Benzaldehyde Schiff bases regulation to the metabolism, hemolysis, and virulence genes expression in vitro and their structure–microbicidal activity relationship

In silico screening and synthesis of stable tilmicosin-hydrazone derivatives as potential DNA disruptors towards Staphylococcus aureus

In this study, 30 tilmicosin-hydrazone derivatives were designed using MOE software. Six candidate molecules with strong binding affinity to DNA or DNA-Topo II complexes, as indicated by molecular docking results, were synthesized. These candidates were evaluated for their in vitro antibacterial activities against common Gram-positive and Gram-negative bacteria. Compounds Z-12 and Z-22 demonstrated superior inhibitory effects against most tested strains compared to reference drugs tilmicosin and erythromycin, with minimum inhibitory concentrations (MIC) of 1 μg/mL against S. aureus 25,923 and S. aureus 29,213. HPLC results indicated that Z-12 and Z-22 exhibited improved stability in acidic aqueous solutions compared to tilmicosin. UV-vis, fluorescence spectroscopy, and gel electrophoresis studies confirmed their intercalation into DNA base pairs via a static quenching mechanism. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) revealed irreversible oxidation processes on the glassy carbon electrode, providing insights into their potential metabolic pathways. Finally, a mouse wound infection model demonstrated that Z-12 and Z-22 exhibited good antibacterial efficacy, biocompatibility, and enhanced wound healing effects, surpassing those of tilmicosin. These findings, coupled with their prolonged metabolic half-life, highlight their potential as effective antibacterial agents.

Siloxane-Mediated Schiff Base Bio-Based Curing Agent: Achieving Epoxy Vitrimer with Excellent Mechanical Properties, Low Dielectric Constant and Rapid Degradation Characteristics

Epoxy resin is indispensable in various applications due to its outstanding properties. However, its limited recyclability and associated environmental issues pose significant challenges for sustainable development. To address this issue, integrating recyclable Schiff base groups into epoxy resin systems to construct epoxy vitrimer with dynamic properties has become a promising strategy. Herein, a rapid degradation, enhanced mechanical properties, and low dielectric constant epoxy vitrimer (EP-BOB) is proposed through a unique rigid-flexible structure bio-based curing agent (BOB). BOB is synthesized using siloxane as a flexible chain to bridge with vanillin in a one-pot process. The incorporation of the Schiff base structure imparted exceptional degradability to EP-BOB, allowing it to fully degrade within 45 min. In addition, due to the unique rigid-flexible structure, EP-BOB exhibited lower dielectric constant (1.2-2.6) and outstanding mechanical properties (60.5 MPa tensile strength). Furthermore, Raman spectroscopy and scanning electron microscopy shows that EP-BOB can be completely degraded in the amine solution to recycle carbon fibers (CFs) without damage. Especially, the Schiff base can endow EP-BOB UV-shielding and antibacterial properties. This work opens up a new strategy for designing a rigid-flexible structure epoxy vitrimer using silicone to achieve multifunctional and high-performance EP.

Antitubercular drugs: possible role of natural products acting as antituberculosis medication in overcoming drug resistance and drug-induced hepatotoxicity

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

N-Acylhydrazones are a versatile class of organic compounds with a diversity of potential applications. In this study, two new structure-related 3,4,5-trimethoxybenzoyl-containing N-acylhydrazones were synthesized and fully characterized, both in solution and in the solid state. The compounds differ with respect to the carbonyl precursors, i.e., 3-substituted salicylaldehydes with either a methyl or a nitro group. Single crystals of both compounds were isolated from the respective mother liquors and, in both cases, XRD confirmed the obtention of the (E)-isomer, in an anti-conformation. Computational calculations (gas and water phases) were performed in order to confirm some of the structural and vibrational aspects of the compounds. An important intramolecular H bond involving the phenolic hydroxy group and the azomethine nitrogen was identified in the solid state and seems to be maintained in solution. Moreover, the presence of the electron-withdrawing nitro substituent makes this interaction stronger. However, the contact should probably not subsist for the nitro compound under physiological conditions since the presence of this substituent significantly affects the pKa of the phenol: an apparent value of 5.68 ± 0.02 was obtained. This also impacts the basicity of the azomethine nitrogen and, as a consequence, increases the hydrazone's susceptibility to hydrolysis. Nevertheless, both compounds are stable at physiological-like conditions, especially the methyl-derived one, which qualifies them for further toxicological and activity studies, such as those involving trivalent metal ions sequestering in the context of neurodegenerative diseases.

