Schiff bases as potential fungicides and nitrification inhibitors

Development of a Multifunctional Composite Hydrogel for Enhanced Wound Healing: Hemostasis, Sterilization, and Long-Term Moisturizing Properties

Meeting the diverse requirements of effective wound repair while surpassing the single-function limitations of traditional wound dressings is a significant challenge. In this study, we successfully synthesized an inclusion complex of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) and iodine using the saturated aqueous solution method. Additionally, dialdehyde cellulose (DAC) was extracted from fat-free cotton through oxidation. To enhance wound healing, l-glutamine (l-glu) was utilized as a functional molecule, resulting in composite hydrogels with hemostatic, sterilizing, and wound-healing-promoting properties that were achieved by adsorbing the resulting inclusion complex. Through TG and SEM analysis, we confirmed that iodine was effectively accommodated by cyclodextrin and was uniformly attached to the hydrogel. The hydrogel exhibits exceptional long-term moisturizing and bactericidal properties, while also demonstrating excellent swelling, oxygen permeability, hemolytic, and mechanical properties, fully satisfying the requirements of wound treatment. External coagulation tests revealed that the hydrogel can rapidly coagulate 4.5 times its own weight of blood. Moreover, in a full-thickness scald mouse model, the hydrogel effectively promotes wound healing. The development of this multifunctional composite hydrogel presents a novel approach to advance wound dressing research, holding substantial potential for practical applications.

Insights on the structural characteristics and molecular dynamic studies of methyl vanillin Schiff base bio-compounds

A new crystalline form of Schiff base, N-cyclohexyl-1-(3,4-dimethoxyphenyl)methanimine (CHADMB) was obtained from methanolic solution of cylohexylamine and (methylvanillin) 3,4dimethoxybenzaldehyde. Single crystal X-ray diffraction study reveals that the compound crystallized in monoclinic crystal system with P21/c space group having four molecules per unit cell (Z = 4). Hirshfeld surface (HS) analysis and 2D fingerprint plots reveals that weak non-covalent interactions are responsible for crystal packing. The UV-Vis spectroscopy study reveals that the optical band gap of the compound is 4.25 eV. The dielectric properties were studied as a function of frequency at room temperature and the results show that these properties can be exploited for optoelectronic applications. Thermal stability of the compound is revealed by thermogravimetric and differential thermogravimetric analysis. The in vitro antimicrobial activity against Gram negative (E. coli and P. aeruginosa and Gram positive (S. aureus ) bacterial strains and two fungal strains (C. albicans and A. niger) were studied by agar well diffusion method. It is found that the Schiff base is inhibiting the growth of the tested species to varying degrees. Molecular docking studies indicate that alkyl-pi and pi-pi weak interactions enhance the binding affinity of Schiff base-protein complexes. Molecular dynamics study reveals interaction of CHADMB complexed with bacterial protein, EC showed maximum stability which is in agreement with experimental result.Communicated by Ramaswamy H. Sarma.

Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Diversity of Sclerotium rolfsii antagonist fungi isolated from soils of the rhizosphere of tomato crops and identification of some antifungal compounds

Sclerotium rolfsii Sacc. the causative agent of white rot is one of the destructive pathogens of nightshade crops. In Côte d'Ivoire, this fungal pathogen constitutes a major constraint for the cultivation of tomato (Solanum lycopersicum) with 41.01% crop losses in humid forest areas. Controlling this fungus with synthetic chemicals can be effective, but harmful to human health and the environment. The use of biological control agents could be an alternative approach to control S. rolfsii. In this perspective, the objective of this work was to select fungi from the rhizosphere of tomato crops capable of inhibiting the growth of S. rolfsii. To do this, 153 fungi were isolated from the rhizosphere and from direct confrontation tests 10 fungi whose antagonistic power of S. rolfsii varied between 27 and 60% were selected. Molecular identification (ITS) of these antagonist fungi revealed that the isolates belonged to the genera Talaromyces sp. (n = 4), Trichoderma sp. (n = 3), Penicillium sp. (n = 2) and Clonostachys sp. (n = 1). Among these fungi, Talaromyces purpureogenus and Talaromyces assiutensis were able to diffuse compounds in agar capable of inhibiting the growth of S. rolfsii. The chemical study of these 2 fungi made it possible to identify mitorubrin and mitorubrinol produced by T. purpureogenus and spiculisporic acid produced by T. assiutensis. Mitorubrin and mitorubrinol had inhibitory activities of 100 and 70% at 10 mg/mL, respectively, whereas spiculisporic acid showed moderate inhibition of 38 at 20 mg/mL of the growth of S. rolfsii; however, its abundant production by the fungus could be an advantage in the control of this phytopathogen. Isolated from the same biotope as S. rolfsii, T. purpureogenus and T. assiutensis represent favorable candidates for the biological control against S. rolfsii.

