title: Conjugated Oligo-Aromatic Compounds Bearing a 3,4,5-Trimethoxy Moiety: Investigation of Their Antioxidant Activity Correlated with a DFT Study.
abstract: A series of heterocyclic compounds bearing the well-known free radical scavenging 3,4,5-trimethoxybenzyloxy group, was synthesized. The key compound 4-(3,4,5-trimethoxybenzyl-oxy)benzohydrazide was converted into thiosemicarbazide derivatives, which were subsequently cyclized with NaOH to provide 1,2,4-triazole derivatives. Alternative treatment of the acid hydrazide with carbon disulfide in the presence of KOH led to the corresponding 1,3,4-oxadiazole and various alkylated derivatives. The newly synthesized compounds were purified and the structures of the products were elucidated and confirmed on the basis of their analytical and spectral data. Their antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) and Ferric Reducing Antioxidant Power (FRAP) assays. The thiosemicarbazide derivatives were highly active in both antioxidant assays with the lowest IC50 value for DPPH radical scavenging. Theoretical calculations based on density functional theory (DFT) were performed to understand the relative importance of NH, SH and CH hydrogens on the radical scavenging activities of these compounds.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. hudasalah55@yahoo.com.|General Directorate of Curricula, Ministry of Education, Baghdad 3310, Iraq. hudasalah55@yahoo.com.
authors.forename: Huda S
authors.initials: HS
authors.lastname: Kareem
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. csi_ndiana@um.edu.my.
authors.forename: Nurdiana
authors.initials: N
authors.lastname: Nordin
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. heidelberg@um.edu.my.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Heidelberg
authors.affiliation: Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia. azlina_aziz@um.edu.my.
authors.forename: Azlina
authors.initials: A
authors.lastname: Abdul-Aziz
authors.affiliation: Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. azhar70@um.edu.my.
authors.forename: Azhar
authors.initials: A
authors.lastname: Ariffin
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D015394:Molecular Structure; D018384:Oxidative Stress / Q000187:drug effects; D012663:Semicarbazides / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014230:Triazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D012663:Semicarbazides; D014230:Triazoles; C005151:thiosemicarbazide
keywords: antioxidant; hydrogen atom transfer; oxadiazole; single electron transfer; thiosemicarbazide; triazole