Phytochemical Profile, GC-MS Profiling and In Vitro Evaluation of Some Biological Applications of the Extracts of Origanum syriacum L. and Cousinia libanotica D.C

Indigenous to Lebanon, Origanum syriacum L. and Cousinia libanotica D.C. are notable plants in the Middle East, with O. syriacum known for its aromatic qualities and C. libanotica being less explored. Both plants have a significant role in traditional medicine for treating various ailments. This study aimed to evaluate the phytochemical composition and biological properties of the extracts from these plants. The extracts were obtained through cold maceration with solvents of increasing polarity. The ethyl acetate extract of O. syriacum exhibited the highest total polyphenol content. High-performance liquid chromatography (HPLC) identified fifteen compounds in both C. libanotica and O. syriacum extracts, whereas gas chromatography-mass spectrometry (GC-MS) analysis unveiled 179 volatile compounds. Notably, the O. syriacum-MeOH extract showed moderate antioxidant activity. Both plants' methanolic extracts demonstrated significant anti-Alzheimer's potential. The O. syriacum-dichloromethane and C. libanotica-cyclohexane extracts displayed the highest cytotoxicities against the HCT-116 cell line. For anti-proliferative activity against the Caco-2 cell line, the O. syriacum-methanol and C. libanotica-cyclohexane extracts were the most effective. This study provides valuable insights into the phytochemistry and potential therapeutic applications of extracts from these two oriental plant species.

Diquinol Functionality Boosts the Superoxide Dismutase Mimicry of a Zn(II) Complex with a Redox-Active Ligand while Maintaining Catalyst Stability and Enhanced Activity in Phosphate Solution

In the current work, we demonstrate ligand design concepts that significantly improve the superoxide dismutase (SOD) activity of a zinc complex; the catalysis is enhanced when two quinol groups are present in the polydentate ligand. We investigate the mechanism through which the quinols influence the catalysis and determine the impact of entirely removing a chelating group from the original hexadentate ligand. Our results suggest that SOD mimicry with these compounds requires a ligand that coordinates Zn(II) strongly in both its oxidized and reduced forms and that the activity proceeds through Zn(II)-semiquinone complexes. The complex with two quinols displays greatly enhanced catalytic ability, with the activity improving by as much as 450% over a related complex with a single quinol. In the reduced form of the diquinol complex, one quinol appears to coordinate to the zinc much more weakly than the other. We believe that superoxide can more readily displace this portion of the ligand, facilitating its coordination to the metal center and thereby hastening the SOD reactivity. Despite the presence of two redox-active groups that may communicate through intramolecular hydrogen bonding and redox tautomerism, only one quinol undergoes two-electron oxidation to a para-quinone during the catalysis. After the formation of the para-quinone, the remaining quinol deprotonates and binds tightly to the metal, ensuring that the complex remains intact in its oxidized state, thereby maintaining its catalytic ability. The Zn(II) complex with the diquinol ligand is highly unusual for a SOD mimic in that it performs more efficiently in phosphate solution.

Cytotoxic and Luminescent Properties of Novel Organotin Complexes with Chelating Antioxidant Ligand

A novel polydentate chelating antioxidant ligand and series of organotin complexes on its base were synthesized and characterized by NMR ¹H, ¹³C, ¹¹⁹Sn, IR spectroscopy, X-ray, and elemental analysis. Their antioxidant activity was evaluated in DPPH and NBT-tests, and as lipoxygenase inhibitory activity. It was shown that ligand alone is a radical scavenger, while introducing tin in the structure of the compound significantly decreases its activity. For the ligand alone the ability to strongly suppress the formation of advanced glycation end products (AGEs) was shown, which may be associated with the established antiradical activity. All synthesized compounds appeared to be moderate lipoxygenase inhibitors. The stability of compounds to hydrolysis under different pH was estimated. The ligand undergoes decomposition after about an hour, while organotin complexes on its base demonstrate vast stability, showing signs of decomposition only after 5 h of experimentation. Cytotoxicity of compounds was studied by standard MTT-test, which showed unorthodox results: the ligand itself demonstrated noticeable cytotoxicity while the introduction of organotin moiety either did not affect the toxicity levels or reduced them instead of increasing. Organotin complexes possess luminescence both as powders and DMSO solutions, its quantum yields reaching 67% in DMSO. The combination of luminescence with unique cytotoxic properties allows us to propose the synthesized compounds as perspective theranostic agents.

