Binding characterization of anthraquinone derivatives by stabilizing G-quadruplex DNA leads to an anticancerous activity

G-quadruplex is a non-canonical secondary structure identified in the telomeric region and the promoter of many oncogenes. Anthraquinone derivatives, a well-known inducer of telomere disruption in malignant cells and activate the apoptotic pathway. We used biophysical and biochemical studies to confirm the interaction of synthesized anthraquinone derivatives with the human telomeric G-quadruplex sequence. The binding affinity of N-2DEA and N-1DEA are K _b = 4.8 × 10⁶ M^-1 and K _b = 7.6 × 10⁵ M^-1, respectively, leading to hypochroism, fluorescence quenching with minor redshift and ellipticity variations indicating ligand binding in the external groove. We found that sodium ions induced stabilization more rather than potassium ions. Molecular docking of complex demonstrates a molecule's exterior binding to a quadruplex. The investigation of ROS activity indicated that the cell initiates mortality in response to the IC₅₀ concentration. Cellular morphology, nuclear condensation, and fragmentation were altered in the treated cell, impairing cellular function. Finally, the transcriptional regulatory study paves the way for drug design as an anti-cancer agent because of the tremendous possibilities of changing substituent groups on anthraquinones to improve efficacy and selectivity for G-quartet DNA. Our research focused on how ligand binding to telomere sequences induces oxidative stress and inhibits the growth of malignant cells.

Mixture of Anthraquinone Sulfo-Derivatives as an Inexpensive Organic Flow Battery Negolyte: Optimization of Battery Cell

Anthraquinone-2,7-disulfonic acid (2,7-AQDS) is a promising organic compound, which is considered as a negolyte for redox flow batteries as well as for other applications. In this work we carried out a well-known reaction of anthraquinone sulfonation to synthesize 2,7-AQDS in mixture with other sulfo-derivatives, namely 2,6-AQDS and 2-AQS. Redox behavior of this mixture was evaluated with cyclic voltammetry and was almost identical to 2,7-AQDS. Mixture was then assessed as a potential negolyte of anthraquinone-bromine redox flow battery. After adjusting membrane-electrode assembly composition (membrane material and flow field)), the cell demonstrated peak power density of 335 mW cm^-2 (at SOC 90%) and capacity utilization, capacity retention and energy efficiency of 87.9, 99.6 and 64.2%, respectively. These values are almost identical or even higher than similar values for flow battery with 2,7-AQDS as a negolyte, while the price of mixture is significantly lower. Therefore, this work unveils the promising possibility of using a mixture of crude sulfonated anthraquinone derivatives mixture as an inexpensive negolyte of RFB.

Rhein Derivatives, A Promising Pivot?

Rhein, an anthraquinone derivative, has been employed widely, especially for the treatment of intractable diseases like diabetic nephropathy, arthritis, and cancer in a unique action mechanism. In the last decades, considerable efforts have been made in structural modification of rhein. This paper reviewed patents on pharmacological activity and therapeutic application of rhein and its derivatives from 1978 to 2018. Particularly, an analysis of patents was made, with the top 10 most valuable patents presented, and the interpretation of the legal status of patents was given. Given the properties of superior pharmacological activity, rich resources, cheap price, low toxicity, and mature extraction process, it is believed that an in-depth investigation on rhein and its derivatives is worth trying.

Study on Redox Properties and Cytotoxicity of Anthraquinone Derivatives to Understand Antitumor Active Anthracycline Substances

This study demonstrates the relation between the redox properties and cytotoxicity of anthraquinone derivatives with a hydroxyl and methoxy group. The redox behavior of the anthraquinone derivatives was initially observed via cyclic voltammetry and their characteristics were investigated using molecular orbital calculations. The cytotoxicity of the anthraquinone derivatives was then evaluated using human leukemia HL-60 and H₂O₂ resistant HP100 cells, and its correlation with the redox properties of these compounds was investigated. Therefore, it was suggested that the anthraquinone derivatives express cytotoxicity through H₂O₂ production, and that generation of the oxidized radical form influences their cytotoxicity.

Density Functional Theory Analysis of Anthraquinone Derivative Hydrogenation over Palladium Catalyst

A density functional theory (DFT) analysis was conducted on the hydrogenation of 2-alkyl-anthraquinone (AQ), including 2-ethyl-9,10-anthraquinone (eAQ) and 2-ethyl-5,6,7,8-tetrahydro-9,10-anthraquinone (H₄ eAQ), to the corresponding anthrahydroquinone (AQH₂ ) over a Pd₆ H₂ cluster. Hydrogenation of H₄ eAQ is suggested to be more favorable than that of eAQ owing to a higher adsorption energy of the reactant (H₄ eAQ), lower barrier of activation energy, and smaller desorption energy of the target product (2-ethyl-5,6,7,8-tetrahydro-9,10-anthrahydroquinone, H₄ eAQH₂ ). For the most probable reaction routes, the energy barrier of the second hydrogenation step of AQ is circa 8 kcal mol^-1 higher than that of the first step. Electron transfer of these processes were systematically investigated. Facile electron transfer from Pd₆ H₂ cluster to AQ/AQH intermediate favors the hydrogenation of C=O. The electron delocalization over the boundary aromatic ring of AQ/AQH intermediate and the electron-withdrawing effect of C=O are responsible for the electron transfer. In addition, a pathway of the electron transfer is proposed for the adsorption and subsequent hydrogenation of AQ on the surface of Pd₆ H₂ cluster. The electron transfers from the abstracted H atom (reactive H) to a neighbor Pd atom (Pd_H ), and finally goes to the carbonyl group through the C₄ atom of AQ aromatic ring (C₄ ).

Nigrosporins A and B, New Phytotoxic and Antibacterial Metabolites Produced by a Fungus Nigrospora oryzae

Nigrosporin A and B, two new phytotoxic and antibacterial metabolites were isolated from a culture filtrate of Nigrospora oryzae. The active principles were absorbed on XAD-2 resin and purified by successive ODS-HPLC. The structures were identified by spectroscopic and derivatization analysis as naphthoquinone derivatives. The substances showed phytotoxic activities, such as root elongation inhibition, necrotic effects, oxygen evolution inhibition, starch synthesis inhibition, and CO2 fixation inhibition at concentrations of 10-100 ppm. They also showed growth inhibition activity against Bacillus subtilis in a disc diffusion assay as well as when compared with streptomycin.