Biological Investigations and Spectroscopic Studies of New Moxifloxacin/Glycine-Metal Complexes

Triphenylphosphine Derivatives of Allylbenzenes Express Antitumor and Adjuvant Activity When Solubilized with Cyclodextrin-Based Formulations

Allylbenzenes (apiol, dillapiol, myristicin and allyltetramethoxybenzene) are individual components of plant essential oils that demonstrate antitumor activity and can enhance the antitumor activity of cytotoxic drugs, such as paclitaxel, doxorubicin, cisplatin, etc. Triphenylphosphine (PPh3) derivatives of allylbenzenes are two to three orders of magnitude more potent than original allylbenzenes in terms of IC50. The inhibition of efflux pumps has been reported for allylbenzenes, and the PPh3 moiety is deemed to be responsible for preferential mitochondrial accumulation and the depolarization of mitochondrial membranes. However, due to poor solubility, the practical use of these substances has never been an option. Here, we show that this problem can be solved by using a complex formation with cyclodextrin (CD-based molecular containers) and polyanionic heparin, stabilizing the positive charge of the PPh3 cation. Such containers can solubilize both allylbenzenes and their PPh3 derivatives up to 0.4 mM concentration. Furthermore, we have observed that solubilized PPh3 derivatives indeed work as adjuvants, increasing the antitumor activity of paclitaxel against adenocarcinomic human alveolar basal epithelial cells (A549) by an order of magnitude (in terms of IC50) in addition to being quite powerful cytostatics themselves (IC50 in the range 1-10 µM). Even more importantly, CD-solubilized PPh3 derivatives show pronounced selectivity, being highly toxic for the A549 tumor cell line and minimally toxic for HEK293T non-tumor cells, red blood cells and sea urchin embryos. Indeed, in many cancers, the mitochondrial membrane is more prone to depolarization compared to normal cells, which probably explains the observed selectivity of our compounds, since PPh3 derivatives are known to act as mitochondria-targeting agents. According to the MTT test, 100 µM solution of PPh3 derivatives of allylbenzenes causes the death of up to 85% of A549 cancer cells, while for HEK293T non-cancer cells, only 15-20% of the cells died. The hemolytic index of the studied substances did not exceed 1%, and the thrombogenicity index was < 1.5%. Thus, this study outlines the experimental foundation for developing combined cytostatic medications, where effectiveness and selectivity are achieved through decreased concentration of the primary ingredient and the inclusion of adjuvants, which are safe or practically harmless substances.

Exploring the Interaction Between the Newly Designed Antitumor Zn(II) Complex and CT-DNA/BSA: Spectroscopic Methods, DFT Computational Analysis, and Docking Simulation

A new zinc(II) complex formulated as [Zn(pipr-ac)2], where pipr-ac stands for piperidineacetate, was synthesized and structurally identified with the help of experimental and DFT methods. Frontier molecular orbital (FMO) analysis demonstrated that the new complex has higher biological activity compared to the free ligand. Molecular electrostatic potential (MEP) showed the nitrogen atoms and oxygen of carbonyl groups are the active sites of Zn(II) compound. Also, natural bond orbital (NBO) analysis confirmed the charge transfer from the ligating atoms to the metal ion and formation of four coordinated Zn(II) complex. MTT assay illustrated a noticeable cytotoxic activity of the new zinc(II) complex compared to cisplatin on K562 cell line. The CT-DNA and serum albumin (SA) binding of the Zn(II) complex were explored individually. In this regard, UV-Vis spectroscopy and florescence titration revealed the occurrences of fluorescence quenching of CT-DNA/SA by metal compound via static mechanism and creation of hydrogen bonds and van der Waals interactions between them. The binding was further confirmed by viscosity measurement and gel electrophoresis assay for CT-DNA and circular dichroism spectroscopy for SA. Moreover, molecular docking simulation demonstrated that the new compound binds mainly through hydrogen bonds to the groove of DNA and hydrogen bonds and van der Waals interactions to site I of SA.

Mucosal Adhesive Chitosan Nanogel Formulations of Antibiotics and Adjuvants (Terpenoids, Flavonoids, etc.) and Their Potential for the Treatment of Infectious Diseases of the Gastrointestinal Tract

Bacterial infections are usually found in the stomach and the first part of the small intestine in association with various pathologies, including ulcers, inflammatory diseases, and sometimes cancer. Treatment options may include combinations of antibiotics with proton pump inhibitors and anti-inflammatory drugs. However, all of them have high systemic exposure and, hence, unfavorable side effects, whereas their exposure in stomach mucus, the predominant location of the bacteria, is limited. Chitosan and nanogels based on chitosan presumably are not absorbed from the gastrointestinal tract and are known to adhere to the mucus. Therefore, they can serve as a basis for the local delivery of antibacterial drugs, increasing their exposure at the predominant location of therapeutic targets, thus improving the risk/benefit ratio. We have used E. coli ATCC 25922 (as a screening model of pathogenic bacteria) and Lactobacilli (as a model of a normal microbiome) to study the antibacterial activity of antibacterial drugs entrapped in a chitosan nanogel. Classical antibiotics were studied in a monotherapeutic regimen as well as in combination with individual terpenoids and flavonoids as adjuvants. It has been shown that levofloxacin (LF) in combination with zephirol demonstrate synergistic effects against E. coli (cell viability decreased by about 50%) and, surprisingly, a much weaker effect against Lactobacilli. A number of other combinations of antibiotic + adjuvant were also shown to be effective. Using FTIR and UV spectroscopy, it has been confirmed that chitosan nanogels with the drug are well adsorbed on the mucosal model, providing prolonged release at the target location. Using an ABTS assay, the antioxidant properties of flavonoids and other drugs are shown, which are potentially necessary to minimize the harmful effects of toxins and radicals produced by pathogens. In vivo experiments (on sturgeon fish) showed the effective action of antibacterial formulations developed based on LF in chitosan nanogels for up to 11 days. Thus, chitosan nanogels loaded with a combination of drugs and adjuvants can be considered as a new strategy for the treatment of infectious diseases of the gastrointestinal tract.

