Antioxidant, anti-quorum sensing, biofilm inhibitory activities and chemical composition of Patchouli essential oil: in vitro and in silico approach

Pogostemon cablin Extract Promotes Wound Healing through OR2AT4 Activation and Exhibits Anti-Inflammatory Activity

Skin healing occurs through an intricate process called wound healing which comprises four phases: coagulation and hemostasis, inflammation, cellular proliferation, and remodeling. Chronic wounds often arise because of prolonged or excessive inflammation, which hinders the healing process and wound closure. Despite the recognized efficacy of Pogostemon cablin (patchouli) in wound healing, the precise mechanism of action of Pogostemon cablin extract (PCE) on inflammation and wound healing remains poorly understood. In this study, we investigated the effects of PCE on cell proliferation and wound healing, as well as its anti-inflammatory activity, using in vitro experiments. We found that PCE increased cell proliferation and expression of the cell proliferation marker Ki67 and accelerated wound healing in human keratinocytes through the activation of OR2AT4. Furthermore, PCE exhibited anti-inflammatory effects by decreasing the levels of pro-inflammatory cytokines interleukin-6 and -8 in lipopolysaccharide-treated and TNF-α-exposed THP-1 and HaCaT cells, respectively. Overall, these findings suggest that PCE holds therapeutic potential by promoting cell proliferation, facilitating wound healing, and exerting anti-inflammatory effects.

The Influence of Physical Fields (Magnetic and Electric) and LASER Exposure on the Composition and Bioactivity of Cinnamon Bark, Patchouli, and Geranium Essential Oils

In recent years, essential oils (EOs) have received increased attention from the research community, and the EOs of cinnamon, patchouli, and geranium have become highly recognized for their antibacterial, antifungal, antiviral, and antioxidant effects. Due to these properties, they have become valuable and promising candidates for addressing the worldwide threat of antimicrobial resistance and other diseases. Simultaneously, studies have revealed promising new results regarding the effects of physical fields (magnetic and electric) and LASER (MEL) exposure on seed germination, plant growth, biomass accumulation, and the yield and composition of EOs. In this frame, the present study aims to investigate the influence of MEL treatments on cinnamon, patchouli, and geranium EOs, by specifically examining their composition, antimicrobial properties, and antioxidant activities. Results showed that the magnetic influence has improved the potency of patchouli EO against L. monocytogenes, S. enteritidis, and P. aeruginosa, while the antimicrobial activity of cinnamon EO against L. monocytogenes was enhanced by the electric and laser treatments. All exposures have increased the antifungal effect of geranium EO against C. albicans. The antioxidant activity was not modified by any of the treatments. These findings could potentially pave the way for a deeper understanding of the efficiency, the mechanisms of action, and the utilization of EOs, offering new insights for further exploration and application.

Bioactive Phyto-Compounds with Antimicrobial Effects and AI: Results of a Desk Research Study

Resistance of microorganisms to antibiotics represents a formidable global challenge, manifesting in intricate public health ramifications including escalated mortality rates and augmented healthcare costs. The current efforts to manage antimicrobial resistance (AMR) are limited mainly to the standard therapeutic approaches. The aim of this study is to present and analyze the role of artificial intelligence (AI) in the search for new phyto-compounds and novel interactions with antimicrobial effects. The ambition of the current research study is to support researchers by providing summarized information and ideas for future research in the battle with AMR. Inevitably, the AI role in healthcare is growing exponentially. The reviewed AI models reveal new data on essential oils (EOs) as potential therapeutic agents. In terms of antibacterial activity, EOs show activity against MDR bacteria, reduce resistance by sensitizing bacteria to the action of antibiotics, and improve therapeutic efficiency when combined with antibiotics. AI models can also serve for the detailed study of other therapeutic applications of EOs such as respiratory diseases, immune diseases, neurodegenerative diseases, and oncological diseases. The last 5 years have seen an increasing application of AI in the search for potential plant sources to control AMR. For the time being, the application of machine-learning (ML) models is greater in the studies of EOs. Future attention of research teams may also be directed toward a more efficient search for plant antimicrobial peptides (PAMPs). Of course, investments in this direction are a necessary preface, but the excitement of new possibilities should not override the role of human intelligence in directing research processes. In this report, tradition meets innovation to address the "silent pandemic" of AMR.

