Cuminaldehyde potentiates the antimicrobial actions of ciprofloxacin against Staphylococcus aureus and Escherichia coli

Ralstonia solanacearum infection induces tobacco root to secrete chemoattractants to recruit antagonistic bacteria and defensive compounds to inhibit pathogen

BACKGROUND

Plant root exudates play crucial roles in maintaining the structure and function of the whole belowground ecosystem and regulating the interactions between roots and soil microorganisms. Ralstonia solanacearum causes bacterial wilt disease in many plants, while root exudate-mediated inhibition of pathogen infection is poorly understood. Here, we characterize the chemical divergence between root exudates of healthy and diseased tobacco plants and the effects of that variability on the rhizosphere microbial community and the occurrence of bacterial wilt.

RESULTS

Compared with the healthy plants, root exudates in diseased plants showed distinct exudation patterns and metabolite profiles including increased amounts of flavonoids, phenylpropanoids, terpenoids and defense-related hormones, as well as distinct bacterial community composition, as illustrated by an increased abundance of Ralstonia and decreased abundances of Bacillus and Streptomyces in diseased plants rhizosphere. Pathogen infection stimulated roots to secrete more defensive compounds to inhibit pathogen growth. Change of root exudates modulated rhizosphere microbial community. Specific root exudates could benefit plants by attracting antagonistic Bacillus amyloliquefaciens and inhibiting pathogens. Bacillus amyloliquefaciens could utilize specific root exudates as carbon sources. Benzyl cinnamatel promoted the biofilm formation and colonization of B. amyloliquefaciens on roots.

CONCLUSION

To defend against pathogen invasion, tobacco plants recruited antagonistic and plant growth-promoting rhizobacteria to the rhizosphere by modifying root exudate profiles. Specific signal molecules are recommended to recruit beneficial microorganisms for controlling bacterial wilt. The results provide insights concerning the metabolic divergence of root exudates integral to understanding root-microorganism interaction. © 2024 Society of Chemical Industry.

A Comprehensive Review on the Antibacterial, Antifungal, Antiviral, and Antiparasitic Potential of Silybin

Silybin, a flavonolignan extracted from the seeds of the plant species Silybum marianum (L.) Gaertn., has a variety of pharmacological activities, including antimicrobial activity against several microorganisms of clinical interest. This review analyzes the existing studies on silybin's antimicrobial activity and possible mechanisms of action. Silybin has been shown to inhibit the growth of Gram-positive and Gram-negative bacteria, as well as some fungi, viruses, and protozoa. In general, possible mechanisms of antimicrobial action include the inhibition of efflux pumps, prevention of biofilm formation, reduction of the expression of virulence factors, induction of apoptosis-like effects, and plasma membrane damage, as well as the inhibition of nucleic acid and protein synthesis. Silybin has been shown to have synergistic effects when combined with conventional antibiotics against both drug-sensitive and drug-resistant microorganisms. However, the low bioavailability observed for this flavonolignan has been a challenge to its clinical use. In this context, nanotechnology has been used to increase silybin's bioavailability while enhancing its antimicrobial activity. Furthermore, certain structural modifications have been able to enhance its antimicrobial activity in comparison to that of the natural molecule. Overall, this review provides insights into the scientific understanding of the mechanism of action of silybin and its desired properties for the effective treatment of infections.

Cuminaldehyde in combination with tetracycline shows promising antibiofilm activity against drug-resistant Pseudomonas aeruginosa

Pseudomonas aeruginosa, an opportunistic pathogen often causes biofilm-linked infections. A combinatorial approach involving tetracycline (antibiotic) and cuminaldehyde (phytochemical) was explored to combat this infectious pathogen. The results showed that both tetracycline and cuminaldehyde individually demonstrated antibacterial effects. However, when the compounds were applied together, there was a significant increase in their antimicrobial potential. The determined fractional inhibitory concentration index of 0.43 indicated a synergistic interaction between the two compounds. Furthermore, a series of experiments demonstrated that the combined application of cuminaldehyde and tetracycline could lead to a significant enhancement of their antibiofilm potential. This enhanced antibiofilm potential was attributed to the accumulation of reactive oxygen species and increased cell membrane permeability. Besides, this combinatorial application reduced the secretion of various virulence factors from P. aeruginosa. Therefore, this combined approach holds promise for effectively treating P. aeruginosa biofilms.

Cuminaldehyde and Tobramycin Forestall the Biofilm Threats of Staphylococcus aureus: A Combinatorial Strategy to Evade the Biofilm Challenges

Staphylococcus aureus, an opportunistic Gram-positive pathogen, is known for causing various infections in humans, primarily by forming biofilms. The biofilm-induced antibiotic resistance has been considered a significant medical threat. Combinatorial therapy has been considered a reliable approach to combat antibiotic resistance by using multiple antimicrobial agents simultaneously, targeting bacteria through different mechanisms of action. To this end, we examined the effects of two molecules, cuminaldehyde (a natural compound) and tobramycin (an antibiotic), individually and in combination, against staphylococcal biofilm. Our experimental observations demonstrated that cuminaldehyde (20 μg/mL) in combination with tobramycin (0.05 μg/mL) exhibited efficient reduction in biofilm formation compared to their individual treatments (p < 0.01). Additionally, the combination showed an additive interaction (fractional inhibitory concentration value 0.66) against S. aureus. Further analysis revealed that the effective combination accelerated the buildup of reactive oxygen species (ROS) and increased the membrane permeability of the bacteria. Our findings also specified that the cuminaldehyde in combination with tobramycin efficiently reduced biofilm-associated pathogenicity factors of S. aureus, including fibrinogen clumping ability, hemolysis property, and staphyloxanthin production. The selected concentrations of tobramycin and cuminaldehyde demonstrated promising activity against the biofilm development of S. aureus on catheter models without exerting antimicrobial effects. In conclusion, the combination of tobramycin and cuminaldehyde presented a successful strategy for combating staphylococcal biofilm-related healthcare threats. This combinatorial approach holds the potential for controlling biofilm-associated infections caused by S. aureus.