Mononuclear Co(II) polypyridyl complexes: synthesis, molecular structure, DNA binding/cleavage, radical scavenging, docking studies and anticancer activities

Mononuclear Co(II) complexes [CoII(L)Cl2]; 1, [CoII(L)(bpy)Cl]PF6; 2, [CoII(L)(phen)Cl]PF6; 3 and [CoII(L)(pic)Cl]; 4, (where L = N,N-bis(pyridin-2-ylmethyl)aniline, bpy = 2,2/-bipyridine, phen = 1,10-phenanthroline, pic = picolinic acid) were systematically synthesized and...

Di-2-picolylamine triggers caspase-independent apoptosis by inducing oxidative stress in human liver hepatocellular carcinoma cells

Di-2-picolylamine (DPA) is an organic compound that has been shown to possess antioxidant properties when conjugated to form a metal complex. The basis of this study was to determine the effects of DPA on the proliferation and apoptosis of human hepatocellular carcinoma cells and elucidate the possible mechanisms. The methylthiazol tetrazolium assay served to measure cell viability and generated an IC₅₀ of 1591 µM. Luminometry was used to investigate caspase activity and ATP concentration. It was observed that the decreased cell viability was associated with reduced ATP levels. Despite increased Bax and caspase 9 activity, cell death was caspase independent as indicated by the reduction in caspase 3/7 activity. This was associated with the downregulation poly(ADP-ribose) polymerase cleavage (Western blotting). However, the Hoescht assay depicted nuclear condensation and apoptotic body formation with elevated DPA levels suggesting DNA damage in HepG2 cells. DNA damage assessed by the comet assay confirmed an increased comet tail formation. The presence of oxidative stress was investigated by quantifying reactive species (malondialdehyde and nitrates concentration) and Western blotting to confirm the expression of antioxidant proteins. The DPA increased lipid peroxidation (RNS), a marker of oxidative stress, consequently causing cell death. The accompanying upregulation of stress-associated proteins superoxide dismutase (SOD2), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and Hsp70 verifies oxidative stress.

Synthesis, Redox Properties and Antibacterial Activity of Hindered Phenols Linked to Heterocycles

A series of benzotriazole, cyclic amides and pyrimidine derivatives, containing 2,6-di-tert-butyl-phenol fragments, were synthesized. The redox properties of obtained compounds were studied using the cyclic voltammetry on a platinum electrode in acetonitrile. The oxidation potentials of all substances were comparable to those of BHT. The obtained compounds were tested for their antibacterial activity, and N-(2-(3,5-di-tert-butyl-4-hydroxyphenyl)-2-oxoethyl)isatin (32 μg/mL) exerted good activity against Staphylococcus aureus.

Adaptable Eu-containing polymeric films with dynamic control of mechanical properties in response to moisture

Self-healing polymers often have a trade-off between healing efficiency and mechanical stiffness. Stiff polymers that sacrifice their chain mobility are slow to repair upon mechanical failure. We herein report adaptable polymer films with dynamically moisture-controlled mechanical and optical properties, therefore having tunable self-healing efficiency. The design of the polymer film is based on the coordination of europium (Eu) with dipicolylamine (DPA)-containing random copolymers of poly(n-butyl acrylate-co-2-hydroxy-3-dipicolylamino methacrylate) (P(nBA-co-GMADPA)). The Eu-DPA complexation results in the formation of mechanically robust polymer films. The coordination of Eu-DPA has proven to be moisture-switchable given the preferential coordination of lanthanide metals to O over N, using nuclear magnetic resonance and fluorescence spectroscopy. Water competing with DPA to bind Eu3+ ions can weaken the cross-linking networks formed by Eu-DPA coordination, leading to the increase of chain mobility. The in situ dynamic mechanical analysis and ex situ rheological studies confirm that the viscofluid and the elastic solid states of Eu-polymers are switchable by moisture. Water speeds up the self-healing of the polymer film by roughly 100 times; while it can be removed after healing to recover the original mechanical stiffness of polymers.