Exploring the anticancer potential of fluoro flavone analogues: insights from molecular docking and dynamics studies with Aurora Kinase B

Aurora Kinase B belongs to the serine kinase family. It plays an essential role in cell division and participates in mitosis and chromatid segregation. Overexpression, polymorphism, and splicing variants in the protein lead to tumorigenesis, leading to cancer. Flavones belong to the class of flavonoids and are derived from plants and show anti-cancer activities. Fluoro flavones and their analogs are taken from the PubChem database, resulting in 3882 compounds which is 90% similar to the fluoro flavones. Lipinski's rule of five, REOS and PAINS drug-like filters were applied which resulted 2448 compounds. These compounds are docked with Aurora Kinase B using SP and XP modules of Glide software. The best binding scores for SP docking were - 9.153 kcal/mol for the compound with CID: 44298667, and XP docking was - 10.287 kcal/mol with CID: 101664315. Enrichment calculations were done using Aurora Kinase B's decoys to validate the docking result. The resulting R2 = 0.96 from enrichment calculations suggests that the docking protocol is valid. The SP and XP docking lead compounds and the Fluoro flavone were subjected to 100 ns MD simulation to probe the protein-ligand complex stability. Also, the binding free energies between the Aurora kinase B and lead compounds were computed by Prime MM/GBSA module. The result suggests that the lead compounds bind more strongly with Aurora Kinase B than the Fluoro flavone. These lead compounds can be further evaluated in vitro and in vivo and can be used as future novel drugs for the curation of cancer.

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Essential oils and their blends: mechanism of antibacterial activity and antibiofilm potential on food-grade maize starch packaging films

Essential oils are highly complex volatile chemical compounds utilized for food preservation. The present study compares the antibacterial, and antibiofilm activities of essential oils (EOs) and their blends. Three EOs-basil, clove, and lemongrass-and their blends were evaluated against five food-borne bacterial pathogens. A concentration-dependent effect with maximum inhibition at minimum inhibitory concentration values was recorded while no synergistic activity was observed on blending of EOs. The mechanism of antibacterial action was identified as ROS burst, leakage of cytoplasmic content, and DNA degradation through fluorescence microscopy, electrical conductivity, and DNA cleavage studies. The role of EOs on biofilm growth was deciphered with lemongrass EO being most effective as it curbed biofilm formation on the surface of corn-starch packaging films. This work highlights the antibacterial action mechanism of EOs and their potential role in curtailing biofilm growth on food-grade packaging material.

Oxidative Stress-Mediated Repression of Virulence Gene Transcription and Biofilm Formation as Antibacterial Action of Cinnamomum burmannii Essential Oil on Staphylococcus aureus

This work aimed to identify the chemical compounds of Cinnamomum burmannii leaf essential oil (CBLEO) and to unravel the antibacterial mechanism of CBLEO at the molecular level for developing antimicrobials. CBLEO had 37 volatile compounds with abundant borneol (28.40%) and showed good potential to control foodborne pathogens, of which Staphylococcus aureus had the greatest inhibition zone diameter (28.72 mm) with the lowest values of minimum inhibitory concentration (1.0 μg/mL) and bactericidal concentration (2.0 μg/mL). To unravel the antibacterial action of CBLEO on S. aureus, a dynamic exploration of antibacterial growth, material leakage, ROS formation, protein oxidation, cell morphology, and interaction with genome DNA was conducted on S. aureus exposed to CBLEO at different doses (1/2-2×MIC) and times (0-24 h), indicating that CBLEO acts as an inducer for ROS production and the oxidative stress of S. aureus. To highlight the antibacterial action of CBLEO on S. aureus at the molecular level, we performed a comparative association of ROS accumulation with some key virulence-related gene (sigB/agrA/sarA/icaA/cidA/rsbU) transcription, protease production, and biofilm formation in S. aureus subjected to CBLEO at different levels and times, revealing that CBLEO-induced oxidative stress caused transcript suppression of virulence regulators (RsbU and SigB) and its targeted genes, causing a protease level increase destined for the biofilm formation and growth inhibition of S. aureus, which may be a key bactericidal action. Our findings provide valuable information for studying the antibacterial mechanism of essential oil against pathogens.

