic methods, electronic circular dichroism (ECD), 13C NMR calculations, DP4+ probability analyses, and single crystal X-ray diffractions. Many compounds exhibited anti-pathogenic microorganism activity against the bacterium Pseudomonas syringae pv. actinidiae and four pathogenic microorganisms.

Hexahydroazulene-2(1H)-one Sesquiterpenoids with Bridged Cyclobutane, Oxetane, and Tetrahydrofuran Rings from the Stems of Daphne papyracea with α-Glycosidase Inhibitory Activity.

Chemical investigation of an alcoholic extract from the stem of Daphne papyracea ("Xuehuagou") led to the isolation of the tetracyclic sesquiterpenoid daphnepapytone A (1), containing a unique caged skeleton with a cyclobutane ring having three tetrasubstituted chirality centers. Also isolated were new guaiane sesquiterpenoids, namely, daphnepapytones B-H (2-8), and one 1,5-diphenylpentanone 2-hydroxy-5-oxo-daphneone (9), together with 26 known compounds. The cyclic metabolites share a 5-isoprenyl-hexahydroazulene-2(1H)-one skeleton with different substitution patterns and a bridged cyclobutane, oxetane, or tetrahydrofuran ring. The planar structures and relative configuration of the new compounds were elucidated on the basis of spectroscopic analysis aided by DFT 13C NMR calculations. The absolute configurations of 1-7 were determined by X-ray single-crystal diffraction or TDDFT-ECD calculations. Daphnepapytones A and C (1 and 3), 2-hydroxy-5-oxodaphneone (9), daphnenone (10), daphneone (11), and 3-methyldaphneolone (12) showed α-glycosidase inhibitory activity, with IC50 values of 159.0, 102.3, 139.3, 43.3, 145.0, and 126.1 μM, respectively.

Spectroscopic, Thermal, Microbiological, and Antioxidant Study of Alkali Metal 2-Hydroxyphenylacetates.

The structural, spectral, thermal, and biological properties of hydroxyphenylacetic acid and lithium, sodium, potassium, rubidium, and cesium 2-hydroxyphenylacetates were analyzed by means of infrared spectroscopy FT-IR, electronic absorption spectroscopy UV-VIS, nuclear magnetic resonance 1H and 13C NMR, thermogravimetric analysis (TG/DSC), and quantum-chemical calculations at B3LYP/6-311++G** level. Moreover, the antioxidant (ABTS, FRAP, and CUPRAC assays), antibacterial (against E. coli, K. aerogenes, P. fluorescens, and B. subtilis) and antifungal (against C. albicans) properties of studied compounds were measured. The effect of alkali metal ions on the structure, thermal, and biological properties of 2-hydroxyphenylacetates was discussed.

Triterpenoids From Kadsura coccinea With Their Anti-inflammatory and Inhibited Proliferation of Rheumatoid Arthritis-Fibroblastoid Synovial Cells Activities.

One new 3,4-seco-17,13-friedo-lanostane triterpenoid heilaohuacid A (1), one new 3,4-seco-17,14-friedo-lanostane triterpenoid heilaohuacid B (2), five new 3,4-seco-lanostane triterpenoids heilaohuacids C-D (3–4) and heilaohumethylesters A-C (7–9), one new 3,4-seco-cycloartane triterpenoid heilaohuacid E (5), and one new intact-lanostane triterpenoid heilaohuacid F (6), together with twenty-two known analogues (10–31), were isolated from heilaohu. Their structures were determined using HR-ESI-MS data, 1D and 2D NMR spectra, 13C NMR calculations, and electronic circular dichroism (ECD) calculations. Heilaohuacids A and B (1 and 2) contain a 3,4-seco ring A and unprecedented migration of Me-18 from C-13 to C-17 or C-14 to C-18. This type of lanostane triterpenoid derivatives was rarely reported so far. More importantly, all compounds against inflammatory cytokines IL-6 and TNF-α levels on LPS-induced RAW 264.7 macrophages were evaluated, and compounds 4 and 31 significantly inhibited the release level of IL-6 with IC50 values of 8.15 and 9.86 μM, respectively. Meanwhile, compounds 17, 18, and 31 significantly inhibited proliferation of rheumatoid arthritis-fibroblastoid synovial (RA-FLS) cells in vitro with IC50 values of 7.52, 8.85, and 7.97 μM, respectively.

