Mendes Rodrigo A, E Silva Bruno L S, Takeara Renata, Freitas Renato G, Brown Alex, de Souza Gabriel L C
Departamento de Química, Universidade Federal de Mato Grosso, Cuiabá, Mato Grosso, 78060-900, Brazil.
Instituto de Ciências Exatas e Tecnologia, Universidade Federal do Amazonas, Itacoatiara, Amazonas, 69100-000, Brazil.
J Mol Model. 2018 Mar 22;24(4):101. doi: 10.1007/s00894-018-3632-9.
The structures and energetics of two dihydrochalcones (phloretin and its glycoside phlorizin) were examined with density functional theory, using the B3LYP, M06-2X, and LC-ω PBE functionals with both the 6-311G(d,p) and 6-311 + G(d,p) basis sets. Properties connected to antioxidant activity, i.e., bond dissociation enthalpies (BDEs) for OH groups and ionization potentials (IPs), were computed in a variety of environments including the gas-phase, n-hexane, ethanol, methanol, and water. The smallest BDEs among the four OH groups for phloretin (three for phlorizin) were determined (using B3LYP/6-311 + G(d,p) in water) to be 79.36 kcal/mol for phloretin and 79.98 kcal/mol for phlorizin while the IPs (at the same level of theory) were obtained as 139.48 and 138.98 kcal/mol, respectively. By comparing with known antioxidants, these values for the BDEs indicate both phloretin and phlorizin show promise for antioxidant activity. In addition, the presence of the sugar moiety has a moderate (0-6 kcal/mol depending on functional) effect on the BDEs for all OH groups. Interestingly, the BDEs suggest that (depending on the functional chosen) the sugar moiety can lead to an increase, decrease, or no change in the antioxidant activity. Therefore, further experimental tests are encouraged to understand the substituent effect on the BDEs for phloretin and to help determine the most appropriate functional to probe BDEs for dihydrochalcones.
采用密度泛函理论，使用B3LYP、M06 - 2X和LC - ωPBE泛函以及6 - 311G(d,p)和6 - 311 + G(d,p)基组，研究了两种二氢查耳酮（根皮素及其糖苷根皮苷）的结构和能量。在包括气相、正己烷、乙醇、甲醇和水在内的多种环境中，计算了与抗氧化活性相关的性质，即OH基团的键解离焓（BDEs）和电离势（IPs）。根皮素的四个OH基团（根皮苷为三个）中最小的BDEs（在水中使用B3LYP/6 - 311 + G(d,p)计算），根皮素为79.36 kcal/mol，根皮苷为79.98 kcal/mol，而IPs（在相同理论水平下）分别为139.48和138.98 kcal/mol。通过与已知抗氧化剂比较，这些BDEs值表明根皮素和根皮苷都具有抗氧化活性的潜力。此外，糖部分的存在对所有OH基团的BDEs有适度（取决于泛函，为0 - 6 kcal/mol）的影响。有趣的是，BDEs表明（取决于所选泛函）糖部分可导致抗氧化活性增加、降低或无变化。因此，鼓励进行进一步的实验测试，以了解取代基对根皮素BDEs的影响，并有助于确定用于探测二氢查耳酮BDEs的最合适泛函。
