Dactylfungins and Tetralones: Bioactive Metabolites from a Nematode-Associated Laburnicola nematophila.

A chemical investigation of Laburnicola nematophila, isolated from cysts of the plant parasitic nematode Heterodera filipjevi, affored three dactylfungin derivatives (1-3) and three tetralone congeners (4-6). Dactylfungin C (1), laburnicolin (4), and laburnicolenone (5) are previously undescribed natural products. Chemical structures of the isolated compounds were determined based on 1D and 2D NMR spectroscopic analyses together with HR-ESI-MS spectrometry and comparison with data reported in the literature. The relative configurations of compounds 1, 2, and 4-6 were determined based on their ROESY data and analysis of their coupling constants (J values). The absolute configurations of 4-6 were determined through the comparison of their measured and calculated TDDFT-ECD spectra. Compounds 1-3 were active against azole-resistant Aspergillus fumigatus.

Synthesis of a tetralone derivative of ampicillin to control ampicillin-resistant Staphylococcusaureus.

Due to the rapid emergence of antibiotic resistant new bacterial strains and new infections, there is an urgent need for novel or newly modified and efficient alternatives of treatment. However, conventional antibiotics are still used in therapeutic settings but their efficacy is uncertain due to the rapid evolution of drug resistance. In the present study, we have synthesized a new derivative of conventional antibiotic ampicillin using SN2-type substitution reaction. NMR and mass analysis of the newly synthesized derivative of ampicillin confirmed it as ampicillin-bromo-methoxy-tetralone (ABMT). Importantly, ABMT is revealed to have efficient activity against Staphylococcus aureus (S. aureus) with a MIC value of 32 µg ml-1 while ampicillin was not effective, even at 64 µg ml-1 of concentration. Electron microscopy results confirmed the membrane-specific killing of S. aureus at 1 h of treatment. Additionally, molecular docking analysis revealed a strong binding affinity of ABMT with ß-lactamase via the formation of a closed compact bridge. Our findings, avail a new derivative of ampicillin that could be a potential alternative to fight ampicillin-resistant bacteria possibly by neutralizing the ß-lactamase action.

Research progress in pharmacological activities and structure-activity relationships of tetralone scaffolds as pharmacophore and fluorescent skeleton.

The tetralone and tetralone derivatives, as crucial structural scaffolds of potential novel drugs targeted at multiple biological end-points, are normally found in several natural compounds and also, it can be used as parental scaffold and/or intermediate for the synthesis of a series of pharmacologically active compounds with a broad-spectrum of bioactivities including antibacterial, antitumor, CNS effect and so on. Meanwhile, SAR information of its analogues has drawn attentions among medicinal chemists, which could contribute to the further research related to tetralone derivatives aimed at multiple targets. This review encompasses pharmacological activities, SAR analysis and docking study of tetralone and its derivatives, expecting to provide a general retrospect and prospect on tetralone derivatives.

The inhibition of catechol O-methyltransferase and monoamine oxidase by tetralone and indanone derivatives substituted with the nitrocatechol moiety.

The enzymes, catechol O-methyltransferase (COMT) and monoamine oxidase (MAO) are important drug targets, and inhibitors of these enzymes are established therapy for symptomatic Parkinson's disease (PD). COMT inhibitors enhance the bioavailability of levodopa to the brain, and therefore are combined with levodopa for the treatment of motor fluctuations in PD. Inhibitors of the MAO-B isoform, in turn, are used as monotherapy or in conjunction with levodopa in PD, and function by reducing the central degradation of dopamine. It has been reported that 1-tetralone and 1-indanone derivatives are potent and specific inhibitors of MAO-B, while compounds containing the nitrocatechol moiety (e.g. tolcapone and entacapone) are often potent COMT inhibitors. The present study attempted to discover compounds that exhibit dual COMT and MAO-B inhibition by synthesizing series of 1-tetralone, 1-indanone and related derivatives substituted with the nitrocatechol moiety. These compounds are structurally related to series of nitrocatechol derivatives of chalcone that have recently been investigated as potential dual COMT/MAO inhibitors. The results show that 4-chromanone derivative (7) is the most promising dual inhibitor with IC50 values of 0.57 and 7.26 µM for COMT and MAO-B, respectively, followed by 1-tetralone derivative (4d) with IC50 values of 0.42 and 7.83 µM for COMT and MAO-B, respectively. Based on their potent inhibition of COMT, it may be concluded that nitrocatechol compounds investigated in this study are appropriate for peripheral COMT inhibition, which represents an important strategy in the treatment of PD.