Evaluation of Emulsification Techniques to Optimize the Properties of Chalcone Nanoemulsions for Antifungal Applications

Background/Objectives: Nanoemulsions (NEs) possess properties that enhance the solubility, bioavailability and therapeutic efficacy of drugs. Chalcones are compounds known for their antifungal properties. In this study, we evaluated different emulsification techniques to create alginate nanoemulsions containing chalcone (1E,4E)-1,5-bis (4-methoxyphenyl) penta-1,4-dien-3-one (DB4OCH3). Our goal was to develop an antifungal formulation targeting Candida albicans strains. Methods: Ultrasound and ultrasound combined with high-speed homogenization techniques were used to prepare alginate-stabilized nanoemulsions. Particle size, zeta potential and encapsulation efficiency were evaluated. Additionally, in vitro release studies were conducted. Results: The combined emulsification technique produced stable nanoparticles with high encapsulation efficiency and antifungal activity, with a minimum inhibitory concentration of 8.75 μg/mL for the nanoemulsions compared to 312 µg/mL for free DB4OCH3. NEs' effectiveness can be attributed to their ability to form nanodroplets efficiently, facilitating the solubilization of the chalcone in the oily phase. The particle size varied between 195.70 ± 2.69 and 243.40 ± 4.49 nm, with an increase in chalcone concentration leading to larger particle sizes. The zeta potential showed values from -91.77 ± 5.58 to -76.90 ± 4.44 mV. The UHS-7 sample exhibited an encapsulation efficiency of 92.10% ± 0.77, with a controlled in vitro release of 83% after 34 h. Molecular docking simulations showed that the aromatic nature of DB4OCH3 resulted in the formation of apolar interactions with aromatic residues located in the active site of the TMK, as observed in their respective co-crystallized inhibitors, within an affinity energy range that enables optimum specificity of the ligand for these two pathways. Pharmacokinetic analyses indicated high passive cell permeability and low hepatic clearance, and phase I metabolism reduces its oral bioavailability and metabolic stability, suggesting a promising active ingredient as an oral drug with control of the daily oral dose administered. Conclusions: The combined nanoemulsification technique led to the formation of finely dispersed nanodroplets that favored the solubilization of the chalcone in the oil phase, which led to a better performance in the antifungal properties. DB4OCH3 shows promise as an oral drug with controlled dosing.

CAPE derivatives: Multifaceted agents for chronic wound healing

Chronic wounds significantly impact the patients' quality of life, creating an urgent interdisciplinary clinical challenge. The development of novel agents capable of accelerating the healing process is essential. Caffeic acid phenethyl ester (CAPE) has demonstrated positive effects on skin regeneration. However, its susceptibility to degradation limits its pharmaceutical application. Chemical modification of the structure improves the pharmacokinetics of this bioactive phenol. Hence, two novel series of CAPE hybrids were designed, synthesized, and investigated as potential skin regenerative agents. To enhance the stability and therapeutic efficacy, a caffeic acid frame was combined with quinolines or isoquinolines by an ester (1a-f) or an amide linkage (2a-f). The effects on cell viability of human gingival fibroblasts (HGFs) and HaCaT cells were evaluated at different concentrations; they are not cytotoxic, and some proved to stimulate cell proliferation. The most promising compounds underwent a wound-healing assay in HGFs and HaCaT at the lowest concentrations. Antimicrobial antioxidant properties were also explored. The chemical and thermal stabilities of the best compounds were assessed. In silico predictions were employed to anticipate skin penetration capabilities. Our findings highlight the therapeutic potential of caffeic acid phenethyl ester (CAPE) derivatives 1a and 1d as skin regenerative agents, being able to stimulate cell proliferation, control bacterial growth, regulate ROS levels, and being thermally and chemically stable. An interesting structure-activity relationship was discussed to suggest a promising multitargeted approach for enhanced wound healing.

Combinatorial application of cuminaldehyde and gentamicin shows enhanced antimicrobial and antibiofilm action on Pseudomonas aeruginosa

The emergence of biofilm-induced drug tolerance poses a critical challenge to public healthcare management. Pseudomonas aeruginosa, a gram-negative opportunistic bacterium, is involved in various biofilm-associated infections in human hosts. Towards this direction, in the present study, a combinatorial approach has been explored as it is a demonstrably effective strategy for managing microbial infections. Thus, P. aeruginosa has been treated with cuminaldehyde (a naturally occurring phytochemical) and gentamicin (an aminoglycoside antibiotic) in connection to the effective management of the biofilm challenges. It was also observed that the test molecules could show increased antimicrobial activity against P. aeruginosa. A fractional inhibitory concentration index (FICI) of 0.65 suggested an additive interaction between cuminaldehyde and gentamicin. Besides, a series of experiments such as crystal violet assay, estimation of extracellular polymeric substance (EPS), and microscopic images indicated that an enhanced antibiofilm activity was obtained when the selected compounds were applied together on P. aeruginosa. Furthermore, the combination of the selected compounds was found to reduce the secretion of virulence factors from P. aeruginosa. Taken together, this study suggested that the combinatorial application of cuminaldehyde and gentamicin could be considered an effective approach towards the control of biofilm-linked infections caused by P. aeruginosa.

Discovery of potential anti- Staphylococcus aureus natural products and their mechanistic studies using machine learning and molecular dynamic simulations

The structure-activity analysis (SAR) and machine learning were used to investigate potential anti-S. aureus agents in a faster method. In this study, 24 oxygenated benzene ring components with S. aureus inhibition capacity were confirmed by literature exploring and in-house experiments, and the SAR analysis suggested that the hydroxyl group position may affect the anti-S. aureus activity. The 2D-MLR-QSAR model with 9 descriptors was further evaluated as the best model among the 21 models. After that, hesperetic acid and 2-HTPA were further explored and evaluated as the potential anti-S. aureus agents screening in the natural product clustering library through the best QSAR model calculation. The antibacterial capacities of hesperetic acid and 2-HTPA had been investigated and proved the similar predictive pMIC value resulting from the QSAR model. Besides, the two novel components were able to inhibit the growth of S. aureus by disrupting the cell membrane through the molecular dynamics simulation (MD), which further evidenced by scanning electron microscopy (SEM) test and PI dye results. Overall, these results are highly suggested that QSAR can be used to predict the antibacterial agents targeting S. aureus, which provides a new paradigm to research the molecular structure-antibacterial capacity relationship.