Europium(III) Macrocyclic Chelates Appended with Tyrosine-based Chromophores and Di-(2-picolyl)amine-based Receptors: Turn-On Luminescent Chemosensors Selective to Zinc(II) Ions

Zinc ions play an important role in many biological processes in the human body. To selectively detect Zn²⁺ , two EuDO3A-based complexes (DO3A=1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylic acid) appended with tyrosine as a chromophore and di-(2-picolyl)amine (DPA) as the Zn²⁺ recognition moiety were developed as suitable luminescent sensors. Their luminescence intensity is affected by the photoinduced electron transfer mechanism. Upon addition of Zn²⁺ , both probes display an up to sevenfold enhancement in Eu³⁺ emission. Competition experiments demonstrated their specificity toward Zn²⁺ over other metal ions, while also revealing the nonspecificity of the derivatives lacking the DPA-moiety, thus confirming the essential role of the DPA for the recognition of Zn²⁺ . The induced emission changes of Eu³⁺ allow for precise quantitative analysis of Zn²⁺ , establishing these lanthanide-based complexes as viable chemosensors for biological applications.

Bis(2-pyridylmethyl)amine-functionalized alizarin: an efficient and simple colorimetric sensor for fluoride and a fluorescence turn-on sensor for Al3+ in an organic solution

Bis(2-pyridylmethyl)amine-functionalized alizarin (H₂L) can visibly sense F⁻ and fluorescence-turn-on sense Al³⁺ sensitively in organic solvents. The presence of NiCl₂ increases the chromic sensitivity to F⁻.

Superoxide dismutase activity enabled by a redox-active ligand rather than metal

Reactive oxygen species are integral to many physiological processes. Although their roles are still being elucidated, they seem to be linked to a variety of disorders and may represent promising drug targets. Mimics of superoxide dismutases, which catalyse the decomposition of O₂^•- to H₂O₂ and O₂, have traditionally used redox-active metals, which are toxic outside of a tightly coordinating ligand. Purely organic antioxidants have also been investigated but generally require stoichiometric, rather than catalytic, doses. Here, we show that a complex of the redox-inactive metal zinc(II) with a hexadentate ligand containing a redox-active quinol can catalytically degrade superoxide, as demonstrated by both reactivity assays and stopped-flow kinetics studies of direct reactions with O₂^•- and the zinc(II) complex. The observed superoxide dismutase catalysis has an important advantage over previously reported work in that it is hastened, rather than impeded, by the presence of phosphate, the concentration of which is high under physiological conditions.

Antioxidant and antimicrobial activity of bioactive prodigiosin produces from Serratia marcescens using agricultural waste as a substrate

The objective of this investigation was to explore the antioxidant and antimicrobial property of bioactive prodigiosin produced from Serratia marcescens using rice bran. The antioxidant potential of prodigiosin was examined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2'-azino-bis 3-ethylbenzthiazoline-6-sulfonic acid (ABTS) radical scavenging method via UV-visible, electron spin resonance spectrum (ESR), cyclic voltammetry and excitation emission spectrum. The antimicrobial activity of prodigiosin was examined against foodborne pathogens. The shelf life extending capacity of prodigiosin was evaluated with meat extract powder (MEP) as a model food material. The DPPH and ABTS radicals were completely scavenged by prodigiosin at the concentration of 10 mg/L. The food spoilage was inhibited by the addition of prodigiosin with MEP and it was compared with conventional preservative. The prodigiosin has prohibited the growth of foodborne pathogens effectively and the shelf life of the food was also extended significantly. The antimicrobial edible preservative developed in this study inhibited the growth of the microbial populations that produced through storage of the MEP and free radical scavenging activity. The results reveal that the bioactive prodigiosin effectively scavenged the free radical and inhibited the bacterial growth in food stuff.

