Phenolic OH Research Articles

Copper(II) Complexes of Pyridine-2,6-dicarboxamide Ligands with High SOD Activity.

Copper(II) complexes of pyridine-based ligands functionalized with alanine (PydiAla) and tyrosine (PydiTyr) moieties have been synthesized as novel superoxide dismutase mimics. The complexes were characterized by pH-potentiometric, spectroscopic (UV-vis, circular dichroism, mass spectrometry, electron paramagnetic resonance spectroscopy), computational (DFT), and X-ray diffraction methods. Both ligands form high stability copper(II) complexes via the (Npy,N-,N-) donor set supported by the binding of the carboxylate pendant arms. Although the coordination mode is the same for the two systems, the tyrosine containing counterpart exhibits increased copper(II) binding affinity, which is most likely due to the presence of the aromatic moiety of the side chains. Both copper(II) complexes are capable of binding N-methylimidazole, and the formation of the corresponding ternary species was observed at physiological pH. The binary and ternary copper(II) complexes exhibit high SOD activity. The PydiTyr complex exhibits about 1 order of magnitude higher activity than the PydiAla complex. This is probably due to the presence of the phenolic OH group in the former species, which promotes the binding of the superoxide anion radical to the metal center. The results serve as a basis for designing highly efficient copper(II) mimics for medical and practical applications.

Synthesis, Characterization and Antioxidant Activity of Two Novel Oxovanadium (IV) Curcuminoids

The reaction of bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione (curcumin) and two novel ligands of bis[4- tetrabenzylglucose-3-methoxyphenyl]-1,6-heptadiene-3,5-dione (bis(tetrabenzylglucose)curcumin) (BTBGC) and bis[4-tetraacetylglucose- 3-methoxyphenyl]-1,6-heptadiene-3,5-dione (bis(tetraacetylglucose)curcumin) (BTAGC) with vanadium in methanol, in a 2:1 molar ratio, which yield the complexes of ML2 where M is [VO]2+, have been synthesized and characterized by FT-IR, mass spectrometry, 1H NMR spectroscopy and elemental analysis. These novel compounds were also examined for their antioxidant activity (using Trolox Equivalent Antioxidant Capacity (TEAC) antioxidant assay as a measure of their overall ability to scavenge free radicals compared to antioxidant standards such as Trolox); compounds with free hydroxyl groups were more active than those one whose locking such and also the metal complexes showed more activity than Trolox. The antioxidant capacity was decreased in BTBGC, BTAGC and their complexes compared to curcumin and its oxovanadium (IV) complex, corroborating the importance of curcumin’s free phenolic OH groups for scavenging oxidants potential. Also, the presence of the methoxy group increases the activity.

A pyridinyl-phenanzine conjugated microporous polymer decorated with ultrafine Ag nanoparticles mediates the rapid reduction of nitrophenol

In this study we used classical Suzuki polycondensation to prepare a pyridinyl-phenanzine (TPPQP) conjugated microporous polymer (CMP) that featured a spherical morphology with a large surface area (371 m2 g−1) and high thermal stability (Td10 = 625 °C; char yield = 81.7 wt%). The framework of the TPPQP CMP presented many dynamic pyridinic units could capture Ag+ ions from solution and facilitate their self-reduction to Ag nanoparticles, thereby forming [email protected] CMP nanocatalysts. The [email protected] CMP nanocatalysts were strong reducing agents for pollutant nitrophenols, converting them into safe amino forms at standard temperature and pressure with a high normalized rate of 19.4 mg−1 s−1. The pyridinic units in the TPPQP CMP structure played an important role in the catalytic reaction, interacting with the phenolic OH groups of p-nitrophenol to accelerate the reduction.

Theoretical investigations on the antioxidant potential of 2,4,5-trihydroxybutyrophenone in different solvents: A DFT approach