Application of cuminaldehyde and ciprofloxacin for the effective control of biofilm assembly of Pseudomonas aeruginosa: A combinatorial study

Pseudomonas aeruginosa is widely associated with biofilm-mediated antibiotic resistant chronic and acute infections which constitute a persistent healthcare challenges. Addressing this threat requires exploration of novel therapeutic strategies involving the combination of natural compounds and conventional antibiotics. Hence, our study has focused on two compounds; cuminaldehyde and ciprofloxacin, which were strategically combined to target the biofilm challenge of P. aeruginosa. The minimum inhibitory concentration (MIC) of cuminaldehyde and ciprofloxacin was found to be 400 μg/mL and 0.4 μg/mL, respectively. Moreover, the fractional inhibitory concentration index (FICI = 0.62) indicated an additive interaction prevailed between cuminaldehyde and ciprofloxacin. Subsequently, sub-MIC doses of cuminaldehyde (25 μg/mL) and ciprofloxacin (0.05 μg/mL) were selected for an array of antibiofilm assays which confirmed their biofilm inhibitory potential without exhibiting any antimicrobial activity. Furthermore, selected doses of the mentioned compounds could manage biofilm on catheter surface by inhibiting and disintegrating existing biofilm. Additionally, the test combination of the mentioned compounds reduced virulence factors secretion, accumulated reactive oxygen species and increased cell-membrane permeability. Thus, the combination of cuminaldehyde and ciprofloxacin demonstrates potential in combating biofilm-associated Pseudomonal threats.

Lipid Metabolites as Potential Regulators of the Antibiotic Resistome in Tetramorium caespitum

Antibiotic resistance genes (ARGs) are ancient but have become a modern critical threat to health. Gut microbiota, a dynamic reservoir for ARGs, transfer resistance between individuals. Surveillance of the antibiotic resistome in the gut during different host growth phases is critical to understanding the dynamics of the resistome in this ecosystem. Herein, we disentangled the ARG profiles and the dynamic mechanism of ARGs in the egg and adult phases of Tetramorium caespitum. Experimental results showed a remarkable difference in both gut microbiota and gut resistome with the development of T. caespitum. Meta-based metagenomic results of gut microbiota indicated the generalizability of gut antibiotic resistome dynamics during host development. By using Raman spectroscopy and metabolomics, the metabolic phenotype and metabolites indicated that the biotic phase significantly changed lipid metabolism as T. caespitum aged. Lipid metabolites were demonstrated as the main factor driving the enrichment of ARGs in T. caespitum. Cuminaldehyde, the antibacterial lipid metabolite that displayed a remarkable increase in the adult phase, was demonstrated to strongly induce ARG abundance. Our findings show that the gut resistome is host developmental stage-dependent and likely modulated by metabolites, offering novel insights into possible steps to reduce ARG dissemination in the soil food chain.

Interactions between Macrophages and Biofilm during Staphylococcus aureus-Associated Implant Infection: Difficulties and Solutions

Staphylococcus aureus (S. aureus) biofilm is the major cause of failure of implant infection treatment that results in heavy social and economic burden on individuals, families, and communities. Planktonic S. aureus attaches to medical implant surfaces where it proliferates and is wrapped by extracellular polymeric substances, forming a solid and complex biofilm. This provides a stable environment for bacterial growth, infection maintenance, and diffusion and protects the bacteria from antimicrobial agents and the immune system of the host. Macrophages are an important component of the innate immune system and resist pathogen invasion and infection through phagocytosis, antigen presentation, and cytokine secretion. The persistence, spread, or clearance of infection is determined by interplay between macrophages and S. aureus in the implant infection microenvironment. In this review, we discuss the interactions between S. aureus biofilm and macrophages, including the effects of biofilm-related bacteria on the macrophage immune response, roles of myeloid-derived suppressor cells during biofilm infection, regulation of immune cell metabolic patterns by the biofilm environment, and immune evasion strategies adopted by the biofilm against macrophages. Finally, we summarize the current methods that support macrophage-mediated removal of biofilms and emphasize the importance of considering multi-dimensions and factors related to implant-associated infection such as immunity, metabolism, the host, and the pathogen when developing new treatments.

Antileishmanial Effects of Bunium Persicum Crude Extract, Essential Oil, and Cuminaldehyde on Leishmania Major: In Silico and In Vitro Properties

PURPOSE

Cuminaldehyde (CA), an oxidized aldehyde monoterpene, is a major essential oil component in cumin seeds, which has shown different promising medical effects. In this study, we comprehensively evaluated the antileishmanial potential of Bunium persicum (Boiss) B. Fedtsch (Apiaceae) and one of its main essential oil constituents, CA, focus on the mechanisms of action.

METHODS

We used a molecular docking approach to examine the capability of CA for binding to IL-12P40 and TNF-α. The colorimetric assay was performed to assess the effect of B. persicum crude extract, essential oil, and CA, against Leishmania major promastigotes and intracellular amastigotes. The expression of IFN-γ, IL-12P40, TNF-α, and IL-10 genes was detected using quantitative real-time polymerase chain reaction qPCR.

RESULTS

Docking analyses in the current study indicated CA binds to IL-12P40 and TNF-α. These products were safe, extremely antileishmanial, and significantly promoted Th1-related cytokines (IFN-γ, IL-12P40, TNF-α), while downregulating the Th2 phenotype (IL-10).

CONCLUSION

Cumin essential oil and its major component, CA, possessed powerful antileishmanial activity. The primary mechanism of activity involves an immunomodulatory role toward Th1 cytokine response. Therefore, cumin essential oil and CA deserve further explorations as promising medications for treating leishmaniasis.