Tetralone derivatives are MIF tautomerase inhibitors and attenuate macrophage activation and amplify the hypothermic response in endotoxemic mice.

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine playing crucial role in immunity. MIF exerts a unique tautomerase enzymatic activity that has relevance concerning its multiple functions and its small molecule inhibitors have been proven to block its pro-inflammatory effects. Here we demonstrate that some of the E-2-arylmethylene-1-tetralones and their heteroanalogues efficiently bind to MIF's active site and inhibit MIF tautomeric (enolase, ketolase activity) functions. A small set of the synthesised derivatives, namely compounds (4), (23), (24), (26) and (32), reduced inflammatory macrophage activation. Two of the selected compounds (24) and (26), however, markedly inhibited ROS and nitrite production, NF-κB activation, TNF-α, IL-6 and CCL-2 cytokine expression. Pre-treatment of mice with compound (24) exaggerated the hypothermic response to high dose of bacterial endotoxin. Our experiments suggest that tetralones and their derivatives inhibit MIF's tautomeric functions and regulate macrophage activation and thermal changes in severe forms of systemic inflammation.

Synthesis of new α-Aryl-α-tetralones and α-Fluoro-α-aryl-α-tetralones, preliminary antiproliferative evaluation on drug resistant cell lines and in silico prediction of ADMETox properties.

α-aryl-α-tetralones and α-fluoro-α-aryl-α-tetralones derivatives were synthesized by palladium catalyzed α-arylation reaction of α-tetralones and α-fluoro-α-tetralones, with bromoarenes in moderate to good yields. These compounds were evaluated for their in vitro anti-proliferative effects against human breast cancer and leukemia cell lines with diverse profiles of drug resistance. The most promising compounds, 3b, 3c, 8a and 8c, were effective on both neoplastic models. 3b and 8a induced higher toxicity on multidrug resistant cells and were able to avoid efflux by ABCB1 and ABCC1 transporters. Theoretical calculations of the physicochemical descriptors to predict ADMETox properties were favorable concerning Lipinski's rule of five, results that reflected on the low effects on non-tumor cells. Therefore, these compounds showed great potential for development of pharmaceutical agents against therapy refractory cancers.

The evaluation of 1-tetralone and 4-chromanone derivatives as inhibitors of monoamine oxidase.

Monoamine oxidase (MAO) is of much clinical relevance, and inhibitors of this enzyme are used in the treatment for neuropsychiatric and neurodegenerative disorders such as depression and Parkinson's disease. The present study synthesises and evaluates the MAO inhibition properties of a series of 33 1-tetralone and 4-chromanone derivatives in an attempt to discover high-potency compounds and to expand on the structure-activity relationships of MAO inhibition by these classes. Among these series, eight submicromolar MAO-A inhibitors and 28 submicromolar MAO-B inhibitors are reported, with all compounds acting as specific inhibitors of the MAO-B isoform. The most potent inhibitor was a 1-tetralone derivative (1h) with IC50 values of 0.036 and 0.0011 µM for MAO-A and MAO-B, respectively. Interestingly, with the reduction of 1-tetralones to the corresponding alcohols, a decrease in MAO inhibition potency is observed. Among these 1-tetralol derivatives, 1p (IC50 = 0.785 µM) and 1o (IC50 = 0.0075 µM) were identified as particularly potent inhibitors of MAO-A and MAO-B, respectively. Potent compounds such as those reported here may act as leads for the future development of MAO-B specific inhibitors. The present study describes the MAO inhibitory activities of a series of 1-tetralone and 4-chromanone derivatives. Numerous high-potency MAO-B specific inhibitors were identified.

Synthesis and Antiproliferative Evaluation of Novel Longifolene-Derived Tetralone Derivatives Bearing 1,2,4-Triazole Moiety.

Seventeen novel 2-(5-amino-1-(substituted sulfonyl)-1H-1,2,4-triazol-3-ylthio)-6- isopropyl-4,4-dimethyl-3,4-dihydronaphthalen-1(2H)-one compounds were synthesized from the abundant and naturally renewable longifolene and their structures were confirmed by FT-IR, NMR, and ESI-MS. The in vitro cytotoxicity of the synthesized compounds was evaluated by standard MTT assay against five human cancer cell lines, i.e., T-24, MCF-7, HepG2, A549, and HT-29. As a result, compounds 6d, 6g, and 6h exhibited better and more broad-spectrum anticancer activity against almost all the tested cancer cell lines than that of the positive control, 5-FU. Some intriguing structure-activity relationships were found and are discussed herein by theoretical calculation.