Isolation, absolute configurations and bioactivities of pestaphilones A–I: Undescribed methylated side chain containing-azaphilones from Pestalotiopsis oxyanthi

Nine undescribed side chain containing azaphilones, pestaphilones A–I, were isolated from the Anoectochilus roxburghii endophytic fungus Pestalotiopsis oxyanthi. The structures of these isolates were identified by spectroscopic data, electronic circular dichroism (ECD) calculations and comparisons, quantum-chemical 13C NMR calculations with DP4+ probability analysis, Rh2(OCOCF3)4-induced ECD, acetonide formation, selective oxidation reaction and X-ray crystallographic data. Structurally, pestaphilones A–I were the first azaphilones characteristically formed via a methyl group at C-9 in the C7 side chain. More importantly, a selective oxidation reaction was firstly set up to resolve the absolute configuration of flexible side chain containing azaphilones, and an acetonide formation based Rh2(OCOCF3)4-induced ECD experiment was performed to identify the configurations of the oxygenated pyranoquinone core in the azaphilones. In bioassay, pestaphilones A–F displayed potential immunosuppressive activity in concanavalin A (Con A)-induced T lymphocyte proliferation, with IC50 values ranging from (9.36 ± 1.14) μM to (35.21 ± 3.25) μM.

Synthesis and optical properties of a fluorene-benzothiadiazole anthracene copolymer

A novel green-emitting terpolymer of Poly[2,7-(9,9-dihexylfluorene)-co-4,7-(2,1,3-benzothiadiazole)-co-9,10-(anthracene)] (PFABT), containing 9,9-dihexylfluorene and anthracene as electron-pushing unit and benzothiadiazole as electron-pulling unit, was synthesized via Suzuki coupling reaction. Poly[2,7-(9,9-dihexylfluorene)-co-9,10-(anthracene)] (PFA) and Poly[2,7-(9,9-dihexylfluorene)-co-4,7-(2,1,3-benzothiadiazole)] (PFBT) copolymers were also synthesized for comparative purposes. These copolymers were characterized by GPC, FTIR and 13C NMR and computational calculations were performed using density functional theory (DFT) and its time-dependent version (TDDFT) at CAM-B3LYP/6–311 +G(d,p) level. Natural transition orbitals (NTO) and vertical excitation energies were obtained from oligomer models that represent the PFA, PFBT and PFABT polymers. The NTO densities showed that the excitation of the anthracene moiety is responsible for the S1 state on both PFA and PFABT, and that the S2 state of PFBT and PFABT is a consequence of the excitation of the benzothiadiazole-anthracene moiety. We also studied polymer light-emitting diodes (PLEDs) of blends of poly(9-vinylcarbazole) (PVK) as a host matrix with PFA, PFBT or PFABT as guests. The concentrations of the copolymers in the PVK were varied at 5, 25 and 50 wt%. The PL spectra for all blends exhibited one band at 400 nm attributed to PVK and another centered at 535 nm assigned to the PFO derivatives emission. We observed an increase in energy transfer efficiency, E < FRET> , with an increase in the weight ratio of the copolymer (PFA, PFBT or PFABT) into the PVK matrix. All the PLEDs emitted a greenish color, and the concentration of the polymer guest impacted on the performance of the diode.

Peniazaphilones A—I, Produced by Co‐culturing of Mangrove Endophytic Fungi, Penicillium sclerotiorumTHSH‐4 and Penicillium sclerotiorumZJHJJ‐18

Main observation and conclusionCo‐culturing the mangrove endophytic fungus Penicillium sclerotiorum THSH‐4 with Penicillium sclerotiorum ZJHJJ‐18 in PDB medium resulted in the production of nine new azaphilones derivatives, peniazaphilones A—I (1—9), and six known azaphilones derivatives (10—15). Their structures were elucidated by analysis of detailed spectroscopic data, single‐crystal X‐ray diffraction, ECD spectra, 13C NMR calculation and DP4+ analysis. It is noteworthy that compound 1 with an isoquinoline quinone moiety, was isolated from natural source for the first time. Besides, compound 2 is the third reported phenylhydrazone derivative from fungi. In the bioactivity assays, compounds 1, 12, 14 and 15 (IC50 = 4.71—17.64 μmol/L) exhibited potent inhibition of LPS‐induced NO release from RAW264.7 without obvious cytotoxicity within 50 μmol/L compared to the positive control indomethacin (IC50 = 35.27 μmol/L). Moreover, compounds 1 and 13 displayed moderate to strong cytotoxicity to A549 and MDA‐MB‐435, with IC50 values in the range of 6.84—14.63 μmol/L. Together compound 1 showed moderate broad‐spectrum antibacterial activity.