Synergistic interaction of cuminaldehyde and tobramycin: a potential strategy for the efficient management of biofilm caused by Pseudomonas aeruginosa

Pseudomonas aeruginosa, an opportunistic pathogen, has been found to cause several chronic and acute infections in human. Moreover, it often shows drug-tolerance and poses a severe threat to public healthcare through biofilm formation. In this scenario, two molecules, namely, cuminaldehyde and tobramycin, were used separately and in combination for the efficient management of biofilm challenge. The minimum inhibitory concentration (MIC) of cuminaldehyde and tobramycin was found to be 150 µg/mL and 1 µg/mL, respectively, against Pseudomonas aeruginosa. The checkerboard assay revealed that the fractional inhibitory concentration (FIC) index of cuminaldehyde and tobramycin was 0.36 suggesting a synergistic association between them. The sub-MIC dose of cuminaldehyde (60 µg/mL) or tobramycin (0.06 µg/mL) individually did not show any effect on the microbial growth curve. However, the same combinations could affect microbial growth curve of Pseudomonas aeruginosa efficiently. In connection to biofilm management, it was observed that the synergistic interaction between cuminaldehyde and tobramycin could inhibit biofilm formation more efficiently than their single use (p < 0.01). Further investigation revealed that the combinations of cuminaldehyde and tobramycin could generate reactive oxygen species (ROS) that resulted in the increase of membrane permeability of bacterial cells leading to the efficient inhibition of microbial biofilm formation. Besides, the synergistic interaction between cuminaldehyde (20 µg/mL) and tobramycin (0.03 µg/mL) also showed significant biofilm dispersal of the test microorganism (p < 0.01). Hence, the results suggested that synergistic action of cuminaldehyde and tobramycin could be applied for the efficient management of microbial biofilm.

In Silico and In Vitro Analysis of Sulforaphane Anti-Candida Activity

Oropharyngeal candidiasis/candidosis is a common and recurrent opportunistic fungal infection. Fluconazole (FLZ), one of the most used and effective antifungal agents, has been associated with a rise of resistant Candida species in immunocompromised patients undergoing prophylactic therapy. Sulforaphane (SFN), a compound from cruciferous vegetables, is an antimicrobial with yet controversial activities and mechanisms on fungi. Herein, the in silico and antifungal activities of SFN against C. albicans were investigated. In silico analyzes for the prediction of the biological activities and oral bioavailability of SFN, its possible toxicity and pharmacokinetic parameters, as well as the estimates of its gastrointestinal absorption, permeability to the blood-brain barrier and skin, and similarities to drugs, were performed by using different software. SFN in vitro anti-Candida activities alone and in combination with fluconazole (FLZ) were determined by the broth microdilution method and the checkerboard, biofilm and hyphae formation tests. Amongst the identified probable biological activities of SFN, nine indicated an antimicrobial potential. SFN was predicted to be highly absorbable by the gastrointestinal tract, to present good oral availability, and not to be irritant and/or hepatotoxic. SFN presented antifungal activity against C. albicans and prevented both biofilm and hyphae formation by this microorganism. SFN was additive/synergistic to FLZ. Overall, the data highlights the anti-Candida activity of SFN and its potential to be used as an adjuvant therapy to FLZ in clinical settings.

Effect of Ruta graveolens Extract on the Major Virulence Factors in Methicillin Resistant Staphylococcus aureus

Purpose

Rising Antibiotic Resistance has put the world in real threat. Methicillin resistant Staphylococcus aureus (MRSA), is a predominant cause of suppurative chronic skin and soft-tissue infections. Novel insights have focused the light on plant extracts. In this study, Ruta graveolens ethanolic active extract was tested for its potential anti-virulence activities in MRSA.

Materials and Methods

A total of 100 MRSA strains causing skin and soft tissue infections were isolated and antibiotic susceptibility testing was done. Ability to form biofilm was tested phenotypically. Furthermore, the antimicrobial activity of Ruta graveolens was evaluated followed by detection of its Minimum inhibitory concentration (MIC). The inhibitory activity of this extract on biofilm formation was investigated. Afterwards, we investigated its effect on the transcription of biofilm-related genes and mecA gene.

Results

All tested isolates were sensitive to Vancomycin and Linezolid while high resistance was noted with both Fusidic acid (83%) and Gentamicin (68%). (83%) of the isolates were biofilm producers. Ruta graveolens extract showed strong antimicrobial activity against the MRSA strains with MIC 0.78 mg/mL. At subinhibitory concentration (1/2 MIC), the extract had high biofilm inhibitory effects with mean inhibition (70%). Moreover, transcriptional analysis results showed that the mean percentages of inhibition in expression of mecA, icaA and icaD genes were 52.3%, 34.8% and 33.7%, respectively, in which all showed statistically significant difference (p ≤ 0.05).

Conclusion

The current study proposes the ability of Ruta graveolens extract to reduce the biofilm formation and antibiotic resistance of MRSA through downregulation of some biofilm forming genes and mecA gene which confers resistance to B-lactam antibiotics. This may decrease our reliance on antibiotics and improve our ability to effectively treat biofilm-related skin and soft-tissue infections caused by MRSA.

An optimized herbal combination for the treatment of liver fibrosis: Hub genes, bioactive ingredients, and molecular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Liver fibrosis is a chronic liver disease that can lead to cirrhosis, liver failure, and hepatocellular carcinoma, and it is associated with long-term adverse outcomes and mortality. As a primary resource for complementary and alternative medicine, traditional Chinese medicine (TCM) has accumulated a large number of effective formulas for the treatment of liver fibrosis in clinical practice. However, studies on how to systematically optimize TCM formulas are still lacking.

AIM OF THE REVIEW

To provide a methodological reference for the systematic optimization of TCM formulae against liver fibrosis and explored the underlying molecular mechanisms; To provide an efficient method for searching for lead compounds from natural sources and developing from herbal medicines; To enable clinicians and patients to make more reasonable choices and promote the effective treatment toward those patients with liver fibrosis.