Hydroethanolic extract of Juglans regia L. green husks: A source of bioactive phytochemicals.

Juglans regia L. (walnut) green husks are an important fraction of waste resulting from the walnut production, thus representing an interesting natural matrix to explore as a source of bioactive compounds. In this work, the hydroethanolic extract of walnut green husks was studied considering the phytochemical composition and the biological activity using different cell model assays, most of them evaluated for the first time for this matrix. From the HPLC-DAD-ESI/MSn analysis, sixteen compounds were identified, being the extract mostly composed of naphthalene derivatives (including tetralone derivatives) and less abundant in phenolic compounds (hydroxycinnamic acids and flavonols). The cytotoxic potential of the extract was assessed against tumour (MCF-7, NCI-H460, HeLa and HepG2) and non-tumour (PLP2) cell lines. Moreover, the antioxidant activity of the extract was evaluated by inhibition of the oxidative haemolysis (OxHLIA) and the formation of thiobarbituric acid reactive substances (TBARS), and the anti-inflammatory potential by the inhibition of the NO production by the RAW264.7 cell culture. The antibacterial effects of the extract were also evaluated against Gram-negative and Gram-positive bacteria. The results obtained represent a stepping stone for the development of future applications using walnut green husks as a source of added value compounds with bioactive potential.

A novel open-tubular capillary electrochromatography using carboxymethyl-ß-cyclodextrin functionalized gold nanoparticles as chiral stationary phase.

Enantioselective open tubular capillary electrochromatography with carboxymethyl-ß-cyclodextrin conjugated gold nanoparticles as stationary phase was developed. This novel open tubular column was fabricated through layer-by-layer self-assembly of gold nanoparticles on a 3-mercaptopropyl-trimethoxysilane-modified fused-silica capillary and subsequent surface functionalization of the gold nanoparticles through self-assembly of 6-mercapto-ß-cyclodextrin. The 6-mercapto-ß-cyclodextrin was firstly synthesized and determined by extensive spectroscopic data. Scanning electron microscopy, energy dispersive X-ray analysis spectroscopy, and electroosmotic flow experiments were carried out to characterize the prepared open tubular column. Then, the separation effectiveness of the open tubular column was verified by two pairs of ɑ-tetralones derivatives enantiomers and two pairs of basic drug enantiomers (tramadol hydrochloride and zopiclone) as mode analytes. Factors that influence the enantioseparation were optimized, and under the optimized conditions, satisfactory separation results were obtained for the four enantiomers: compound A, compound B, tramadol hydrochloride, and zopiclone with resolutions of 3.79, 1.56, 1.03, 1.60, respectively. For the combination of gold nanoparticles and negatively charged carboxymethyl-ß-cyclodextrin, the open tubular column exhibited wider separation range for neutral and basic drugs. Moreover, the repeatability and stability of the column were studied through the run-to-run and day-to-day investigations.

α-Tetralone glycosides from the green walnut husks of Juglans mandshurica Maxim. and their cytotoxic activities.

Five new α-tetralone glycosides, juglanbiosides A-E (1-5), together with an α-tetralone derivative (15) and nine known 1,4-naphthoquinones (6-14) were isolated from the 95% EtOH extract of green walnut husks of Juglans mandshurica Maxim. Their structures were elucidated by comprehensive spectroscopic methods (1H, 13C NMR, DEPT, HSQC, HMBC, CD, HR-ESI-MS). In vitro cytotoxicities of all the isolated compounds were evaluated against BGC-823, HCT-15 and K562 cancer cell lines.[Formula: see text].

Intramolecular Büchner Reaction and Oxidative Aromatization with SeO2 or O2.

Intramolecular Büchner reaction of 1-diazo-5-phenylpentan-2-ones followed by oxidation with SeO2 or O2 in the presence of silica gel regioselectively gave 8-formyl-1-tetralones or one-carbon-lacking 1-tetralones, respectively.

Introduction of amino moiety enhances the inhibitory potency of 1-tetralone chalcone derivatives against LPS-stimulated reactive oxygen species production in RAW 264.7 macrophages.