Alkaloids From the Marine Fungus Lecanicillium fusisporum Using an Amino Acid-Directed Strategy

An amino acid-directed strategy has been developed to explore the potential of marine fungi to produce alkaloids. The marine fungus Lecanicillium fusisporum was cultured in glucose-peptone-yeast (GPY) medium to which were added L-tryptophan, L-phenylalanine, L-threonine, D, L-methionine, L-serine, L-lysine and L-valine. A new indole alkaloid, lecasporinoid (1), along with five known alkaloids (2−6) were discovered from the culture broth. The planar structure of lecasporinoid (1) was determined by HR-ESIMS, and 1D and 2D NMR spectroscopic data. The absolute configuration was established by optical rotation and 13C NMR calculations combining with a chemical synthetic approach.

Structurally Diverse Polycyclic Salicylaldehyde Derivative Enantiomers from a Marine-Derived Fungus Eurotium sp. SCSIO F452.

To enlarge the chemical diversity of Eurotium sp. SCSIO F452, a talented marine-derived fungus, we further investigated its chemical constituents from a large-scale fermentation with modified culture. Four pairs of new salicylaldehyde derivative enantiomers, euroticins F-I (1–4), as well as a known one eurotirumin (5) were isolated and characterized. Compound 1 features an unprecedented constructed 6/6/6/5 tetracyclic structures, while 2 and 3 represent two new types of 6/6/5 scaffolds. Their structures were established by comprehensive spectroscopic analyses, X-ray diffraction, 13C NMR, and electronic circular dichroism calculations. Selected compounds showed significant inhibitory activity against α-glucosidase and moderate cytotoxic activities against SF-268, MCF-7, HepG2, and A549 cell lines.

Nitric oxide inhibitory terpenes and its glycosides from Ainsliaea bonatii

Seven new terpenes and its derivatives classified into a p-menthane glycoside (1), a guaianolide glycoside (2), three eudesmane and its glycosides (3–5), and two mono-terpene derivatives (9 and 10) were isolated from Ainsliaea bonatii, together with three known guaianolides (6–8). Their structures were elucidated by spectroscopic data analysis, and absolute configurations were determined by DP4+ probability analysis via calculated 13C NMR data of isomers. Compounds 6 and 9 showed nitric oxide (NO) inhibitory effects in LPS-induced RAW 264.7 macrophage cells with IC50 values of 9.3 and 10.6 μM, respectively.

Seleno-Functionalization of BODIPY Fluorophores Assisted by Oxidative Nucleophilic Hydrogen Substitution

Background: The most current reported methods of chalcogen insertion into BODIPY’s nuclei are based on nucleophilic substitution reactions of halogenated derivatives, metal-catalyzed cross-coupling reactions, or assistance by radical mechanisms. Recent reports describe Oxidative Nucleophilic Hydrogen Substitution (ONHS) reactions involving the functionalization of BODIPY nuclei by thiols, but the generalities of the strategy for other chalcogens was not yet demonstrated. Herein we report our contribution on the selenium-functionalization of BODIPY by ONHS in high yield. Objective: Aryl-Se-functionalization of 2,6-brominated BODIPY’s nuclei by ONHS reaction. Method: The procedure consists of a direct reaction of 2,6-brominated BODIPYs with in situ generated PhSeH in THF, at room temperature, under a nitrogen atmosphere. The corresponding products were isolated and purified by conventional flash column chromatography. Full structure characterization was performed by 1H, 13C, 19F, and 77Se NMR and DFT calculation. Results: Densely functionalized 2,6-dibrominated/3,5-diseleno-BODIPYs were obtained as corresponding products, leading to versatile molecular scaffolds. Their structural features were contrary to those initially expected by the original experimental applied conditions. A mechanistic investigation was performed to conclude that ONHS reaction is governing the transformation, thereby damaging the nucleophilic substitution of the halogen atoms. Conclusion: To sum up, new densely functionalized BODIPY derivatives were synthesized by a highly selective, simple, fast, metal-free, and efficient insertion of PhSe- residues into the 3,5-positions, governed by an Oxidative Nucleophilic Hydrogen Substitution (ONHS) reaction in high yields. It was observed that the presence of halogen (Br) into the 2,6-positions of the BODIPY core is mandatory for the ONHS reaction, which is completely inert when the 2,6-hydrogenated analogues are used in the same experimental conditions.