Synthesis,characterization, luminescence,antibacterial, and catalytic activities of a palladium(II) complex involving a Schiff base

A new Pd(II) complex of fluorine-containing Schiff base ligand, [Pd₂(L)₂Cl₂] (1) [L?=?N-(4-fluorobenzylidene)-2,6-diethylbenzenamine], has been synthesized using solvothermal method and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV–vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a μ-chloro-bridged dinuclear cyclometallated Pd(II) complex. Thermal analysis indicates that 1 is quite stable to heat. 1 exhibits quadruple emissions in the solid state (λ _max?=?766?nm) and possesses fluorescence lifetimes (τ ₁?=?87.20?ns, τ ₂?=?190.45?ns, and τ ₃?=?1805.10?ns at 616?nm); broad structureless bands at 690–800?nm are tentatively assigned to an excimeric ³IL transition. The Schiff base (L) and its palladium(II) compound (1) have been screened for their antibacterial activity against several bacteria, and the results are compared with the activity of penicillin. Moreover, 1 has been shown to be highly effective in the Heck reaction of 4-bromotoluene with acrylic acid.     

α-Keggin tungstogermanate-supported transition metal complexes: hydrothermal synthesis,characterization, and magnetism of Cu2(phen)4(GeW12O40) and [Ni2(bpy)4(H2O)2(GeW12O40)]⋅2H2O

Two new α-Keggin polyoxometalates, [Cu₂(phen)₄(GeW₁₂O₄₀)] (1) and [Ni₂(bpy)₄(H₂O)₂(GeW₁₂O₄₀)]·2H₂O (2) (phen?=?1,10-phenanthroline, bpy?=?2,2′-bipyridine), have been hydrothermally synthesized and characterized by elemental analysis, IR, TG, single-crystal X-ray diffraction, and magnetic properties. Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, and 1 is assembled into two-dimensional (2-D) layers parallel to (1?0?1) based on the adjacent phen π···π stacking interactions (3.788(8)?Å). Variable temperature magnetic measurements show ferromagnetic behavior from 300 to 2?K. Compound 2 crystallizes in the triclinic system, space group P-1, and 2 is assembled into 2-D layers parallel to (1?0?1) based on the adjacent bpy π···π stacking interactions (3.07?Å). Variable temperature magnetic measurements show a weak ferromagnetic behavior from 300 to 26?K followed by antiferromagnetic behavior below 26?K.     

Construction of Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-1H-benzimidazole and 1,4-benzenedicarboxylate

Three new Cd(II) complexes incorporating both 2-(1H-imidazol-1-methyl)-1H-benzimidazole (imb) and 1,4-benzenedicarboxylate (bdic^2?), [CdCl(bdic)_1/2(imb)₂]_n (1), {[Cd(bdic)(imb)(H₂O)]·DMF·2H₂O}_n (2), and [Cd(bdic)(imb)]·3H₂O}_n (3), have been prepared and structurally characterized by single crystal X-ray diffraction. Bdic^2? anions connect the?Cd-imb-Cd-imb?chains leading to a 2-D structure of 1. Bdic^2?(A) and bdic^2?(B) anions link the binuclear [Cd₂(imb)₂(H₂O)₂] units forming a 2-D structure of 2. Complex 3 features a 2-D structure involving supramolecular “double-layer” motifs. IR spectra and thermogravimetric curves are consistent with the results of the X-ray crystal structure analysis; 1–3 exhibit good fluorescence in the solid state at room temperature.     

Two new triterpenoids from the fungus Diplodia cupressi

Abstract

One new pentanortriterpenoid, 23,24,25,26,27-pentanorlanost-7,9(11)-dien-3β,22-diol (1), one new triterpenoid, lanost-8-en-3β,22S,23S-triol (2), together with the known triterpenoid, 23,24,25,26,27-pentanorlanost-8-en-3β,22-diol (3), were obtained from culture of the fungus Diplodia cupressi associated with the moss Polytrichum commune. The structures of the new compounds were elucidated by extensive spectroscopic techniques including HR-ESIMS and 1?D and 2?D NMR experiments. The cytotoxicity of these compounds against human cancer cell lines (A549, Hep G2, Hepa 1c1c7, and Hela) was evaluated and compound 2 exhibited weak inhibitory activity with IC₅₀ value of 35.0?±?2.3?μM against the proliferation of the Hepa 1c1c7 cells.     

