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Selected anthraquinones as potential free radical scavengers and P-glycoprotein inhibitors


Disruption of homeostasis can increase the amount of free radicals formed during metabolic processes. This phenomenon known as oxidative stress can have numerous negative outcomes. The role of dietary antioxidants is to help the prevention of oxidative stress. We investigated free radical scavenging capacity of six structurally similar anthraquinones (alizarin, purpurin, chrysophanol, emodin, aloe-emodin and 1,3,8- trihydroxyanthraquinone) for inactivating a set of ten hydroxy and peroxy free radicals. Antioxidant capacity of anthraquinones was estimated by considering Gibbs free energy of three studied reaction mechanisms: hydrogen atom transfer (HAT), single-electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET). Geometry of all participants in chemical reactions was optimized using M06-2X/6-311++G(d,p) level of theory. Benzene, pentyl ethanoate, dimethyl sulfoxide and water were used to investigate impact of solvent polarity on thermodynamic feasibility of antiradical reactions. It was found that HAT and SPLET mechanisms are operative and competitive, while SET-PT mechanism is not thermodynamically plausible. Among studied anthraquinones AL and PU showed the highest scavenging capacity. Their reactivity toward free radicals decrease as follows:OH > (CH3)3C−OOCH3 > CCl3−O−O > PhO > OOH ≈ CH2=CH−O−O ≈ CH3–O–O ≈ CH2=CH−CH2−O−O >> O2•‒. Inhibition activity of anions of selected six anthraquinones toward P-glycoprotein was estimated using docking analysis. Obtained results suggest all investigated compounds as potential inhibitors of P-glycoprotein at physiological conditions, indicating them as potential protectors against patient resistance toward various anticancer drugs.

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Publication details

The article was received on 08 Jan 2018, accepted on 15 Feb 2018 and first published on 15 Feb 2018

Article type: Paper
DOI: 10.1039/C8OB00060C
Citation: Org. Biomol. Chem., 2018, Accepted Manuscript
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    Selected anthraquinones as potential free radical scavengers and P-glycoprotein inhibitors

    S. Jeremić, A. Amić, M. Stanojević-Pirković and Z. Markovic, Org. Biomol. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C8OB00060C

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