Cytotoxic labdane diterpenes and bisflavonoid atropisomers from leaves of Araucaria bidwillii

Chemical investigation of a methanolic extract of leaves from Araucaria bidwillii (Araucariaceae) from Egypt afforded four new labdane diterpenoidal metabolites (1–4) together with one known diterpene, 7-oxocallitrisic acid (5), two triterpenoidal metabolites, 2-O-acetyl-11-keto-boswellic acid (6) and β-sitosterol-3-O-glucopyranoside (7), phloretic acid (8), and two methylated bisflavonoids, agathisflavone-4′,7,7″-trimethyl ether (9) and cupressuflavone-4′,7,7″-trimethyl ether (10). The new metabolites 1–4 were unambiguously identified by applying extensive 1D and 2D NMR spectroscopic studies as well as HRESIMS. The relative and absolute configurations of 1–4 were determined using ROESY and the modified Mosher's method, respectively. All isolated compounds were assessed for their antimicrobial, antitubercular and cytotoxic activities. Among the tested compounds, the new labdane diterpenes 1–4 revealed significant cytotoxic activity against mouse lymphoma L5178Y cell line with IC₅₀ values ranging from 1.4 to 12.9 μM, respectively.     

Pellynols M−O,cytotoxic polyacetylenic alcohols from a Niphates sp. marine sponge

Three new polyacetylenic alcohols, pellynols M?O (1–3), along with two known ones, melyne A (4) and melyne B (5), were isolated from a Niphates sp. marine sponge collected off the South China Sea. The structures of new compounds were determined based on a combination of 1D and 2D NMR analysis, ESI-MSⁿ fragmentation, and chemical (ozonolysis) method. Their absolute configurations were assigned by modified Mosher's method. All the isolates showed potent cytotoxic activity against PC9 and HepG2 human cancer cell lines with IC₅₀ values of 2.9–7.6?μM.     

Guianofruits C–I from fruit oil of andiroba (Carapa guianensis,Meliaceae)

Two novel chukrasone-type limonoids, named Guianofruits C and D (1 and 2), a guianolide derivative named Guianofruit E (3), and four novel phragmalin–type limonoids named Guianofruits F–I (4–7), were isolated from the fruit oil of Carapa guianensis AUBLET (Meliaceae), a traditional medicine in Brazil and Latin American countries. Their structures were mainly elucidated based on spectroscopic analyses using 1D and 2D NMR techniques. The effects of compounds 1–6 on the production of NO by LPS-activated mouse peritoneal macrophages were investigated. Two new chukrasone-type limonoids, Guianofruits C (1) and D (2), exhibited moderate inhibitory activities.     

Erysacleuxins C and D,new isoflavones from the twigs of Erythrina sacleuxii Hua and their cytotoxic activity

Two previously undescribed isoflavones, erysacleuxin C (1) and erysacleuxin D (2), together with seven known compounds (3–9), were isolated and identified from the EtOAc extract of the twigs of Erythrina sacleuxii Hua (Leguminosae). The structures of the isolated compounds were determined on the basis of their spectroscopic and spectrometric data. Evaluation of their cytotoxicity against the human cancer HeLa-S3 cell lines indicated IC₅₀ values of 130.4, 54.9 and 73.9 µM for erysacleuxin C (1), erysacleuxin D (2) and butin (9), respectively.     

Identification of active chemical constituents of Asplenium ruprechtii Sa. Kurata based on in vitro neuroprotective activity evaluation

Mining structural novel and bioactive natural products from traditional Chinese drugs and folk medicines have attracted attention from pharmacologists and pharmaceutical chemists for a long time. In this study, the chemical constituents of Asplenium ruprechtii Sa. Kurata was systematically studied based on the evaluation of neuroprotective activity on hydrogen peroxide (H₂O₂)-induced damage of SH-SY5Y cell lines. Sixteen chemical monomers (1–16), including two new structures of 9,19-cycloartane-triterpenoid saponins (1,2), were discovered. Their chemical structures were established based on extensive spectroscopic data analysis, including the one- and two-dimensional (1D and 2D) nuclear magnetic resonance (NMR) data and high-resolution electrospray ionization mass spectrometry (HRESIMS). All monomer compounds were docked with an “active pocket” at the N-terminal of the GluN2B protein, where compounds 13–16 were found to possess high binding scores, which warrant further study on the molecular mechanism. Our findings provide insight and research techniques for discovering new drugs based on neuroprotective activity.     