Gallium(III) Amide Corroles: DNA Interaction and Photodynamic Activity in Cancer Cells

A series of gallium(III) amide corroles including meso-5,15-bis(pentafluorophenyl)-10-(4-Pyridinamide-phenyl)corrole gallium (III) (1-Ga), meso-5,15-bis(pentafluorophenyl)-10-(4-Furamide-phenyl)corrole gallium(III) (2-Ga) and meso-5,15-bis(pentafluorophenyl)-10-(4-Thiophenamide-phenyl)corrole gallium(III) (3-Ga) were synthesized. The interaction of these complexes with DNA and their photodynamic antitumor activities have been studied. UV spectra titration showed that these gallium(III) corroles interact with calf thymus DNA (CT-DNA) through an external binding mode. All three gallium(III) corroles can effectively generate singlet oxygen under illumination and have good photostability. Among the three gallium(III) corroles, 2-Ga exhibited excellent photodynamic antitumor activity against the tested tumor cell lines under light irradiation (625±2 nm, 0.3 mW/cm2 , 1.08 J/cm2 ). The best phototoxicity was observed by 2-Ga against HepG2 cells (IC50 =6.3±0.9), which is even better than temoporfin (IC50 =8.4±1.8). It could block HepG2 cells in the sub-G0 phase and effectively induce apoptosis of HepG2 cells under 625 nm light irradiation.

Acylhydrazones and Their Biological Activity: A Review

Due to the structure of acylhydrazones both by the pharmacophore -CO-NH-N= group and by the different substituents present in the molecules of compounds of this class, various pharmacological activities were reported, including antitumor, antimicrobial, antiviral, antiparasitic, anti-inflammatory, immunomodulatory, antiedematous, antiglaucomatous, antidiabetic, antioxidant, and actions on the central nervous system and on the cardiovascular system. This fragment is found in the structure of several drugs used in the therapy of some diseases that are at the top of public health problems, like microbial infections and cardiovascular diseases. Moreover, the acylhydrazone moiety is present in the structure of some compounds with possible applications in the treatment of other different pathologies, such as schizophrenia, Parkinson's disease, Alzheimer's disease, and Huntington's disease. Considering these aspects, we consider that a study of the literature data regarding the structural and biological properties of these compounds is useful.

The role of aldehyde-functionalized crosslinkers on the property of chitosan hydrogels

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Dynamic Protein and Polypeptide Hydrogels Based on Schiff Base Co-assembly for Biomedicine

Stimuli-responsive hydrogels are promising building blocks for biomedical devices, attributable to their excellent hydrophilicity, biocompatibility, and dynamic responsiveness to temperature, light, pH, and water content. Although hydrogels find interesting applications...

Spirocyclic derivatives as antioxidants: a review

In recent years, spiro compounds have attracted significant interest in medicinal chemistry due to their numerous biological activities attributed primarily to their versatility and structural similarity to important pharmacophore centers. Currently, the development of drugs with potential antioxidant activities is of great importance since numerous investigations have shown that oxidative stress is involved in the development and progression of numerous diseases such as cancer, senile cataracts, kidney failure, diabetes, high blood pressure, cirrhosis, and neurodegenerative diseases, among others. This article provides an overview of the synthesis and various antioxidant activities found in naturally occurring and synthetic spiro compounds. Among the antioxidant activities reviewed are DPPH, ABTS, FRAP, anti-LPO, superoxide, xanthine oxidase, peroxide, hydroxyl, and nitric oxide tests, among others. Molecules that presented best results for these tests were spiro compounds G14, C12, D41, C18, C15, D5, D11, E1, and C14. In general, most active compounds are characterized for having at least one oxygen atom; an important number of them (around 35%) are phenolic compounds, and in molecules where this functional group was absent, aryl ethers and nitrogen-containing functional groups such as amine and amides could be found. Recent advances in the antioxidant activity profiles of spiro compounds have shown that they have a significant position in discovering drugs with potential antioxidant activities.

