Novel Macrocycles. Part 6. Synthesis, Structures and Cation Binding from Optical Spectroscopy of 9,10-Anthraquinone-crown Ethers

The 9,10-anthraquinone-[12]crown-4, [15]crown-5 and [18]crown-6 derivatives were synthesized from 1,2-dihydroxy-9,10-anthraquinone and 1,8-dihydroxy-9,10-anthraquinone which were condensed with dihalides or ditosylates of polyethylene glycols in alkali carbonate/DMSO. The 9,10-anthraquinone derived polyoxacyclo-alkanes were characterized with IR, mass spectrometry, ¹H, ¹³C spectroscopy and elemental analysis. The cation binding properties were studied with UV-vis spectroscopy. The association constants found in acetonitrile were selectively dependent on the cation radius and macrocycle size as well as the molecular structures. The observed results from UV-vis studies, however, showed the stronger complexing role of 1,2-derived macrocycles compared to those of 1,8-derivatives. The theoretical conformational analysis and the energy optimisations of the 9,10-anthraquinone-macrocycles carried out with MM+ method explained the binding results.     

Metal Complexes with 1,5- and 1,8-Dihydroxy-9,10-Anthraquinones: Electronic Absorption Spectra and Structure of Ligands

Metal complexes with 1,5-dihydroxy-9,10-anthraquinone are studied by the spectrophotometric, quantum-chemical, and correlation methods. It was established that the ligand in these complexes can occur in seven excited states that differ not only in the ionization degree but also in the prevailing contribution of the tautomeric 9,10-, 1,10-, and 1,5-anthraquinoid structures. In all known complexes with 1,8-dihydroxy-9,10-anthraquinone and singly ionized ligand, this ligand has the 1,10-anthraquinoid structure; in complexes with the doubly ionized ligand, the latter ligand most often has the 9,10-anthraquinoid structure. The known complexes are classified according to the ligand structures.     

1,8-二羟基-9,10-二氢蒽的合成

以1,8-二羟基蒽醌为原料,经甲醚化,锌粉和金属钠还原,去甲基等4步反应合成1,8-二羟基-9,10-二氢蒽,总产率为37.1,8-二甲氧基蒽醌用NaBH₄/CF₃COOH还原生成二聚产物,并测定了其单晶结构.     

Iridoids and anthraquinones from the Malaysian medicinal plant,Saprosma scortechinii (Rubiaceae)

A further investigation of the leaves and stems of Saprosma scortechinii afforded 13 compounds, of which 10 are new compounds. These were elucidated as the bis-iridoid glucosides, saprosmosides G (1) and H (2), the iridoid glucoside, 6-O-epi-acetylscandoside (3), and the anthraquinones, 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone (4), 1-methoxy-3-hydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-beta-primeveroside (5), 1,3-dihydroxy-2-carbomethoxy-9,10-anthraquinone 3-O-beta-primeveroside (6), 1,3,6-trihydroxy-2-methoxymethyl-9,10-anthraquinone (7), 1-methoxy-3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (8), 1,3,6-trihydroxy-2-hydroxymethyl-9,10-anthraquinone 3-O-beta-primeveroside (9), and 3,6-dihydroxy-2-hydroxymethyl-9,10-anthraquinone (10). Structure assignments for all compounds were established by means of mass and NMR spectroscopies, chemical methods, and comparison with published data. The new anthraquinones were derivatives of munjistin and lucidin.     

Anthraquinones from the roots of Prismatomeris malayana

A novel anthraquinone, 1,3-dihydroxy-5,6-dimethoxy-2-methoxymethyl-9,10-anthraquinone (9) and a new natural product, 2-hydroxymethyl-1-methoxy-9,10-anthraquinone (8) were isolated from the roots of Prismatomeris malayana together with seven known anthraquinones, tectoquinone (1), 1-hydroxy-2-methyl-9,10-anthraquinone (2), rubiadin (3), rubiadin-1-methyl ether (4), 1,3-dihydroxy-5,6-dimethoxy-2-methyl-9,10-anthraquinone (5), nordamnacanthal (6), and damnacanthal (7). Their structures were determined on the basis of spectroscopic data. Some of the anthraquinones were tested for anticancer, antifungal, and antimalarial activities.     

