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structure of dihydrochalcones and related derivatives and their scavenging and antioxidant activity against oxygen and nitrogen radical speciesdihydrochalcones结构及相关衍生品和他们对氧和氮自由基的清除和抗氧化活性物种.pdf

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Molecules 2011, 16, 1749-1760; doi:10.3390/molecule OPEN ACCESS molecules ISSN 1420-3049 /journal/molecules Article Structure of Dihydrochalcones and Related Derivatives and Their Scavenging and Antioxidant Activity against Oxygen and Nitrogen Radical Species Alexandre L. A. Bentes, Rosivaldo S. Borges, Waldinei R. Monteiro, Luiz G. M. de Macedo and Cláudio N. Alves * Laboratório de Planejamento e Desenvolvimento de Fármacos, Universidade Federal do Pará, CP 11101, 66075-110, Belém, PA, Brazil * Author to whom correspondence should be addressed; E-Mail: nahum@ufpa.br; Fax: 55-91-3201-7635. Received: 21 November 2010; in revised form: 21 December 2010 / Accepted: 5 January 2011 / Published: 21 February 2011 Abstract: Quantum mechanical calculations at B3LYP/6-31G** level of theory were employed to obtain energy (E), ionization potential (IP), bond dissociation enthalpy (O-H BDE) and stabilization energies (ΔEiso) in order to infer the scavenging activity of dihydrochalcones (DHC) and structurally related compounds. Spin density calculations were also performed for the proposed antioxidant activity mechanism of 2,4,6- trihydroxyacetophenone (2,4,6-THA). The unpaired electron formed by the hydrogen abstraction from the phenolic hydroxyl group of 2,4,6-THA is localized on the phenolic oxygen at 2, 6, and 4 positions, the C and C carbon atoms at ortho positions, and the C
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