Screening of potential phytomolecules against MurG as drug target in nosocomial pathogen Pseudomonas aeruginosa: perceptions from computational campaign

The nosocomial infection outbreak caused by Pseudomonas aeruginosa remains a public health concern. Multi-drug resistant (MDR) strains of P. aeruginosa are rapidly spreading leading to a huge mortality rate because of the unavailability of promising antimicrobials. MurG glycotransferase [UDP-N-acetylglucosamine-N-acetylmuramyl (pentapeptide) pyrophosphoryl-undecaprenol N-acetylglucosamine transferase] is located at the plasma membrane and plays a key role in murein (peptidoglycan) biosynthesis in bacteria. Since MurG is required for bacterial cell wall synthesis and is non-homologous to Homo sapiens; it can be a potential target for the antagonist to treat P. aeruginosa infection. The discovery of high-resolution crystal structure of P. aeruginosa MurG offers an opportunity for the computational identification of its prospective inhibitors. Therefore, in the present study, the crystal structure of MurG (PDB ID: 3S2U) from P. aeruginosa was selected, and computational docking analyses were performed to search for functional inhibitors of MurG. IMPPAT (Indian medicinal plants, phytochemicals and therapeutic) phytomolecule database was screened by computational methods with MurG catalytic site. Docking results identified Theobromine (-8.881 kcal/mol), demethoxycurcumin (-8.850 kcal/mol), 2-alpha-hydroxycostic acid (-8.791 kcal/mol), aurantiamide (-8.779 kcal/mol) and petasiphenol (-8.685 kcal/mol) as a potential inhibitor of the MurG activity. Further, theobromine and demethoxycurcumin were subjected to MDS (molecular dynamics simulation) and free energy (MM/GBSA) analysis to comprehend the physiological state and structural stability of MurG-phytomolecules complexes. The outcomes suggested that these two phytomolecules could act as most favorable natural hit compounds for impeding the enzymatic action of MurG in P. aeruginosa, and thus it needs further validation by both in vitro and in vivo analysis. HIGHLIGHTSThe top phytomolecules such as theobromine, demethoxycurcumin, 2-alpha-hydroxycostic acid, aurantiamide and petasiphenol displayed promising binding with MurG catalytic domain.MurG complexed with theobromine and demethoxycurcumin showed the best interaction and stable by MD simulation at 100 ns.The outcome of MurG binding phytomolecules has expanded the possibility of hit phytomolecules validation.Communicated by Ramaswamy H. Sarma.

Synthesis, antimicrobial properties and in silico studies of aryloxyacetic acid derivatives with hydrazone or thiazolidine-4-one scaffold

In this work, twenty hydrazide-hydrazone and 4-thiazolidinone derivatives were synthesized starting from m-cresol. Antimicrobial evaluation was carried out by microdilution method against Enterococcus faecalis and Staphylococcus aureus as Gram-positive bacteria and Escherichia coli and Pseudomonas aeruginosa as Gram-negative bacteria, and three pathogenic fungi Candida albicans, Candida parapsilosis and Candida krusei. Some compounds possessed considerable antimicrobial properties against the tested microorganisms, particularly against E. coli. 4-Thiazolidinones containing 3-methoxyphenyl and 3,5-dichlorophenyl moieties (4h and 4i) were found to be the most active derivatives with MICs of 2 μg/mL against E. coli. N'-[(3,5-dichlorophenyl)methylidene]-2-(3-methylphenoxy)acetohydrazide (3i) also displayed antifungal activity against Candida krusei that was comparable to fluconazole. Calculated drug-likeness and ADMET parameters of the most active compounds confirmed their potential as antimicrobial drug candidates. Molecular docking investigations were carried out in the thiamine diphosphate-binding site of pyruvate dehydrogenase multienzyme complex E1 component (PDHc-E1) to clarify the potential antibacterial mechanism against E. coli. The results showed the potential and importance of developing new hydrazones and 4-thiazolidinones that would be effective against microbial strains.Communicated by Ramaswamy H. Sarma.

