Antiplasmodial Securinega alkaloids from Phyllanthus fraternus: Discovery of natural (+)-allonorsecurinine

The chemical investigation of the antimalarial plant Phyllanthus fraternus G. L. Webster (Phyllanthaceae) resulted in the discovery of the Securinega alkaloid (+)-allonorsecurinine (1), previously reported as a synthetic compound, together with the known ent-norsecurinine (2), nirurine (3), bubbialine (4), epibubbialine (5) and the lignan phyllanthin (6). The structure and absolute configuration of the new compound were elucidated on the basis of extensive spectroscopic analysis, optical rotation, and GIAO NMR shift calculation followed by CP3 analysis. The antiplasmodial activity of these compounds was evaluated against chloroquine-resistant (W2) and -sensitive (3D7) strains of Plasmodium falciparum. Among them, ent-norsecurinine (2) and (+)-allonorsecurinine (1) showed the strongest activity (IC₅₀: 1.14 ± 0.32 and 2.57 ± 0.53 µM) respectively, against W2 but one of the weakest against 3D7.     

Cytotoxic gephyromycins from the Streptomyces sp. SS13I

Two new gephyromycins (1–2), belonging to angucyclinones, were identified from Streptomyces sp. SS13I. Their structures were elucidated by analysis of HRESIMS, 1D and 2D NMR spectroscopic data, and the structure of 1 was further elucidated by X-ray diffraction data. The absolute configurations of compounds 1–2 were evidenced by ECD calculations. To our best knowledge, Compounds 1–2 were the second reported gephyromycin-type angucyclinones. Compound 2 exhibited significant cytotoxicity against PC3 cell lines with IC₅₀ values of 1.38 ± 0.47 μM.     

Visconata: A rare flavonol having long chain fatty acid from Dodonaea viscosa which inhibits Human neutrophil elastase (HNE)

A series of flavonoids were isolated from Dodonaea Viscosa and tested for inhibition of human neutrophil elastase (HNE), enzyme involved in inflammatory disorders. Isolated compounds were identified as a novel flavonol (1) along with eight known flavonoids (2–9). Novel flavonol, visconata (1) has a very rare skeleton having odd numbered long chain (C19) fatty acid, which was completely identified by mass fragmentation and 2D NMR analysis. All compounds (1–9) inhibited HNE in dose dependent manner with IC₅₀s ranging between 2.4 and 150 μM. Visconata (1) emerged to be the most potent compound with 2.4 μM of IC₅₀. In kinetic studies, compound (1) was observed to be reversible, noncompetitive inhibitor having K_i = 1.8 μM, whereas other flavonoids (2–9) displayed mixed type inhibition.     

A new cytotoxic salannin-class limonoid alkaloid from seeds of Azadirachta indica A. Juss

Azadiramide A (1), a new salannin-class limonoid alkaloid, inhibits growth of human breast cancer MDA-MB-231 cell line with IC₅₀ value of 2.70±0.63 μmol/L.     

Novel dual inhibitors against FP-2 and PfDHFR as potential antimalarial agents: Design,synthesis and biological evaluation

A series of novel 2,4-diaminopyrimidine-modified compounds was designed and synthesized. Compound 14 showed micromolar dual inhibitory effect on both FP-2 and PfDHFR, and potential inhibition to the proliferation of P. falciparum 3D7 strain and chloroquine-resistant P. falciparum Dd2 strain.     

Anti-inflammatory chromone alkaloids and glycoside from Dysoxylum binectariferum

Herein we report isolation of a new chromone alkaloid chrotacumine K (12) from fruits and a chromone glycoside schumaniofioside A (13) from leaves of Dysoxylum binectariferum Hook f. Schumaniofioside A is reported for the first time from Meliaceae family. Other known alkaloids isolated include rohitukine (1) and chrotacumine E (6). The structure of new alkaloid 12 was elucidated on the basis of extensive 1D and 2D NMR analysis, synthesis and chemical hydrolysis. Chemically, chrotacumine K (12) is a 3′-O-acetyl rohitukine which on chemical or enzymatic hydrolysis produces rohitukine. The new alkaloid 12 is also present in seeds and stem-barks of this plant. The glycoside schumaniofioside A (13) is present only in leaves, and in abundance (～1% w/w of dried leaves). The isolated compounds and extracts were evaluated for in vitro effect on the proinflammatory cytokines (TNF-α and IL-6) in human monocytic THP-1 cells. The alkaloid 12 displayed potent inhibition (57%) of TNF-α at 0.3 µM, and was non-toxic to THP-1 cells up to 40 µM, indicating its excellent therapeutic window. Furthermore, a nitrobenzoyl ester analog 15e showed better inhibition of IL-6 than parent natural product chrotacumine K.     

