Anthraquinone Dimers Research Articles

Chemical constituents of Rumex dentatus L. and their antimicrobial and anti-inflammatory activities

Antimicrobial bioactivity-guided isolation of the root extract of Rumex dentatus L. resulted in the characterization of nineteen natural products, including three undescribed compounds (rumexs A−C). Rumexs A and B are rare anthraquinone-anthrone dimers consisting of an emodin-10-C-glycoside linked via C-10 to C-7 of a chrysophanol moiety. They differed only in their configuration at C-10; their absolute configurations were determined by NOESY and ECD analysis. LC-HRMS analysis was performed to identify nineteen compounds. Anthraquinone derivatives such as anthraquinone aglycone, oxanthrone C-glycoside, anthraquinone O-glycoside and anthraquinone dimer were found to be the dominant components of R. dentatus. In addition, naphthol, naphthoquinone, chromone, flavonoid, isocoumarin, and lignanamide derivatives were also identified. Chrysophanol and emodin were the most abundant compounds in the crude ethanol extract; their contents were determined by HPLC to be 7.38 and 5.74 mg/g, respectively. The fractions and isolated compounds were tested for their inhibitory activity against Staphylococcus aureus, Candida albicans, and Escherichia coli. Most of them showed inhibitory activity against S. aureus, some fractions and 2-methoxy-6-acetyl-7-methyljuglone exhibited moderate inhibitory activity against C. albicans, and 2-methoxy-6-acetyl-7-methyljuglone had moderate inhibitory effects against E. coli. Emodin exhibited inhibitory activity against NO release in LPS-reduced RAW264.7 cells in a concentration-dependent manner.

An All-Atom Theory of Electron Transfer at Nanocrystal/Molecule Interfaces: A Hybrid LCAO/DFT Approach

Interfacial electron transfer (IET) probabilities and rates between CdSe and CdS nanocrystals of diameters 2, 4, and 6 nm, and an anthraquinone dimer (AQ2H+), have been studied. To account for elec...

An Insoluble Anthraquinone Dimer with Near-Plane Structure as a Cathode Material for Lithium-Ion Batteries.

Conjugated carbonyl-based organic electrode materials for lithium-ion batteries have gained increasing interests owing to their many advantages such as resource abundance and sustainable development. However, serious dissolution in organic liquid electrolytes is often encountered, resulting in inferior electrochemical performance such as poor cycling stability. Herein, a new molecular design strategy was developed to address the dissolution issue of 9,10-anthraquinone (AQ). An AQ dimer with near-plane molecular structure, 1,4-bis(9,10-anthraquinonyl)benzene (BAQB), was facilely synthesized. The near-plane structure was proved by DFT calculations. It was found that the obtained BAQB was insoluble in ether electrolyte. Compared to AQ, BAQB displayed remarkably enhanced cycling stability. After 100 cycles at 0.2 C, a high capacity retention of 91.6 % was achieved (195 mAh g-1 ). BAQB also exhibited excellent rate performance (138 mAh g-1 at 10 C). The results demonstrate the effectiveness of the near-plane molecular design concept. This work provides a new idea for rational molecular design to inhibit the dissolution of conjugated carbonyl-based organic electrode materials.

An investigation of the inhibitory mechanism of α-glucosidase by chysalodin from Aloe vera

The aim of our study is to provide new type skeleton of α-glucosidase inhibitor from food source. A new 6′-O-(E)–cinnamoyl-7-methoxy-aloin A (1) was isolated from Aloe vera. Also, known chysalodin (2) was the first report for A. vera. These structures were identified with based on HR-ESI Mass and 1/2D-NMR spectra. These isolated compounds were tested for their inhibitory activities against α-glucosidase by using spectrophotometer. Of these, compound 2 exhibited inhibitory activity, with an IC50 value of 13.4 ± 1.5 μM. An enzyme kinetic study identified the mechanism of binding of the ligand with the enzyme; the ligand binds in the active site of the enzyme in a competitive mode. Additionally, fluorescence quenching between the ligand and receptor revealed a two-to-one reaction. Finally, this finding provides that anthraquinone dimer (2) could be a starting point for the design of new class of α-glucosidase inhibitor.