Investigation of some basil genotypes in terms of their effect on bacterial communication system, and antimicrobial activity

The exponential growth of multiresistant bacterial strains creates the need to explore new or combined strategies to combat bacterial resistance. Medicinal plant-derived compounds against pathogenic bacteria may provide new, simple approaches to developing more environmentally friendly antimicrobial agents. Many researchers focus on exploring novel or combined strategies for combating bacterial resistance. Aromatic plants containing essential oils, such as basil, are often used as therapeutic agents in the pharmaceutical industry. Recent research has shown that basil is effective against certain harmful food phytopathogenic bacteria and has antimicrobial and anti-quorum sensing properties, which were investigated in this study. Our results have shown that the essential oil and ethanol extract of basil exhibits both antibacterial activity and anti-quorum sensing activity against some Gram-negative and Gram-positive bacterial species. It has also been found to have antifungal effects on C. albicans. Among the tested microorganisms, the genotypes of PI 531396, PI 296390, PI 414199, PI 253157, PI 296391, PI 652071, midnight, and Dino cultivars have been found to be more effective than other genotypes. The highest effect on quorum sensing system was found in Moonlight and Dino cultivars, PI 296391, PI 414199, PI 652070, PI 172997 and PI 190100 genotypes. Dendrogram analysis has shown that there is a relationship between different genotypes depending on microorganisms and anti-quorum sensing activity. Ames 29184, PI 207498, and PI 379412 genotypes were in the same group. Biplot analyses were performed to determine the relationship between the studied properties, and the results showed that more than 47% of the total variation was in all forms.

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.

Biofilm control strategies in the light of biofilm-forming microorganisms

Biofilm is a complex consortium of microorganisms attached to biotic or abiotic surfaces and live in self-produced or acquired extracellular polymeric substances (EPSs). EPSs are mainly formed by lipids, polysaccharides, proteins, and extracellular DNAs. The adherence to the surface of microbial communities is seen in food, medical, dental, industrial, and environmental fields. Biofilm development in food processing areas challenges food hygiene, and human health. In addition, bacterial attachment and biofilm formation on medical implants inside human tissue can cause multiple critical chronic infections. More than 30 years of international research on the mechanisms of biofilm formation have been underway to address concerns about bacterial biofilm infections. Antibiofilm strategies contain cold atmospheric plasma, nanotechnological, phage-based, antimicrobial peptides, and quorum sensing inhibition. In the last years, the studies on environmentally-friendly techniques such as essential oils and bacteriophages have been intensified to reduce microbial growth. However, the mechanisms of the biofilm matrix formation are still unclear. This review aims to discuss the latest antibiofilm therapeutic strategies against biofilm-forming bacteria.

Genomic landscape of the emerging XDR Salmonella Typhi for mining druggable targets clpP, hisH, folP and gpmI and screening of novel TCM inhibitors, molecular docking and simulation analyses

Typhoid fever is transmitted by ingestion of polluted water, contaminated food, and stool of typhoid-infected individuals, mostly in developing countries with poor hygienic environments. To find novel therapeutic targets and inhibitors, We employed a subtractive genomics strategy towards Salmonella Typhi and the complete genomes of eight strains were primarily subjected to the EDGAR tool to predict the core genome (n = 3207). Human non-homology (n = 2450) was followed by essential genes identification (n = 37). The STRING database predicted maximum protein-protein interactions, followed by cellular localization. The virulent/immunogenic ability of predicted genes were checked to differentiate drug and vaccine targets. Furthermore, the 3D models of the identified putative proteins encoded by the respective genes were constructed and subjected to druggability analyses where only "highly druggable" proteins were selected for molecular docking and simulation analyses. The putative targets ATP-dependent CLP protease proteolytic subunit, Imidazole glycerol phosphate synthase hisH, 7,8-dihydropteroate synthase folP and 2,3-bisphosphoglycerate-independent phosphoglycerate mutase gpmI were screened against a drug-like library (n = 12,000) and top hits were selected based on H-bonds, RMSD and energy scores. Finally, the ADMET properties for novel inhibitors ZINC19340748, ZINC09319798, ZINC00494142, ZINC32918650 were optimized followed by binding free energy (MM/PBSA) calculation for ligand-receptor complexes. The findings of this work are expected to aid in expediting the identification of novel protein targets and inhibitors in combating typhoid Salmonellosis, in addition to the already existing therapies.