A Family of Ethyl N-Salicylideneglycinate Dyes Stabilized by Intramolecular Hydrogen Bonding: Photophysical Properties and Computational Study

In this work we report solvatochromic and luminescent properties of ethyl N-salicylideneglycinate (1), ethyl N-(5-methoxysalicylidene)glycinate (2), ethyl N-(5-bromosalicylidene)glycinate (3), and ethyl N-(5-nitrosalicylidene)glycinate (4) dyes. 1–4 correspond to a class of N-salicylidene aniline derivatives, whose photophysical properties are dictated by the intramolecular proton transfer between the OH-function and the imine N-atom, affording tautomerization between the enol-imine and keto-enamine forms. Photophysical properties of 1–4 were studied in different pure non-polar and (a)protic polar solvents as well as upon gradual addition of NEt₃, NaOH, and CH₃SO₃H. The DFT calculations were performed to verify the structures of 1–4 as well as their electronic and optical properties.

Synthesis, characterization and biochemical behaviour of macrocyclic complexes of Zn(II) and Co(II) metals

A series of Zn(II) and Co(II) complexes have been synthesized by template condensation of bis(benzil)-4-chloro-1,2-phenylenediamine and bis(benzil)-4-fluoro-1,2-phenylenediamine, respectively, with 4-chloro-1,2-phenylenediamine and 4-fluoro-1,2-phenylenediamine in the presence of transition metal chlorides. The complexes have been characterized by physicochemical and spectroscopic techniques. Based on these studies, an octahedral geometry has been proposed around the metal ions. The newly synthesized ligands and their metal complexes have been screened for antimicrobial and anticancer activities. The in vitro cytotoxicity towards the HeLa cell line has been evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

Development of chitosan nanocapsules for the controlled release of hexaconazole

Accelerated use of pesticides in cutting edge agriculture prompted us to explore smart nanoformulations to subside the consumption of these perilous chemicals. Polymer nanocapsules carrying a fungicide, hexaconazole were developed through ionotropic gelation method utilizing chitosan and tripolyphosphate (TPP). The nanocapsules were characterized by photon correlation spectroscope (PCS), transmission electron microscope (TEM), and Fourier transform infra-red (FTIR) spectroscope. Nanocapsules were optimized for size and high encapsulation efficiency using central composite design (CCD) software. The encapsulation efficiency of nanocapsules for hexaconazole was 73% as assessed by gas chromatography (GC). Nanocapsules were analysed and compared with commercial formulation for controlled release in vitro at three different pH values. Release of hexaconazole from nanocapsules was fastest at pH 4 in comparison to pH 7 and pH 10. Release study in soil was also conducted and revealed a controlled pattern for nanoformulation. The fungicidal activity of the prepared nanoformulation was evaluated against R. solani and was compared with commercial formulation of hexaconazole. The cytotoxicity assay performed on vero cell lines by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay confirmed that nanoformulation is less toxic than commercial formulation of pesticide.

Eco-friendly PEG-based controlled release nano-formulations of Mancozeb: Synthesis and bioefficacy evaluation against phytopathogenic fungi Alternaria solani and Sclerotium rolfsii

Controlled release (CR) nano-formulations of Mancozeb (manganese-zinc double salt of N,N-bisdithiocarbamic acid), a protective fungicide, have been prepared using laboratory-synthesized poly(ethylene glycols) (PEGs)-based functionalized amphiphilic copolymers without using any surfactants or external additives. The release kinetics of the developed Mancozeb CR formulations were studied and compared with that of commercially available 42% suspension concentrate and 75% wettable powder. Maximum amount of Mancozeb was released on 42nd day for PEG-600 and octyl chain, PEG-1000 and octyl chain, and PEG-600 and hexadecyl chain, on 35th day for PEG-1000 and hexadecyl chain, on 28th day for PEG-1500 and octyl chain, PEG-2000 and octyl chain, PEG-1500 and hexadecyl chain, and PEG-2000 and hexadecyl chain in comparison to both commercial formulations (15th day). The diffusion exponent (n value) of Mancozeb in water ranged from 0.42 to 0.62 in tested formulations. The half-release (t_1/2) values ranged from 17.35 to 35.14 days, and the period of optimum availability of Mancozeb ranged from 18.54 to 35.42 days. Further, the in vitro bioefficacy evaluation of developed formulations was done against plant pathogenic fungi Alternaria solani and Sclerotium rolfsii by poison food technique. Effective dose for 50% inhibition in mgL^-1 (ED₅₀) values of developed formulations varied from 1.31 to 2.79 mg L^-1 for A. solani, and 1.60 to 3.14 mg L^-1 for S. rolfsii. The present methodology is simple, economical, and eco-friendly for the development of environment-friendly CR formulations of Mancozeb. These formulations can be used to optimize the release of Mancozeb to achieve disease control for the desired period depending upon the matrix of the polymer used. Importantly, the maximum amount of active ingredient remains available for a reasonable period after application. In addition, the developed CR formulations were found to be suitable for fungicidal applications, allowing use of Mancozeb in lower doses.