Antibacterial anthraquinone dimers from marine derived fungus Aspergillus sp

As a continue investigation of the bioactive secondary metabolites from marine derived fungi, two new anthraquinone dimers (1, 2), along with three known anthraquinones (3–5) and two known xanthones (6, 7) were isolated from the marine-derived fungus Aspergillus versicolor. Their structures, including the absolute configurations, were elucidated by NMR, HRMS, and comparison with reported ones. Among them, compounds 1 and 2 were identified as anthraquinone dimers which dimerized by a rare C-O-C ether linkage, and both of them showed selective antibacterial activity against Gram-positive Staphylococcus aureus; whilst compound 6 exhibited moderate cytotoxicity against human cancer cell lines.

Synthesis and crystal structure of a wheel-shaped supramolecular coordination complex

Supramolecular coordination complex (SCC) possessing spatially arranged three anthraquinone dimers in a slipped-cofacial orientation was achieved by the treatment of Re2(CO)10, 2-hydroxymethylanthraquinone and tritopic N-donor via fac-Re(CO)3-directed one pot approach. The off-set π-stacking and C≡O···H bonding interactions stabilize the ring structure.

Redox Active Oligomers Synthesized from Anthraquinone for Use in Rechargeable Lithium Batteries

Using redox active organic materials, that contain no scarce metal resources, as a positive-electrode active material instead of conventionally used rare-metal oxides can be a solution to the resource problem of the current rechargeable lithium batteries. Several types of organic positive-electrode materials have been proposed. Among them, low-molecular-weight crystalline organic compounds have been drawing attentions recently, since these compounds tend to show high utilization ratios during the charge/discharge processes. 9,10-Anthraquinone (AQ) (Fig. 1a), one of those low-molecular-weight crystalline organic compounds, also shows a capacity close to its theoretical value [1,2]; however, the electrode using AQ tends to seriously degrade upon cycling because of the dissolution of the redox-related molecules into the electrolyte solution during cycling.To suppress the dissolution and to improve their cycle stability, we focused our attention on the oligomerization technique. In this study, an anthraquinone dimer and a trimer connected by the -C≡C- bonds (Figs. 1b and 1c) were newly synthesized using the Sonogashira cross-coupling reaction; and their performances as positive-electrode active materials were compared with the AQ-monomer. The positive electrodes using the dimer and trimer as active materials showed initial discharge capacities of about 200 mAh/g, with the average voltages of 2.2-2.3 V vs. Li+/Li. These values are close to those of the AQ monomer, suggesting the two-electron redox reaction per AQ unit. Fig. 2 compares the cycle-life performances of the electrode using the AQ-monomer, dimer, and trimer. While the capacity of the AQ-monomer electrode rapidly decreased, the synthesized dimer and trimer showed better cycle stabilities. In particular, the trimer retained almost a constant capacity during 50 cycles without drastic decay. The oligomerization of the AQ units effectively reduces the solubility. The present study revealed that oligomerization of the redox active molecular units was an effective way to extend the cycle-life without losing the discharge capacity.

Cytotoxic anthraquinone dimers from Melandrium firmum

Two new anthraquinone dimers, melrubiellin A (1) and melrubiellin B (2), were isolated from the aerial part of Melandrium firmum Rohrbach, along with seven known compounds (3-9). The structures of these compounds were elucidated by spectral analyses, including 1D and 2D NMR (COSY, HMQC, HMBC and NOESY) experiments. Compound 1 and 2 exhibited significant cytotoxicity towards HeLa, NCI-H460, Hep G2, Hep 3B and MKN-28 cell lines with IC50 values ranging from 5.26 to 81.16 μM.

Two new anthraquinone dimers from the stem bark of Pentas schimperi (Rubiaceae)

Two new anthraquinone dimers, schimperiquinones A (1) and B (2), together with the known 2-hydroxymethylanthraquinone (3), cleomiscosin A (4), oleanolic acid (5) and sitosterol 3-O-β-d-glucoside (6) were isolated from the stem bark of Pentas schimperi. Their structures were elucidated on the basis of spectroscopic analysis and comparison with published data or by comparison with authentic samples. To the best of our knowledge, it is the first report of cleomiscosin A, a coumarinolignan from the genus Pentas. Compound 2 exhibited in vitro cytotoxicity (IC50=33.05μM) against the human cancer cell the BGC-823.

