Antioxidants had a growing interest owing to their protective roles in food and pharmaceutical products against oxidative deterioration and in the body and against oxidative stress-mediated pathological processes. Screening of antioxidant properties of plants and plant-derived compounds requires appropriate methods, which address the mechanism of antioxidant activity and focus on the kinetics of the reactions including the antioxidants. Many studies evaluating the antioxidant activity of various samples of research interest using different methods in food and human health have been conducted. These methods are classified, described, and discussed in this review. Methods based on inhibited autoxidation are the most suited for termination-enhancing antioxidants and for chain-breaking antioxidants, while different specific studies are needed for preventive antioxidants. For this purpose, the most common methods used in vitro determination of antioxidant capacity of food constituents were examined. Also, a selection of chemical testing methods was critically reviewed and highlighted. In addition, their advantages, disadvantages, limitations and usefulness were discussed and investigated for pure molecules and raw extracts. The effect and influence of the reaction medium on the performance of antioxidants are also addressed. Hence, this overview provides a basis and rationale for developing standardized antioxidant methods for the food, nutraceuticals, and dietary supplement industries. In addition, the most important advantages and shortcomings of each method were detected and highlighted. The chemical principles of these methods are outlined and critically discussed. The chemical principles of methods of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS·+) scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging, Fe3+-Fe2+ transformation assay, ferric reducing antioxidant power (FRAP) assay, cupric ions (Cu2+) reducing power assay (Cuprac), Folin-Ciocalteu reducing capacity (FCR assay), peroxyl radical (ROO·), superoxide radical anion (O2·-), hydrogen peroxide (H2O2) scavenging assay, hydroxyl radical (OH·) scavenging assay, singlet oxygen (1O2) quenching assay, nitric oxide radical (NO·) scavenging assay and chemiluminescence assay are outlined and critically discussed. Also, the general antioxidant aspects of main food components were discussed by a number of methods, which are currently used for the detection of antioxidant properties of food components. This review consists of two main sections. The first section is devoted to the main components in the food and pharmaceutical applications. The second general section comprises some definitions of the main antioxidant methods commonly used for the determination of the antioxidant activity of components. In addition, some chemical, mechanistic and kinetic basis, and technical details of the used methods are given.

https://link.springer.com/content/pdf/10.1007/s00204-020-02689-3.pdf

Antioxidants and antioxidant methods: an updated overview

Novel 2-aminopyridine liganded Pd(II) N-heterocyclic carbene complexes: Synthesis, characterization, crystal structure and bioactivity properties

The first synthesis, carbonic anhydrase inhibition and anticholinergic activities of some bromophenol derivatives with S including natural products.

Synthesis, characterization, crystal structure of novel bis-thiomethylcyclohexanone derivatives and their inhibitory properties against some metabolic enzymes.

Novel thymol bearing oxypropanolamine derivatives as potent some metabolic enzyme inhibitors - Their antidiabetic, anticholinergic and antibacterial potentials.

The novel N-propylphthalimide-substituted and 4-vinylbenzyl-substituted N-heterocyclic carbene (NHC) precursors were synthesized by N-substituted benzimidazolium with aryl halides. The novel N-propylphthalimide-substituted and 4-vinylbenzyl-substituted NHC precursors have been characterized by using 1 H NMR, 13 C NMR, FTIR spectroscopy, and elemental analysis techniques. They were tested for the inhibition of AChE and hCA enzymes and demonstrated efficient inhibition profiles with Ki values in the range of 351.0-1269.9 nM against hCA I, 346.6-1193.1 nM against hCA II, and 19.0-76.3 nM against AChE. On the other hand, acetazolamide, a clinically used molecule, utilized as CA inhibitor, obtained a Ki value of 1246.7 nM against hCA I and 1407.6 nM against hCA II. Additionally, tacrine inhibited AChE and obtained a Ki value of 174.6 nM.