Covalent Conjugates of Allylbenzenes and Terpenoids as Antibiotics Enhancers with the Function of Prolonged Action

The drug resistance of pathogenic bacteria is often due efflux pumps-specific proteins that remove foreign compounds from bacterial cells. To overcome drug resistance, adjuvants are often used that can inhibit efflux pumps or other systems that ensure the resistance of bacteria to the action of antibiotics. We assumed that a new level of effectiveness with the use of an antibiotic + an adjuvant pair could be achieved by their joint delivery into the pathogen. To test this hypothesis, we constructed a series of molecular carriers based on poly-(olygo-, dendry)mers based on cyclodextrin-grafted PEI or mannan, as well as glycol chitosan, covalently bound to antibiotic, adjuvant, and the oligosaccharide ligand to the macrophage mannose receptor (CD206), which we studied earlier and showed high efficiency and selectivity of delivery of a therapeutic "cargo" to macrophages. Moxifloxacin was used as an antibiotic, and terpenoid and allylbenzene compounds were used as adjuvants, for which we previously discovered the ability to inhibit bacterial efflux pumps. We show that: (a) the resulting structures were stable in vitro for a long time (up to 10 days); (b) they were adsorbed on bacterial cells, providing a local increase in the concentration of the antibiotic and adjuvant in pathogen cells; (c) they were internalized by bacterial cells, ensuring the accumulation of both antibiotic and adjuvant inside bacterial cells; (d) the adjuvant, after entering the bacterial cell, provided inhibition of the efflux pumps; (e) due to this action of the adjuvant, combined with the targeted delivery by the carrier, the antibiotic's half-life in rats increased by more than 2 times, the effective concentration of the drug in the blood plasma (AUC) increased up to 8-10 times; (f) a significant increase in the effectiveness of the antibacterial action against Gram+ and Gram- cells was achieved (up to 3 times). Potentially, such an approach would significantly increase the effectiveness of therapies for a number of infectious and other diseases, reduce the dosage of antibiotics, shorten the duration of treatment, and reduce the risk of developing bacterial resistance. Moreover, the use of a polymer carrier with covalently bound organic molecules of different structures will avoid problems linked to different (suboptimal) solubility and bio-distribution of the administered molecules, which would be almost inevitable when using the same compounds separately. It would be very difficult to find antibiotic/adjuvant pairs that simultaneously achieve optimal concentrations in the same target cells. In our case, terpenoids and alkylbenzenes used as adjuvants are practically insoluble as individual compounds, and their unacceptable pharmacological properties would not allow them to be used as efflux pump inhibitors.

Synthesis, Characterization, Antimicrobial and Antimalarial Activities of Azines Based Schiff Bases and their Pd(II) Complexes

Herein, we report synthesis, characterization, antimicrobial and antimalarial activities of azines Schiff base ligands (L1 -L4 ) and their palladium (II) complexes (C1 -C4 ) of [Pd(L)(OAc)2 ] type. The azine ligands (L1 -L4 ) were prepared by condensation of carbonyl compounds with hydrazine hydrate and their complexes by the reaction of palladium acetate with L1 -L4 ligands in 1 : 1 molar ratio. The prepared ligands and their complexes were characterized by spectral characterization using 1 H &13 C-NMR, FT-IR and mass spectral studies, which revealed that the ligands coordinates via azomethine nitrogen and heteroatom or aryl carbon with palladium. Moreover, Schiff bases and their palladium (II) complexes have been screened for their antibacterial (S. aureus, B. subtillis, and S. typhi, P. aeruginosa), antifungal (C. albicans, A. niger, and A. clavatus) and antimalarial (P. falciparum) activities. The Schiff base L4 showed good results for antibacterial against S. aureus (MIC, 50 μg/mL) and antimalarial against P. falciparum (IC50 , 0.83 μg/mL). The complex C1 showed best antibacterial activity (MIC, 62.5 μg/mL) against S. typhi and the complex C4 exhibited remarkable antimalarial activity (IC50 , 0.42 μg/mL) among the tested compounds. Thus, azines based ligands and their Pd complexes can be good antimicrobial and antimalarial agents if explored further.