Copper(II) complexes of 2-amino-5-chloro-3-fluoropyridine: syntheses and magnetic properties of (3,5-FCAP)2CuX2 and (3,5-FCAPH)2CuX4

Using 2-amino-5-chloro-3-fluoropyridine, two new copper halide coordination complexes and two new salts have been synthesized: [(3,5-FCAP)₂CuCl₂] (1), [(3,5-FCAP)₂CuBr₂](2), (3,5-FCAPH)₂[CuCl₄] (3) and (3,5-FCAPH)₂[CuBr₄] (4) [3,5-FCAP?=?2-amino-5-chloro-3-fluoropyridine; 3,5-FCAPH?=?2-amino-5-chloro-3-fluoropyridinium]. These complexes have been analyzed through single-crystal X-ray diffraction and temperature-dependent magnetic susceptibility. Compounds 1 and 2 crystallize in the triclinic space group P-1, while 3 and 4 crystallize in the monoclinic space group P2₁/c. All structures were distinct, with 1 giving a bihalide bridged chain, 2 yielding a halide bridged dimer, 3 forming a two-halide bridged chain via short Cl???Cl contacts, and 4 producing a rectangular sheet via short Br???Br contacts. All four compounds exhibit anti-ferromagnetic interactions and were fit to linear chain (1 and 3), dimer (2), and rectangular 2-D sheet (4) models. The resulting J/k_B values are ?3.4(1), ?31.3(8), ?0.9(1), and ?9.46(6)?K with an α value (α?=?J?/J) of 0.06(2), respectively.     

Synthesis,characterization, and antibacterial activity of organotin(IV) complexes with 2-hydroxyacetophenone thiocarbohydrazone

Six new organotin(IV) complexes were synthesized by direct reaction of RSnCl₃ (R?=?Me, Bu and Ph) or R₂SnCl₂ (R?=?Me, Bu and Ph) and 2-hydroxyacetophenone thiocarbohydrazone [H₂APTC] under purified nitrogen in the presence of base in 1?:?2?:?1 molar ratio (metal: base: ligand). Complexes 2–7 have been characterized by elemental analyses, molar conductivity, UV-Visible, IR and ¹H NMR spectral studies. Complexes 2–7 are non-electrolytes. The molecular structure of [Me₂Sn(APTC)]?·?(C₂H₅OH) (5) has been determined by X-ray diffraction analysis. The thiocarbohydrazone ligand (1) and 2–7 have been tested for antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi and Enterococci aeruginosa.     

A vic -dioxime ligand bearing fluorescent coumarin moieties and its complexes; preparation,spectroscopy, and electrochemistry

The synthesis of a new vic-dioxime ligand, N,N′²-dihydroxy-O ¹,O ²-bis(4-methyl-2-oxo-2H-chromen-7-yl)oxalimidamid (LH₂) (1), bearing functional coumarins and its soluble mono- {Ni(II), Cu(II), Co(II)} and dinuclear {UO₂(II)} complexes are presented. The fluorescence properties due to the 7-hydroxy-4-methylcoumarin fluorophore, which is conjugated with vic-dioxime that functions as the MN₄ core of 1 and its complexes, are also reported. The formation of coordination complexes resulted in the blue shift in excitation spectrum and fluorescence quenching of 1. Both mononuclear {(LH)₂M, M=Ni(II), Cu(II), and Co(II)} and homodinuclear {(LH)₂(UO₂)₂(OH)₂)} complexes have been obtained with metal?:?ligand ratios of 1?:?2 and 2?:?2, respectively. The characterizations of the new compounds were made by elemental analysis, ¹H-NMR, FT-IR, UV-Vis, and LCMS data. Redox behavior of 1, involving oxime and coumarin moieties, and its complexes with Ni(II), Cu(II), Co(II) and UO₂(II) were investigated by cyclic voltammetry. The comparison of the electrochemical behavior of 1 with its complexes enabled us to identify metal-, oxime- and coumarin-based signals.     