Self-healing and mechanical performance of dynamic glycol chitosan hydrogel nanocomposites

Evaluation of Schiff base nanocomposite hydrogels properties using a benzaldehyde multifunctional amphiphilic polyacrylamide crosslinker in conjunction with glycol chitosan.

Injectable Self-Healing Hydrogels Containing CuS Nanoparticles with Abilities of Hemostasis, Antibacterial activity, and Promoting Wound Healing

Injectable self-healing hydrogels containing functional nanoparticles (NPs) have attracted much attention in many fields of biomedicine. A series of injectable self-healing hydrogels containing PEGylation CuS NPs based on N-carboxyethyl chitosan (CEC) and oxidized sodium alginate (OA) were developed by taking advantages of the unique functions of CuS NPs and chitosan, referred to as CuS NP hydrogels or CEC-OA_m-CuS_n, where "m" stands for the concentration percentage of the added OA solution (w/v) and "n" represents the molar concentration of CuS NPs in the hydrogels. The physical properties of CuS NP hydrogels, syringeability, rapid self-repair ability, and photothermal performance were systematically investigated. The multiple functions for CuS NP hydrogels requested in the skin healing process were explored. The results showed that CuS NP hydrogels had not only adjustable physical properties and good injectable self-healing characteristics but also excellent functionalities, concurrently including hemostatic ability, bacteria killing capability, and cell migration and proliferation promotion. In vivo wound healing and histomorphological examinations of immunofluorescence staining in a mouse full-thickness wound model demonstrated good acceleration effects of these hydrogels for infected wound healing. Therefore, these injectable self-healing CuS NP hydrogels which possess the abilities of hemostasis, antibacterial activity, and infected-wound healing promotion exhibit great potential as in situ wound dressings.

Controllable Synthesis and Biological Application of Schiff Bases from d-Glucosamine and Terephthalaldehyde

Theoretically, the two aldehydes of terephthalaldehyde (TPA) are equivalent, so the single or double Schiff base from TPA and d-glucosamine (Glc) may be formed at the same time. However, it is preferred to produce separately a single Schiff base (L₁ ) or double Schiff base (L₂ ) for different synthesis systems of anhydrous methanol or water-methanol. We calculated the Δ_r G of the formation of compounds L₁ and L₂ by density functional theory (DFT). In an anhydrous methanol system, the Δ_r G values of L₁ and L₂ are both below zero and L₂ is lower, suggesting the spontaneous formation of the two Schiff bases. Though adjusting the molar ratio of Glc to TPA, L₁ and L ₂ both were separately formed in anhydrous methanol. However, in the water-methanol system, L₂ was absent, which is most likely due to higher Δ_r G (4.95 eV) and better water solubility. The results also exhibits that the positive charge of C in -CHO for TPA is smaller in a mixed solvent than that in methanol, which confirms that the nucleophilic reaction of the Schiff base is more difficult in a mixed solvent. Therefore, we could realize to control the synthesis of a pure single or double Schiff base from Glc and TPA by adjusting the molar ratio and solvent. The as-prepared two kinds of Schiff bases have strong optical properties, high bacteriostatic activity, and can be used as fluorescent probes for tumor cell imaging.

A Fe3+-crosslinked pyrogallol-tethered gelatin adhesive hydrogel with antibacterial activity for wound healing

A tunicate-inspired gelatin-based hydrogel prepared by a simple mixing method, exhibits strong adhesion and antibacterial capacity, and facilitates wound healing.

N-Benzylanilines as Fatty Acid Synthesis Inhibitors against Biofilm-related Methicillin-resistant Staphylococcus aureus

Bacterial fatty acid synthase system is a well validated target for the development of novel antimicrobial agents. This study reports the synthesis of Schiff bases and their reductive N-benzylanilines. Most N-benzylanilines were active against Gram-positive bacteria, among which compound 4k performed best against both S. aureus and MRSA with the MIC value at 0.5 mg/L. Moreover, we identified the strong antibacterial activity for compound 4k against 19 clinical MRSA strains isolated from different specimen, which indicated its potential in clinical application. In vitro biofilm inhibition and microscopy assay revealed compound 4k inhibits biofilm formation and eradicates preformed biofilm effectively. The size-exclusion chromatography and docking study indicated that compound 4k mimics the binding mode of triclosan with saFabI. The efficiency of the protein-inhibitor interaction was evaluated by measuring NADPH reduction using trans-2-octenoyl-CoA as substrate. Overall, our data demonstrate that N-benzylaniline is a promising scaffold for anti-staphylococcal drug development.