Novel N-propylphthalimide- and 4-vinylbenzyl-substituted benzimidazole salts: Synthesis, characterization, and determination of their metal chelating effects and inhibition profiles against acetylcholinesterase and carbonic anhydrase enzymes

This paper contains the synthesis of the new 2-morpholinoethyl substituted bis-(NHC)Pd(II) complexes and their catalytic activity in direct arylation reaction. The new bis-(NHC)Pd(II) complexes have been prepared from Ag(I)NHC complexes by using transmetallation method. The new bis-(NHC)Pd(II) complexes have been characterized by using 1H NMR, 13C NMR, FTIR spectroscopy and elemental analysis techniques. Molecular and crystal structure of the complex 1a and its ligand (N-benzylbenzimidazole) were obtained by single crystal X-ray diffraction method. The new bis-(NHC)Pd(II) complexes exhibit activity in the reaction after being examined as catalysts in the direct arylation (C–H activation) reaction.

Synthesis, Characterization and Crystal Structure of New 2-Morpholinoethyl-Substituted Bis-(NHC)Pd(II) Complexes and the Catalytic Activity in the Direct Arylation Reaction

Palladium-catalyzed direct arylation of heteroaromatics has become a popular method for producing carbon–carbon bonds via C–H bond activation. A wide diversity of heteroaromatics such as furan, thiophenes and thiazoles can be used for this reaction. This paper reports the synthesis of N-propylphthalimide-substituted bis-(NHC)PdX2 complexes (NHC = N-heterocyclic carbene), and their catalytic activity in direct arylation reactions. The complexes have been prepared from Ag(I)NHC precursors by transmetallation and characterized by spectroscopy and elemental analysis. The bis-(NHC)PdX2 complexes show excellent activity as catalysts in the direct arylation reactions of 2-n-butylfuran, 2-n-butylthiophene and 2-isopropylthiazole.

N -Propylphthalimide-substituted bis-(NHC)PdX 2 complexes: synthesis, characterization and catalytic activity in direct arylation reactions

New 4-vinylbenzyl-substituted bis(NHC)-Pd(II) complexes: Synthesis, characterization and the catalytic activity in the direct arylation reaction

This study reports the synthesis, characterisation and antimicrobial activity of five novel silver N-heterocyclic carbene (Ag–NHC) complexes obtained by N-propylphthalimide and N-methyldioxane substituted benzimidazolium salts with silver oxide. The reactions were performed at room temperature for 24 h in the absence of light. The obtained complexes were identified and characterised by 1H and 13C NMR, FT-IR and elemental analysis techniques. The minimum inhibitory concentration (MIC) of the complexes was determined for E. coli, P. aeruginosa, E. faecalis, S. aureus, C. tropicalis and C. albicans in vitro through agar and broth dilution. The results indicated that these complexes exhibit antimicrobial activity. In particular, complex 3 presented the significant broad spectrum antimicrobial activity.

https://www.tandfonline.com/doi/pdf/10.3109/14756366.2016.1156102

Yakup Sarı

Papers

Novel N-propylphthalimide- and 4-vinylbenzyl-substituted benzimidazole salts: Synthesis, characterization, and determination of their metal chelating effects and inhibition profiles against acetylcholinesterase and carbonic anhydrase enzymes

Synthesis, Characterization and Crystal Structure of New 2-Morpholinoethyl-Substituted Bis-(NHC)Pd(II) Complexes and the Catalytic Activity in the Direct Arylation Reaction

N -Propylphthalimide-substituted bis-(NHC)PdX 2 complexes: synthesis, characterization and catalytic activity in direct arylation reactions

New 4-vinylbenzyl-substituted bis(NHC)-Pd(II) complexes: Synthesis, characterization and the catalytic activity in the direct arylation reaction

Benzimidazolium-based novel silver N-heterocyclic carbene complexes: synthesis, characterisation and in vitro antimicrobial activity.