Identification and Screening of Novel Anti-Cancer Compounds for Aurora Kinase-A from Chemical Database

Aurora kinase is a group of enzymes that belongs to a serine-threonine family and plays a critical role in cellular division. Aurora Kinase A is overexpressed and distributed beyond the nucleus and is involved in tumorigenesis. Flavones are a class of flavonoids that are present in plants that show anticancer activity. Similar compounds of 2'Fluoroflavones are retrieved from the PubChem database. Then drug-like filters viz. REOS and PAINS were applied to remove toxic compounds using Canvas software, resulting in 3882 compounds being subjected to Glide docking with Aurora kinase A. The lead compounds were selected on the merit of hydrogen bonding, salt bridge, as well as pi-pi interactions, 4-(6-Fluoro-4-oxychromen-2yl) benzoic acid, has been found one of the best molecules from docking studies. The binding mode of the lead compound with AURKA reveals that the amino acid residues viz, Lys162, Ala213, and His280 are more important for binding with the binding affinity of -11.760 kcal/mol. The molecular dynamics simulations of 100 ns were done, which shows the mean RMSD value of 1.77 Å for all 3 complexes of the protein and Fluoroflavone and its analogs. This shows that Fluoroflavone and its 2 best analogs are tightly attached to the active sites and thus have conformational stability. Our finding suggests that 4-(6-fluoro-4-oxochromen-2-yl)benzoic acid and 4-(4-Oxochromen-2-yl)benzoate can be further used in vitro and in vivo experiments and can probably serve as a novel drug for cancer treatment.

Nematicidal and Molecular Docking Investigation of Essential Oils from Pogostemon cablin Ecotypes against Meloidogyne incognita

Root-knot nematode, Meloidogyne incognita is one of the most destructive nematodes worldwide. Essential oils (EOs) are being extensively utilized as eco-benign bionematicides, although the precise mechanism of action remains unclear. Pogostemon cablin Benth. is well-known as "Patchouli". It is native to South East Asia and known for ethno-pharmacological properties. In this study, chemical composition and potential nematicidal effect of EOs hydrodistilled from the leaves of P. cablin grown at three different locations in India were comprehensively investigated to correlate their mechanism of action for target specific binding affinities toward nematode proteins. Aromatic volatile Pogostemon essential oils (PEO) from Northern India (PEO-NI), Southern India (PEO-SI) and North Eastern India (PEO-NEI) were analyzed by Gas Chromatography-Mass Spectrometry (GC/MS) to characterize forty volatile compounds. Maximum thirty-three components were identified in PEO-NEI. Sesquiterpenes were predominant with higher content of α-guaiene (2.3-24.4 %), patchoulol (6.1-32.7 %) and α-bulnesene (5.9-27.1 %). Patchoulol was the major component in PEO-SI (32.7±1.2 %) and PEO-NEI (29.2±1.1 %), while α-guaiene in PEO-NI (24.4±1.2 %). In vitro nematicidal assay revealed significant nematicidal action (LC₅₀ 44.6-87.0 μg mL^-1 ) against juveniles of M. incognita within 24 h exposure. Mortality increases with increasing time to 48 h (LC₅₀ 33.6-71.6 μg mL^-1 ) and 72 h (LC₅₀ 27.7-61.2 μg mL^-1 ). Molecular modelling and in silico studies revealed multi-modal inhibitive action of α-bulnesene (-22 to -13 kJ mol^-1 ) and α-guaiene (-22 to -12 kJ mol^-1 ) against three target proteins namely, acetyl cholinesterase (AChE), odorant response gene-1 (ODR1), odorant response gene-3 (ODR3). Most preferable binding mechanism was observed against AChE due to pi-alkyl, pi-sigma, and hydrophobic interactions. Structure nematicidal activity relationship suggested the presence of hydroxy group for nematicidal activity is nonessential, rather highly depends on synergistic composition of sesquiterpene hydrocarbons.