Development and Evaluation of EDTA-Treated Rabbits for Bioavailability Study of Chelating Drugs Using Levofloxacin, Ciprofloxacin, Hemiacetal Ester Prodrugs, and Tetracycline

Laboratory rabbits are fed foods rich with cationic metals, and while fasting cannot empty gastric contents because of their coprophagic habits. This implies that, in rabbits, the oral bioavailability of chelating drugs could be modulated by the slow gastric emptying rates and the interaction (chelation, adsorption) with gastric metals. In the present study, we tried to develop a rabbit model with low amounts of cationic metals in the stomach for preclinical oral bioavailability studies of chelating drugs. The elimination of gastric metals was achieved by preventing food intake and coprophagy and administering a low concentration of EDTA 2Na solution one day before experiments. Control rabbits were fasted but coprophagy was not prevented. The efficacy of rabbits treated with EDTA 2Na was evaluated by comparing the gastric contents, gastric metal contents and gastric pH between EDTA-treated and control rabbits. The treatment with more than 10 mL of 1 mg/mL EDTA 2Na solution decreased the amounts of gastric contents, cationic metals and gastric pH, without causing mucosal damage. The absolute oral bioavailabilities (mean values) of levofloxacin (LFX), ciprofloxacin (CFX) and tetracycline hydrochloride (TC), chelating antibiotics, were significantly higher in EDTA-treated rabbits than those in control rabbits as follows: 119.0 vs. 87.2%, 9.37 vs. 13.7%, and 4.90 vs. 2.59%, respectively. The oral bioavailabilities of these drugs were significantly decreased when Al(OH)₃ was administered concomitantly in both control and EDTA-treated rabbits. In contrast, the absolute oral bioavailabilities of ethoxycarbonyl 1-ethyl hemiacetal ester (EHE) prodrugs of LFX and CFX (LFX-EHE, CFX-EHE), which are non-chelating prodrugs at least in in vitro condition, were comparable between control and EDTA-treated rabbits irrespective of the presence of Al(OH)₃, although some variation was observed among rabbits. The oral bioavailabilities of LFX and CFX from their EHE prodrugs were comparable with LFX and CFX alone, respectively, even in the presence of Al(OH)₃. In conclusion, LFX, CFX and TC exhibited higher oral bioavailabilities in EDTA-treated rabbits than in control rabbits, indicating that the oral bioavailabilities of these chelating drugs are reduced in untreated rabbits. In conclusion, EDTA-treated rabbits were found to exhibit low gastric contents including metals and low gastric pH, without causing mucosal damage. Ester prodrug of CFX was effective in preventing chelate formation with Al(OH)₃ in vitro and in vivo, as well as in the case of ester prodrugs of LFX. EDTA-treated rabbits are expected to provide great advantages in preclinical oral bioavailability studies of various drugs and dosage formulations. However, a marked interspecies difference was still observed in the oral bioavailability of CFX and TC between EDTA-treated rabbits and humans, possibly due to the contribution of adsorptive interaction in rabbits. Further study is necessary to seek out the usefulness of the EDTA-treated rabbit with less gastric contents and metals as an experimental animal.

Tamarindus indica Extract as a Promising Antimicrobial and Antivirulence Therapy

The worldwide crises from multi-drug-resistant (MDR) bacterial infections are pushing us to search for new alternative therapies. The renewed interest in medicinal plants has gained the attention of our research group. Tamarindus indica L. (T. indica) is one of the traditional medicines used for a wide range of diseases. Therefore, we evaluated the antimicrobial activities of ethanolic extract of T. indica. The inhibitions zones, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and fractional inhibitor concentration indices (FICI) against Gram+ve and −ve pathogens were detected. The bioactive compounds from T. indica extract were identified by mass spectroscopy, thin-layer chromatography, and bio-autographic assay. We performed scanning electron microscopy (SEM) and molecular docking studies to confirm possible mechanisms of actions and antivirulence activities, respectively. We found more promising antimicrobial activities against MDR pathogens with MIC and MBC values for Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), i.e., (0.78, 3.12 mg/mL) and (1.56, 3.12 mg/mL), respectively. The antimicrobial activities of this extract were attributed to its capability to impair cell membrane permeability, inducing bacterial cell lysis, which was confirmed by the morphological changes observed under SEM. The synergistic interactions between this extract and commonly used antibiotics were confirmed (FICI values < 0.5). The bioactive compounds of this extract were bis (2-ethylhexyl)phthalate, phenol, 2,4-bis(1,1-dimethylethyl), 1,2-benzenedicarboxylic acid, and bis(8-methylnonyl) ester. Additionally, this extract showed antivirulence activities, especially against the S. aureus protease and P. aeruginosa elastase. In conclusion, we hope that pharmaceutical companies can utilize our findings to produce a new formulation of T. indica ethanolic extract with other antibiotics.

Moxifloxacin Metal Complexes: Synthesis, Characterisation, Antimicrobial and Antidiabetic Activities with Docking Studies

Six new metal complexes of Fe(III), Cu(II), and Hg(II) were synthesised, i.e., three (2, 4, and 5) with moxifloxacin (mono-ligand) and the other three (1, 3 and 6) with moxifloxacin and hydrazine (biligand). These were characterised through UV-Vis, FT-IR, elemental analysis (CHN), atomic absorption spectroscopy, TGA, scanning electron microscopy (SEM), and powder XRD studies. Further, all of these compounds were screened for their antimicrobial, cytotoxic, and antidiabetic potential. The study revealed that the synthesised metal complexes possess an excellent ability to become antifungal agents compared to moxifloxacin. Additionally, the cytotoxicity of compounds 1, 3, and 4 was in the acceptable range with much better antidiabetic potential as compared to the ligand moxifloxacin. Interestingly, the α-amylase inhibition activity of complexes 1 and 3 was found very close to the standard drug acarbose. Furthermore, the computational studies also authenticate the results of the antidiabetic potential of complexes 1, 3, and 4 by presenting the necessary interactions of these compounds with their respective binding sites. The overall results indicate that the antifungal and antidiabetic ability of moxifloxacin is enhanced significantly by complexation with the given metals and the secondary ligand, thereby making it a suitable lead compound for yet another avenue of an antifungal and antidiabetic agent in the field of drug discovery and development.