New sesquiterpenes from the roots of Coriaria nepalensis

Six new trace sesquiterpenes, corialactones A–D (1–4), coriantone (5), corianol (6), together with nine known ones (7–15), were isolated from the roots of Coriaria nepalensis. The structures of 1–6 were elucidated through a combination of extensive NMR spectroscopic analysis, HRESIMS, CD, Rh₂(OCOCF₃)₄-induced CD, Snatzke's method, and X-ray crystallography. Compounds 2–4, and 6 possess characteristic structural units compared with the previously reported sesquiterpenes from this family. In vivo system, compounds 5, 6 and 10 showed anti-convulsant activity by 20%, 60%, and 20% at the dose of 5 mg/kg, respectively.     

Thioquinomycins A-D,novel naphthothiophenediones from the marine-derived Streptomyces sp. SS17F

Thioquinomycins A-D (1–4), four novel naphthothiophenediones were isolated from the rice-based medium of the marine-derived Streptomyces sp. SS17F. Their structures were elucidated by spectroscopic methods and HRESIMS data. The absolute configurations of all the compounds were elucidated by X-ray diffraction analysis, ECD and Mosher's method combined with ¹⁹F-NMR. Compounds 1–4 showed moderate cytotoxicity against NCI-H1975 with IC₅₀ values from 17.5 to 50?μM. In addition, compounds 1–4 also exhibited inhibitory activities against PKCα and ROCK2 protein kinase.     

Cytotoxic aromatic polyketides from an insect derived Streptomyces sp. NA4286

Chemical study of the insect-derived bacterium, Streptomyces sp. NA4286, led to the discovery of four new polyketides, murayaquinones B-E (1–4), together with a known compound, murayaquinone (5). The structures of new compounds (1–4) were determined by extensive analysis of their NMR and HRESIMS data. The absolute configuration of (+)-1 and (?)-1 was assigned through comparison of experimental and calculated ECD spectra. Murayaquinone D (3) exhibited potent cytotoxic activities against six human cancer cell lines with IC₅₀ values ranging from 1.03 to 9.99 μM.     

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.     

Three new inositol derivatives from Chisocheton paniculatus

Three new inositol derivatives (1–3) were isolated from the leaves of Chisocheton paniculatus collected in Vietnam, along with four known compounds, including a limonoid (4), two triterpenoids (5–6), and a tocopherol (7). The structures of the new compounds were elucidated by 1D- and 2D-NMR and HRESIMS analyses. Compound 4 showed the highest cytotoxicities against the human lung cancer A549 and cervical cancer HeLa cell lines, with IC₅₀ values of 7.3 and 8.8 µM, respectively, among the isolated compounds. Compounds 5 and 7 displayed moderate to weak cytotoxicities against the A549, HeLa, and human stomach cancer GSU cell lines, with IC₅₀ values ranging from 17.7 to 68.0 µM.     

Two acridones and two coumarins from the roots of Paramignya trimera

Two acridones, paratrimerins C (1) and D (2), and two coumarins, paratrimerins E (3) and F (4), were isolated from the CHCl₃ and EtOAc extracts of Paramignya trimera (Rutaceae), together with twelve known compounds (5–16). Their structures were elucidated on the basis of spectroscopic data. All isolated compounds possessed significant α-glucosidase inhibitory activity in a concentration-dependent manner, and showed more potent inhibitory activity, with IC₅₀ values ranging from 14.6 to 112.2 μM, than the positive control acarbose (IC₅₀, 214.5 μM). The biosynthesis of the isolated coumarins and acridones was proposed.     

Divaccinosides A–D,four rare iridoid glucosidic truxillate esters from the leaves of Vaccinium bracteatum

Divaccinosides A–D (1–4), four rare iridoid glucoside cyclodimers in the truxillate forms, were characterized from the leaves of Vaccinium bracteatum. They were presumably biosynthesized from two known iridoid glucoside monomers, vaccinoside (5) and 10-O-trans-p-coumaroyl-6α-hydroxyl-dihydromonotropein (6), via a [2+2] cycloaddition reaction. The structures of the new compounds were established by comprehensive spectroscopic measurements, combined with chemical conversions and single crystal X-ray crystallographic analyses.     

