Appraisal of Cinnamaldehyde Analogs as Dual-Acting Antibiofilm and Anthelmintic Agents

Unraveling anthelmintic targets and mechanisms of action of trans-cinnamaldehyde from cinnamon essential oil

Parasitic nematodes pose a significant global socio-economic threat and contribute to neglected diseases. Current infection control relies on drug therapy, but increasing anthelmintic resistance highlights the urgent need for novel treatments. In this study, we investigate the molecular targets and mechanisms of action of trans-cinnamaldehyde (TCA), a principal component of Cinnamon Essential Oil (Cinnamomum verum EO), using Caenorhabditis elegans as a model organism. Our research offers new insights into the anthelmintic effects of TCA by identifying its specific interactions with key Cys-loop receptors and detailing its inhibitory mechanisms. The anthelmintic activity of C. verum EO and TCA manifests as rapid alterations in locomotor activity and inhibition of egg hatching. TCA screening of mutant worms lacking Cys-loop receptors reveal multiple receptor targets, including the levamisole-sensitive nicotinic ACh receptor (L-AChR), GABA-activated chloride channel (UNC-49) and glutamate-activated chloride channel. The mechanism behind the egg hatching inhibition by TCA remains unclear, as none of the mutants studied were found to be resistant to TCA. Furthermore, TCA increases the paralyzing effects of the anthelmintics levamisole and monepantel in a synergistic manner, offering a route for more effective polytherapy strategies. Electrophysiological studies on C. elegans Cys-loop receptors, in both native and heterologous systems, were used to elucidate the molecular mechanisms of TCA-induced paralysis. TCA reduces ACh- and GABA-elicited macroscopic currents and decreases single-channel activity and open durations of native muscle L-AChR channels, indicating an inhibitory action. Thus, by acting through a different mechanism to that of classical anthelmintics, TCA may be beneficial to counteract resistance in combined anthelmintic therapies. Our findings underscore the potential of the multitarget compound TCA as a valuable tool in integrated pharmacological strategies.

Antimicrobial activity of Cinnamomum zeylanicum essential oil against colistin-resistant gram-negative bacteria

In the current study, we evaluated the antimicrobial activity of Cinnamomum zeylanicum Blume essential oil (Cinn-EO) against a group of thirteen clinical colistin-resistant Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. The GCMS analysis showed that cinnamaldehyde was the major compound (94.29%) of the Cinn-EO. The diameter of the inhibition zone by Cinn-EO varied from 24 to 37 mm. The minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values ranged between 0.625 and 5 mg/mL. Interestingly, the MBC/MIC was equal to 1 for most tested bacterial strains, indicating an advanced bactericidal effect of Cinn-EO against colistin-resistant Gram-negative bacteria. The absorption, distribution, metabolism, elimination, and toxicity (ADMET) prediction showed good pharmacokinetic properties of the tested cinnamaldehyde. The results suggest that cinnamaldehyde could be a potential alternative to treat infection caused by colistin-resistant Gram-negative bacteria.

Antifungal activity of Cinnamaldehyde derivatives against fluconazole-resistant Candida albicans

BACKGROUND

Candida albicans is an opportunistic pathogen commonly found in human mucous membranes. In light of the escalating challenge posed by antibiotic resistance of C. albicans strains worldwide, it is an urgently necessary to explore alternative therapeutic options.

OBJECTIVE

This study aims to assess the efficacy of two Cinnamaldehyde derivatives, 2-Cl Cinnamaldehyde (2-Cl CA) and 4-Cl Cinnamaldehyde (4-Cl CA), against C. albicans through both in vitro experiments and in vivo murine models and to evaluate their potential as new drug candidates for treating C. albicans.