MATERIALS AND METHODS

TCM formulas related to treating liver fibrosis were collected from the Web of Science, PubMed, the China National Knowledge Infrastructure (CNKI), Wan Fang, and the Chinese Scientific Journals Database (VIP). Furthermore, the TCM compatibility patterns were mined using association analysis. The core TCM combinations were found by designing an optimized formulas algorithm. Finally, the hub target proteins, potential molecular mechanisms, and active compounds were explored through integrative pharmacology and docking-based inverse virtual screening (IVS) approaches.

RESULTS

We found that the herbs for reinforcing deficiency, activating blood, removing blood stasis, and clearing heat were the basis of TCM formulae patterns. Furthermore, the combination of Salviae Miltiorrhizae (Salvia miltiorrhiza Bunge; Chinese salvia/Danshen), Astragali Radix (Astragalus membranaceus (Fisch.) Bunge; Astragalus/Huangqi), and Radix Bupleuri (Bupleurum chinense DC.; Bupleurum/Chaihu) was identified as core groups. A total of six targets (TNF, STAT3, EGFR, IL2, ICAM1, PTGS2) play a pivotal role in TCM-mediated liver fibrosis inhibition. (-)-Cryptotanshinone, Tanshinaldehyde, Ononin, Thymol, Daidzein, and Formononetin were identified as active compounds in TCM. And mechanistically, TCM could affect the development of liver fibrosis by regulating inflammation, immunity, angiogenesis, antioxidants, and involvement in TNF, MicroRNAs, Jak-STAT, NF-kappa B, and C-type lectin receptors (CLRs) signaling pathways. Molecular docking results showed that key components had good potential to bind to the target genes.

CONCLUSION

In summary, this study provides a methodological reference for the systematic optimization of TCM formulae and exploration of underlying molecular mechanisms.

Aqueous Extract from Cuminum cyminum L. Seed Alleviates Ovalbumin-Induced Allergic Rhinitis in Mouse via Balancing of Helper T Cells

Cuminum cyminum L. (cumin) seeds are widely used as a spice. Although we previously reported that the aqueous extract of cumin seeds suppresses the degranulation of rat basophilic RBL-2H3 cells, it has not been clarified whether the extract alleviates actual allergy symptoms in vivo. Therefore, in this study, we investigated the effect of oral administration of cumin seed aqueous extract (CAE) in ovalbumin (OVA)-induced allergic rhinitis. BALB/c mice were randomly divided into the following three groups: control group (five mice), OVA group (five mice), and OVA + CAE group (five mice). Allergic rhinitis was induced by sensitization (intraperitoneal, 25 μg OVA and 1.98 mg aluminum hydroxide gel) followed by challenge (intranasal, 400 μg OVA). The oral administration of CAE (25 mg/kg) reduced the sneezing frequency of OVA-induced allergic rhinitis model mice. In addition to reducing the serum immunoglobulin E and IL-4 levels, the oral administration of CAE reduced the production of T-helper type-2 (Th2) cytokines (IL-4, IL-5, IL-10, and IL-13) in the splenocytes of the model mice. Furthermore, a significant increase in the ratio of Th1 to Th2 cells was observed in the CAE-administered group. Our findings suggest that the ingestion of CAE improves T cell balance, the dominant state of Th2, and alleviates allergic rhinitis symptoms.

Unveiling Antimicrobial and Antioxidant Compositional Differences between Dukkah and Za'atar via SPME-GCMS and HPLC-DAD

Interest in plant-based diets has been on the rise in recent years owing to the potential health benefits of their individual components and the notion that plant-based diets might reduce the incidence of several diseases. Egyptian dukkah and Syrian za’atar are two of the most historic and famous Middle Eastern herbal blends used for their anti-inflammatory, hypolipidemic, and antidiabetic effects. Headspace SPME-GCMS and HPLC-DAD were adopted for characterizing the aroma profile and phenolic compounds of both herbal blends, respectively. Further, vapor-phase minimum inhibitory concentration was employed for assessing each blend’s antibacterial potential, while their antioxidant potential was estimated via in vitro antioxidant assays. SPME headspace analysis indicated the abundance of ethers and monoterpene hydrocarbons, while HPLC revealed the presence of several phenolics including rosmarinic acid, ferulic acid, and rutin. Biological investigations affirmed that vapor-phase of the tested blends exhibited antibacterial activities against Gram-positive and Gram-negative pathogens, while the antioxidant potential of the blends was investigated and expressed as Trolox (125.15 ± 5.92 to 337.26 ± 13.84 μM T eq/mg) and EDTA (18.08 ± 1.62 to 51.69 41 ± 5.33 μM EDTA eq/mg) equivalent. The presented study offers the first insight into the chemical profile and biological activities of both dukkah and za’atar.

Transcriptomic and proteomic analysis of Staphylococcus aureus response to cuminaldehyde stress

The previous study indicated that cuminaldehyde (CUM) could be used as an antibacterial agent in sauced beef to reduce the propagation of Staphylococcus aureus (S. aureus). This research took sauced beef treated with 0.4 μL/mL CUM as the research object. Transcriptomic and proteomic methods were used to comprehensively analyze the changes in genes and proteins of S. aureus under CUM stress. A total of 258 differentially expressed genes (DEGs, 178 up-regulated and 80 down-regulated) and 384 differentially expressed proteins (DEPs, 61 up-regulated and 323 down-regulated) were found. It was observed that CUM destroyed the cell wall and cell membrane by inhibiting the synthesis of peptidoglycan and fatty acid. Low energy consumption strategies were formed by reducing glycolysis and ribosome de novo synthesis. The levels of genes and proteins associated with the glycine, serine, threonine, methionine, cysteine, and branched-chain amino acids were dramatically changed, which impaired protein synthesis and reduced bacterial viability. In addition, the up-regulated DEGs and DEFs involved in DNA replication, recombination and single-stranded DNA-binding contributed to DNA repair. Moreover, ATP-binding cassettes (ABC) transporters were also perturbed, such as the uptake of betaine and iron were inhibited. Thus, this study revealed the response mechanism of S. aureus under the stress of CUM, and provided a theoretical basis for the application of CUM in meat products.