Nodupetide,a potent insecticide and antimicrobial from Nodulisporium sp. associated with Riptortus pedestris

Nodupetide (1), a new cyclodepsipeptide unique in its incorporation of a 3-hydroxy-4-methylhexanoic acid (HMHA) derived motif, was discovered from Nodulisporium sp. IFB-A163, a fungus residing in the insect (Riptortus pedestris) gut. The nodupetide structure was elucidated by its MS/MS and 2D NMR spectra, and its absolute configuration by the X-ray crystallography and modified Marfey’s method. Nodupetide is insecticidal against rice brown planthopper (Nilaparvata lugens) with an LD₅₀ value of 70 ng/larva, and inhibitory towards the drug-resistant human pathogenic bacterium Pseudomonas aeruginosa with its MIC value (5.0 μM) comparable to that (3.2 μM) of ciprofloxacin, a prescribed antibacterial agent co-assayed equally.     

Synthesis,structure and fluorescence of a novel three-dimensional inorganic–organic hybrid polymer constructed from trimetallic clusters and mixed carboxylate ligands

A new inorganic–organic hybrid framework coordination polymer, Cd₃(BDC)_0.5(BTC)₂(DMF)(H₂O)·3DMF·H₃O·H₂O 1, in which two carboxylate ligands, 1,4-benzenedicarboxylic acid (H₂BDC) and 1,3,5-benzenetricarboxylic acid (H₃BTC), coordinate with cadmium ions, has been synthesized under mild conditions and its structure solved by single-crystal X-ray diffraction (XRD) analysis. Polymer 1 crystallizes in the monoclinic system, space group P2₁/c (No. 14) with a=15.750(3) Å, b=14.501(3) Å, c=19.363(4) Å, β=113.67(3)°, V=4050.4(14) Å³, Z=4, R1=0.0374 and wR2=0.1148. Its structure revealed that the nine vertices of the secondary building units are linked by benzene rings from both H₃BTC and H₂BDC ligands to form a 3D network with 10×10 Å channels along [001] direction. Complex 1 is characterized by inductively coupled plasma analysis, powder XRD, infrared spectroscopy and thermogravimetric analysis. Polymer 1 exhibits intense fluorescence at 358 and 377 nm with λ_excitation=208 nm in the solid state at room temperature.     

Diterpenoids from the aerial parts of Leonurus macranthus

One cis clerodane-type (1) and three highly oxygenated labdane-type diterpenes (2-4) were isolated from the aerial parts of Leonurus macranthus. Compound 1 represents the first example of cis clerodane-type diterpene in the plants of Leonurus genus.     

Assembling of a novel 3D Ag(I)-MOFs with mixed ligands tactics: Syntheses,crystal structure and catalytic degradation of nitrophenol

A novel 3D Ag(I)-MOFs, [Ag₂(H₃ddcba)(dpp)₂] (1), which features pcu (4¹²·6³) topology were successfully synthesized. Complex 1 exhibits predominant catalytic activity towards the degradation of o-nitrophenol (2-NP), m-nitrophenol (3-NP) and p-nitrophenol (4-NP) in aqueous solution.     

Design,synthesis and biological evaluation of quinazolin-4(3H)-one Schiff base conjugates as potential antiamoebic agents

In an effort to develop novel antiamoebic scaffolds having better efficacy than the standard drug metronidazole (IC₅₀ = 1.80 μM) used against Entamoeba histolytica, quinazolin-4(3H)-one Schiff base conjugates were synthesized and evaluated against HM1: IMSS strain of E. histolytica. Out of the thirteen compounds (S2-S14), six compounds (S2, S3, S4, S5, S6 and S11) were found to be better inhibitors than metronidazole and showed low cytotoxicity on HeLa cells, a cervical cancer cell line. The structure of intermediate compound S1 was confirmed by crystal structure studies.     

Cytotoxic arylbenzofuran and stilbene derivatives from the twigs of Artocarpus heterophyllus

Four new natural products, including three arylbenzofurans named heterophyllenes A-C (1–3), and one stilbene named heterophyllene D (4), together with twenty-one known compounds were isolated from the twigs of Artocarpus heterophyllus and their structures elucidated by spectroscopic methods, mainly 1D and 2D NMR spectroscopy. The cytotoxic activity of selected compounds against KB, MCF-7 and NCI-H187 cell lines was evaluated. Heterophyllene C (3) exhibited cytotoxicity against the MCF-7 cell line with an IC₅₀ value of 12.56 μM. Additionally, the known compounds norartocarpin and artocarpin showed cytotoxic activity against MCF-7 and KB cell lines with IC₅₀ values of 10.04 and 13.57 μM, respectively. Both compounds also displayed cytotoxicity against the NCI-H187 cell line with values of 14.78 and 14.21 μM, respectively.     