The design and synthesis of a series of thirty-two halogenated 1-tetralone or 6-amino-1-tetralone chalcone derivatives was achieved by the Claisen-Schmidt condensation reaction and were evaluated for their inhibitory effects against ROS production in LPS-stimulated RAW 264.7 macrophages. It was observed that the introduction of amino moiety into 1-tetralone skeleton greatly increased the inhibitory potency compared to corresponding 1-tetralone chalcones. Among the synthesized compounds, compound 18 which consists of 6-amino-1-tetralone skeleton together with o-fluorobenzylidene showed the most potent ROS inhibitory effect with IC50 value of 0.25 ±â€¯0.13 µM. SAR analysis revealed that amino moiety at the 6th position of 1-tetralone chalcones have an important role for exerting the greater ROS inhibitory potency in LPS-stimulated RAW 264.7 macrophages than those exhibited by 1-tetralone chalcones alone.

2-Benzylidene-1-Indanone Analogues as Dual Adenosine A1/A2a Receptor Antagonists for the Potential Treatment of Neurological Conditions.

Previous studies explored 2-benzylidine-1-tetralone derivatives as innovative adenosine A1 and A2A receptor antagonists for alternative non-dopaminergic treatment of Parkinson's disease. This study's aim is to investigate structurally related 2-benzylidene-1-indanones with substitutions on ring A and B as novel, potent and selective adenosine A1 and A2A receptor blockers. 2-Benzylidene-1-indanone derivatives were synthesised via acid catalysed aldol condensation reactions and evaluated via radioligand binding assays to ascertain structure activity relationships to govern A1 and A2A AR affinity. The results indicated that hydroxy substitution at C4 of ring A and meta (3'), or para (4') substitution on ring B of the 2-benzylidene-1-indanone scaffold (2C: ) is preferred over substitution at C5 (2D: ) or C6 (2E: ) of ring A for adenosine A1 receptor activity and selectivity in the micromolar range. Furthermore, substitution at the meta (3') position of ring B with chlorine lead to the highly potent and selective adenosine A2A receptor antagonist, compound 2 H: . Compound 2C: and the 2Q: behaved as adenosine A1 receptor antagonists in the performed GTP shift assays. In view of these findings, compounds 2C: , 2 H: , 2Q: and 2P: are potent and selective adenosine A1 and A2A receptor antagonists for the potential treatment of neurological conditions.

Two new tetralone glycosides from the green walnut husks of Juglans mandshurica Maxim.

Two new tetralone glycosides, 4(S)-5-methoxy juglanoside A (1), 4(S)-5-methoxy juglanoside D (2), together with ten known compounds (3-12) have been isolated from the green walnut husks of Juglans mandshurica Maxim. Their structures were elucidated on the basis of their ESI-MS, 1 D and 2 D NMR spectroscopic data. In addition, all compounds were evaluated for their cytotoxic activities against the cancer BGC-823 (human gastric carcinoma), HCT-15 (human colorectal carcinoma) and K562 (human chronic myeloid leukemia) cell lines. The results showed aglycones of naphthoquinones had stronger cytotoxic activities than glycosides of tetralone.

Three new tetralol analogs from soil-derived fungus Myrothecium verrucaria with anti-inflammatory activity.

Three new tetralol analogs, myrochromanols A-C (1-3), together with 11 known trichothecenes (4-14), were isolated from a soil fungus Myrothecium verrucaria HL-P-1. The structures of the three new compounds were elucidated by extensive spectroscopic analysis including HRESIMS, NMR, and ECD calculation. All of the new compounds were tested for their anti-inflammatory activity and cytotoxicity. Compounds 1 and 3 inhibited lipopolysaccharide (LPS)-induced NO production in BV2 cells with IC50 values of 26.04 and 25.80 µM, respectively.

New tetralone derivatives from the leaves of Cyclocarya paliurus.

Two new tetralone derivatives, named cyclopalosides A (1) and B (2), were isolated from the leaves of Cyclocarya paliurus by column chromatography on silica gel, reversed-phase C18 silica gel and preparative HPLC. Their chemical structures were established on the basis of extensive analyses of spectroscopic data. Their structural characteristic is tetralone glycoside with a caffeoyl unit. The antioxidant activities of compound 1 were evaluated by using hydroxyl, superoxide anion, and DPPH radical scavenging assay.

Synthesis and Evaluation of 2-benzylidene-1-tetralone Derivatives for Monoamine Oxidase Inhibitory Activity.