In Vitro and In Silico Screening of Anti-Vibrio spp., Antibiofilm, Antioxidant and Anti-Quorum Sensing Activities of Cuminum cyminum L. Volatile Oil

Cuminum cyminum L. essential oil (cumin EO) was studied for its chemical composition, antioxidant and vibriocidal activities. Inhibition of biofilm formation and secretion of some virulence properties controlled by the quorum sensing system in Chromobacterium violaceum and Pseudomonas aeruginosa strains were also reported. The obtained results showed that cuminaldehyde (44.2%) was the dominant compound followed by β-pinene (15.1%), γ-terpinene (14.4%), and p-cymene (14.2%). Using the disc diffusion assay, cumin EO (10 mg/disc) was particularly active against all fifteen Vibrio species, and the highest diameter of growth inhibition zone was recorded against Vibrio fluvialis (41.33 ± 1.15 mm), Vibrio parahaemolyticus (39.67 ± 0.58 mm), and Vibrio natrigens (36.67 ± 0.58 mm). At low concentration (MICs value from 0.023–0.046 mg/mL), cumin EO inhibited the growth of all Vibrio strains, and concentrations as low as 1.5 mg/mL were necessary to kill them (MBCs values from 1.5–12 mg/mL). Using four antioxidant assays, cumin EO exhibited a good result as compared to standard molecules (DPPH = 8 ± 0.54 mg/mL; reducing power = 3.5 ± 0.38 mg/mL; β-carotene = 3.8 ± 0.34 mg/mL; chelating power = 8.4 ± 0.14 mg/mL). More interestingly, at 2x MIC value, cumin EO inhibited the formation of biofilm by Vibrio alginolyticus (9.96 ± 1%), V. parahaemolyticus (15.45 ± 0.7%), Vibrio cholerae (14.9 ± 0.4%), and Vibrio vulnificus (18.14 ± 0.3%). In addition, cumin EO and cuminaldehyde inhibited the production of violacein on Lauria Bertani medium (19 mm and 35 mm, respectively). Meanwhile, 50% of violacein inhibition concentration (VIC50%) was about 2.746 mg/mL for cumin EO and 1.676 mg/mL for cuminaldehyde. Moreover, elastase and protease production and flagellar motility in P. aeruginosa were inhibited at low concentrations of cumin EO and cuminaldehyde. The adopted in-silico approach revealed good ADMET properties as well as a high binding score of the main compounds with target proteins (1JIJ, 2UV0, 1HD2, and 3QP1). Overall, the obtained results highlighted the effectiveness of cumin EO to prevent spoilage with Vibrio species and to interfere with the quorum sensing system in Gram-negative bacteria by inhibiting the flagellar motility, formation of biofilm, and the secretion of some virulence enzymes.

Mitochondrial Imbalance of Trypanosoma cruzi Induced by the Marine Alkaloid 6-Bromo-2'-de-N-Methylaplysinopsin

Chagas disease, caused by Trypanosoma cruzi, affects seven million people worldwide and lacks effective treatments. Using bioactivity-guided fractionation, NMR, and electrospray ionization-high resolution mass spectrometry (ESI-HRMS) spectral analysis, the indole alkaloid 6-bromo-2'-de-N-methylaplysinopsin (BMA) was isolated and chemically characterized from the marine coral Tubastraea tagusensis. BMA was tested against trypomastigotes and intracellular amastigotes of T. cruzi, resulting in IC₅₀ values of 62 and 5.7 μM, respectively, with no mammalian cytotoxicity. The mechanism of action studies showed that BMA induced no alterations in the plasma membrane permeability but caused depolarization of the mitochondrial membrane potential, reducing ATP levels. Intracellular calcium levels were also reduced after the treatment, which was associated with pH alteration of acidocalcisomes. Using matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF)/MS analysis, alterations of mass spectral signals were observed after treatment with BMA, suggesting a different mechanism from benznidazole. In silico pharmacokinetic-pharmacodynamic (PKPD) parameters suggested a drug-likeness property, supporting the promising usefulness of this compound as a new hit for optimizations.

Umbelliferose Isolated from Cuminum cyminum L. Seeds Inhibits Antigen-Induced Degranulation in Rat Basophilic Leukemia RBL-2H3 Cells

Cuminum cyminum L. (cumin) is an annual plant of the Umbelliferae family native to Egypt. We previously showed that the aqueous extract of cumin seeds suppresses degranulation by downregulating the activation of antigen-induced intracellular signaling molecules in rat basophilic leukemia RBL-2H3 cells. However, the active substances in the extract have not yet been identified. Accordingly, herein, we aimed to ascertain the water-soluble substances present in cumin seeds that inhibit degranulation, which led to the identification of umbelliferose, a characteristic trisaccharide present in plants of the Umbelliferae family. Our study is the first to reveal the degranulation-suppressing activity of umbelliferose, and quantification studies suggest that cumin seed powder contains 1.6% umbelliferose. Raffinose, an isomer of umbelliferose, was also found to significantly suppress antigen-induced degranulation, but less so than umbelliferose. Both umbelliferose and raffinose contain sucrose subunits in their structures, with galactose moieties bound at different sites. These differences in structure suggest that the binding of galactose to the sucrose subunit at the α1-2 bond contributes to its strong degranulation-inhibiting properties.

Development of a Remote, Course-Based Undergraduate Experience to Facilitate In Silico Study of Microbial Metabolic Pathways

Course-based undergraduate research experiences (CUREs) often occur in a physical lab space, but they can also be offered remotely while maintaining course expectations and providing opportunity for authentic student engagement in research. Using a novel framework, remote Microbial Ecology CURE students used microbes isolated via antimicrobial-challenged Winogradsky columns to investigate phylogeny and metabolism through a hypothesis-driven meta-analysis (MA). Students used 16S rRNA and key metabolic enzymes to compare phylogeny; enzymes were modeled and evaluated for putative conserved domains, culminating in primer design and analysis. Using in silico tools facilitated student development of bioinformatics skills. The MA was subdivided into discrete sections in order to (i) provide a timeline for students to remain on schedule throughout a remote-learning lab experience, (ii) encourage feedback throughout the project, and (iii) facilitate student understanding of the experimental design. MA deliverables were designed to be specific figures with individual titles, legends, and analyses to enable their feedback for subsequent presentations. The six key formative deliverables included a word cloud (used to develop the works cited list and hypothesis), a 16S rRNA phylogenetic tree, an annotated metabolic pathway and three-dimensional model of the key metabolic enzyme, a phylogenetic tree based on the key metabolic enzyme, design and analysis of a primer set for the key metabolic enzyme, and a summative poster and graphical abstract. The MA project yielded poster presentations at virtual conferences, lab presentations, and written reports. Using the hypothesis-based MA model encouraged an authentic research experience, enabling students to develop, discuss, and progress in meaningful experiments.