Structural assemblies of four Cd(II) coordination polymers based on 5-methylisophthalic acid

Four new metal-organic coordination polymers, Cd(mip)(DMF)(1), Cd(mip)(EtOH)(2), Cd₂(mip)₂(H₂O)₅·3H₂O (3), Cd(mip)(bpp)(H₂O)·H₂O (4) (H₂mip = 5-methylisophthalic acid, bpp = 1,3-di(4-pyridyl)propane) have been hydro(solvo)thermally synthesized and characterized by IR, thermogravimetric (TG) analysis, powder X-ray diffraction and single-crystal X-ray diffraction. 1 and 2 are isostructural, and two adjacent Cd centers are bridged by four carboxylate groups in μ₂-carboxylato-κ¹O_.:κ¹O′ and μ₂Ο; κ²O,O′ fashion to form a linear (Cd–O–Cd)_n chain. The adjacent (Cd–O–Cd)_n chains are further connected by mip bridges to form a 3D framework. 3 features two types of chiral layers: One left-handed and another right-handed, which lead to racemic solid-state compound. 4 exhibits a two-dimensional wave-like (2D) (4,4) layer structure with infinite 1D linear chain. In addition, the luminescent properties of 1–4 are also discussed.     

Bioactive compounds from the scale insect fungus Conoideocrella tenuis BCC 44534

Eleven new compounds, including two quinone derivatives of bioxanthracene, conoideocrellones A (1) and B (2), two bioxanthracenes 3 and 4, four isocoumarins and isocoumarin glycosides 7–10, two phenolic compounds 16 and 17, and a diterpenoid compound, conoideocin A (18), were isolated from culture of the scale-insect pathogenic fungus Conoideocrella tenuis BCC 44534. Seventeen known compounds, compounds 5 and 6, ES-242-2 and its atropisomer, isocoumarins and isocoumarin glycosides 11–15, 3,4,6-trihydroxymellein, cis-4,6-dihydroxymellein, metarhizins A (19) and B (20), BR-050 (21), 5α,8α-epidioxy-24(R)-methylcholesta-6,22-dien-3β-ol, zeorin, and conoideocrellide A, were also isolated from this fungus. Structures of these compounds were elucidated by NMR and MS data analyses. Compound 4 was active against Plasmodium falciparum K1 (IC₅₀ 6.6?μg/mL), while it did not show cytotoxicity. Conoideocrellone A (1) and compounds 3 and 7 exhibited cytotoxic activity, while conoideocin A (18) showed broad range of biological activities including antimalarial, antibacterial, and cytotoxic activities.     

Syntheses,crystal structures,DFT calculation and solid-state spectroscopic properties of new zincate(II) complexes with N-(4-substituted phenyl)-N'-(4-nitrophenyl)-oxamate

The electronic effects electron donating and withdrawing groups R on the properties of N-(4-R-phenyl)-N'-(4-nitrophenyl)oxamito zincate(II) complexes was investigated featuring R = Me (a), H (b), F (c), Cl (d) and Br (e). The N-(4-R-phenyl)-N'-(4-nitrophenyl)oxamide ligands 2 were synthesized by reacting ethyl 4-nitrooxanilate with the respective 4-substituted anilines. Subsequent treatment with [nBu₄N]OH and [Zn(OAc)₂(H₂O)₂] gave the respective zincate complexes [nBu₄N]₂[Zn(N-(4-nitrophenyl)-N'-(4-substituted phenyl)oxamides)₂] (3). Spectroscopic methods were used to describe compounds 2a–e and 3a–e. Single crystal X-ray diffraction analysis confirmed the formation of 3a–c in the solid state. The tetrahedral coordination sphere of the zinc (II) ion features four amide nitrogen donor atoms based on two ethanediamide ligands. The UV–Vis spectra of Complexes 3a–e display a characteristic LLCT (π → π *) band, which was confirmed by TD-DFT calculations. DFT calculations show that the Zn(II) orbitals do not contribute to the HOMO or LUMO, with the latter being primarily found on the two 4-nitrophenyl rings for compounds 3a ? e, while the HOMO-1 and HOMO are located on the 4-substituted phenyl rings. Notably, HOMO and LUMO energies and gabs do not differ significantly. Transitions from HOMO to LUMO + 1 are the most important for all ligands. The luminescence properties of solid compounds 3a ? e were also investigated at 298 K. Solid state photoluminescence studies reveal that these complexes emit strong yellow-orange luminescence at 450–600 nm with a maximum at about ～ 500 nm in the cyan region. Furthermore, the thermal stabilities of compounds 3a ? e have been investigated.     