2,4,5-trihydroxybutyrophenone (THBP) is a synthetic molecule possessing phenolic OH groups as well as non-phenolic CHx (x = 2 and 3) groups which are believed to be responsible for its antioxidant behavior. The antioxidant nature of THBP has been systematically investigated through quantum chemical calculation by density functional theory (DFT) method with B3LYP hybrid functional and 6-311G++(d,p) basis set in gas, water and methanol media. The principal pathways such as hydrogen atom transfer (HAT), sequential proton loss electron transfer (SPLET) and single electron transfer-proton transfer (SETPT) were considered for antioxidant reactions. Changes of enthalpy (ΔH) and free energy (ΔG) were computed for OH radical scavenging by THBP. In addition, geometry, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), energy gap (Eg), the other descriptors (electron affinity (EA), ionization potential (IP), global hardness (η), softness (σ), electrophilicity (ω), chemical potential (μ), electronegativity (χ) etc.), Fukui function, molecular electrostatic potential (MEP) surface and spin density were also taken into account. The calculated data values were compared with those of gallic acid (GA), a well-recognized antioxidant, calculated at the same level and also with literature of those compounds claiming efficient antioxidant. The values of the calculated thermochemical parameters convey evidence in favor of THBP as an antiradical molecule which is strongly supported by the descriptor values. The free radical scavenging reaction may occur preferentially at 5-OH > 4-OH > α-CH2 positions of the molecule.

Two New Pentacyclic Triterpenoids, an Alkaloid and a Long-chain Fatty Acid from Albizia Coriaria (Welw ex. Oliver)

Herein, we report the occurrence of four new compounds in ethanolic extract of Albizia coriaria Welw ex. Oliver leaves along with other compounds previously reported in this species. The compounds were isolated and characterized using column chromatography, Fourier Transform Infrared (FTIR) and gas chromatography/mass spectrometry. FTIR spectrum of the extract showed phenolic OH stretching (3362.30 cm-1), C=O (1660.08 cm-1), CO stretching (1369.46 cm-1 and 1319.00 cm-1) and CN stretch (1072.44 cm-1) which confirmed the presence of alcohols, carboxylic acids and nitrogen-containing compounds. Oleanolic acid (1), oleanolic acid acetate (2), pterin-6-carboxylic acid (3), undecanol (4), betulinic acid (5), betulin (6) and benzyl alcohol (7) were tentatively identified in the extract. Compounds 1-4 are being reported for the first time in Albizia coriaria.

Synthesis, Characterization, and Thermal Analysis of a New Acidicazo Ligand's Metal Complexes

The researchers wanted to make a new azo imidazole as a follow-up to their previous work. The ligand 4-[(2-Amino-4-phenylazo)-methyl]-cyclohexane carboxylic acid as a derivative of trans-4-(aminomethyl) cyclohexane carboxylic acid diazonium salt, and synthesis a series of its chelate complexes with metalions, characterized these compounds using a variety technique, including elemental analysis, FTIR, LC-Mass, 1H-NMRand UV-Vis spectral process as well TGA, conductivity and magnetic quantifications. Analytical data showed that the Co (II) complex out to 1:1 metal-ligand ratio with square planner and tetrahedral geometry, respectively while 1:2 metal-ligand ratio in the Cu(II), Cr(III), Mn(II), Zn(II), Ru(III)and Rh(III)complexes with octahedral geometry except Mn complex has tetrahedral geometry. The Ligand functions as a neutral tridentate ligand in all complex investigations, coordinating Cr(III), Zn(II), Ru(III), and Rh(III) ions via the N atom of amine and azo groups, as well as the O phenolic OH group. When coordinated with the Cu(II), Co(II), and Mn(II) ions via the two N atoms of the amine and azo groups, this Ligand functions as a neutral bidentate.

The inhibition of p-hydroxyphenyl hydroxyl group in residual lignin on enzymatic hydrolysis of cellulose and its underlying mechanism

The controlling factors of the inhibition on enzymatic hydrolysis caused by residual lignin were identified with molecular level understanding of the mechanism. Residual lignin samples with different properties were isolated, characterized and added into the enzymatic hydrolysis of Avicel. It was found that the phenolic hydroxyl group (OH) was the main inhibitor in residual lignin, and the p-hydroxyphenyl OH was the crucial sub-structure that exhibited the highest inhibition and non-productive adsorption, ascribing to its higher electrophilicity and lower steric hindrance. The H-bond interaction and π-π stacking between phenolic OH of lignin and phenolic OH of tyrosine on the planar face of carbohydrate binding module of cellulase were probably responsible for the non-productive adsorption. The binding sites of H-bonds may be the H in phenolic OH of lignin and the O in phenolic OH of tyrosine, respectively, and that of the π-π stacking may be the benzene rings of them.