Synthesis and Biological Evaluation of Novel Cinnamic Acid-Based Antimicrobials

The main antimicrobial resistance (AMR) nosocomial strains (ESKAPE pathogens such as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are the most widespread bacteria in cutaneous infections. In this work we report the synthesis, in silico skin permeability prediction, antimicrobial, antibiofilm, and wound healing properties of novel cinnamic acid-based antimicrobials (DM1–11) as novel antibacterial drugs for the treatment of ESKAPE-related skin infections. Antimicrobial and wound healing scratch assays were performed to evaluate the antibacterial properties of DM1–11. In silico skin permeability capabilities of DM1–11 were evaluated using Swiss-ADME online database. Cytotoxicity assays were performed on keratinocytes and fibroblasts. DM2, bearing a catechol group on the aromatic ring of the cinnamic portion of the molecule, possesses a significant antibacterial activity against S. aureus (MIC range 16–64 mg/L) and contrasts the biofilm-mediated S. epidermidis infection at low concentrations. Wound healing assays showed that wound closure in 48 h was observed in DM2-treated keratinocytes with a better healing pattern at all the used concentrations (0.1, 1.0, and 10 µM). A potential good skin permeation for DM2, that could guarantee its effectiveness at the target site, was also observed. Cytotoxicity studies revealed that DM2 may be a safe compound for topical use. Taking together all these data confirm that DM2 could represent a safe wound-healing topical agent for the treatment of skin wound infections caused by two of main Gram-positive bacteria belonging to ESKAPE microorganisms.

Essential Oils from Indigenous Iranian Plants: A Natural Weapon vs. Multidrug-Resistant Escherichia coli

Aim of this study was to investigate the antimicrobial properties of herbal plant essential oils (EOs) from selected Iranian plant species such as Ferulago angulata, Zataria multiflora, Cuminum cyminum, and Mentha longifolia against antibiotic-resistant Escherichia coli (E. coli) strains. For this purpose, the Escherichia coli strains, isolated from raw cow’s milk and local dairy products (yogurt, cream, whey, cheese, and confectionery products) collected from different areas of Hamedan province, Iran, were investigated for their resistance to antibiotics (i.e., streptomycin, tetracycline, gentamicin, chloramphenicol, ciprofloxacin, and cefixime). Thus, the E. coli strains were tested for their susceptibility to the above-mentioned essential oils. Regarding antibiotics, the E. coli strains were highly sensitive to ciprofloxacin. In relation to essential oils, the most effective antibacterial activity was observed with Zataria multiflora; also, the bacteria were semi-sensitive to Cuminum cyminum and Mentha longifolia essential oils. All strains were resistant to Ferulago angulata essential oil. According to the results, the essential oil of Zataria multiflora can be considered as a practical and alternative antibacterial strategy to inhibit the growth of multidrug-resistant E. coli of dairy origin.

Cuminaldehyde exhibits potential antibiofilm activity against Pseudomonas aeruginosa involving reactive oxygen species (ROS) accumulation: a way forward towards sustainable biofilm management

Pseudomonas aeruginosa often causes various acute and chronic infections in humans exploiting biofilm. Molecules interfering with microbial biofilm formation could be explored for the sustainable management of infections linked to biofilm. Towards this direction, the antimicrobial and antibiofilm activity of cuminaldehyde, an active ingredient of the essential oil of Cuminum cyminum was tested against Pseudomonas aeruginosa. In this regard, the minimum inhibitory concentration (MIC) of cuminaldehyde was found to be 150 μg/mL against the test organism. Experiments such as crystal violet assay, estimation of total biofilm protein, fluorescence microscopy and measurement of extracellular polymeric substances (EPS) indicated that the sub-MIC doses (up to 60 µg/mL) of cuminaldehyde demonstrated considerable antibiofilm activity without showing any antimicrobial activity to the test organism. Moreover, cuminaldehyde treatment resulted in substantial accumulation of cellular reactive oxygen species (ROS) that led to the inhibition of microbial biofilm formation. To this end, the exposure of ascorbic acid was found to restore the biofilm-forming ability of the cuminaldehyde-treated cells. Besides, a noticeable reduction in proteolytic activity was also observed when the organism was treated with cuminaldehyde. Taken together, the results demonstrated that cuminaldehyde could be used as a promising molecule to inhibit the biofilm formation of Pseudomonas aeruginosa.

Anti-Inflammatory and Antimicrobial Volatile Oils: Fennel and Cumin Inhibit Neutrophilic Inflammation via Regulating Calcium and MAPKs

Neutrophilic inflammatory diseases, such as chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), or psoriasis, exert a huge burden on the global health system due to the lack of safe and effective treatments. Volatile oils from terrestrial plants showed impressive therapeutic effects against disorders of the skin, digestive system, lungs, liver, metabolism, and nervous system. However, their effect on the immune system and neutrophil function is still elusive. Fennel, cumin, marjoram, lavender, caraway, and anise are the common nutraceuticals that are widely used in the Mediterranean diet. The volatile oils of these herbs were screened for various biological activities, including anti-inflammatory, anti-allergic, antimicrobial, and antiviral effects. Several oils showed anti-inflammatory and antimicrobial potential. Fennel (Foeniculum vulgare) and cumin (Cuminum cyminum) fruits' volatile oils significantly suppressed the activation of human neutrophils, including respiratory burst and the degranulation induced by formyl peptide receptor agonists fMLF/CB and MMK1 in the human neutrophils (IC₅₀, 3.8–17.2 µg/ml). The cytotoxic effect and free-radical scavenging effects (ABTS, DPPH) of these oils did not account for the observed effects. Both fennel and cumin volatile oils significantly shortened calcium influx recovery time and inhibited phosphorylation of mitogen-activated protein kinases (p38, JNK, and ERK) expression. The gas chromatography–mass spectrometry analysis of these oils revealed the presence of estragole and cuminaldehyde as the major components of fennel and cumin volatile oils, respectively. Our findings suggested that cumin and fennel, common in the Mediterranean diet, hold the potential to be applied for the treatment of neutrophilic inflammatory diseases.