Divergent Approach to the Bisanthraquinone Natural Products: Total Synthesis of (S)-Bisoranjidiol and Derivatives from Binaphtho-para-quinones

The development of the first asymmetric synthesis of a chiral anthraquinone dimer is outlined, resulting in the first total synthesis of (S)-bisoranjidiol. Rather than a biomimetic dimerization retrosynthetic disconnection, the anthracenyl ring systems are generated after formation of the axially chiral binaphthalene framework. This synthetic strategy has enabled the synthesis of several analogues. Key features of the synthesis include the enantioselective coupling of a hindered 2-naphthol containing substitution peri to the site of C-C bond formation, the regioselective oxidation of 8,8'-hydroxylated binaphthols to binaphtho-para-quinones, and a tandem regioselective Diels-Alder/aromatization reaction.

Two new anthraquinone dimers from the fruit bodies of Bulgaria inquinans

Two new dimeric anthraquinone derivatives, bulgareone A(1) and bulgareone B(2), were isolated from the fruit bodies of Bulgaria inquinans. Their structures were elucidated on the basis of extensive spectroscopic analysis. The in vitro cytotoxic activity of compounds 1 and 2 was assayed. They displayed inhibitive activities against human cancer cell lines HL60 and K562.

Bioactive anthraquinone dimers from the leafhopper pathogenic fungus Torrubiella sp. BCC 28517

Torrubiellins A (1) and B (2), two new dimeric anthraquinones were isolated from the leafhopper pathogenic fungus Torrubiella sp. BCC 28517. The structures of the new compounds were elucidated by analyses of the NMR spectroscopic and mass spectrometry data. Torrubiellin B (2) exhibited broad range of biological activities.

平面型1-氯蒽醌二聚体中分子间弱相互作用的理论研究

The geometries of planar 1-chlorine anthraquinone dimers were optimized at B3LYP/6-311G(d,p) and six stable dimers were gotten. The interaction energies and corrected BSSE were calculated at MP2/6-311+G(d,p). The nature of intermolecular bonds in 1-chlorine anthraquinone dimers were discussed based on the molecular electrostatic potential. The electron density topological analysis of intermolecular bonds were investigated by “Atoms in Molecules” theory. The calculated results indicates that the intermolecular bonds in 1-chlorine anthraquinone dimers are all weak interactions with electrostatic properties; The interactions in parallel configurations are stronger than those in T-shape configurations; The electrostatic changes of electron-acceptors could be used as a measure of the strength of intermolecular bonds.

A new triglucosylated naphthalene glycoside from Aloe vera L.

A new triglucosylated naphthalene derivative, named aloveroside A ( 1), together with two known anthraquinone dimers and two 6-phenyl-2-pyrone derivatives, was isolated from the Aloe vera ethanolic extracts. The structure of 1 was established as 1-(((4-(1- O-β-D-glucopyranosyl -(1→4)-β-D-xylopyranoside)-hydroxymethyl)-1-hydroxy-8- O-α-L-rhamnopyranoside)naphthalene-2-yl)-ethanone by means of spectroscopic evidences and chemical methods. All these compounds were tested for their BACE inhibitory activity but no significant activities were found.

New anthraquinone derivatives from the roots of Berchemia floribunda

A new naphthoquinone–anthraquinone dimer named floribundiquinone E ( 1) and a new anthraquinone 2-acetylphyscion ( 2) were isolated from the roots of Berchemia floribunda Brongn. Their structures were elucidated on the basis of spectroscopic methods.

