Antimicrobial activities of Eugenol and Cinnamaldehyde against the human gastric pathogen Helicobacter pylori

Cinnamaldehyde: An effective component of Cinnamomum cassia inhibiting Helicobacter pylori

ETHNOPHARMACOLOGICAL RELEVANCE

Cinnamomum cassia Presl (Cinnamomum cassia) is a common traditional Chinese medicine, which can promote the secretion and digestion of gastric juice, improve the function of gastrointestinal tract. Cinnamaldehyde (CA) is a synthetic food flavoring in the Chinese Pharmacopoeia.

AIM OF THE STUDY

This study aimed to search for the active ingredient (CA) of inhibiting H. pylori from Cinnamomum cassia, and elucidate mechanism of action, so as to provide the experimental basis for the treatment of H. pylori infection with Cinnamomum cassia.

MATERIALS AND METHODS

It's in vitro and in vivo pharmacological properties were evaluated based on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and an acute gastric inflammation model in mice infected with H. pylori. Drug safety was evaluated using the CCK8 method and high-dose administration in mice. The advantageous characteristics of CA in inhibiting H. pylori were confirmed using acidic conditions and in combination with the antibiotics. The mechanism underlying the action of CA on H. pylori was explored using scanning electron microscopy (SEM), adhesion experiments, biofilm inhibition tests, ATP and ROS release experiments, and drug affinity responsive target stability (DARTS) screening of target proteins. The protein function and target genes were verified by molecular docking and Real-Time quantitative reverse transcription PCR (qRT-PCR).

RESULTS

The results demonstrated that CA was found to be the main active ingredient against H. pylori in Cinnamomum cassia in-vitro tests, with a MIC of 8-16 μg/mL. Moreover, CA effectively inhibited both sensitive and resistant H. pylori strains. The dual therapy of PPI + CA exhibited remarkable in vivo efficacy in the acute gastritis mouse model, superior to the standard triple therapy. DARTS, molecular docking, and qRT-PCR results suggested that the target sites of action were closely associated with GyrA, GyrB, AtpA, and TopA, which made DNA replication and transcription impossible, then leading to inhibition of bacterial adhesion and colonization, suppression of biofilm formation, and inhibition ATP and enhancing ROS.

CONCLUSIONS

This study demonstrated the suitability of CA as a promising lead drug against H. pylori, The main mechanisms can target GyrA ect, leading to reduce ATP and produce ROS, which induces the apoptosis of bacterial.

Cu-catalyzed click reaction in synthesis of eugenol derivatives as potent antimalarial agents

Eugenol(1), a terpenoid found in Ocimum, has various biological activities. The present study aims at extraction, isolation of the plant secondary metabolite eugenol (1), it's derivatisation and structure identification as bioactive molecules. Synthesis and antiplasmodial activity (in-vitro and in-vivo), of a series of fourteen novel eugenol-based 1,2,3-triazole derivatives was done in the present study. Derivatives 5a-5n showed good antimalarial activity against the strain Plasmodium falciparum NF54. Derivative 5 m, IC50 at 2.85 µM was found to be several times better than its precursor 1 (106.82 µM) whereas the derivative 5n showed three fold better activity than compound 1, in vitro. The structure-activity relationship of the synthesised compounds indicated that the presence of triazole ring in eugenol analogues is responsible for their good activity. Compound 5m, was further evaluated for in-vivo antimalarial activity which showed about 79% parasitemia suppression. It is the first report on antimalarial activity of triazole eugenol derivatives.

A comprehensive account on ethnobotany, phytochemistry and pharmacological insights of genus Celtis

The plants of Celtis L. genus have been traditionally used to cure aches, sore throats, fevers, cancer, sexually transmitted diseases, sexual weakness, diarrhea, stomach problems, amenorrhea, menstrual disorders, kidney stones, and pain. The review aims to give a comprehensive account of the current state of ethnopharmacology, phytochemistry, and biological activities of the Celtis genus, as well as to describe the potential area of future avenues. Information on the Celtis genus was obtained from internet sources such as Google Scholar, Web of Science, PubMed, ScienceDirect, and so on by using appropriate keywords, including ethnobotanical, pharmacological, pharmaceutical, bioactivity, phytochemistry, and botanical features of the Celtis genus. This review identified 14 species in the genus Celtis that have a phytopharmacological investigation, including C.africana Burm. f., C. australis L., C. occidentalis L., C. sinensis Pers., C. philippensis Blanco., C. tetrandra Roxb., C. tessmannii Rendle., C. jessoensis Koidz., C. adolfi-friderici Engl., C. iguanaea (Jacq.) Sarg., C. laevigata Wild., C. pallida Torr., C. zenkeri Engl., and C. tournefortii Lam. This genus contains many classified phytoconstituents, such as terpenoids, organic acids, flavonoids, and volatile compounds. Their extracts and pure substances have been shown to have the same anticancer, antibacterial, anti-inflammatory, antioxidant, hepatoprotective, cardioprotective, urease-inhibiting, and antidiarrheal properties as their traditional uses. In terms of current information on ethnopharmacology, phytochemicals, and pharmacological uses, the data acquired in this review could be beneficial and needed for future research. Some phytoconstituents (for instance, kaempferol, myricetin, quercetin, and eugenol) and extracts (for example, leaves, seeds, and ripe fruits extracts of C. australis) showed tremendous results in preliminary testing with promising antimicrobial, anticancer, and urease inhibitory effects. Further research and clinical investigations are needed to develop them as lead compounds and neutraceuticals, which may provide an advance over traditional medicinal systems.