New bioactive pyrrospirones C−I from a marine-derived fungus Penicillium sp. ZZ380

Seven rare pyrrospirones C?I (1–7) as well as 18 known compounds were isolated from a marine-derived fungus Penicillium sp. ZZ380. Structures of the new pyrrospirones were elucidated by extensive NMR spectroscopic analyses, HRESIMS data, and Mosher's method. Pyrrospirone D (2) was also confirmed by X-ray diffraction analysis. Pyrrospirone G (5) showed potent activity in inhibiting the proliferation of different glioma cells with IC₅₀ values of 1.06–8.52 μM and pyrrospirones C (1), F (4), and I (7) had antimicrobial activity against the growth of both methicillin-resistant Staphylococcus aureus and Escherichia coli with MIC values of 2.0–5.0 μg/mL.     

Synthesis,characterization and ethylene polymerization of 1-(2,6-dimethyl-4-fluorenylphenylimino)-2-aryliminoacenaphthylnickel bromides

A series of 1-(2,6-dimethyl-4-fluorenylphenylimino)-2-aryliminoacenaphthylene compounds (aryl = 2,6-di(Me)Ph (L1), 2,6-di(Et)Ph (L2), 2,6-di(i-Pr)Ph (L3), 2,4,6-tri(Me)Ph (L4), 2,6-di(Et)-4-MePh (L5)) was prepared and used to form their corresponding dibromonickel complexes (D1–D5). Both L1–L5 and D1–D5 were fully characterized by FT-IR and elemental analysis as well as NMR measurements in the case of ligands L1–L5. The molecular structure of the representative complex D5 was confirmed by single crystal X-ray diffraction revealing a distorted trigonal bipyramidal geometry around the nickel center. On activation with either ethylaluminium sesquichloride (Et₃Al₂Cl₃, EASC) or methylaluminoxane (MAO), all nickel complexes exhibited high activities up to 9.82 × 10⁶ g of PE (mol of Ni)⁻¹ h⁻¹ for ethylene polymerization. In comparison with the polyethylenes obtained with related Ni pre-catalysts, the polyethylenes obtained in this work possessed relatively higher molecular weights and lower levels of branching, highlighting the significant influence of the remote fluorenyl substituent.     

New borrelidin derivatives from an endophytic Streptomyces sp.

Three new borrelidin-type macrolactones, designated as borrelidins J?L (4–6), together with borrelidin A (1), borrelidin E (2), and 12-desnitrile-12-carboxyl-borrelidin (3) were isolated from a plant endophytic Streptomyces sp. NA06554. Their structures were determined by extensive spectroscopic analysis including HRESIMS, 1D and 2D NMR data. The antibacterial activities for compounds 1–6 were examined. Borrelidins A (1) and L (6) showed potent and moderate antibacterial activity against Micrococcus luteus, respectively, whereas other derivatives (2–5) are almost inactive, which allows us to propose a plausible structure-activity relationship.     

Saxifraganoids A and B,two novel cucurbitane triterpenoid glycosides from Saxifraga umbellulata var. pectinata

Two novel cucurbitane triterpenoid glycosides, named saxifraganoids A (1) and B (2), were isolated from Saxifraga umbellulata var. pectinata. Their structures including absolute configurations were elucidated based on the analysis of spectroscopic data (1D, 2D NMR and HRMS), and single-crystal X-ray diffraction. Compound 1 represents the first example of cucurbitane triterpenoid with a Δ¹⁷⁽²⁰⁾, and compound 2 contained an unusual N-acetylglucosamine at C-16. The protective effects against liver injury induced by carbon tetrachloride (CCl₄) in the human embryonic-liver L-02 cells of these two compounds were evaluated.     

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.