Composition and Structure of Ethanol-Lignins of Coniferous and Deciduous Wood and Products of their Catalytic Telomerization with 1,3-Butadiene

The composition and structure of ethanol-lignins of coniferous (abies, pine) and deciduous (aspen, birch) wood and products of their catalytic telomerization with 1,3-butadiene has been studied with use of the methods 31P-NMR, gel-permeation chromatography, scanning electron microscopy and elemental analysis. Data on the nature and content of hydroxyl groups in ethanol-lignins were obtained using phosphorylation of lignins with 2-chloro‑4,4,5,5,-tetramethyl‑1,3,2-dioxaphospholane.The studied lignins differ from each other in the content of aliphatic, phenolic and carboxyl groups. The total content of hydroxyl groups increases in the series of ethanol-lignins: birch < aspen < pine < abies. For the modification of ethanol-lignins, the reaction of catalytic telomerization with 1,3-butadiene was used at 70 °C and 90 °C in the presence of a complex of palladium (II) diacetate with the sodium salt of triphenylphosphine trisulfate. By comparing the number of aliphatic, phenolic and carboxyl OH- groups in the initial and telomerized ethanol-lignins, it was found that only aliphatic and phenolic hydroxyl groups participate in the telomerization reaction. Telomerization of ethanol-lignins with 1,3-butadiene increases their average molecular weight and reduces polydispersity. The morphology of telomerized and initial samples of ethanol-lignins varies significantly

Reaction Mechanisms of Photoinduced Quinone Methide Intermediates Formed via Excited-State Intramolecular Proton Transfer or Water-Assisted Excited-State Proton Transfer of 4-(2-Hydroxyphenyl)pyridine.

Femtosecond and nanosecond transient absorption spectroscopies combined with theoretical calculations were performed to investigate the formation mechanisms of quinone methides (QMs) from 4-(2-hydroxyphenyl)pyridine (1). In acetonitrile (ACN), the singlet excited state of 1 (1(S1)) with the cis-form underwent a thermodynamically favorable and ultrafast ESIPT to produce the singlet excited state QM, which could either relax first into highly vibrational states of its ground state followed by hydrogen transfer to return to the starting compound or alternatively may undergo a dehydrogenation to produce a radical species (1-R). In ACN-H2O, 1(S1) interacted with water molecules to form a solvated species, which induced water-assisted ESPT to the pyridine nitrogen to generate the singlet excited state QM in a concerted asynchronous manner that was initiated by deprotonation of the phenolic OH. These results provide deeper insights into the formation mechanisms of QMs in different solvent environments, which is important in the application of QMs in biological and chemical systems as well as in the design of molecules for efficient QM formation.

Chemoselective Attachment of the Water-Soluble Dark Quencher Hydrodabcyl to Amino Groups in Peptides and Preservation of Its Spectroscopic Properties over a Wide pH Range.

The water-soluble quencher hydrodabcyl can be activated as an N-succinimidyl ester that is readily accessible from crude hydrodabcyl and storable for a long time. With primary and secondary amines, it reacts swiftly and chemoselectively, even in the presence of other competing nucleophiles such as those typically present in natural peptides. One of the three phenolic OH groups of hydrodabcyl is amenable to selective mono-Boc protection resulting in reduced polarity, advantageous to its further use in organic synthesis. The advantages of hydrodabcyl over dabcyl in spectrometric applications are exemplified by the pH dependence of its absorbance spectra.

Multicomponent crystals of p-coumaric acid and trans-ferulic acid: structures and physicochemical properties

• P -coumaric and trans-ferulic acids co-crystallised with 4,4’-bipyridine and dioxane. • Only p -coumaric acid co-crystallised with pyridine. • Persistence of carboxylic acid homosynthon for dioxane and pyridine compounds. • Formation of heterosynthons for 4,4’-bipyridine co-crystals. • Greater thermal stability of trans-ferulic acid compounds. p -coumaric acid ( p CA) and trans -ferulic acid (TFA) formed multicomponent crystals with 4,4’-bipyridine (BIPY) and 1,4-dioxane (DX). p CA also co-crystallised with pyridine (PYR). The crystal structures, thermal analysis, Hirshfeld surfaces and Fourier transform infrared spectroscopy of the compounds are presented. Both ( p CA)·(BIPY) and (TFA)·(BIPY) displayed the supramolecular heterosynthons, COOH···N pyr and OH···N pyr . The ( p CA)·(DX), (TFA)·(DX) and ( p CA)·(PYR) crystal structures featured the carboxylic acid homosynthon and the (phenol)OH···O/N heterosynthon. The observed supramolecular synthons can be related to the molecular sizes of the co-crystal formers thus allowing for the design of specific supramolecular motifs. Differential scanning calorimetry (DSC) results showed that (TFA)·(BIPY) has a higher thermal stability than ( p CA)·(BIPY) . The thermal stability of the dioxane and pyridine compounds followed the trend, (TFA)·(DX) > ( p CA)·(DX) > ( p CA)·(PYR) . The greater thermal stability of the TFA co-crystals can be related to the presence of the methoxy group which formed an intramolecular hydrogen bond with the hydroxyl group.