Synthesis and Evaluation of In Vitro Antibacterial and Antitumor Activities of Novel N,N-Disubstituted Schiff Bases

To get inside the properties of N,N-disubstituted Schiff bases, we synthesized three high-yielding benzaldehyde Schiff bases. We used the reaction between salicylaldehyde and different diamine compounds, including diamine, ethanediamine, and o-phenylenediamine, determining the structure of obtained molecules by nuclear magnetic resonance spectroscopy and electrospray ionization mass spectroscopy. We thus evaluated the microbicidal and antitumor activity of these compounds, showing that salicylaldehyde-hydrazine hydrate Schiff base (compound 1a) significantly inhibited the growth of S. aureus; salicylaldehyde-o-phenylenediamine Schiff base (compound 1c) displayed a strong capability to inhibit the proliferation of leukemia cell lines K562 and HEL. Moreover, we observed that the antibacterial action of 1a might be associated with the regulation of the expression of key virulence genes in S. aureus. Compound 1c resulted in a strong apoptotic activity against leukemia cells, also affecting the cell cycle distribution. Overall, our novel N,N-disubstituted Schiff bases possess unique antibacterial or antitumor activities that exhibit the potent application prospect in prophylactic or therapeutic interventions, providing new insights for developing new antibacterial and anticancer chemical agents.

Isoniazid derivatives and their anti-tubercular activity

Tuberculosis (TB), which has been a scourge of humanity for thousands of years, is a worldwide pandemic disease caused mainly by Mycobacterium tuberculosis (MTB). The emergence of drug-resistant TB (DR-TB), multidrug-resistant TB (MDR-TB), extensively drug-resistant TB (XDR-TB) and totally drug-resistant TB (TDR-TB) increase the challenges to eliminate TB worldwide. Isoniazid (INH), a critical frontline anti-TB drug, is one of the most effective drugs used to treatment of TB infection for more than 60 years. Unfortunately, bacterial strains resistant to INH are becoming common which mainly due to the long-term widely use even abuse. Therefore, there is an urgent need to develop novel anti-TB agents. Numerous efforts have been undertaken to develop new anti-TB agents, but no new drug has been introduced for more than 5 decades. It has been suggested that the incorporation of lipophilic moieties into the framework of INH can increase permeation of the drug into bacterial cells, thereby enhancing the anti-TB. Therefore, INH derivatives with greater lipophilicity are emerging as one of the most potential anti-TB agents. Indeed, the INH derivative LL-3858 is in initial stages of phase II clinical trial for the treatment of TB and may be approved to treat TB in the near future. This review aims to summarize the recent advances made towards the discovery anti-TB agents holding INH as a nucleus including INH hybrids and INH hydrazide-hydrazone derivatives.

Synthesis, structural and spectroscopic studies of 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide

The synthesis of a new hydrazone, 2-oxoacenaphthylen-1(2H)-ylidene nicotinohydrazide, and its structural and spectroscopic characterization is reported. The obtained powder was recrystallized from DMSO and ethanol that afforded small crystals used for single-crystal X-ray diffraction studies. The compound was found to crystallize in two polymorphs, depending on the crystallization conditions. One of the polymorphs (form I) crystallizes in the centrosymmetric P2₁/c monoclinic space group, the other (form II) crystallizes in the non-centrosymmetric, but achiral, orthorhombic space group P2₁2₁2₁. Conformation of the molecules is similar in both polymorphs, but the network of weak intermolecular interactions determining the crystal packing is different. In form II an additional C-H⋯O bond connects molecules related by the screw-axis running parallel to the a-axis. Crystals of both polymorphs were also screened by FT-IR and Raman microscopy; a detailed analysis of the spectra and comparison with those of the isolated molecule calculated by ab-initio HF/MP2 and DFT/B3LYP methods using a correlation consistent cc-pVDZ basis set is presented. In addition, UV-vis and NMR studies were performed in solution.

