1,3,8-Trihydroxy-6-methylanthraquinone monohydrate

Zhu, Jun; Li, Ying; Wang, Hengshan; Pan, Ying‐Ming; Zhang, Yong

doi:10.1107/s1600536806049178

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…The X-ray crystal and molecular structure of emodin was solved using data collected at 125 K. Indeed, our structure agrees with the molecular structure of emodin monohydrate reported, (TEVVOG in CCDC) from data at 153 K, whose Rf was 8.04%, [18] compared with ours of 5.91%; this provided standard deviations of 0.003 Å for C-C bonds, more precise than those reported earlier of 0.004 Å [18]. Additionally, our hydrogen atoms were all found experimentally from the Fourier difference electron density.…”

Section: Resultssupporting

confidence: 85%

Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

et al. 2020

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The naturally occurring anthraquinone emodin is found in many plants that have been part of traditional Chinese medicine (TCM) for thousands of years. Recent pharmacological studies suggest that emodin might be a valuable therapeutic option for the treatment of various diseases. We describe the antioxidant effects of emodin on the superoxide radical. Our techniques include X-ray crystallography, density functional theory (DFT), and a recently developed cyclovoltammetry improvement, the rotating ring-disk electrode (RRDE) method. X-ray results show offset π–π stacking of emodin units in the crystal, and this type of interaction is supported by the DFT, which indicates one superoxide interacting via π–π stacking with the quinone moiety, by transferring one electron to the ring, and inducing some quinone aromatization. The second superoxide seems to form a stable complex after interacting with the H(hydroxyl) in position 3 of emodin. We show that one molecule of emodin sequesters two molecules of superoxide: one forming a complex with H(hydroxyl) in position 3, and the other due to π–π oxidation of superoxide and emodin ring reduction. We conclude that emodin is a very strong antioxidant. Color variation in the voltaic cell was observed during the RRDE study. This was analyzed and explained using a mini-grid gold electrode for UV-Vis spectroscopy in the voltaic cell.

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Section: Resultssupporting

confidence: 85%

Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

et al. 2020

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“…To evaluate the physicochemical stability of EM and its cocrystals, thermal analysis including TGA and DSC was conducted (Figure S4). The DSC patterns of EM starting material (determined as a monohydrate according to XRPD data and compared with literature, 37 Figure S5), coformers, and cocrystals presented in Figure S6 revealed the different thermal properties of various EM solid forms. The melting points (T onset , in Table S3) of EM cocrystals are found to lie in between the melting point values of individual components, in accordance with most cocrystal cases.…”

Section: ■ Results and Discussionmentioning

confidence: 95%

Fine-Tuning the Colors of Natural Pigment Emodin with Superior Stability through Cocrystal Engineering

Zhang

et al. 2018

Crystal Growth & Design

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Due to the increasing concern of toxicity when using synthetic pigments, naturally occurring materials have regained attention. However, the limited hues and instability restrict their applications. Emodin (EM) is considered as a naturally sourced pigment and has been added in chemic necessities for many years. In this work, continuous color changes can be achieved by careful selection of coformers via a cocrystal engineering approach. This fine color tuning could be attributed to the different π–π and charge-transfer interactions after cocrystal formation. Furthermore, EM cocrystals were found to have superior stability in formulations. Fine color modifications and better stability behaviors in cocrystals may provide a new pathway to develop naturally sourced pigments without chemical synthesis.

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“…The single-crystal X-ray structures of chrysophanol ( 1 ) [54], emodin ( 2 ) [55], and physcion ( 3 ) [56] show that the C(1)–OH and C(8)–OH groups interact with the C(9)=O oxygen atom of the carbonyl group forming an intramolecular hydrogen bond. This is in agreement with our experimental NMR data and DFT-calculated structures.…”

Section: Resultsmentioning

confidence: 99%

Solvent-Dependent Structures of Natural Products Based on the Combined Use of DFT Calculations and 1H-NMR Chemical Shifts

et al. 2019

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Detailed solvent and temperature effects on the experimental 1H-NMR chemical shifts of the natural products chrysophanol (1), emodin (2), and physcion (3) are reported for the investigation of hydrogen bonding, solvation and conformation effects in solution. Very small chemical shift of │Δδ│ < 0.3 ppm and temperature coefficients │Δδ/ΔΤ│ ≤ 2.1 ppb/K were observed in DMSO-d6, acetone-d6 and CDCl3 for the C(1)–OH and C(8)–OH groups which demonstrate that they are involved in a strong intramolecular hydrogen bond. On the contrary, large chemical shift differences of 5.23 ppm at 298 K and Δδ/ΔΤ values in the range of −5.3 to −19.1 ppb/K between DMSO-d6 and CDCl3 were observed for the C(3)–OH group which demonstrate that the solvation state of the hydroxyl proton is a key factor in determining the value of the chemical shift. DFT calculated 1H-NMR chemical shifts, using various functionals and basis sets, the conductor-like polarizable continuum model, and discrete solute-solvent hydrogen bond interactions, were found to be in very good agreement with the experimental 1H-NMR chemical shifts even with computationally less demanding level of theory. The 1H-NMR chemical shifts of the OH groups which participate in intramolecular hydrogen bond are dependent on the conformational state of substituents and, thus, can be used as molecular sensors in conformational analysis. When the X-ray structures of chrysophanol (1), emodin (2), and physcion (3) were used as input geometries, the DFT-calculated 1H-NMR chemical shifts were shown to strongly deviate from the experimental chemical shifts and no functional dependence could be obtained. Comparison of the most important intramolecular data of the DFT calculated and the X-ray structures demonstrate significant differences for distances involving hydrogen atoms, most notably the intramolecular hydrogen bond O–H and C–H bond lengths which deviate by 0.152 tο 0.132 Å and 0.133 to 0.100 Å, respectively, in the two structural methods. Further differences were observed in the conformation of –OH, –CH3, and –OCH3 substituents.

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1,3,8-Trihydroxy-6-methylanthraquinone monohydrate

Cited by 8 publications

References 11 publications

Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

Emodin Scavenging of Superoxide Radical Includes π–π Interaction. X-Ray Crystal Structure, Hydrodynamic Voltammetry and Theoretical Studies

Fine-Tuning the Colors of Natural Pigment Emodin with Superior Stability through Cocrystal Engineering

Solvent-Dependent Structures of Natural Products Based on the Combined Use of DFT Calculations and 1H-NMR Chemical Shifts

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