BACKGROUND: Chalcone has been identified as a promising lead for the design of Monoamine Oxidase (MAO) inhibitors. This study attempted to discover potent and selective chalcone-derived MAO inhibitors by synthesising a series consisting of various cyclic chalcone derivatives. The cyclic chalcones were selected based on the possibility that their restricted structures would confer a higher degree of MAO isoform selectivity, and included the following chemical classes: 1-indanone, 1- tetralone, 1-benzosuberone, chromone, thiochromone, 4-chromanone and 4-thiochromanone. METHODS: The cyclic chalcone derivatives were synthesised via a one-pot Claisen-Schmidt condensation reaction. The MAO inhibitory properties of the chalcone derivatives were evaluated with the recombinant human MAO-A and MAO-B enzymes and the potencies were expressed as the IC50 values. A selected inhibitor was docked into an active site model of MAO-B. RESULTS: The results showed that the cyclic chalcones are in general good potency, and in most instances specific inhibitors of the MAO-B isoform. Among these compounds, the 4-chromanone derivative was the most potent MAO-B inhibitor with an IC50 value of 0.156 µM. To further investigate the MAO inhibition of cyclic chalcones, a series of twenty-three 2-benzylidene-1-tetralone derivatives were synthesised and evaluated as MAO inhibitors. Most 2-benzylidene-1-tetralones possess good inhibitory activity and specificity for MAO-B with the most potent inhibitor displaying an IC50 value of 0.0064 µM, while the most potent MAO-A inhibitor possessed an IC50 value of 0.754 µM. CONCLUSION: This study thus shows that certain cyclic chalcones are human MAO-B inhibitors, compounds that could be suitable for the treatment of neurodegenerative disorders such as Parkinson's disease.

Total Synthesis and Structural Determination of XR774, a Tyrosine Kinase Inhibitor.

Total synthesis and structural determination of XR774 has been accomplished. The benzo[ j]fluoranthene skeleton has been constructed by regioselective coupling between tetraline 3 and tetralone 4 successively followed by the sequential transformation including the Birch reduction to prepare allylic alcohol, simultaneous bromination of vinylic and aromatic moieties, and the nickel-mediated intramolecular coupling reaction. The optical resolution of racemic 17 led to the first total synthesis of (-)-XR774.

Design, Synthesis, and Evaluation of (2-(Pyridinyl)methylene)-1-tetralone Chalcones for Anticancer and Antimicrobial Activity.

BACKGROUND: Chalcones, natural products produced by plants as a natural defense mechanisms against various pathogens, are molecules with structures that include two aromatic rings joined by an α, ß unsaturated carbonyl system. Previous research has demonstrated that chalcones exhibit a wide variety of biological activities, including anticancer, antifungal, and antibiotic properties. OBJECTIVE: Our goal is to synthesize novel heterocyclic-containing chalcones and have their biological activities evaluated. Methods Sixteen chalcones were synthesized by the crossed aldol condensation of substituted tetralones with substituted pyridinylaldehydes. The products were purified by recrystallization in MeOH/H2O and characterized by 1H NMR, 13C NMR, and HRMS. Anticancer assays were performed by NCI (National Cancer Institute) against the NCI-60 panel of 60 different human cancer cell lines, including leukemia, non-small-cell lung cancer, colon, central nervous system, melanoma, ovarian, renal, prostate, and breast cancer. Antimicrobial assays were performed by COADD (Community for Open Antimicrobial Drug Discovery) against Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Cryptococcus neoformans var. grubii, and Candida albicans. RESULT: Chalcone 3d had demonstrated growth inhibition greater than 60% against a variety of cancers: leukemia (MOLT-4, SR), non-small cell lung cancer (NCI-H522), colon cancer (HCT- 116), prostate cancer (DU-145), and breast cancer (MCF7, MDA-MB-468) and was also cytotoxic to three different cell lines (CCRF-CEM, RPMI-8226, and KM12). 5c was active against leukemia (CCRF-CEM, RPMI-8226, SR) and breast cancer (MCF7) and 5e was active only against leukemia (RPMI-8226, SR). 5h was partially active and the best compound with growth inhibition of MRSA by 75%. 3b was the best compound against EC, KP, and PA and 3f had the greatest activity against AB. For fungi, 3f and 3e demonstrated the best growth inhibition. CONCLUSION: A small library of heterocyclic-containing chalcones was developed and initial screening demonstrates modest activity against cancers, bacteria, and fungi.