Green Synthesized of Thymus vulgaris Chitosan Nanoparticles Induce Relative WRKY-Genes Expression in Solanum lycopersicum against Fusarium solani, the Causal Agent of Root Rot Disease

Fusarium solani is a plant pathogenic fungus that causes tomato root rot disease and yield losses in tomato production. The current study's main goal is testing the antibacterial efficacy of chitosan nanoparticles loaded with Thyme vulgaris essential oil (ThE-CsNPs) against F. solani in vitro and in vivo. GC-MS analysis was used to determine the chemical constituents of thyme EO. ThE-CsNPs were investigated using transmission electron microscopy before being physicochemically characterized using FT-IR. ThE-CsNPs were tested for antifungal activity against F. solani mycelial growth in vitro. A pot trial was conducted to determine the most effective dose of ThE-CsNPs on the morph/physiological characteristics of Solanum lycopersicum, as well as the severity of fusarium root rot. The relative gene expression of WRKY transcript factors and defense-associated genes were quantified in root tissues under all treatment conditions. In vitro results revealed that ThE-CsNPs (1%) had potent antifungal efficacy against F. solani radial mycelium growth. The expression of three WRKY transcription factors and three tomato defense-related genes was upregulated. Total phenolic, flavonoid content, and antioxidant enzyme activity were all increased. The outfindings of this study strongly suggested the use of ThE-CsNPs in controlling fusarium root rot on tomatoes; however, other experiments remain necessary before they are recommended.

Mannosylated Polymeric Ligands for Targeted Delivery of Antibacterials and Their Adjuvants to Macrophages for the Enhancement of the Drug Efficiency

Bacterial infections and especially resistant strains of pathogens localized in macrophages and granulomas are intractable diseases that pose a threat to millions of people. In this paper, the theoretical and experimental foundations for solving this problem are proposed due to two key aspects. The first is the use of a three-component polymer system for delivering fluoroquinolones to macrophages due to high-affinity interaction with mannose receptors (CD206). Cytometry assay determined that 95.5% macrophage-like cells were FITC-positive after adding high-affine to CD206 trimannoside conjugate HPCD-PEI1.8-triMan, and 61.7% were FITC-positive after adding medium-affine ligand with linear mannose label HPCD-PEI1.8-Man. The second aspect is the use of adjuvants, which are synergists for antibiotics. Using FTIR and NMR spectroscopy, it was shown that molecular containers, namely mannosylated polyethyleneimines (PEIs) and cyclodextrins (CDs), load moxifloxacin (MF) with dissociation constants of the order of 10⁻⁴–10⁻⁶ M; moreover, due to prolonged release and adsorption on the cell membrane, they enhance the effect of MF. Using CLSM, it was shown that eugenol (EG) increases the penetration of doxorubicin (Dox) into cells by an order of magnitude due to the creation of defects in the bacterial wall and the inhibition of efflux proteins. Fluorescence spectroscopy showed that 0.5% EG penetrates into bacteria and inhibits efflux proteins, which makes it possible to increase the maximum concentration of the antibiotic by 60% and maintain it for several hours until the pathogens are completely neutralized. Regulation of efflux is a possible way to overcome multiple drug resistance of both pathogens and cancer cells.

Chelation of Zinc with Biogenic Amino Acids: Description of Properties Using Balaban Index, Assessment of Biological Activity on Spirostomum Ambiguum Cellular Biosensor, Influence on Biofilms and Direct Antibacterial Action

The complexation of biogenic molecules with metals is the widespread strategy in screening for new pharmaceuticals with improved therapeutic and physicochemical properties. This paper demonstrates the possibility of using simple QSAR modeling based on topological descriptors for chelates study. The presence of a relationship between the structure (J) and lipophilic properties (logP) of zinc complexes with amino acids, where two molecules coordinate the central atom through carboxyl oxygen and amino group nitrogen, and thus form a double ring structure, was predicted. Using a cellular biosensor model for Gly, Ala, Met, Val, Phe and their complexes Zn(AA)₂, we experimentally confirmed the existence of a direct relationship between logP and biological activity (Ea). The results obtained using topological analysis, Spirotox method and microbiological testing allowed us to assume and prove that the chelate complex of zinc with methionine has the highest activity of inhibiting bacterial biofilms, while in aqueous solutions it does not reveal direct antibacterial effect.