Hybrid metal complexes with opposed biological modes of action – promising selective drug candidates

The oxidative stress is considered to be involved in the pathogenesis of many diseases. The antioxidative defense system in the living organism regulates the toxic impact of ROS and there is strong evidence that the antioxidants prevent some pathologies including cancer. The specific chemical properties of metal-based drugs impart innovative pharmacological profiles to this type of therapeutic agents, most likely in relation to novel biomolecular mechanisms. This review will focus on a novel approach to design polyfunctional metal-based physiollogically active compounds with opposed modes of action – prooxidant metal center and antioxidant 2,6-dialkylphenol group. The synthesis and anti/prooxidant activity and cytotoxicity studies of novel organometallic/coordination compounds (ferrocenes, complexes with di-(2-picolyl)amine ligand, porphyrins, pyridines, thiols, carboxylates) based on either biogenic metals (Fe, Mn, Co, Cu, Zn, Ni) or exogenic metals (Sn, Au, Rh) are presented and discussed. The results allow us to conclude that combining in one molecule a redox active metal center and cytoprotective functional organic moiety with antioxidative function is a promising way to rational metallodrug design in modern medicinal chemistry.

Hydroxyalkyloxy substituted tetraphenylporphyrins: Mechanism and superoxide scavenging activity

The novel electrochemical approach based on coulometric response of electro-generated superoxide (O[Formula: see text] was used to determine scavenging properties of 2H-5,10,15,20-tetrakis (4-hydroxyphenyl)porphyrin (H[Formula: see text]T(4-OHPh)P); 2H-5,10,15,20-tetrakis[4-(2-hydroxyethyloxy)phenyl]porphyrin (H[Formula: see text]T(4-OH(CH[Formula: see text]OPh)P); 2H-5,10,15,20-tetrakis[4-(4-hydroxybutyloxy)phenyl]porphyrin (H[Formula: see text]T(4-OH(CH[Formula: see text]OPh)P); Zn-5,10,15,20-tetrakis[4-(4-hydroxyethyloxy)phenyl]porphyrin (ZnT(4-OH(CH[Formula: see text]OPh)P) superoxide. It has been identified that the porphyrins under study possess good antioxidant properties. The analysis of possible interactions between porphyrins and superoxide anion-radical has shown that high values of superoxide scavenging activity of tetraphenylporphyrins with alcohol chains can be explained by the nucleophilic attack of O[Formula: see text] on the C–C bonds of alcohol.

Electrochemical determination of antioxidant properties of a series of tetraphenylporphyrin derivatives and their zinc complexes

Zinc complexes of a series of substituted tetraphenylporphyrins containing OH-groups in the phenyl rings were synthesized. Their antioxidant capacity was estimated in reaction of the porphyrins with 2,2′-diphenyl-1-picrylhydrazyl (DPPH) by cyclic voltammetry. The electron absorption spectra of the all synthesized compounds before and after the reaction with 2,2′-diphenyl-1-picrylhydrazyl were recorded. The effect of structure of the porphyrins and zinc complexes on their antioxidant capacity was discussed.

The coulometric approach to the superoxide scavenging activity determination: The case of porphyrin derivatives influence on oxygen electroreduction

The electrochemical and antioxidant properties of 5,10,15,20-tetrakis(3′-hydroxyphenyl)porphyrin ( H 2 T (m- OHPh ) P ) and 5,10,15,20-tetrakis(4′-hydroxyphenyl)porphyrin ( H 2 T (p- OHPh ) P ) were tested by the cyclic voltammetry (CV) method. It is shown that in dimethylsulfoxide (DMSO) the electroreduction processes of oxygen and porphyrins are under diffusion control. The electroreduction of H 2 T (m- OHPh ) P and H 2 T (p- OHPh ) P with potentials about -1 V are irreversible due to the chemical step (EC process) which leads to products with oxidation potentials about -0.5 V. Additionally in case of oxygen and porphyrin coreduction, both H 2 T (m- OHPh ) P and H 2 T (p- OHPh ) P influence the O 2•- electrosynthesis. The nonlinear dependence of the O 2•- peak current vs. porphyrin concentrations makes the available amperometric approach unsuitable for antioxidant activity estimation. To solve this problem, the coulometric parameters were calculated. The excellent linearity of the coulometric response of superoxide ion vs. porphyrins concentration was demonstrated for a wide concentration range. On the basis of coulometric responses, we constructed a parameter which separated the radical scavenging activity and variation of oxygen electroreduction. The superoxide scavenging activities of H 2 T (m- OHPh ) P and H 2 T (p- OHPh ) P were determined using the developed approach. The effect of OH group position on the superoxide scavenge activity is shown: H 2 T (p- OHPh ) P has a higher activity (slope = 0.75 L.mmol-1) than H 2 T (m- OHPh ) P (slope = 0.60 L.mmol-1).