Dinuclear Zn(II) and Hg(II) complexes of an angular dipyridyl ligand: syntheses,crystal structures,and properties

The angular polytopic dipyridyl ligand 2,6-bis(quinoline-2-carboxamido)pyridine (H₂L) was prepared. Assemblies of H₂L with ZnAc₂ and HgAc₂ resulted in two new dinuclear complexes [Zn₂(L)(Ac)₂]?·?1.5H₂O?·?0.5CH₃OH (1) and [Hg₂(L)(Ac)₂]?·?5H₂O?·?CH₃OH (2) where the doubly deprotonated L^2? bi-chelate as μ-kN,N′?:?kN″,N″′, bridging the two metal centers (Ac?=?acetate). In 1, the two Zn(II) ions are also doubly bridged by two Ac ions in a μ-kO?:?kO′ coordination, and thus each metal center adopts a distorted tetrahedral geometry. In 2, each Ac ion is only terminal to Hg(II), in a rare distorted triangular or T-shaped coordination geometry. Free H₂L, 1, and 2 emit interesting bluish-green fluorescence with strong intensities. Thermogravimetric analysis of 1 shows that the dinuclear structure of 1 is stable to 382°C.     

Structures,luminescence, and antibacterial studies of two transition metal complexes involving Schiff bases

Two new transition metal complexes of Schiff bases, [Pd₂(L1)₂Cl₂] (1) and [Zn(L2)₂] (2), [L1?=?N-(4-fluorobenzylidene)-2,6-diisopropylbenzenamine and L2?=?2,4-dibromo-6-((E)(mesitylimino)methyl)phenol], have been synthesized solvothermally and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, UV-vis absorption spectra, and single-crystal X-ray diffraction. Complex 1 is a μ-chloro-bridged dinuclear cyclometallated Pd(II) complex, whereas 2 is mononuclear with the Zn^II tetrahedrally coordinated by two L2. Both 1 and 2 display photoluminescence in the solid state at 298?K (fluorescence lifetimes τ?=?22.516?ns at 468?nm for 1, τ?=?3.697?μs at 490?nm for 2). These Schiff bases and their metal compounds have been screened for antibacterial activity against several bacteria, and the results are compared with the activity of penicillin.     

A new diterpenoid alkaloid from Aconitum hemsleyanum

Abstract

A new C₁₉-diterpenoid alkaloid named hemsleyaline (1), along with fourteen known alkaloids (2-15), were isolated from the roots of Aconitum hemsleyanum Pritz. (Ranunculaceae), a herbal medicine in southwest China. Their structures were established on the basis of extensive spectroscopic analyses. Compound 1 showed mild cholinesterase inhibitory effect with IC₅₀ value of 471?±?9?μM.     

1-D Chain lanthanide coordination polymers based on mixed 2,4-dichlorophenoxyacetate and 1,10-phenanthroline ligands: crystal structures and luminescent properties

Two new isostructural 1-D lanthanide coordination polymers, {[Ln(2,4-dcp)₃(phen)] _n [(Ln?=?Eu (1); Tb (2)], [2,4-dcp?=?2,4-dichlorophenoxyacetate, phen?=?1,10-phenanthroline], were obtained under hydrothermal conditions and characterized by IR spectroscopy, elemental analyses, thermogravimetry analyses, powder X-ray diffraction, and single-crystal X-ray diffraction. Both structures exhibit similar 1-D infinite chains with a {Ln₂(2,4-dcp)₆(phen)₂} dimeric repeat unit, with lanthanides in an eight-coordinate environment. The results of thermal analysis indicate that 1 and 2 are quite stable to heat. 3-D fluorescence spectra of 1 and 2 were detected at room temperature under excitation and the emission wavelengths of 250–460?nm and 420–750?nm with the same interval of 5?nm, respectively. Interestingly, 1 and 2 possess longer fluorescence lifetimes than other complexes (τ?=?1.61?ms for 1 at 611?nm; 1.79?ms for 2 at 543?nm).     

Chemical constituents and cytotoxic activity from the wood-decaying fungus Xylaria sp. SWUF08-37

Abstract

A new cyclic pentapeptide, pentaminolarin (1), and a new cytochalasin, xylochalasin (2), along with thirteen known compounds (3–15) were isolated from the wood-decaying fungus Xylaria sp. SWUF08-37. The absolute configurations of 1 were determined by a combination of Marfey’s method and TDDFT ECD calculation and the absolute configurations of 2 were established by TDDFT ECD calculation. Compound 12 showed moderate cytotoxicity against HeLa (IC₅₀?=?19.60?µg/mL), HT29 (IC₅₀?=?17.31?µg/mL), HCT116 (IC₅₀?=?14.28?µg/mL), MCF-7 (IC₅₀?=?15.38?µg/mL), and Vero (IC₅₀?=?24.97?µg/mL) cell lines by MTT assay. Compounds 1 and 2 showed slight cytotoxicity against all tested cancer cell lines.     