Spectroscopic Analyses and Antimicrobial Activity of Novel Ciprofloxacin and 7-Hydroxy-4-methylcoumarin, the Plant-Based Natural Benzopyrone Derivative

Coumarin is highly distributed in nature, notably in higher plants. The biological features of coumarin include antibacterial, anticancer and antioxidant effects. It is well known that metal ions present in complexes accelerate the drug action and the efficacy of organic therapeutic agents. The main aim of the current study is the synthesis of different complexes of the interaction between ciprofloxacin hydrochloride (CIP) and coumarin derivative 7-hydroxy-4-methylcoumarin (HMC) with Zr(IV). The chelates of CIP with Zr(IV) were prepared and characterized by elemental analysis, melting point, conductance measurements, spectroscopic techniques involving IR, UV-Vis, ¹H NMR, and thermal behavior (TG-DTG) in the presence of HMC, dimethylformamide (DMF), pyridine (Py), and triethylamine (Et₃N). Results of molar conductivity tests showed that the new synthesized complexes are electrolytes with a 1:1 or 1:2 electrolyte ratio, with the chloride ions functioning as counter ions. According to IR spectra, CIP acts as a neutral bidentate ligand with Zr(IV) through one carboxylato oxygen and the carbonyl group, HMC as a monodentate through the carbonyl group, and DMF through the oxygen atom of the carbonyl group and the N atom of Py and Et₃N. The thermal behavior of the complexes was carefully investigated using TG and DTG techniques. TG findings signal that water molecules are found as hydrated and coordinated. The thermal decomposition mechanisms proposed for CIP, HMC, and Zr(IV) complexes are discussed and the activation energies (E_a), Gibbs free energies (∆G*), entropies (∆S*), and enthalpies (∆H*) of thermal decomposition reactions have been calculated using Coats–Redfern (CR) and Horowitz–Metzeger (HM) methods. The studied complexes were tested against some human pathogens and phytopathogens, including three Gram-positive bacteria (Bacillus subtilis, B. cereus, Brevibacterium otitidis) and three Gram-negative bacteria (Escherichiacoli, Pseudomonas aeruginosa and Klebsiella pneumoniae), and compared to the free CIP and HMC parent compounds.

Antioxidative, cytotoxic, and antibacterial properties of self-assembled glycine-histidine-based dipeptides with or without silver nanoparticles in bio-inspired film

Recent years have seen much attention being given to self-assembly of dipeptide-based structures, especially to self-regulation of dipeptide structures with different amino acid sequences. In this study we investigated the effects of varying solvent environments on the self-assembly of glycine-histidine (Gly-His) dipeptide structures. First we determined the morphological properties of Gly-His films formed in different solvent environments with scanning electron microscopy and then structural properties with Fourier-transform infrared (FTIR) spectroscopy. In addition, we studied the effects of Gly-His films on silver nanoparticle (AgNP) formation and the antioxidant and cytotoxic properties of AgNPs obtained in this way. We also, assessed antibacterial activities of Gly-His films against Gram-negative Escherichia coli and Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. Silver nanoparticle-decorated Gly-His films were not significantly cytotoxic at concentrations below 2 mg/mL but had antibacterial activity. We therefore believe that AgNP-decorated Gly-His films at concentrations below 2 mg/mL can be used safely against bacteria.

Evaluation of the Antimicrobial Activity of Four Plant Essential Oils against Some Food and Phytopathogens Isolated from Processed Meat Products in Egypt

Synthetic preservatives are widely utilized by the food industry to inhibit the microbial contamination and increase food safety and shelf life. The excessive utilization of synthetic preservatives can have a negative impact on human health and the environment. There is a great interest to find out natural substances as possible food-preservatives. The consumers’ preference for food products with natural ingredients prompted food manufacturers to utilize natural-based preservatives in their production. It is worth noting that plant essential oils (EOs) among the natural-based substances have been efficiently used as antimicrobial agents against phyto- and food pathogens. The current study was conducted to evaluate the microbial contamination of three industrial meat products from five governorates in Egypt, identify the predominant bacterial and fungal isolates and determine the antimicrobial efficacy of some EOs (thyme, fennel, anise and marjoram) against the most predominant microbial isolates. A sensory test was also performed to estimate the customer preferences for specific organoleptic aspects of meat products after EOs treatment. Results showed that there is a promising antimicrobial activity of all studied EOs against some microbial isolates in a dose-dependent manner. In particular, thyme EO showed the highest significant antibacterial activity against P. fluorescence and E. coli. Whereas the marjoram EO showed the highest activity against P. aeruginosa. In addition, the sensory test revealed that the treatment with anise and marjoram EOs showed the highest acceptability by the testers and did not show significant differences on the organoleptic properties with respect to control. As overall, the obtained results of the current research are promising and proved feasibility of employing plant EOs as possible preservatives for processed meat products.

Biochemical Characterization of New Gemifloxacin Schiff Base (GMFX-o-phdn) Metal Complexes and Evaluation of Their Antimicrobial Activity against Some Phyto- or Human Pathogens