Highly sensitive fluorescent sensor targeting CuCl2 based on thiophene attached anthracene compound (TA)

A novel thiophene attached anthracene (TA) based fluorescent compound was designed and synthesized. The TA showed a high quantum yield (Qy = 0.34) in regard to fluorescence. We applied this TA compound to detect specific metal compound and found that it could identify CuCl₂ from other metals through dramatic fluorescence change at λ_max = 460 nm. It showed strong quenching fluorescence property with CuCl₂ while with other metal compounds it exhibited strong blue fluorescence emission. UV/Vis absorption spectroscopy clearly demonstrated that the quenching property of TA at λ_max = 460 nm was due to overlapping of the fluorescence peak of TA at λ_max = 460 nm and the absorption band of CuCl₂ (from 190 nm to 525 nm). Binding constant (K′), which was 0.0895 mM^?2, indicated a complexation ratio between TA and CuCl₂ as 1:2 and this interaction induced quenching property.     

Synthesis and antimicrobial activities of novel quinazolin-4(3H)-one derivatives containing a 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole moiety

A series of novel quinazolin-4(3H)-one derivatives (6a–6y) containing a 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole moiety were designed and synthesized, and their structures were fully characterized by ¹H NMR, ¹³C NMR, HRMS and IR spectra. Among them, the structure of compound 6u was unambiguously confirmed via single crystal X-ray diffraction analysis. The obtained bioassay results showed that compounds 6h, 6k, 6l and 6y had the EC₅₀ (half-maximal effective concentration) values of 34.8, 28.2, 41.5 and 42.5 μg/mL against the phytopathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo), respectively, which were significantly better than commercial bactericide Bismerthiazol (EC₅₀ = 95.8 μg/mL). Additionally, compounds 6a and 6b exhibited the strong inhibition activity against the pathogen Xanthomonas axonopodis pv. citri (Xac).     

Bistachybotrysins D and E,one stereoisomeric pair of cytotoxic phenylspirodrimane dimers from Stachybotrys chartarum

Bistachybotrysins D and E (1 and 2), one stereoisomeric pair of phenylspirodrimane dimers, were isolated from Stachybotrys chartarum CGMCC 3.5365. They represent novel phenylspirodrimane dimers with a central [6,5,6]-tricyclic carbon scaffold containing a cyclopentanone core. The structures of 1 and 2 were elucidated through extensive spectroscopic data analysis, and their absolute configurations were characterized by calculated electronic circular dichroism (ECD). Compounds 1 and 2 displayed potent cytotoxic activity against the four human tumor cell lines HCT116, BGC823, Daoy and HepG2 with IC_ (50)values ranging from 6.7 μmol/L to 11.6 μmol/L. Furthermore, a plausible biogenetic pathway for 1 and 2 is proposed.     

Assembly of two novel Lindqvist polyoxoanion-templated coordination polymers with standard honeycomb cavities

Two novel polyoxometalate(POM)-templated coordination polymers: [Cu₂(phnz)₃][M₆O₁₉] (M = Mo for 1, W for 2; phnz = phenazine), have been hydrothermally synthesized and characterized by routine physical methods and single crystal X-ray diffraction. In the compounds, Lindqvist POMs as templates induce the [Cu₂(phnz)₃] complexes to 2D hexagonal metal-organic framework (MOF), which represents 6³ topologies of dimensions ca. 13.515 × 13.515 × 13.515 Å. Furthermore, the 2D sheets are held together by Lindqvist POMs into 3D supramolecular networks with 1D channel, and Lindqvist POMs site in the channels. The successful syntheses and isolation of two compounds provide a novel example of the utility of POM clusters as templates for self-assembly extended framework with cavities.     