Synthesis,structure, and biological evaluation of three Cu(II) and Ni(II) (E)-3-(3,4-dimethoxyphenyl)acrylate complexes with organic diamines as potential urease inhibitors

Three new complexes (1–3) have been synthesized and characterized by X-ray single crystal determination and evaluated for inhibitory activity on jack bean urease. All the complexes contained a new cinnamic acid derivative as the ligand (C₁₁H₁₂O₄), (E)-3-(3,4-dimethoxyphenyl)acrylic acid, and crystallized in monoclinic C2/c space group. Complex 1 (C₁₁H₁₁O₄)₄(C₃N₂H₈)₂Cu₂ (C₃N₂H₈?=?1,2-diaminopropane) was obtained with a?=?20.488(2), b?=?19.596(2), c?=?15.2500(13), β?=?93.502(2)°, V?=?6111.2(10)?ų, Z?=?4, R ₁ ?=?0.0616, and wR ₂ ?=?0.2059. Complex 2 (C₁₁H₁₁O₄)₄(C₃N₂H₈)₂Cu₂ (C₃N₂H₈=1,3-diaminopropane) was obtained with a?=?20.2494(12), b?=?19.5732(12), c?=?14.8940(8), β?=?96.884(2)°, V?=?5860.6(6)?ų, Z?=?4, R ₁ ?=?0.0409, and wR ₂ ?=?0.1107. Complex 3 (C₁₁H₁₁O₄)₂(C₂N₂H₆)₂Ni₂·H₂O (C₂N₂H₆?=?ethylenediamine) was obtained with a?=?28.359(2), b?=?6.5422(5), c?=?16.8587(14), β?=?101.359(2)°, V?=?3066.5(4)?ų, Z?=?4, R ₁ ?=?0.0422, and wR ₂ ?=?0.1190. It was found that copper(II) complexes 1 [IC₅₀?=?4.71?μM] and 2 [IC₅₀?=?3.15?μM] showed strong inhibitory activity against jack bean urease compared with acetohydroxamic acid [IC₅₀?=?10.01?μM] as a positive reference. Unfortunately, 3 exhibited no inhibitory activity.     

Synthesis and investigation of antibacterial activities and carbonic anhydrase and acetyl cholinesterase inhibition profiles of novel 4,5-dihydropyrazol and pyrazolyl-thiazole derivatives containing methanoisoindol-1,3-dion unit

Novel 4,5-dihydropyrazole derivatives (3a–i), 3-(4-((3aR,4S,7R,7aS)-1,3-dioxo-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindol-2(3H)-yl)phenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothio amide, were obtained by the addition of thiosemicarbazide (2) to the chalcones (1a–i). The addition–cyclization of 2,4′-dibromoacetophenone (4) to pyrazole derivatives (3a–i) gave the new pyrazolyl-thiazole derivatives (5a–i), (3aR,4S,7R,7aS)-2-(4-(1-(4-(4-bromophenyl)thiazol-2-yl)-5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindole-1,3(2H)-dione. Antibacterial and acetylcholinesterase (AChE) enzyme and human carbonic anhydrase (hCA) I, and II isoform inhibitory activities of the compounds 3a–i and 5a–i were investigated. Some of the compounds showed promising antibacterial activity. In addition, the hCA II and I were effectively inhibited by the lately synthesized derivatives, with K_i values in the range of 18.90?±?2.37 ?58.25?±?13.62?nM for hCA II and 5.72?±?0.98 ?37.67?±?5.54?nM for hCA I. Also, the K_i parameters of these compounds for AChE were obtained in the range of 25.47?±?11.11???255.74?±?82.20?nM. Also, acetazolamide, clinical molecule, was used as a CA standard inhibitor that showed K_i value of 70.55?±?12.30?nM against hCA II, and 67.17?±?9.1?nM against hCA I, and tacrine inhibited AChE showed K_i value of 263.67?±?91.95.     