Four novel ligand-metal complexes were synthesized through the reaction of Fe(III), pleaseCo(II), Zn(II), and Zr(IV) with Schiff base gemifloxacin reacted with ortho-phenylenediamine (GMFX-o-phdn) to investigate their biological activities. Elemental analysis, FT-IR, ¹H NMR, UV-visible, molar conductance, melting points, magnetic susceptibility, and thermal analyses have been carried out for insuring the chelation process. The antimicrobial activity was carried out against Monilinia fructicola, Aspergillus flavus, Penicillium italicum, Botrytis cinerea, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, and P. aeruginosa. The radical scavenging activity (RSA%) was in vitro evaluated using ABTS method. FT-IR spectra indicated that GMFX-o-phdn chelated with metal ions as a tetradentate through oxygen of carboxylate group and nitrogen of azomethine group. The data of infrared, ¹H NMR, and molar conductivity indicate that GMFX–o-phdn reacted as neutral tetra dentate ligand (N₂O₂) with metal ions through the two oxygen atoms of the carboxylic group (oxygen containing negative charge) and two nitrogen atoms of azomethine group (each nitrogen containing a lone pair of electrons) (the absent of peak corresponding to ν(COOH) at 1715 cm⁻¹, the shift of azomethine group peak from 1633 cm⁻¹ to around 1570 cm⁻¹, the signal at 11 ppm of COOH and the presence of the chloride ions outside the complex sphere). Thermal analyses (TG-DTG/DTA) exhibited that the decaying of the metal complexes exists in three steps with the final residue metal oxide. The obtained data from DTA curves reflect that the degradation processes were exothermic or endothermic. Results showed that some of the studied complexes exhibited promising antifungal activity against most of the tested fungal pathogens, whereas they showed higher antibacterial activity against E. coli and B. cereus and low activity against P. fluorescens and P. aeruginosa. In addition, GMFX-o-phdn and its metal complexes showed strong antioxidant effect. In particular, the parent ligand and Fe(III) complex showed greater antioxidant capacity at low tested concentrations than that of other metal complexes where their IC₅₀ were 169.7 and 164.6 µg/mL, respectively.

Recent Approaches towards Control of Fungal Diseases in Plants: An Updated Review

Recent research demonstrates that the number of virulent phytopathogenic fungi continually grows, which leads to significant economic losses worldwide. Various procedures are currently available for the rapid detection and control of phytopathogenic fungi. Since 1940, chemical and synthetic fungicides were typically used to control phytopathogenic fungi. However, the substantial increase in development of fungal resistance to these fungicides in addition to negative effects caused by synthetic fungicides on the health of animals, human beings, and the environment results in the exploration of various new approaches and green strategies of fungal control by scientists from all over the world. In this review, the development of new approaches for controlling fungal diseases in plants is discussed. We argue that an effort should be made to bring these recent technologies to the farmer level.

The antibacterial activity of fluoroquinolone derivatives: An update (2018-2021)

Bacterial infection is amongst the most common diseases in community and hospital settings. Fluoroquinolones, exerting the antibacterial activity through binding to type II bacterial topoisomerase enzymes, DNA gyrase and topoisomerase IV, are mainstays of chemotherapy. At present, fluoroquinolones are the most valuable antibacterial agents used popularly. However, the emergence of more virulent and resistant pathogens by the development of either mutated DNA-binding proteins or efflux pump mechanism for fluoroquinolones results in an urgent demand to develop new fluoroquinolones to withstand the drug resistance and to obtain a broader spectrum of activity. This review aims to outline the recent advances of fluoroquinolone derivatives with antibacterial potential and to summarize the structure-activity relationship (SAR) so as to provide an insight for rational design of more active candidates, covering articles published between January 2018 and June 2021.

Chemical Composition and Antimicrobial Properties of Mentha × piperita cv. 'Kristinka' Essential Oil

Several economically important crops, fruits and vegetables are susceptible to infection by pathogenic fungi and/or bacteria postharvest or in field. Recently, plant essential oils (EOs) extracted from different medicinal and officinal plants have had promising antimicrobial effects against phytopathogens. In the present study, the potential microbicide activity of Mentha × piperita cv. ‘Kristinka’ (peppermint) EO and its main constituents have been evaluated against some common phytopathogens. In addition, the cell membrane permeability of the tested fungi and the minimum fungicidal concentrations were measured. The antifungal activity was tested against the following postharvest fungi: Botrytis cinerea, Monilinia fructicola, Penicillium expansum and Aspergillus niger, whereas antibacterial activity was evaluated against Clavibacter michiganensis, Xanthomonas campestris, Pseudomonas savastanoi and P. syringae pv. phaseolicola. The chemical analysis has been carried out using GC-MS and the main components were identified as menthol (70.08%) and menthone (14.49%) followed by limonene (4.32%), menthyl acetate (3.76%) and β-caryophyllene (2.96%). The results show that the tested EO has promising antifungal activity against all tested fungi, whereas they demonstrated only a moderate antibacterial effect against some of the tested bacteria.

Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes

String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4'E)-4,4'-(ethane-1,2-diyldiazanylylidene)bis{7-[(4Z)-3-(aminomethyl)-4-(methoxyimino)pyrrolidin-1-yl]-1-cyclopropyl-6-fluoro-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid} (GMFX-en) and its metal complexes were identified and confirmed by elemental analyses, FT-IR, UV/VIS, ¹ H-NMR spectra, magnetic susceptibility, conductometric measurements and thermal analyses. The FT-IR spectral data showed the chelation behavior of GMFX-en toward the metal ions through oxygen of carboxylate group and nitrogen of azomethine group. In the light of all spectral data, these complexes presumably have octahedral geometry configurations. Thermal analysis specified that the decaying of the metal complexes exist in two or three steps with the final residue metal oxides. Antimicrobial activity of the new prepared metal complexes was screened against some common phytopathogens and their mode of action has been also discussed. The potential phytotoxic effectiveness of the new complexes was furthermore inspected on two commonly experimental plants. The complexes showed significant antimicrobial and phytotoxic effects against the majority of tested phytopathogens and the two tested plants, respectively. The potential antimicrobial activity of the complexes proved their possibility to be used successfully in agropharmacutical industry to control many serious phytopathogens. The phytotoxicity of the studied complexes also indicated their possibility as potential bio-based herbicides alternatives to weed control in crop fields.