Simultaneous quantitation of 1,8,9-anthracenetriol, 1,8-dihydroxy-9,10-anthraquinone, and 1,8,1',8'-tetrahydroxy-10,10'-dianthrone by reversed-phase high-performance liquid chromatography

A sensitive and specific reversed-phase high-performance liquid chromatographic method was developed for the simultaneous analysis of anthralin (1,8,9-anthracenetriol) and its known degradation products: quinone (1,8-dihydroxy-9,10-anthraquinone) and dimer (1,8,1',8'-tetrahydroxy-10,10'-dianthrone). The method provides for rapid and simple quantitation of nanogram amounts of the three compounds. The molar absorptivities for anthralin in different solvents and solvent systems, including the mobile phase, are presented.     

Solubilities of some recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives in supercritical carbon dioxide

The solubility of four recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives, as potential complexing agents in some extraction and membrane transport experiments, have been measured in supercritical carbon dioxide. The measurements were carried out in the pressure range 120-400 atm at temperatures 35, 45, 55, 65, and 75 degrees C. The measured solubilities were correlated using the model proposed by Chrastil. The calculated results show good agreement with the experimental data.     

Lead ion-selective membrane electrodes based on some recently synthesized 9,10-anthraquinone derivatives

Four different 9,10-anthraquinone derivatives were studied to characterize their abilities as lead ion carrier in PVC membrane electrodes. The electrode based on 1,8-dihydroxy-2,7-bis(prop-2′-enyl)-9,10-anthraquinone exhibits a Nernstian response for Pb²⁺ ions over a wide concentration range (2.0×10⁻³–2.0×10⁻⁶ M). The response time of the sensor is 30 s and the membrane can be used for more than four months without observing any deviation. The electrode revealed comparatively good selectivities with respect to alkali, alkaline earth and some transition and heavy metal ions. It was used as an indicator electrode in potentiometric titration of sulfate ions with a lead ion solution.     

Tautomerism of anthraquinones: VIII. Tautomerism and conformations of 1,4-diamino-9,10-anthraquinone

The compound widely known as 1,4-diamino-9,10-anthraquinone is in fact an equilibrium mixture of 4,9-diamino-1,10-anthraquinone and tautomeric imino forms, 10-amino-9-hydroxy-1,4-anthraquinone 1-imine and its conformer, and 4-amino-1-hydroxy-9,10-anthraquinone 9-imine or 4,9-dihydroxy-1,10-anthraquinone diimine. Amino-imino tautomerism and rotational isomerism are responsible for fine structure of the π_l,π*-absorption of the title compound.     

Anthraquinones from the roots of Prismatomeris tetrandra

Three new anthraquinones, 1-hydroxy-2,3-dimethoxy-7-methyl-9,10-anthraquinone, 1,3-dihydroxy-5,6-dimethoxy-2-methyl-9,10-anthraquinone, and 3-hydroxy-1,5,6-trimethoxy-2-methyl-9,10-anthraquinone, along with five known anthraquinones were isolated from the roots of Prismatomeris tetrandra. Their structures were determined on the basis of spectroscopic data.     

Normal coordinate analysis of fused-ring p-quinones: In-plane vibrations of 1,4-naphthoquinone and 9,10-anthraquinone

A normal coordinate analysis of the in-plane vibrations of 1,4-benzoquinone, 1,4-naphthoquinone, 9,10-anthraquinone and their fully deuterated analogues has been performed by using the overlay technique. The 38 parameters Modified Internal Valence Force Field has been successfully derived by combining those available for catacondensed aromatic hydrocarbons and for chlorinated p-benzoquinones. The results of the calculations clear up most of the remaining uncertainties in the vibrational assignments of 1,4-naphthoquinone and 9,10-anthraquinone. The reported force field provides a useful framework on which to base the vibrational analyses of the family of fused-ring p-quinones.     