Synthesis,spectral characterization,theoretical, antimicrobial,DNA interaction and in vitro anticancer studies of Cu(II) and Zn(II) complexes with pyrimidine-morpholine based Schiff base ligand

Novel Cu(II) (1) and Zn(II) (2) complexes with 4-(1-(4-morpholinophenyl)ethylideneamino)pyrimidine-5-carbonitrile) (L) have been synthesized and characterized by various spectroscopic and analytical techniques. DFT (density functional theory) studies result confirms that, LMCT mechanism have been done between L and M(II) ions. The antimicrobial studies indicate that the ligand L and complexes 1 & 2 exhibit higher activity against the E. coli bacteria and C. albicans fungi. The groove binding mode of ligand L and complexes 1 & 2 with CT-DNA have been confirmed by electronic absorption, competitive binding, viscometric and cyclic voltammetric studies. The electronic absorption titration of ligand L and complexes 1 & 2 with DNA have been carried out in different buffer solutions (pH 4.0, 7.0 & 10.0). The K_b values of ligand L and complexes 1 & 2 are higher in acidic buffer at pH 4.0 (K_b = 2.42 × 10⁵, L; 2.8 × 10⁵, 1; 2.65 × 10⁵, 2) and the results revealed that, the interaction of synthesized compounds with DNA were higher in the acidic medium than basic and neutral medium. Furthermore, CT-DNA cleavage studies of ligand L and complexes 1 & 2 have been studied. The in vitro anticancer activities results show that complexes 1 & 2 have moderate cytotoxicity against cancer cell lines and low toxicity on normal cell line than ligand L.     

Lanostane triterpenoids from fruiting bodies of the bracket fungus Fomitopsis feei

Three 24-methyl-lanostane triterpenoids, fomitopsins D–F (1–3), were isolated together with four known compounds (4–7) from fruiting bodies of the basidiomycete Fomitopsis feei. The structures were elucidated by spectroscopic analysis and chemical correlations, including the conversion of 1 into a mixture of 2 and 3 under acidic conditions. Compound 1 was previously isolated after conversion to a methyl ester derivative, however, the side-chain stereochemistry was not determined. Fomitopsins E (2) and F (3) exhibited activity against Bacillus cereus with MIC values of 6.25 μg/mL. On the other hand, fomitopsin D (1) showed activity against herpes simplex virus type 1 (HSV-1) with an IC₅₀ value of 17 μg/mL.     

Helicity-induced two-layered Cd(II) coordination polymers built with different kinked dicarboxylates and an organodiimidazole

A new ligand bis-(4-imidazol-1-yl-phenyl)-diazene (azim), incorporating an azo moiety at the center and two imidazole groups at the terminals has been designed and synthesized. Under solvothermal conditions, this ligand reacts with Cd(NO₃)₂·6H₂O and different angular aromatic dicarboxylates to form layered coordination polymers: [Cd(azim)(bcp)]_n (1) and {[Cd(azim)(oba)](H₂O)}_n (2) [bcpH₂ = 1,3-bis-(4′-carboxy phenoxy)benzene; oba = 4,4′-oxybis(benzoate)]. Both 1 and 2 have been characterized by single-crystal X-ray diffraction technique, elemental analysis, PXRD and IR spectroscopy. The structure of each polymer looks like 2D grid where two layers are interpenetrated in a “cloth-like” topology. Both the structures contain single- and double-stranded helical coils where the pitches as well as the width are controlled by the carboxylate co-ligands. The hydrogen-bonding interactions between adjacent layers extend these structures to overall 3D supramolecular architectures.     

Synthesis and structure of a new scorpionate-dithio carboxyl oxovanadium complex and an organic dithio carboxyl compound

A new complex of oxovanadium(IV), V₂O₂[(HB(pz)₃)₂(pyrro)₂ (1) and a dimer-dithio carboxyl compound (C₅H₈NS₂)₂ (2) have been synthesized by the reaction of VOSO₄·nH₂O with NaHB(pz)₃ and pyrrolidine dithio carboxylic acid ammonium salt. They were characterized by element analysis, IR spectra, UV–vis spectra and X-ray diffraction. Structural analyses of 1 and 2 gave the following parameters: 1, triclinic, P-1, a = 7.732(4) Å, b = 14.285(8) Å, c = 17.802(9) Å, α = 101.314(8)°, β = 92.682(9)°, γ = 92.228(9)°, V = 1923.6(18) Å³, and Z = 4; 2, monoclinic, C2/c, a = 13.857(2) Å, b = 10.4213(18) Å, c = 9.436(2) Å, β = 97.099(2), V = 1352.1(4) Å³, and Z = 4. In complex 1, vanadium atom adopts a distorted tetragonal bipyramid structure, which is typical for oxovanadium(IV) complexes. Compound 2 is a dimer-dithio carboxyl compound with S–S bond. In addition, thermal analysis was performed for analyzing the stabilization of the complexes.