Meloxicam and Study of Their Antimicrobial Effects against Phyto- and Human Pathogens

Recently, the design of new biological metal-ligand complexes has gained a special interest all over the world. In this research, new series of mixed ligand complexes from meloxicam (H₂mel) and glycine (Gly) were synthesized. Structures of the compounds were investigated employing elemental analyses, infrared, electronic absorption, ¹H NMR, thermal analyses, effective magnetic moment and conductivity. The estimated molar conductivity of the compounds in 1 × 10^-3 M DMF solution indicates the non-electrolyte existence of the examined complexes. Additionally, the effective magnetic moment values refer to the complexes found as octahedral molecular geometry. The data of the infrared spectra showed the chelation of H₂mel and Gly with metal ions from amide oxygen and nitrogen of the thyizol groups of H₂mel and through nitrogen of the amide group and oxygen of the carboxylic group for Gly. Thermal analyses indicated that the new complexes have good thermal stability and initially lose hydration water molecules followed by coordinated water molecules, Gly and H₂mel. The kinetic parameters were calculated graphically using Coats-Redfern and Horowitz-Metzeger methods at n = 1 and n ≠ 1. The density functional theory (DFT) calculations were performed at B3LYP levels. The optimized geometry of the ligand and its complexes were obtained based on the optimized structures. The data indicated that the complexes are soft with η value in the range 0.114 to 0.086, while η = 0.140 for free H₂mel. The new prepared complexes were investigated as antibacterial and antifungal agents against some phyto- and human pathogens and the minimum inhibitory concentration (MIC) data showed that complex (A) has the lowest MIC for Listeria and E. coli (10.8 µg/mL).

Immobilized Metal Affinity Chromatography as a Drug Discovery Platform for Metalloenzyme Inhibitors

Immobilized metal-ion affinity chromatography (IMAC) used to purify recombinant proteins features a resin-bound 1:1 Ni(II)-iminodiacetic acid (IDA) complex. This hemi-saturated Ni(II)-IDA system containing exchangeable sites at the metal ion is re-cast as a surrogate of a coordinatively-unsaturated metalloenzyme active site, with utility for selecting compounds with metal-binding groups from mixtures as potential metalloenzyme inhibitors. Exchanging Ni(II) for other metal ions could broaden the scope of metalloenzyme target. This work examined the performance of Cu(II)-, Fe(III)-, Ga(III)-, Ni(II)-, or Zn(II)-IMAC resins to reversibly bind experimental or clinical metalloenzyme inhibitors of Zn(II)-ACE1, Zn(II)-HDAC, Fe(II)/(III)-5-LO or Cu(II)-tyrosinase from a curated mixture (1-17). Each IMAC system gave a distinct selection profile. The Zn(II)-IMAC system selectively bound the thiol-containing Zn(II)-ACE1 inhibitors captopril and omapatrilat, and the Fe(III)-IMAC system selectively bound the Fe(II)/(III)-5-LO inhibitor licofelone, demonstrating a remarkable IMAC-metalloenzyme metal ion match. IMAC provides a simple, water-compatible platform, which could accelerate metalloenzyme inhibitor discovery.

Mycoremediation effect of Trichoderma harzianum strain T22 combined with ozonation in diesel-contaminated sand

This study aimed to determine the ability of the fungus Trichoderma harzianum strain T22 (Th-T22) to utilize diesel fuel as a carbon source. The potential use of Th-T22 for diesel bioremediation in an artificial soil was tested by inoculating a diesel-sand mixture with a fungal mycelial suspension of Th-T22. Given the ability of ozone to degrade compounds with low biochemical reactivity, the effect of a pre- and post-ozonation was also evaluated. The survival, growth and sporulation of Th-T22 throughout the bioremediation trial were monitored in all the treatments. In the post-ozonation treatments, the biodegradation percentages of diesel removal were 70.16% and 88.35% in Th-T22-inoculated sand treated or untreated with the antibacterial streptomycin, respectively. The results showed that ozonation alone caused good removal efficiencies (41.9%) but it was much more effective if combined with Th-T22 in a post-ozonation regime, whereas pre-ozonation negatively affected the subsequent biodegradation, likely due to its disinfectant and oxidizing effect on Th-T22. The results obtained demonstrated the significant mycoremediation ability of Th-T22 in diesel-contaminated sand and its possible use as a bioremediation agent for diesel spills in polluted sites.