Characterization of a thermotolerant aryl-alcohol oxidase from Moesziomyces antarcticus oxidizing 5-hydroxymethyl-2-furancarboxylic acid

The development of enzymatic processes for the environmentally friendly production of 2,5-furandicarboxylic acid (FDCA), a renewable precursor for bioplastics, from 5-hydroxymethylfurfural (HMF) has gained increasing attention over the last years. Aryl-alcohol oxidases (AAOs) catalyze the oxidation of HMF to 5-formyl-2-furancarboxylic acid (FFCA) through 2,5-diformylfuran (DFF) and have thus been applied in enzymatic reaction cascades for the production of FDCA. AAOs are flavoproteins that oxidize a broad range of benzylic and aliphatic allylic primary alcohols to the corresponding aldehydes, and in some cases further to acids, while reducing molecular oxygen to hydrogen peroxide. These promising biocatalysts can also be used for the synthesis of flavors, fragrances, and chemical building blocks, but their industrial applicability suffers from low production yield in natural and heterologous hosts. Here we report on heterologous expression of a new aryl-alcohol oxidase, MaAAO, from Moesziomyces antarcticus at high yields in the methylotrophic yeast Pichia pastoris (recently reclassified as Komagataella phaffii). Fed-batch fermentation of recombinant P. pastoris yielded around 750 mg of active enzyme per liter of culture. Purified MaAAO was highly stable at pH 2-9 and exhibited high thermal stability with almost 95% residual activity after 48 h at 57.5 °C. MaAAO accepts a broad range of benzylic primary alcohols, aliphatic allylic alcohols, and furan derivatives like HMF as substrates and some oxidation products thereof like piperonal or perillaldehyde serve as building blocks for pharmaceuticals or show health-promoting effects. Besides this, MaAAO oxidized 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) to FFCA, which has not been shown for any other AAO so far. Combining MaAAO with an unspecific peroxygenase oxidizing HMFCA to FFCA in one pot resulted in complete conversion of HMF to FDCA within 144 h. MaAAO is thus a promising biocatalyst for the production of precursors for bioplastics and bioactive compounds. KEY POINTS: • MaAAO from M. antarcticus was expressed in P. pastoris at 750 mg/l. • MaAAO oxidized 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). • Complete conversion of HMF to 2,5-furandicarboxylic acid by combining MaAAO and UPO.

Staphylococcus aureus Biofilm: Morphology, Genetics, Pathogenesis and Treatment Strategies

Staphylococcus aureus is a nosocomial bacterium causing different infectious diseases, ranging from skin and soft tissue infections to more serious and life-threatening infections such as septicaemia. S. aureus forms a complex structure of extracellular polymeric biofilm that provides a fully secured and functional environment for the formation of microcolonies, their sustenance and recolonization of sessile cells after its dispersal. Staphylococcus aureus biofilm protects the cells against hostile conditions, i.e., changes in temperature, limitations or deprivation of nutrients and dehydration, and, more importantly, protects the cells against antibacterial drugs. Drugs are increasingly becoming partially or fully inactive against S. aureus as they are either less penetrable or totally impenetrable due to the presence of biofilms surrounding the bacterial cells. Other factors, such as evasion of innate host immune system, genome plasticity and adaptability through gene evolution and exchange of genetic material, also contribute to the ineffectiveness of antibacterial drugs. This increasing tolerance to antibiotics has contributed to the emergence and rise of antimicrobial resistance (AMR), a serious problem that has resulted in increased morbidity and mortality of human and animal populations globally, in addition to causing huge financial losses to the global economy. The purpose of this review is to highlight different aspects of S. aureus biofilm formation and its overall architecture, individual biofilm constituents, clinical implications and role in pathogenesis and drug resistance. The review also discusses different techniques used in the qualitative and quantitative investigation of S. aureus biofilm and various strategies that can be employed to inhibit and eradicate S. aureus biofilm.

Immune-Modulatory Effects upon Oral Application of Cumin-Essential-Oil to Mice Suffering from Acute Campylobacteriosis

Human campylobacteriosis, commonly caused by Campylobacter jejuni, is a food-borne infection with rising prevalence causing significant health and socioeconomic burdens worldwide. Given the threat from emerging antimicrobial resistances, the treatment of infectious diseases with antibiotics-independent natural compounds is utmost appreciated. Since the health-beneficial effects of cumin-essential-oil (EO) have been known for centuries, its potential anti-pathogenic and immune-modulatory effects during acute experimental campylobacteriosis were addressed in the present study. Therefore, C. jejuni-challenged secondary abiotic IL-10^-/- mice were treated perorally with either cumin-EO or placebo starting on day 2 post-infection. On day 6 post-infection, cumin-EO treated mice harbored lower ileal pathogen numbers and exhibited a better clinical outcome when compared to placebo controls. Furthermore, cumin-EO treatment alleviated enteropathogen-induced apoptotic cell responses in colonic epithelia. Whereas, on day 6 post-infection, a dampened secretion of pro-inflammatory mediators, including nitric oxide and IFN-γ to basal levels, could be assessed in mesenteric lymph nodes of cumin-EO treated mice, systemic MCP-1 concentrations were elevated in placebo counterparts only. In conclusion, our preclinical intervention study provides first evidence for promising immune-modulatory effects of cumin-EO in the combat of human campylobacteriosis. Future studies should address antimicrobial and immune-modulatory effects of natural compounds as adjunct antibiotics-independent treatment option for infectious diseases.