METHODS AND RESULTS

The minimum inhibitory concentrations (MICs) of Cinnamaldehyde 2-Cl and 4-Cl benzene ring derivatives against C. albicans were 25 μg/mL. Time-killing experiments revealed that both Cinnamaldehyde derivatives exhibited fungicidal activity against C. albicans at concentrations of 5 MIC and 10 MIC. In the checkerboard experiment, 4-Cl CA did not show any antagonistic effect when combined with first-line antifungal drugs. Instead, it exhibited additive effects in combination with nystatin. Both 2-Cl and 4-Cl CA demonstrated inhibitory activity against C. albicans biofilm formation, especially at 8 MIC and 16 MIC concentrations. In C. albicans biofilm eradication experiments, although high drug concentrations of 2-Cl and 4-Cl CA were unable to eradicate the biofilm completely, they were still effective in killing C. albicans cells within the biofilm. Moreover, sub-inhibitory concentrations of 4-Cl CA (ranging from 5 to 20 μg/mL) significantly inhibited cell aggregation and hyphal formation. Furthermore, 4-Cl CA effectively inhibited intracellular C. albicans infection in macrophages. Lastly, the effectiveness of 4-Cl CA was evaluated in a mouse model of hematogenous disseminated candidiasis caused by C. albicans, which revealed that 4-Cl CA significantly reduced fungal burden and improved mouse survival compared to the untreated controls.

CONCLUSION

The 4-Cl CA exhibited inhibitory effects against C. albicans through both in vivo and in vitro models, demonstrating its therapeutic potential as a promising new drug candidate for treating drug-resistant candidiasis albicans.

Bioinspired chitosan based functionalization of biomedical implant surfaces for enhanced hemocompatibility, antioxidation and anticoagulation potential: an in silico and in vitro study

Endowing implanted biomaterials with better hemocompatibility, anticoagulation, antioxidant and antiplatelet adhesion is necessary because of their potential to trigger activation of multiple reactive mechanisms including coagulation cascade and potentially causing serious adverse clinical events like late thrombosis. Active ingredients from natural sources including Foeniculum vulgare, Angelica sinensis, and Cinnamomum verum have the ability to inhibit the coagulation cascade and thrombus formation around biomedical implants. These properties are of interest for the development of a novel drug for biomedical implants to potentially solve the current blood clotting and coagulation problems which lead to stent thrombosis. The objective of this study was to incorporate different anticoagulants from natural sources into a degradable matrix of chitosan with varying concentrations ranging from 5% to 15% and a composite containing all three drugs. The presence of anticoagulant constituents was identified using GC-MS. Subsequently, all the compositions were characterized principally by using Fourier transform infrared spectroscopy and scanning electron microscopy while the drug release profile was determined using UV-spectrometry for a 30 days immersion period. The results indicated an initial burst release which was subsequently followed by the sustained release pattern. Compared to heparin loaded chitosan, DPPH and hemolysis tests revealed better blood compatibility of natural drug loaded films. Moreover, the anticoagulation activity of natural drugs was equivalent to the heparin loaded film; however, through docking, the mechanism of inhibition of the coagulation cascade of the novel drug was found to be through blocking the extrinsic pathway. The study suggested that the proposed drug composite expresses an optimum composition which may be a practicable and appropriate candidate for biomedical implant coatings.

Assessing silver nanoparticle and antimicrobial combinations for antibacterial activity and biofilm prevention on surgical sutures

AIMS

To evaluate the effect of silver nanoparticles alone and in combination with Triclosan, and trans-cinnamaldehyde against Staphylococcus aureus and Escherichia coli biofilms on sutures to improve patients' outcomes.

METHODS AND RESULTS

Silver nanoparticles were prepared by chemical method and characterized by UV-visible spectrophotometer and dynamic light scattering. The minimum inhibitory concentration was assessed by the Microdilution assay. The antibiofilm activity was determined using crystal violet assay. A checkerboard assay using the fractional inhibitory concentration index and time-kill curve was used to investigate the synergistic effect of silver nanoparticle combinations. The hemolytic activity was determined using an erythrocyte hemolytic assay. Our results revealed that silver nanoparticles, Triclosan, and trans-cinnamaldehyde (TCA) inhibited S.aureus and E.coli biofilms. Silver nanoparticles with TCA showed a synergistic effect (FICI values 0.35 and 0.45 against S. aureus and E. coli biofilms, respectively), and silver nanoparticles with Triclosan showed complete inhibition of S. aureus biofilm. The hemolytic activity was <2.50% for the combinations.