1α,2α-Epoxy-3β-hydroxy oleanolic acid derivatives regulation of the metabolism, haemolysis and β-lactamase gene expression in vitro and their structure-microbicidal activity relationship

Oleanolic acid (OA), one of the major pentacyclic triterpenes abundantly present in nature, is a promising compound with various biological activities, including anti-inflammatory, anti-ulcer, hepatoprotective, antidiabetic, fungicidal and antiparasitic properties. Therefore, a series of derivatives of 1α,2α-epoxy-3β-hydroxyl oleanolic acid derivatives were designed and synthesized, and their antibacterial activities were investigated in vitro. Based on these results, the compounds with antibacterial activity were screened by RT-PCR to determine whether they can regulate the expression of genes related to metabolism, haemolysis, and β-lactamase in vitro, and the structure-microbicidal activity relationship of each compound was analyzed. Our study shows that some of the modifications in the synthetic compounds, such as the introduction of an ortho-cyano-substituted benzyl group and a short chain alkyl ester at the 28-carboxyl, as well as the introduction of an acetyl group at the 3-hydroxyl group of ring A, could enhance antibacterial activity. This provides basic evidence for the optimization of 1α,2α-epoxy-3β-hydroxyl oleanolic acid derivatives. The antibacterial mechanism of the active OA derivatives appears to involve the regulation of expression of metabolism-associated genes in Escherichia coli, haemolysis-associated genes in Bacillus subtilis, metabolism-related genes in Klebsiella pneumonia and β-lactamase-associated genes in Acinetobacter baumannii. Some OA derivatives were bactericidal to three of the strains and appeared to regulate gene expression associated with metabolism, haemolysis, and β-lactamase in vitro. These newly designed OA derivatives possess unique antibacterial activities and may be potentially useful for prophylactic or therapeutic intervention of bacterial infections.

Acute Toxicity and Gastroprotection Studies of a New Schiff Base Derived Manganese (II) Complex against HCl/Ethanol-Induced Gastric Ulcerations in Rats

Manganese is a crucial element for health. In this study, the gastroprotective efficacy of Mn (II) complex (MDLA) against acidified ethanol (HCl/Ethanol)-induced gastric ulceration in rats was evaluated. The animals were distributed into 5 groups. Groups 1 and 2 received carboxymethylcellulose (CMC), group 3 was pretreated with omeprazole, and groups 4 and 5 were given 10 and 20 mg/kg of MDLA, respectively. After one hour, CMC and HCl/Ethanol were given to groups 2–5 whilst the animals in group 1 were ingested with CMC. After sacrifice, gastric lesions were evaluated by wall mucus, gross appearance, histology, antioxidant enzymes and immunohistochemistry. Group 2 displayed severe gastric damage with a significant reduction in wall mucus. Conversely, gastric lesions were reduced in groups 3–5 by 85.72%, 56.51% and 65.93%, respectively. The rats in groups 3–5 showed up-regulation of heat shock protein 70 (Hsp70) with down-regulation of Bcl-2-associated protein x (Bax). Pretreatment with omeprazole or MDLA led to an increase in the uptake of Periodic Acid Schiff (PAS) stain in the glandular part of the gastric tissue, raised levels of prostaglandin E2 (PGE₂) and superoxide dismutase (SOD), and a reduction in malondialdehyde (MDA) concentrations. These results suggested the gastroprotective action of Mn (II) complex.

Synthesis and biological evaluation of Schiff base-linked imidazolyl naphthalimides as novel potential anti-MRSA agents

Schiff base-linked imidazolyl naphthalimide 9i was a potential anti-MRSA agent, which could effectively inhibit the growth of MRSA.

Antifungal study of substituted 4-pyridylmethylene-4′-aniline Schiff bases

Two substituted 4-pyridylmethylene-4′-aniline Schiff bases showed antifungal activity against.Aspergillus nigerandCandida albicans. They may be useful for the development of safe drug candidates forA. nigerandC. albicanscases of otomycosis.