Bioactive properties of clove (Syzygium aromaticum) essential oil nanoemulsion: A comprehensive review

Syzygium aromaticum, commonly called clove, is a culinary spice with medical uses. Clove is utilized in cosmetics, medicine, gastronomy, and agriculture due to its abundance of bioactive components such as gallic acid, flavonoids, eugenol acetate, and eugenol. Clove essential oil has been revealed to have antibacterial, antinociceptive, antibacterial activities, antifungal, and anticancerous qualities. Anti-inflammatory chemicals, including eugenol and flavonoids, are found in clove that help decrease inflammation and alleviate pain. The anti-inflammatory and analgesic qualities of clove oil have made it a popular natural cure for toothaches and gum discomfort. Due to its therapeutic potential, it has been used as a bioactive ingredient in coating fresh fruits and vegetables. This review article outlines the potential food processing applications of clove essential oil. The chemical structures of components, bioactive properties, and medicinal potential of clove essential oil, including phytochemical importance in food, have also been thoroughly addressed.

Edible nano-encapsulated cinnamon essential oil hybrid wax coatings for enhancing apple safety against food borne pathogens

Post-harvest losses of fruits due to decay and concerns regarding microbial food safety are significant within the produce processing industry. Additionally, maintaining the quality of exported commodities to distant countries continues to pose a challenge. To address these issues, the application of bioactive compounds, such as essential oils, has gained recognition as a means to extend shelf life by acting as antimicrobials. Herein, we have undertaken an innovative approach by nano-encapsulating cinnamon-bark essential oil using whey protein concentrate and imbibing nano-encapsulates into food-grade wax commonly applied on produce surfaces. We have comprehensively examined the physical, chemical, and antimicrobial properties of this hybrid wax to evaluate its efficacy in combatting the various foodborne pathogens that frequently trouble producers and handlers in the post-harvest processing industry. The coatings as applied demonstrated a static contact angle of 85 ± 1.6°, and advancing and receding contact angles of 90 ± 1.1° and 53.0 ± 1.6°, respectively, resembling the wetting properties of natural waxes on apples. Nanoencapsulation significantly delayed the release of essential oil, increasing the half-life by 61 h compared to its unencapsulated counterparts. This delay correlated with statistically significant reductions (p = 0.05) in bacterial populations providing both immediate and delayed (up to 72 h) antibacterial effects as well as expanded fungal growth inhibition zones compared to existing wax technologies, demonstrating promising applicability for high-quality fruit storage and export. The utilization of this advanced produce wax coating technology offers considerable potential for bolstering food safety and providing enhanced protection against bacteria and fungi for produce commodities.

Secondary metabolites of plants and their possible role in the "age of superbugs"

Bacterial infections are a serious cause of high morbidity and mortality worldwide. Over the past decades, the drug resistance of bacterial pathogens has been steadily increasing, while the rate of development of new effective antibacterial drugs remains consistently low. The plant kingdom is sometimes called a bottomless well for the search for new antimicrobial therapies. This is due to the fact that plants are easily accessible and cheap to process, while extracts and components of plant origin often demonstrate a high level of biological activity with minor side effects. The variety of compounds obtained from plant raw materials can provide a wide choice of various chemical structures for interaction with various targets inside bacterial cells, while the rapid development of modern biotechnological tools opens the way to the targeted production of bioactive components with desired properties. The objective of this review is to answer the question, whether antimicrobials of plant origin have a chance to play the role of a panacea in the fight against infectious diseases in the "post-antibiotic era".