Anthraquinone pigments from the crinoid Comanthus bennetti

From the crinoid Comanthus bennetti we isolated and characterized five pigments. One is the known 3-(1′-hydroxypropyl)-1,6,8-trihydroxy-9,10-anthraquinone (rhodoptilometrin). The remaining four had not previously been isolated from a natural source: 3-propyl-1,6,8-trihydroxy- 9,10-anthraquinone; 3-propionyl-1,6,8-trihydroxy-9,10-anthraquinone; 3(2′-hydroxypentyl)-1,6,8- trihydroxy-9,10-anthraquinone; and 2-(1′-hydroxypropyl)-1,4,5,7-tetrahydroxy-9,10-anthraquinone.     

Stereoselective synthesis of 1,8- and 1,5-diketo-trans-syn-trans-perhydroanthracenes

A stereOselective conversion of 1,8- and 1,5-diethoxy-9,10-anthraquinone to 1,8- and 1,5-diketo-$\text{trans}$-$\text{syn}$-$\text{trans}$-perhydroanthracenes by successive sodium borohydride, metal-ammonia, and catalytic reductions is described.     

Electronic structure and spectra of linkage isomers of bis(bipyridine)(1,2-dihydroxy-9,10-anthraquinonato)ruthenium(ii) and their redox series

Linkage isomers of bis(bipyridine)(1,2-dihydroxy-9,10-anthraquinonato)ruthenium(II), 1,2- and 1,9-coordinated complexes, and several of their oxidation products have been prepared chemically and/or electrochemically. For the 1,2-coordinated complex, the one- and two-electron oxidized species have been characterized, and for the 1,9-coordinated complex, the one-electron oxidized species has been characterized. The rich redox activity of these complexes leads to ambiguity in assessing the electronic structure. This paper reports EPR spectra of odd-electron species and detailed analyses of electronic spectra and structure of the complexes, based on INDO molecular orbital calculations. Results of calculations on the related 1-hydroxyanthraquinone complex and the free ligands,1,2-dihydroxy-9,10-anthraquinone (alizarin) and 1-hydroxyanthraquinone, are also briefly discussed.     

Interaction of 1,4-Dihydroxy–9,10-Anthraquinone with Calf Thymus DNA: A Comparison with Anthracycline Anticancer Drugs

The anthracycline drugs adriamycin and daunorubicin, efficient in the treatment of various human cancers, form strong intercalation complexes with DNA. The therapeutic efficacy and toxicity of such anticancer drugs are governed by biochemical reactions of the core dihydroxy-9,10-anthraquinone unit. The high cost and toxic side effects of anthracycline drugs limit their use in cancer therapy. For a few decades, efforts have been made to find cheap, less toxic yet efficient analogues of anthracyclines. This work on 1,4-dihydroxy-9,10-anthraquinone (QH₂), a simple analogue of the anthracyclines, was carried out to compare its biochemical properties with anthracyclines. UV-Vis and fluorescence spectroscopic methods were used to analyze interaction of the compound with calf thymus DNA. The data were used to evaluate the binding constant and site size.     

Spectroscopic Analysis of the Interactions of Anthraquinone Derivatives (Alizarin,Alizarin-DA and Alizarin-DA-Fe) with Bovine Serum Albumin (BSA)

In this paper, three anthraquinones (alizarin (1,2-dihydroxy-9,10-anthraquinone), alizarin-DA (1,2-dihydroxy-9,10-anthraquinone-3-aminomethyl-N,N-diacetic acid) and alizarin-DA-Fe (1,2-dihydroxy-9,10-anthraquinone-3-aminomethyl-N,N-diacetate-ferric(III))) with a tricyclic anthraquinone planar structure are used as quenchers, to study their interaction with bovine serum albumin (BSA) molecules by fluorescence spectroscopy. The results show that these three anthraquinones can bind to BSA molecules efficiently but the stabilities decrease in the order alizarin, alizarin-DA and alizarin-DA-Fe. In addition, synchronous fluorescence spectroscopy indicates that the tryptophan (Trp) residues of BSA molecules are more accessible to alizarin and alizarin-DA than the tyrosine (Tyr) residues, but both have similar accessibility to alizarin-DA-Fe.     