Elicitation-Based Method for Increasing the Production of Antioxidant and Bactericidal Phenolic Compounds in Dionaea muscipula J. Ellis Tissue

The carnivorous plant Dionaea muscipula J. Ellis (Venus flytrap) is a widely known medical herb, capable of producing various phenolic compounds known for their strong antioxidant and antibacterial properties. In the pharmaceutical industry, Venus flytrap is grown in tissue cultures, as the natural population of D. muscipula is very limited. Here, we describe an improved method to increase the quantity and quality of phenolic compounds produced in D. muscipula. This is achieved by combining biotic elicitation (using Cronobacter sakazakii bacteria lysate) of D. muscipula cultured with rotary shaking (hydromechanical stress), which we describe here for the first time. The antibacterial activity and the antioxidant properties of the obtained compounds were studied on two antibiotic-resistant human pathogenic bacteria. The proposed plant culture conditions resulted in an increase in fresh weight, as well as a higher total phenolic content, in comparison to traditional tissue cultures on agar-solidified medium. With the use of high-performance liquid chromatography, we demonstrated that the described elicitation strategy leads to an increased synthesis of myricetin, caffeic acid, ellagic acid and plumbagin in D. muscipula tissue. We also found that a higher level of antioxidant activity, exhibited by the plant extract, corresponded with its higher phenylpropanoid content. The bactericidal activity of the extract against Staphylococcus aureus was dependent on the duration of plant culture under described elicitation conditions, whereas neither elicitation condition (duration or elicitor concentration) seemed relevant for the bactericidal activity of the extract towards Escherichia coli. This suggest that Gram-negative bacteria are less sensitive to compounds derived from Venus flytrap tissue.

Quinolone Complexes with Lanthanide Ions: An Insight into their Analytical Applications and Biological Activity

Quinolones comprise a series of synthetic bactericidal agents with a broad spectrum of activity and good bioavailability. An important feature of these molecules is their capacity to bind metal ions in complexes with relevant biological and analytical applications. Interestingly, lanthanide ions possess extremely attractive properties that result from the behavior of the internal 4f electrons, behavior which is not lost upon ionization, nor after coordination. Subsequently, a more detailed discussion about metal complexes of quinolones with lanthanide ions in terms of chemical and biological properties is made. These complexes present a series of characteristics, such as narrow and highly structured emission bands; large gaps between absorption and emission wavelengths (Stokes shifts); and long excited-state lifetimes, which render them suitable for highly sensitive and selective analytical methods of quantitation. Moreover, quinolones have been widely prescribed in both human and animal treatments, which has led to an increase in their impact on the environment, and therefore to a growing interest in the development of new methods for their quantitative determination. Therefore, analytical applications for the quantitative determination of quinolones, lanthanide and miscellaneous ions and nucleic acids, along with other applications, are reviewed here.

Biological and Spectroscopic Investigations of New Tenoxicam and 1.10-Phenthroline Metal Complexes

In the present work, tenoxicam (H₂Ten) reacted with Mn(II), Co(II), Ni(II), Cu(II) and Zn (II) ions in the presence of 1.10-phenthroline (Phen), forming new mixed ligand metal complexes. The properties of the formed complexes were depicted by elemental analyses, infrared, electronic spectra, proton nuclear magnetic resonance (¹H NMR), mass spectrometry, thermogravimetric (TGA) and differential thermogravimetric (DTG) analysis, molar conductance and magnetic moment. IR spectra demonstrated that H₂Ten acted as a neutral bidentate ligand, coordinated to the metal ions via the pyridine-N and carbonyl group of the amide moiety, and Phen through the nitrogen atoms. Kinetic thermodynamics parameters activation energy (E*), enthalpy of activation (ΔH*), entropy of activation (ΔS*), Gibbs, free energy (ΔG*) associated to the complexes have been evaluated. Antibacterial screening of the compounds was carried out in vitro against Clavibacter michiganensis, Xanthomonas campestris and Bacillus megaterium. Antifungal activity was performed in vitro against Monilinia fructicola, Penicillium digitatum and Colletotrichum acutatum. The possible phytotoxic effect of the studied compounds was also investigated on Solanum lycopersicum (tomatoes) and Lepidium sativum (garden cress) seeds. The anticancer activity was screened against cell cultures of HCT-116 (human colorectal carcinoma), HepG2 (human hepatocellular carcinoma) and MCF-7 (human breast adenocarcinoma).

Antimicrobial Activity and Chemical Composition of Essential Oil Extracted from Solidago canadensis L. Growing Wild in Slovakia

Plant essential oils (EOs) are one of the most relevant natural products due to their biological, medicinal, and nutritional properties. The promising biological effects of many plants EOs encourage researchers to study their biochemical properties to be used as possible natural alternatives for commercial pesticides and not only as herbal medicines. The current research has been conducted to study the microbicide effect of Solidago canadensis L. EO to control some common plant diseases caused by several postharvest phytopathogenic fungi (Monilinia fructicola, Botrytis cinerea, Aspergillus niger, and Penicillium expansum) in comparison with Azoxystrobin as a large spectrum fungicide. The antibacterial activity has been carried out against some phytopathogenic bacteria (Bacillus megaterium and Clavibacter michiganensis (G+ve) and Xanthomonas campestris, Pseudomonas fluorescens, and Pseudomonas syringae pv. phaseolicola (G−ve)) compared to the synthetic antibiotic Tetracycline. Minimum inhibitory concentration was carried out to determine the lowest effective EO dose using a 96-well microplate. The cell membrane permeability was also evaluated by measuring the electric conductivity (EC) to examine the possible mechanisms of action of S. canadensis EO. Chemical characterization of EO has been carried out using gas chromatography and mass spectrometry (GC-MS). Thirty-two identified components in S. canadensis EO presented 97.7% of total compounds in EO. The principal compounds were identified as germacrene D (34.9%), limonene (12.5%), α-pinene (11.6%), β-elemene (7.1%), and bornyl acetate (6.3%). In addition, S. canadensis EO demonstrated promising in vitro antimicrobial activities against the majority of tested phytopathogens at all tested concentrations.