Synthesis and antiviral, insecticidal, and fungicidal activities of gossypol derivatives containing alkylimine, oxime or hydrazine moiety

Gossypol is a part of the cotton plant's defense system against pathogens and herbivorous insects. To discover gossypol analogs with broad spectrum and high activity, a series of gossypol alkylamine Schiff base, oxime and hydrazone derivatives were synthesised and bioassayed. The biological results indicated that most of these derivatives exhibited higher anti-TMV activity than gossypol. Interestingly, the activities of compounds 10, 15, 18, 20, 23 and 26 were much higher than that of ribavirin. Furthermore, compound 26, which was low toxicity to rat, showed better activity than control plant virus inhibitors in the field. Additionally, allyl amine Schiff base (9) displayed remarkable insecticidal activities against Mythimna separata, Helicoverpa armigera and Ostrinia nubilalis, whereas (pyridin-3-yl)methanamine Schiff base (13) showed excellent activity against Culex pipiens pallens. The fungicidal results revealed that all of compounds exhibited good activity against Physalospora piricola.

3,4,5-Trichloroaniline nephrotoxicity in vitro: potential role of free radicals and renal biotransformation

Chloroanilines are widely used in the manufacture of drugs, pesticides and industrial intermediates. Among the trichloroanilines, 3,4,5-trichloroaniline (TCA) is the most potent nephrotoxicant in vivo. The purpose of this study was to examine the nephrotoxic potential of TCA in vitro and to determine if renal biotransformation and/or free radicals contributed to TCA cytotoxicity using isolated renal cortical cells (IRCC) from male Fischer 344 rats as the animal model. IRCC (~4 million cells/mL; 3 mL) were incubated with TCA (0, 0.1, 0.25, 0.5 or 1.0 mM) for 60–120 min. In some experiments, IRCC were pretreated with an antioxidant or a cytochrome P450 (CYP), flavin monooxygenase (FMO), cyclooxygenase or peroxidase inhibitor prior to incubation with dimethyl sulfoxide (control) or TCA (0.5 mM) for 120 min. At 60 min, TCA did not induce cytotoxicity, but induced cytotoxicity as early as 90 min with 0.5 mM or higher TCA and at 120 min with 0.1 mM or higher TCA, as evidenced by increased lactate dehydrogenase (LDH) release. Pretreatment with the CYP inhibitor piperonyl butoxide, the cyclooxygenase inhibitor indomethacin or the peroxidase inhibitor mercaptosuccinate attenuated TCA cytotoxicity, while pretreatment with FMO inhibitors or the CYP inhibitor metyrapone had no effect on TCA nephrotoxicity. Pretreatment with an antioxidant (α-tocopherol, glutathione, ascorbate or N-acetyl-l-cysteine) also reduced or completely blocked TCA cytotoxicity. These results indicate that TCA is directly nephrotoxic to IRCC in a time and concentration dependent manner. Bioactivation of TCA to toxic metabolites by CYP, cyclooxygenase and/or peroxidase contributes to the mechanism of TCA nephrotoxicity. Lastly, free radicals play a role in TCA cytotoxicity, although the exact nature of the origin of these radicals remains to be determined.

Synthesis, biological activities and SAR studies of novel 1-Ethyl-7-methyl-4-oxo-1,4-dihydro-[1,8]naphthyridine-3-carboxylic acid based diacyl and sulfonyl acyl hydrazines

BACKGROUND

Diacyl hydrazines have attracted significant interest in medicine, pesticide chemistry and material science. It is an important class of insect growth regulators. In this study, acyl hydrazine, the essential active group was incorporated in to nalidixic acid with the aim of combining the active groups to generate more potent agrochemical.