A new trans-dioxorhenium(V) complex with 4-aminopyridine: synthesis,structure, electrochemical aspects,DFT, and TD-DFT calculations

The reaction of 1?:?4.4?M proportion of cis-[ReO₂I(PPh₃)₂] and 4-aminopyridine (ampy) in acetone–water gives trans-[ReO₂(ampy)₄]I·2H₂O (1a) in 85% yield. 1a has been characterized by C, H, and N microanalyses, FT-IR, UV–vis, ¹H NMR spectroscopy, and molar conductivity. The X-ray crystal structure of 1a reveals an octahedral trans dioxorhenium(V) complex with a “N₄O₂” coordination for rhenium. 1a has an orthorhombic space group C2221 with a?=?17.576(4), b?=?19.370(4), c?=?15.730(4) Å, V?=?5355(2) ų, and Z?=?8. Geometry optimization of the trans-O,O complex, 1a and its cis-O,O analog, 1b performed at the level of density functional theory reveal that 1a is more stable than 1b by 25?kcal M^–1 in the gas phase. The electronic spectrum of 1a was also analyzed at the level of time-dependent density functional theory. Excitation of 1a in methanol at 450?nm leads to a fluorescent emission at 505?nm with a quantum yield (Ф) of 0.04. Electrochemical studies of 1a in acetonitrile show a quasi-reversible Re(V) to Re(VI) oxidation at 0.618?V versus Ag/AgCl. This redox potential matches with the calculated redox potential of 0.621?V versus Ag/AgCl.     

Anti-glycating and anti-oxidant compounds from traditionally used anti-diabetic plant Geigeria alata(DC) Oliv. & Hiern.

Abstract

A new sesquiterpene lactone geigerianoloide (1) and four known flavonoids axillarin (2), quercetin (3), 3-methoxy-5,7,3',4'-tetrahydroxy-flavone (4) and hispidulin (5) were isolated from Geigeria alata (DC) Oliv. & Hiern. (Asteraceae). Structures were deduced using ¹H- and ¹³C- NMR spectroscopy, mass spectrometry, while the structure of compound 1 was also deduced using X-ray crystallography technique.

Geigeria alata is traditionally used for diabetes, therefore compounds were tested for anti-glycation activity, in which compounds 2 and 3 showed potent activities (IC₅₀ values of 246.97?±?0.83 and 262.37?±?0.22 µM, respectively) compared to IC₅₀ value 294.50?±?1.5 µM of rutin. Moreover, compound 4 exhibited a comparable activity to rutin (IC₅₀?=?293.28?±?1.34 µM). Compound 5 showed a weak activity.

Compounds 2, 3, and 4 exhibited potent DPPH radical scavenging activity (IC₅₀?=?0.1?±?0.00, 0.13?±?0.00 and 0.15?±?0.01 µM, respectively). Compounds 2, 3, and 4 demonstrated significant superoxide anion scavenging activity with IC₅₀ values of 0.14?±?0.001, 0.17?±?0.00, and 0.11?±?0.006 µM, respectively.     

Synthesis and structures of two molybdenum(VI) complexes derived from similar benzohydrazone ligands with catalytic properties

Two new structurally similar molybdenum(VI) complexes, [MoO₂L¹(CH₃OH)] (1) and [MoO₂L²(CH₃OH)] (2), where L¹ is the dianionic form of N′-(2-hydroxy-5-nitrobenzylidene)-2-methylbenzohydrazide and L² is the dianionic form of N′-(2-hydroxy-4-methoxybenzylidene)-2-methylbenzohydrazide, were prepared and structurally characterized by elemental analysis, infrared spectra, and single-crystal X-ray diffraction. 1 crystallizes in the monoclinic space group P2₁/c, with unit cell dimensions a?=?7.941(1), b?=?14.337(2), c?=?15.141(2)?Å, β?=?92.782(2)°, V?=?1721.8(4)?ų, Z?=?4, R₁?=?0.0286, wR₂?=?0.0650, GOOF?=?1.028. 2 crystallizes in the triclinic space group P-1, with unit cell dimensions a?=?8.003(1), b?=?10.608(1), c?=?10.880(1)?Å, α?=?95.745(2)°, β?=?97.627(2)°, γ?=?105.762(2)°, V?=?872.0(2)?ų, Z?=?2, R₁?=?0.0226, wR₂?=?0.0595, GOOF?=?1.116. X-ray analysis indicates that Mo in the complexes are coordinated by the phenolate oxygen, imino nitrogen, and enolate oxygen of the benzohydrazone, methanol, and two oxo groups, generating octahedral coordination. The oxidation of olefins with the complexes as catalysts was evaluated, indicating that the complexes showed excellent catalytic efficiency in oxidation of most aliphatic and aromatic substrates under mild conditions using tert-butyl hydrogen peroxide as oxidant.     