Molecular modeling and antioxidant activity of newly synthesized 3‑hydroxy-2-substituted-thiophene derivatives

A facile synthesis of 3‑hydroxy-4-(4-hydroxyphenylazo)thiophenes with various functional groups at position-2 of thiophene ring and their corresponding O-acetylated products is described. The synthetic strategy is based on cyclization of the precursor ethyl 2-(2-(4-hydroxyphenyl)hydrazono)-3-(phenylamino)-3-thioxopropanoate with the appropriate α-chlorinated reagents (namely; chloroacetone, phenacyl chloride, ethyl chloroacetate and chloroacetonitrile). The produced 3‑hydroxy-4-(4-hydroxyphenylazo)thiophenes were acetylated upon heating in acetic anhydride to yield the corresponding 3‑hydroxy-4-(4-acetoxyphenylazo)thiophenes and/or 3-acetoxy-4-(4-acetoxyphenylazo)thiophenes. The synthesized thiophene derivatives were characterized by IR, 1H NMR and mass spectroscopic analyses. The DFT modeling of the synthesized derivatives offered a reasonable description about why the acetylation reaction was occurred on the phenolic OH group rather than the OH group at position-3 of thiophene ring. While in case of 2-cyano-3‑hydroxy-4-(4-hydroxyphenylazo)-5-(phenylamino)-thiophene, both hydroxyl groups were acetylated. The antioxidant activities for the synthesized compounds were assessed through DPPH technique. The 3-hydroxythiophene derivatives 5a-c displayed significant activity with IC50 values (3.01–26.27 µg/mL) using BHA, BHT and ascorbic acid as reference antioxidants. Meanwhile, the results of molecular docking study that applied on the synthesized thiophene derivatives supported the experimental antioxidant assay.

Solvent Effect on Assembling and Interactions in Solutions of Phenol: Infrared Spectroscopic and Density Functional Theory Study.

This work provides new insight into assembling of phenol in various solvents and competition between different kinds of interactions. To examine both weak and strong interactions, we selected a series of non-aromatic and aromatic solvents. Infrared spectra were measured at low (0.05 M) and high (2 M) phenol content. In addition, we performed density functional theory calculations of the structures and harmonic vibrational spectra of 1:1 complexes of phenol with the solvents and the associates of phenol from dimer to tetramer. Based on these results, we divided the solvents into three groups. The first group consists of non-aromatic solvents weakly interacting with phenol. Depending on the concentration, molecules of phenol in these solvents remain non-bonded or self-associated. In diluted solutions of phenol in chlorinated non-aromatic solvents do not appear free OH groups, since they are involved in a weak OH···Cl interaction. It is of note that in diluted solutions of phenol in tetramethyl ethylene both the non-bonded and bonded OH coexists due to solvent-solvent interactions. The second group consists of aromatic solvents with methyl or chlorine substituents. At low concentration, the molecules of phenol are involved in the phenol-solvent OH···π interaction and the strength of these interactions depends on the solvent properties. At a higher phenol content an equilibrium exists between phenol-solvent OH···π and phenol-phenol OH···OH interactions. Finally, the third group includes the aromatic and non-aromatic solvents with highly polar group (C≡N). In these solvents, regardless of the concentration all molecules of phenol are involved in the solute-solvent OH···NC interaction. Comparison of the experimental and theoretical band parameters reveals that molecules of phenol in non-aromatic solvents prefer the cyclic associates, while in the aromatic solvents they tend to form the linear associates.

Probing Hydrogen-Bonding Interactions within Phenol-Benzimidazole Proton-Coupled Electron Transfer Model Complexes with Cryogenic Ion Vibrational Spectroscopy.