Cytotoxicity against insect cells of entomopathogenic fungi of the genera Hypocrella (anamorph Aschersonia): possible agents for biological control

Extracts from entomopathogenic fungi of the genus Hypocrella (7 species) and its anamorph Aschersonia (11 species) were screened for cytotoxicity to Sf9 and C6/36 insect cells and L929, BHK(21)C13 and HepG2 mammalian cells. Cytotoxic extracts to insect cells (ID50's < or = 10 microg ml(-1)) but not to mammalian cells (ID50's > or = 10 microg ml(-1)) conformed to the criteria of the project and were considered 'lead' extracts for further investigation. 'Leads' were found in two of the Hypocrella species: H. discoidea, and H. tamurai and in three of the Aschersonia species: A. samoensis, A. badia, and A. tamurai. Bioassay-guided fractionation of the cell extract of the fungus A. samoensis BCC 1393 led to the identification of two known anthraquinone dimers, (+)rugulosin (1) and skyrin (2) which showed selective toxicity towards insect cells. (+)Rugulosin (1) and skyrin (2) exhibited strong cytotoxic activity against the insect cell line Sf9 with respective ID50 values of 1.2 and 9.6 microg ml(-1), but showed weak activity toward mammalian cells. This first report of (+)rugulosin (1) and skyrin (2) in A. samoensis is confirmed and demonstrated in another four strains of A. samoensis isolated in Thailand. The preferential cytotoxicity against Sf9 insect cells gives evidence that these insect-pathogenic fungi of the Hypocrella/Aschersonia group might be useful as an agent for pest control.

Anthraquinones as a new class of antiviral agents against human immunodeficiency virus

Various anthraquinones substituted with hydroxyl, amino, halogen, carboxylic acid, substituted aromatic group, and sulfonate were tested to determine their activity against human immunodeficiency virus type 1 (HIV-1) in primary human lymphocytes. Among the compounds tested, polyphenolic and/or polysulfonate substituted anthraquinones were found to possess the most potent antiviral activity. Hypericin, an anthraquinone dimer previously shown to have activity against nonhuman retroviruses also exhibited anti-HIV-1 activity in lymphocytes. Some of the active anthraquinones inhibited HIV-1 reverse transcriptase. However, this enzyme inhibition was selective only for 1,2,5,8-tetrahydroanthraquinone and hypericin. Hypericin interacts nonspecifically with protein suggesting that this effect may dictate its inhibitory activity against the viral reverse transcriptase.

Multifunctional analysis of the interaction of anthralin and its metabolites anthraquinone and anthralin dimer with the inner mitochondrial membrane

We studied the interaction of the antipsoriatic compound anthralin (1.8-dihydroxy-9-anthrone), and its metabolites anthraquinone (1.8-dihydroxy-9.10-anthraquinone) and anthralin dimer (1.8.1'.8'.-tetrahydroxy-10.10'-bis-9[10]-dianthrone) with the inner mitochondrial membrane. Mitochondrial membrane functions such as ubiquinone redox equilibria, redox status of iron sulfur clusters, cyanide-sensitive and cyanide-insensitive oxygen consumption, adenosine triphosphate (ATP) synthesis, ATP hydrolysis, and adenine nucleotide content of mitochondria were analyzed. Anthralin is an inhibitor of mitochondrial oxygen uptake in the presence of ADP and substrate (cyanide-sensitive respiration), inhibits ATP synthesis without affecting ATP hydrolysis, and depletes mitochondria of ATP. Anthralin dimer is a much weaker inhibitor of mitochondrial functions and anthraquinone is almost inactive. Anthralin, but not anthraquinone and anthralin dimer, reverses uncoupler stimulated oxygen consumption, stimulates cyanide-insensitive respiration, reduces mitochondrial ubiquinone-9 and -10 to the corresponding ubiquinols and reduces mitochondrial iron sulfur clusters. Anthralin may induce formation of reactive oxygen species by enhancing autoxidation of mitochondrial components and/or by catalyzed oxidation of anthralin. Taken together, anthralin acts as an electron donor to inner mitochondrial membrane associated redox components, inhibits the electron transport chain, and has an oligomycin-like effect. Anthralin dimer and anthraquinone do not function as electron donors and act by a different reaction mechanism. Respiratory measurements in human keratinocytes revealed similar results as obtained with isolated mitochondria. We suggest that modulation of membrane redox status may be a common concept of anthralin action in target cells such as keratinocytes and neutrophils.