Journal of Molecular Graphics and Modelling 78 (2017) 221–233 Contents lists available at ScienceDirect Journal of Molecular Graphics and Modelling journal homepage: www.elsevier.com/locate/JMGM Topical perspectives Structure, antioxidative potency and potential scavenging of OH • and OOH • of phenylethyl-3,4-dihydroxyhydrocinnamate in protic and aprotic media: DFT study Olivier Holtomo a,b,∗ , Mama Nsangou c,d , Jean Jules Fifen d , Ousmanou Motapon b a Department of Physics, Faculty of Science, University of Bamenda, Bambili P. O. Box 39, Cameroon b Laboratory of Fundamental Physics, Faculty of Science,University of Douala, Douala P. O. Box 24157, Cameroon c Department of Physics, Higher Teacher’s Training College, University of Maroua, Maroua P. O. Box 46, Cameroon d Department of Physics, Faculty of Science, University of Ngaoundere, Ngaoundere P. O. Box 454, Cameroon a r t i c l e i n f o Article history: Received 5 September 2017 Received in revised form 9 October 2017 Accepted 16 October 2017 Available online 28 October 2017 Keywords: PDH DFT H-atom transfer Antioxidant Radical Solvent effects a b s t r a c t DFT methods including B3LYP, B3PW91 and M05–2 x associated to 6–31 + G(d,p) were used for the struc- tural and antioxidant potency studies of phenylethyl-3,4-dihydroxy-hydrocinnamate (PDH). Solvents were employed according to their protric and aprotic character. So, calculated structures agree with the experimental data. O 4 H 4 is propitious to scavenge radicals whatever the medium except in water where O 3 H 3 and O 4 H 4 are competitive. The explicit solvents of dichloromethane (DCM) and water present a disparity of O H bond dissociation enthalpy and free energy (BDE and BDFE). These parameters are low in continuum except in water. The ionization potentials (IP) and potential affinities (PA) are low in solvents. BDE, IP and PA are each, approximatively constant in mixed solvent treatment in water using n-H 2 O (n = 3,5,8). Elsewhere, H-atom transfer (HAT) mechanism is favoured in vacuum and DCM, whereas sequential proton loss electron transfer (SPLET) is likely in protic solvents. A discord between HAT and SPLET in benzene is observed. The PDH compound is more antioxidant and resistant to oxidation than caffeic acid phenethyl ester (CAPE). The potential of scavenging of OH • and OOH • whatever the reaction channel shows that they decay rapidly in any media through HAT. PDH is easily deprotonated in the protic solvents and the resulting product is the most antioxidant and the least resistant to oxidation. © 2017 Elsevier Inc. All rights reserved. 1. Introduction In physiological environment, oxygen is a relatively unreac- tive compound that can be metabolized to form highly reactive oxidants known as reactive oxygen species (ROS) [1,2]. ROS are highly reactive with adjacent molecules such as lipids, pro- teins, and carbohydrates, leading to cellular damage [2]. These occur from the imbalance of oxidants and antioxidants and cause oxidative stress leading to diseases such as cardiovascular, conges- tive heart failure, diabetes, arterial hypertension, cerebrovascular accidents, cancer, cataract, premature ageing etc. [2]. Polyphe- nols are the most important group of naturally occurring potent antioxidants. They constitute one of the most broadly distributed classes of compounds in the vegetable kingdom [2,3]. The role of ∗ Corresponding author at: Department of Physics, Faculty of Science, University of Bamenda, Bambili, P. O. Box 39, Cameroon. E-mail address: holtomoo@gmail.com (O. Holtomo). radical-scavenging antioxidants has received increasing attention in scientific community [1–16]. Phenylethyl-3,4-dihydroxy-hydrocinnamate (PDH) molecule is one of the derivatives of CAPE (caffeic acid phenethyl ester) widely studied [3–10]. They are both naturally occuring phenolic acid and present in propolis honeybee hives in a large proportion [3]. They have been synthesized by Sestili et al. [3]. They have another bioactivities as anti-tumor, anti-inflammatory, immune regula- tion [3,5–7]. It has been shown spectrophotometrically that PDH has iron chelation ability and, by IC 50 (Reduction of the (tB-OOH) tert-butylhydroperoxide (3 mM)-induced cytotoxicity on one hand and reduction of the tB-OOH (200 M)-induced DNA single-strand breakage on the other hand) that PDH has potent antioxidant abil- ity (IC 50 (PDH) = 0.0098 ± 0.0009 M) [3]. The experimental data of bond lengths and bond angles are available only for CAPE molecule [4] having the same molecular backbone. The literature shows that IC 50 (PDH)∼ IC 50 (CAPE) = 0.0062 ± 0.0005 [3]. Many studies have been carried out to search for and to develop antioxidants having natural origin [1–3,5–15]. In this work, the https://doi.org/10.1016/j.jmgm.2017.10.014 1093-3263/© 2017 Elsevier Inc. All rights reserved.