Halogenated Antimicrobial Agents to Combat Drug-Resistant Pathogens

Antimicrobial resistance presents us with a potential global crisis as it undermines the abilities of conventional antibiotics to combat pathogenic microbes. The history of antimicrobial agents is replete with examples of scaffolds containing halogens. In this review, we discuss the impacts of halogen atoms in various antibiotic types and antimicrobial scaffolds and their modes of action, structure-activity relationships, and the contributions of halogen atoms in antimicrobial activity and drug resistance. Other halogenated molecules, including carbohydrates, peptides, lipids, and polymeric complexes, are also reviewed, and the effects of halogenated scaffolds on pharmacokinetics, pharmacodynamics, and factors affecting antimicrobial and antivirulence activities are presented. Furthermore, the potential of halogenation to circumvent antimicrobial resistance and rejuvenate impotent antibiotics is addressed. This review provides an overview of the significance of halogenation, the abilities of halogens to interact in biomolecular settings and enhance pharmacological properties, and their potential therapeutic usages in preventing a postantibiotic era. SIGNIFICANCE STATEMENT: Antimicrobial resistance and the increasing impotence of antibiotics are critical threats to global health. The roles and importance of halogen atoms in antimicrobial drug scaffolds have been established, but comparatively little is known of their pharmacological impacts on drug resistance and antivirulence activities. This review is the first to extensively evaluate the roles of halogen atoms in various antibiotic classes and pharmacological scaffolds and to provide an overview of their ability to overcome antimicrobial resistance.

Characterization of an allosteric inhibitor of fungal-specific C-24 sterol methyltransferase to treat Candida albicans infections

Filamentation is an important virulence factor of the pathogenic fungus Candida albicans. The abolition of Candida albicans hyphal formation by disrupting sterol synthesis is an important concept for the development of antifungal drugs with high safety. Here, we conduct a high-throughput screen using a C. albicans strain expressing green fluorescent protein-labeled Dpp3 to identify anti-hypha agents by interfering with ergosterol synthesis. The antipyrine derivative H55 is characterized to have minimal cytotoxicity and potent inhibition of C. albicans hyphal formation in multiple cultural conditions. H55 monotherapy exhibits therapeutic efficacy in mouse models of azole-resistant candidiasis. H55 treatment increases the accumulation of zymosterol, the substrate of C-24 sterol methyltransferase (Erg6). The results of enzyme assays, photoaffinity labeling, molecular simulation, mutagenesis, and cellular thermal shift assays support H55 as an allosteric inhibitor of Erg6. Collectively, H55, an inhibitor of the fungal-specific enzyme Erg6, holds potential to treat C. albicans infections.

Antibiofilm Activities of Cinnamaldehyde Analogs against Uropathogenic Escherichia coli and Staphylococcus aureus

Bacterial biofilm formation is a major cause of drug resistance and bacterial persistence; thus, controlling pathogenic biofilms is an important component of strategies targeting infectious bacterial diseases. Cinnamaldehyde (CNMA) has broad-spectrum antimicrobial and antibiofilm activities. In this study, we investigated the antibiofilm effects of ten CNMA derivatives and trans-CNMA against Gram-negative uropathogenic Escherichia coli (UPEC) and Gram-positive Staphylococcus aureus. Among the CNMA analogs tested, 4-nitrocinnamaldehyde (4-nitroCNMA) showed antibacterial and antibiofilm activities against UPEC and S. aureus with minimum inhibitory concentrations (MICs) for cell growth of 100 µg/mL, which were much more active than those of trans-CNMA. 4-NitroCNMA inhibited UPEC swimming motility, and both trans-CNMA and 4-nitroCNMA reduced extracellular polymeric substance production by UPEC. Furthermore, 4-nitroCNMA inhibited the formation of mixed UPEC/S. aureus biofilms. Collectively, our observations indicate that trans-CNMA and 4-nitroCNMA potently inhibit biofilm formation by UPEC and S. aureus. We suggest efforts be made to determine the therapeutic scope of CNMA analogs, as our results suggest CNMA derivatives have potential therapeutic use for biofilm-associated diseases.