RESULTS

Various nalidixic acid based diacyl and sulphonyl acyl hydrazines derivatives were synthesized and characterized by spectral techniques. These compounds were screened for the antifungal activity against five pathogenic fungi, nitrification inhibitory activity and insect growth regulator (IGR) activity against Spodoptera litura. The fungicidal activity was screened against R. bataticola, S. rolfsii, R. solani, F. oxysporum and A. porri. Most of the compounds showed moderate to good antifungal activity against A. porri (ED50 = 29.6-495.9 µg/mL). All the compounds showed significant nitrification inhibitory activity at 5% level. IGR activity was examined by feeding method against S. litura.

CONCLUSION

The study revealed that a few compounds possessed good activity against three different pests namely certain fungus, soil bacteria and insect, among which, compound 37 (R' = 4-chlorophenyl) behaved the best.

Design, synthesis, and antibacterial activity of novel Schiff base derivatives of quinazolin-4(3H)-one

Novel imine derivatives of quinazolin-4(3H)-one were designed and synthesized by using aminoethyl moieties to increase the amine bridge of quinazolin-4(3H)-one amine and then introducing various aromatic aldehydes. The target compounds were characterized by proton nuclear magnetic resonance spectroscopy ((1)H NMR), carbon nuclear magnetic resonance spectroscopy ((13)C NMR), mass spectrometry (MS), infrared spectroscopy (IR), elemental analysis, and X-ray diffraction crystallography. Bioassay results indicated that some of the compounds showed good to excellent antibacterial activities against tobacco bacterial wilt and tomato bacterial wilt. The 50% effective concentrations (EC50) of the compounds against tobacco and tomato bacterial wilts ranged from 63.73 μg/mL to 201.52 μg/mL and 38.64 μg/mL to 81.39 μg/mL, respectively, which are lower than that the positive control thiodiazole copper (216.70 and 99.80 μg/mL). These results indicated that novel Schiff base derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco and tomato bacterial wilts.

Synthesis and bioactivity evaluation of novel arylimines containing a 3-aminoethyl-2-[(p-trifluoromethoxy)anilino]-4(3H)-quinazolinone moiety

Twenty-seven novel (E)-3-[2-arylideneaminoethyl]-2-[4-(trifluoromethoxy)anilino]-4(3H)-quinazolinone derivatives were synthesized by reacting various aromatic aldehydes with intermediate 6. The target compounds were characterized by (1)H NMR, (3)C NMR, IR, and elemental analysis. Bioassay results revealed that some of the compounds have strong antifungal activities against six fungi ( Gibberella zeae , Fusarium oxysporum , Clematis mandshurica , Paralepetopsis sasakii , Phytophthora infestans , and Sclerotinia sclerotiorum ) and three bacteria ( Xanthomonas oryzae , tomato bacterial wilt, and tobacco bacterial wilt). Notably, these compounds exhibited the highest activity against tomato bacterial wilt and X. oryzae, with 50% effective concentration (EC50) values ranging from 45.96 to 93.31 μg/mL and from 20.09 to 21.33 μg/mL, respectively, which are superior to those of the commercial antibacterial agents thiodiazole-copper (99.80 μg/mL) and bismerthiazol (92.61 μg/mL). These results indicate that novel arylimine derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco bacterial wilt, tomato bacterial wilt, and X. oryzae. Evaluation of their bactericidal properties in field studies as well as the mechanisms underlying their enhanced antibacterial activity should be interesting topics for future investigations.

Phytotoxicity of new furan-derived aminophosphonic acids, N-aryl furaldimines and 5-nitrofuraldimine

The aim of this work was to synthesize selected furaldimines and their aminophosphonic derivatives and evaluation the phytotoxicity of new obtained products according to OECD 208 Guideline. Four Schiff bases, N-furfurylidene-p-anisidine (1a), N-furfurylidene-p-toluidine (1b), N-furfurylidene-benzhydrylamine (1c), and N-(2-nitrofurfurylidene)-p-toluidine (1d) were synthesized and three new furan-derived N-substituted aminomethylphosphonic acids, namely: 2-furyl N-(p-methoxyphenyl)-aminomethylphosphonic acid (2a), 2-furyl N-(p-methylphenyl)-aminomethylphosphonic acid (2b) and 2-furyl N-(diphenylmethyl)-aminomethylphosphonic acid (2c) were synthesized by the addition of in situ generated bis-(trimethylsilyl) phosphite to azomethine bond of corresponding Schiff bases 1a-c. Three Schiff bases 1a-b and 1d as well as all three aminophosphonic acids 2a-c were analyzed in regard with their phytotoxicity toward two plants, radish (Raphanus sativus) and oat (Avena sativa). It has been found that tested N-furfurylidene-p-anisidine (1a), N-(2-nitrofurfurylidene)-p-toluidine (1d) and aminophosphonic acids 2a-c are toxic for selected plants. N-furfurylidene-p-toluidine (1b) did not show any ecotoxicological impact in used plant growth test.