Cytotoxicity,apoptosis, interaction with DNA,cellular uptake,and cell cycle arrest of ruthenium(II) polypyridyl complexes containing 4,4′-dimethyl-2,2′-bipyridine as ancillary ligand

Two new ruthenium(II) polypyridyl complexes, [Ru(dmb)₂(DNPIP)](ClO₄)₂ (1) (DNPIP?=?2-(2,4-dinitrophenyl)imidazo[4,5-f][1,10]phenanthroline, dmb?=?4,4′-dimethyl-2,2′-bipyridine) and [Ru(dmb)₂(DAPIP)](ClO₄)₂ (2) (DAPIP?=?2-(2,4-diaminophenyl)imidazo[4,5f][1,10]phenanthroline), were synthesized and characterized. The DNA-binding behaviors of these complexes have been studied by UV-Vis absorption titration, viscosity measurements, and photocleavage. The DNA-binding constants are 7.39 (±0.16)?×?10⁴ (s?=?2.68) and 2.73 (±0.16)?×?10^4?(mol?L^?1)^?1 (s?=?0.64) for 1 and 2, respectively. Their evaluation as cytotoxic agents on different cancer cell lines was investigated with IC₅₀ values of 59.5, 51.3, and 70.3?µmol?L^?1 for 1, >100, 87.9, and 77.9?µmol?L^?1 for 2 against BEL-7402, HepG-2, and MCF-7 cells, respectively. Complex 1 is more active than 2 against selected cancer cell lines. The apoptosis induced by these complexes was studied. Cellular uptake showed that these complexes could enter into the cytoplasm and accumulate in the nuclei. The cell cycle arrest and antioxidant activity against hydroxyl radicals were also investigated.     

Three new coordination frameworks based on 2-ethyl-imidazole-4,5-dicarboxylate and 1,10-phenanthroline: syntheses,crystal structures,and luminescence

Three new coordination polymers based on 2-ethyl-imidazole-4,5-dicarboxylate with 1,10-phenanthroline as ligands, Pb(HEIDC)(phen)₂ (1), [Zn(EIDC)(phen)] _n (2), and {[Ba(H₂EIDC)₂(phen)]?·?(phen)₂?·?[Ba(H₂EIDC)(HEIDC)(phen)]} _n (3) (H₃EIDC?=?2-ethyl-1-Himidazole-4,5-dicarboxylate; phen?=?1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analysis, infrared spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. Complex 1 displays a tetranuclear square constructed of four Pb(II) centers, four HEIDC, and eight phen, resulting in a 3-D network with a 1-D open channel along the c-axis via C–H?···?O hydrogen bonds, C–H?···?π, and π–π stacking interactions. Complex 2 is an infinite zigzag chain resulting in the final 3-D supramolecular framework via C–H?···?O and π–π stacking interactions. Complex 3 is composed of two individual Ba chains, exhibiting a 3-D framework via O–H?···?O, O–H?···?N hydrogen bonds, and π–π stacking interactions. The photoluminescence spectra of 1 and 2 in the solid state have been investigated, 1 exhibits green photoluminescence in the solid state at room temperature.     

New cytotoxic bufadienolides from the roots and rhizomes of Helleborus thibetanus Franch

Abstract

Three new bufadienolides 14β, 16β-dihydroxy-3β-[β-D-glucopyranosyl-(1→6)-(β-D-glucopyranosyl)oxy]-5α-bufa-20, 22-dienolide (1), 14β-hydroxy-3β-[β-D-glucopyranosyl-(1→4)-(β-D-glucopyranosyl)oxy]-5α-bufa-20, 22-dienolide (2) and hellebrigenin-3-O-β-D-glucosyl-(1→4)-β-D-glucoside (3), together with eight known bufadienolides (4–11) were isolated from the roots and rhizomes of Helleborus thibetanus. Their structures were elucidated by extensive spectroscopic methods and acid hydrolysis. Compounds 1–7 were evaluated for their cytotoxic activity against HCT116, A549 and HepG2 tumor cell lines. Compound 1 exhibited moderate cytotoxicity against HepG2 cells with IC₅₀ value of 15.1?±?1.72?μM. Compounds 5 and 6 exhibited moderate cytotoxicity against HCT116 cells with IC₅₀ values of 15.12?±?0.58?μM and 13.17?±?2.34?μM, respectively.