Hydrogen-bonding interactions within a series of phenol-benzimidazole model proton-coupled electron transfer (PCET) dyad complexes are characterized using cryogenic ion vibrational spectroscopy. A highly red-shifted and surprisingly broad (>1000 cm-1) transition is observed in one of the models and assigned to the phenolic OH stretch strongly H-bonded to the N(3) benzimidazole atom. The breadth is attributed to a combination of anharmonic Fermi-resonance coupling between the OH stretch and background doorway states involving OH bending modes and strong coupling of the OH stretch frequency to structural deformations along the proton-transfer coordinate accessible at the vibrational zero-point level. The other models show unexpected protonation of the benzimidazole group upon electrospray ionization instead of at more basic remote amine/amide groups. This leads to the formation of HO-+HN(3) H-bond motifs that are much weaker than the OH-N(3) H-bond arrangement. H-bonding between the N(1)H+ benzimidazole group and the carbonyl on the tyrosine backbone is the stronger and preferred interaction in these complexes. The results show that conjugation effects, secondary H-bond interactions, and H-bond soft modes strongly influence the OH-N(3) interaction and highlight the importance of the direct monitoring of proton stretch transitions in characterizing the proton-transfer reaction coordinate in PCET systems.

Comparison of organic acid-based organosolv lignins extracted from the residues of five annual crops

Organosolv lignins were extracted from corn stover, wheat, rice straw, reed straw, and sugarcane bagasse using a mixture of acetic and formic acids, at relatively low temperature and atmospheric pressure. Lignin content, residual carbohydrates, ash levels, proteins, and molecular weights were determined in each extracted lignin. The lignin content of all samples was relatively high, confirming the performance of the pretreatment process. The low molecular weights were in a narrow range, in accordance with the organosolv lignin molar masses. However, some differences between studied lignins were highlighted, in particular in rice straw lignin, which contained the highest silica, calcium, and nitrogen contents. Nuclear magnetic resonance spectroscopies (31P and semi-quantitative Heteronuclear Single Quantum Correlation) underlined the structural similarities and differences between these organosolv lignins. Corn stover and sugarcane bagasse lignins were rich in non-methoxylated (H-Unit) or mono-methoxylated (G-Unit) phenolic units, making them the best promising candidates for production of phenolic resins. Wheat straw lignin was richer in aliphatic OH than in phenolic OH. This is an advantage for use as polyol substitute in polyurethane synthesis. Reed straw lignin was less specific, with a balanced content of OH groups. However, it contained a high concentration of β-O-4 linkages, which is favorable for depolymerization.

Regioselective syntheses and analyses of phlorofucofuroeckol‐A derivatives

AbstractPhlorofucofuroeckol‐A (PFF‐A) is a phlorotannin extracted from various brown algae. PFF‐A shows low toxicity when ingested and various biochemical effects, including antioxidant, anti‐inflammatory, anti‐cancer, and anti‐allergy properties. In this study, various di‐O‐substituted PFF‐A derivatives were synthesized by introducing alkyl or acyl groups at two specific hydroxyls out of the nine nearly equivalent phenolic OH groups present in PFF‐A. The exact molecular structures of the synthesized derivatives were analyzed using two‐dimensional nuclear magnetic resonance (2D NMR) spectroscopy, which confirmed that the substituents were regioselectively introduced at the 1OH and 6OH positions. Small amounts of three mono‐O‐substituted derivatives were generated as by‐products in this reaction, and their structures and regioselectivity were determined using 2D NMR spectroscopy. This study can provide insights into understanding the mechanism of action of eckol‐based compounds and developing new drug candidates.

Chemical and structural characterization of hardwood and softwood LignoForce™ lignins

Knowledge about lignin structure after isolation is paramount for demonstrating its potential for industrial applications. This paper presents for the first time the detailed characterization of LignoForce™ hardwood (LFHL) and softwood (LFSL) kraft lignins that were obtained from industrially realistic lignin production facilities. The moisture content was circa 8 % for both LFHL and LFSL, and their total carbon contents were 62.8 and 64.4 %, respectively. Both samples had low ash and carbohydrate contents and total lignin contents higher than 97 %. The macromolecular properties and functional groups of lignin were characterized by nuclear magnetic resonance, analytical pyrolysis (Py-GC–MS), thermal analysis, mass spectrometry, and size exclusion chromatography. LFHL presented lower aliphatic and phenolic OH groups, higher methoxyl content (S/G ratio of 1.97), lower weight-average apparent molecular mass (Mw) and degree of condensation, higher solubility in organic solvents, and lower thermal stability compared to LFSL. C1-Guaiacol and C1-syringol predominated in the Py-GC–MS analyses of LFSL and LFHL, respectively, whose β-O-4′ contents were 5.8 and 6.2 per 100 aromatic units. The high total OH groups of both lignins suggests their suitability for replacing petroleum-based polyols in the preparation of polyurethane foams. LFHL would be preferable in this application due to its higher solubility in the reaction medium. Also, the lower Mw and glass transition temperature of LFHL would facilitate its blending with polymers in thermoplastic applications. LFSL would be a suitable replacement of phenol in phenol-formaldehyde resins, and its higher Mw and improved thermal stability are expected to be useful for making carbon fibers.