Synthesis, spectral characterization and biological evaluation of copper(II) and nickel(II) complexes with thiosemicarbazones derived from a bidentate Schiff base

Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L=1-Tetralone thiosemicarbazone and X=Cl(-),1/2SO4(2-)). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10-20Ω(-1)cm(2)mol(-1) indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93-1.96BM and 2.91-2.94BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species.

Synthesis, antimalarial activity and cytotoxic potential of new monocarbonyl analogues of curcumin

A series of novel monocarbonyl analogues of curcumin have been designed, synthesized and tested for their activity against Molt4, HeLa, PC3, DU145 and KB cancer cell lines. Six of the analogues showed potent cytotoxicity towards these cell lines with IC(50) values below 1 μM, which is better than doxorubicin, a US FDA approved drug. Several analogues were also found to be active against both CQ-resistant (W2 clone) and CQ-sensitive (D6) strains of Plasmodium falciparum in an in-vitro antimalarial screening. This level of activity warrants further investigation of the compounds for development as anticancer and antimalarial agents.

Synthesis of novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones and evaluation of their biocidal effects

Novel 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-thiones have been synthesized in high yields by treatment of the corresponding oxo analogs with Lawesson's reagent. The structure has been confirmed by X-ray analysis. The compounds were tested for in vitro antifungal activity against Rhizoctonia bataticola, Sclerotium rolfsii, Fusarium oxysporum and Alternaria porii. The compounds exhibited moderate to good activity against all pathogens. Insecticidal activity of these compounds against Spodoptera litura was observed to be comparable to commercial pyrethroid insecticide, cypermethrin. The urease inhibitory activity has also been studied.

Synthesis and antigastric ulcer activity of novel 5-isoproyl-3,8-dimethylazulene derivatives

5-Isoproyl-3,8-dimethylazulene derivatives were synthesized and evaluated for antigastric ulcer activity in vivo. Some of them possess the best activity against gastric ulcer with ulcer index values lower than the drug reference (omeprazole). The structure-activity relationship (SAR) shows that the lipophilic flat structure contributes to quite potent antigastric ulcer activity.

Synthesis, antimicrobial evaluation and QSAR analysis of novel nalidixic acid based 1,2,4-triazole derivatives

Novel nalidixic acid based 1,2,4-triazole derivatives were synthesized and characterized using spectral techniques like (1)H NMR, (13)C NMR, IR and mass spectrometry. All these compounds were screened for antimicrobial activity against five bacteria and two pathogenic fungi. Most of these compounds showed better antimicrobial activity than the parent compound, 4-amino-5-mercapto-1,2,4-triazole. Among all the screened compounds, 3-{6-(2-chlorophenyl)-1,2,4-triazolo [3,4-b] [1,3,4]thiadiazol-3-yl}-1-ethyl-7-methyl-1,8-naphthyridin-4(1H)-one (23) was emerged as promising antimicrobial agent (MIC = 16 μg/mL). Quantitative structure activity relationship (QSAR) analysis was carried out using various distance-based topological indices, steric and hydrophobic parameters. Based on the QSAR analysis it is indicative that lipophilic and steric parameters are the pre-requisites for these molecules to act as potent antimicrobial agents.

Synthesis of nalidixic acid based hydrazones as novel pesticides

Thirty-one substituted hydrazones of nalidixic acid hydrazide were synthesized and characterized by spectral techniques. These compounds were evaluated for various biological activities, namely, fungicidal, insecticidal, and nitrification inhibitory activities. The antifungal activity was evaluated against five pathogenic fungi, namely, Rhizoctonia bataticola , Sclerotium rolfsii , Rhizoctonia solani , Fusarium oxysporum , and Alternaria porii . They showed maximum inihibition against A. porii with ED(50) = 34.2-151.3 microg/mL. The activity was comparable to that of a commercial fungicide, hexaconazole (ED(50) = 25.4 microg/mL). They were also screened for insecticidal activity against third-instar larvae of Spodoptera litura and adults of Callosobruchus maculatus and Tribollium castaneum . Most of them showed 70-100% mortality against S. litura through feeding method at 0.1% dose. These compounds were not found to be effective nitrification inhibitors.