Anthraquinones with antiplasmodial activity from the roots of Rennellia elliptica Korth. (Rubiaceae)

Dichloromethane root extract of Rennellia elliptica Korth. showed strong inhibition of Plasmodium falciparum growth in vitro with an IC?? value of 4.04 μg/mL. A phytochemical study of the dichloromethane root extract has led to the isolation and characterization of a new anthraquinone, 1,2-dimethoxy-6-methyl-9,10-anthraquinone (1), and ten known anthraquinones: 1-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (2), nordamnacanthal (3), 2-formyl-3-hydroxy-9,10-anthraquinone (4), damnacanthal (5), lucidin-ω-methyl ether (6), 3-hydroxy-2-methyl-9,10-anthraquinone (7), rubiadin (8), 3-hydroxy-2-methoxy-6-methyl-9,10-anthraquinone (9), rubiadin-1-methyl ether (10) and 3-hydroxy-2-hydroxymethyl-9,10-anthraquinone (11). Structural elucidation of all compounds was accomplished by modern spectroscopic methods, notably 1D and 2D NMR, IR, UV and HREIMS. The new anthraquinone 1, 2-formyl-3-hydroxy-9,10-anthraquinone (4) and 3-hydroxy-2-methyl-9,10-anthraquinone (7) possess strong antiplasmodial activity, with IC?? values of 1.10, 0.63 and 0.34 μM, respectively.     

Polarized infrared spectra of 1,4-dihydroxy-9,10-anthraquinone aligned in stretched polyethylene

The i.r. absorption spectrum of 1,4-dihydroxy-9,10-anthraquinone (quinizarin) has been studied in a stretched polyethylene matrix using linearly polarized radiation. The resulting two linearly independent spectra show that only three different transition moment directions are present in the 30 observed transitions, and this leads to a classification of the 30 peaks according to the point group symmetry of the excited state involved. This classification makes a complete assignment possible, and settles several questions on the assignment which have been discussed in the literature for several years.     

Five new peltogynoids from underground parts of Iris bungei: a Mongolian medicinal plant

Five new peltogynoids, irisoids A-E (1-5), have been isolated from the underground parts of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods and were found to be 1,8,10-trihydroxy-9-methoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (1), 1,8-dihydroxy-9,10-dimethoxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (2), 1,10-dihydroxy-8,9-dimethoxy-[1]benzopyrano-13,2-c][2]-benzopyran-7(5H)-one (3), 1,8-dihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (4), and 1,8,11-trihydroxy-9,10-methylenedioxy-[1]benzopyrano-[3,2-c][2]-benzopyran-7(5H)-one (5). The structure of irisoid B (2) was established unambiguously by X-ray diffraction study.     

Study of tautomeric transformations of 1,4,5,8-tetraaminoanthraquinone by electronic spectroscopy

Based on the example of 1,4,5,8-tetraamino-9,10-anthraquinone, a method is described for establishing the tautomeric compositions and sequences of tautomeric transformations that occur in known samples of quinones. An analysis of electronic absorption spectra shows that this substance is a dynamic equilibrium mixture of 4,5,8,9-tetraamino-1,10-anthraquinone and the imines tautomeric to it. The tautomeric compositions of different samples of matter differ and can contain 1,4,8-triamino-5-hydroxy-9,10-anthraquinone-10-imine, 4,8,9-triamino-10-hydroxy-1,5-anthraquinone-5-imine, 5,8-diamino-4,9-dihy-droxy-1,10-antraquinonediimine, and 8,10-diamino-5,9-dihydroxy-1,4-antraquinonediimine. Tautomeric equilibrium shifts can accompany not only chemical reactions but physical processes as well, so any investigation of the properties of substances without establishing their tautomeric compositions would be incorrect.