Single and double chain surfactant–cobalt(iii) complexes: the impact of hydrophobicity on the interaction with calf thymus DNA, and their biological activities

Single chain surfactant–cobalt(iii) complexes interact with minor grooves of CT-DNA, whereas double chin surfactant–cobalt(iii) complexes bind with CT-DNA through partial intercalation.

[2,5-Bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene]dichloridomanganese(II): from a mononuclear compound to a three-dimensional supramolecular framework through C-H···Cl hydrogen bonds and π-π stacking interactions

The title compound, [MnCl2(C24H20N6)], has been synthesized and characterized based on the multifunctional ligand 2,5-bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene (L). The Mn(II) centre is five-coordinate with an approximately square-pyramidal geometry. The L ligand acts as a tridendate chelating ligand. The mononuclear molecules are bridged into a one-dimensional chain by two C-H···Cl hydrogen bonds. These chains are assembled into a two-dimensional layer through π-π stacking interactions between adjacent uncoordinated bipyridyl groups. Furthermore, a three-dimensional supramolecular framework is attained through π-π stacking interactions between adjacent coordinated bipyridyl groups.

Cooperative anion recognition in copper(II) and zinc(II) complexes with a ditopic tripodal ligand containing a urea group

The ability of Cu(II) and Zn(II) complexes of the ditopic receptor H2L [1-(2-((bis(pyridin-2-ylmethyl)amino)methyl)phenyl)-3-(3-nitrophenyl)urea] for anion recognition is reported. In the presence of weakly coordinating anions such as ClO4(-), the urea group binds to the metal ion (Cu(II) or Zn(II)) through one of its nitrogen atoms. The study of the interaction of the metal complexes with a variety of anions in DMSO shows that SO4(2-) and Cl(-) bind to the complexes through a cooperative binding involving simultaneous coordination to the metal ion and different hydrogen-bonding interactions with the urea moiety, depending on the shape and size of the anion. On the contrary, single crystal X-ray diffraction studies show that anions such as NO3(-) and PhCO2(-) form 1:2 complexes (metal/anion) where one of the anions coordinates to the metal center and the second one is involved in hydrogen-bonding interaction with the urea group, which is projected away from the metal ion. Spectrophotometric titrations performed for the Cu(II) complex indicate that this system is able to bind a wide range of anions with an affinity sequence: MeCO2(-) ∼ Cl(-) (log K11 > 7) > NO2(-) > H2PO4(-) ∼ Br(-) > HSO4(-) > NO3(-) (log K11 < 2). In contrast to this, the free ligand gives much weaker interactions with these anions. In the presence of basic anions such as MeCO2(-) or F(-), competitive processes associated with the deprotonation of the coordinated N-H group of the urea moiety take place. Thus, N-coordination of the urea unit to the metal ion increases the acidity of one of its N-H groups. DFT calculations performed in DMSO solution are in agreement with both an anion-hydrogen bonding interaction and an anion-metal ion coordination collaborating in the stabilization of the metal salt complexes with tetrahedral anions.

Di-aqua-dichlorido-bis-(pyridine-κN)cobalt(II)

The title mol­ecule, [CoCl₂(C₅H₅N)₂(H₂O)₂], has -1 symmetry with the Co^II ion situated on an inversion centre. The cation has a distorted octa­hedral coordination environment and is surrounded by two N and two Cl atoms in the equatorial plane, while the coordinating water O atoms occupy the axial positions. The crystal exhibits nonmerohedral twinning with two domain states, the volume fractions of which were refined to 0.883 (2) and 0.117 (3). The crystal packing is stabilized by O—H⋯Cl hydrogen-bond inter­actions, forming two-dimensional networks lying parallel to (001). The crystal packing also features π–π inter­actions between the pyridine rings, with centroid–centroid separations of 3.493 (3) and 3.545 (3) Å.