Unveiling the structural properties of water-soluble lignin from gramineous biomass by autohydrolysis and its functionality as a bioactivator (anti-inflammatory and antioxidative)

Due to its low molecular weight and abundant functional groups, water-soluble lignin (WSL) is considered as a more potent antioxidant than traditional industrial lignin in biofields. However, few studies have been conducted to evaluate its intracellular and endogenous reactive oxygen species (ROS)-scavenging ability, especially for the intervention of ROS-related disease in vivo. In this work, WSL in bamboo autohydrolysate (WSL-BM) and wheat stalk autohydrolysate (WSL-WS) were isolated and characterized to comparably analyze their bioactivities. The composition analysis and NMR characterization showed that both WSL-BM and WSL-WS contained relatively similar components and substructures, but WSL-BM contained higher contents of phenolic OH groups. Both WSL samples exhibited excellent biocompatibility with the concentration below 50 μg/mL, while WSL-BM exhibited superior ROS-scavenging ability and ROS-related ulcerative colitis treatment potential at same concentration. In addition, WSL-BM also showed better performance in ameliorating inflammation and oxidative stress in RAW 264.7 cells and colitis mice by activating Nrf2 and suppressing NFκB signaling, resulting in an overall improvement in both macroscopic and histological parameters. Overall, these results implied that WSL from gramineous biomass can be used as a novel anti-inflammatory and antioxidative agent in the biomedical field.

Alkylation of monomeric, dimeric, and polymeric lignin models through carbon-hydrogen activation using Ru-catalyzed Murai reaction

In this study, we have assessed directed carbon-hydrogen activation (CHA) for alkylation of monomeric, dimeric, and polymeric lignin models using Murai's catalyst [RuH2(CO)(PPh3)3]. Based on related work from our laboratory showing that isolated organosolv lignin bears benzylic directing groups ideal for CHA reactions, this approach could offer new methodology for the valorization of biorefinery lignin. Monomeric and dimeric models bearing a keto group at the benzylic position undergo Ru-catalyzed alkylation in good to excellent yield. Similarly, models bearing a benzylic OH group also undergo alkylation via a tandem oxidation/alkylation process enabled by the Ru catalyst. Polymeric models show low levels of functionalization as a result of the poor solubility of the starting polymer. With unsymmetrical models, functionalization occurs first at the least sterically hindered ortho-site, but a subsequent alkylation, leading to disubstituted products can occur at the more sterically hindered site, leading to hexasubstituted arenes. The reaction shows sensitivity to free phenolic OH groups, which appears to reduce the yield in some reactions, and is also a contributing factor to the low yields observed with polymeric lignin models. Combining CHA methodology with lignin isolation technology able to introduce appropriate directing groups for catalytic functionalization will form the basis for improved conversion of lignin to high value chemical products.

Synthesis and radical scavenging activity of new phenolic hydrazone/hydrazide derivatives: Experimental and theoretical studies

Hydrazone and hydrazone-hydrazide-based compounds represent important classes of compounds that continue to attract increasing interest due to their diverse pharmacological actions. In the present study, a series of new phenolic hydrazone/hydrazide derivatives (1–10) have been successfully synthesized and evaluated for their antiradical activity using experimental and theoretical methods. The hydrazones 1–5 were found to be significantly more reactive than their analogs hydrazone-hydrazide 6–10via the main antiradical mechanism as well as toward DPPH and ABTS radicals. The NH group of the hydrazone is more reactive than the NH group of the hydrazide and the phenolic OH groups. The carbonyl group of the hydrazide plays a negative role in the antiradical activity of such molecules. Among the studied compounds, compound 4 was found to be the best radical scavenger with SC50 values (concentration causing 50% of DPPH or ABST scavenging) comparable to those of ascorbic acid and Trolox. These findings provide insights on the structure-activity relationship of hydrazone and hydrazone-hydrazide type compounds, as well as open up new perspectives for the development of novel potent antioxidants.