Nature-Inspired Compounds: Synthesis and Antibacterial Susceptibility Testing of Eugenol Derivatives against H. pylori Strains

The antimicrobial properties of one of the most important secondary metabolites, Eugenol (EU), inspired us to design and synthesize three different series of derivatives enhancing its parent compound's anti-Helicobacter pylori activity. Thus, we prepared semisynthetic derivatives through (A) diazo aryl functionalization, (B) derivatization of the hydroxy group of EU, and (C) elongation of the allyl radical by incorporating a chalcogen atom. The antibacterial evaluation was performed on the reference NCTC 11637 strain and on three drug-resistant clinical isolates and the minimal inhibitory and bactericidal concentrations (MICs and MBCs) highlight the role of chalcogens in enhancing the antimicrobial activity (less than 4 µg/mL for some compounds) of the EU scaffold (32-64 µg/mL).

Antimicrobial Efficacy of Cinnamon Essential Oil against Avian Pathogenic Escherichia coli from Poultry

Colibacillosis, caused by E. coli, is responsible for economic losses in the poultry industry due to mortality, decreased production, and the cost of antibiotic treatments. Prevention of colibacillosis is based on improved biosecurity measures and the use of the vaccine performed with O78 E. coli strains, which is responsible for most cases of colibacillosis. Recently, there has been increased interest in other infection control methods, such as the use of natural compounds. The aim of this study was to evaluate the antimicrobial efficacy of cinnamon essential oil (CEO) against E. coli strains isolated from poultry. The MIC50 and MIC90 of CEO were determined by testing 117 strains belonging to serogroups O78, O2, O128, O139, isolated from laying hens (91 strains), broilers (10 strains), and turkeys (16 strains). The bacterial strains were tested at cell densities of 108 and 106 CFU/mL. At the cell density of 108 CFU/mL, MIC50 and MIC90 were 0.4 and 0.5 µL/mL for most of the tested strains, while they corresponded to 0.5 µL/mL for all strains isolated from broilers and for strains belonging to serogroup O139. At the cell density of 106 CFU/mL, MIC50 and MIC90 were 0.3 and 0.4 µL/mL, regardless of bird species of origin and for strains belonging to serogroups O78 and O2. In addition, a concentration of 0.04 µL/mL of CEO corresponded both to MIC50 and MIC90 for strains belonging to serogroups O139 and O128. Based on these results, cinnamon essential oil showed an effective antibacterial activity against E. coli strains from poultry and could find field application for the prevention of colibacillosis.

Phytochemicals as Antimicrobials: Prospecting Himalayan Medicinal Plants as Source of Alternate Medicine to Combat Antimicrobial Resistance

Among all available antimicrobials, antibiotics hold a prime position in the treatment of infectious diseases. However, the emergence of antimicrobial resistance (AMR) has posed a serious threat to the effectiveness of antibiotics, resulting in increased morbidity, mortality, and escalation in healthcare costs causing a global health crisis. The overuse and misuse of antibiotics in global healthcare setups have accelerated the development and spread of AMR, leading to the emergence of multidrug-resistant (MDR) pathogens, which further limits treatment options. This creates a critical need to explore alternative approaches to combat bacterial infections. Phytochemicals have gained attention as a potential source of alternative medicine to address the challenge of AMR. Phytochemicals are structurally and functionally diverse and have multitarget antimicrobial effects, disrupting essential cellular activities. Given the promising results of plant-based antimicrobials, coupled with the slow discovery of novel antibiotics, it has become highly imperative to explore the vast repository of phytocompounds to overcome the looming catastrophe of AMR. This review summarizes the emergence of AMR towards existing antibiotics and potent phytochemicals having antimicrobial activities, along with a comprehensive overview of 123 Himalayan medicinal plants reported to possess antimicrobial phytocompounds, thus compiling the existing information that will help researchers in the exploration of phytochemicals to combat AMR.

Antibacterial, Antibiofilm and Anti-Inflammatory Activities of Eugenol Clove Essential Oil against Resistant Helicobacter pylori

Eugenol essential oil (EEO) is the major component in aromatic extracts of Syzygium aromaticum (clove) and has several biological properties, such as antibacterial, antioxidant, and anti-inflammatory activities, as well as controlling vomiting, coughing, nausea, flatulence, diarrhea, dyspepsia, stomach distension, and gastrointestinal spasm pain. It also stimulates the nerves. Therefore, the aim of this study was to extract and purify EEO from clove buds and assess its ability to combat resistant Helicobacter pylori. Additionally, EEO's anti-inflammatory activity and its ability to suppress H. pylori biofilm formation, which is responsible for antibiotic resistance, was also investigated. Syzygium aromaticum buds were purchased from a local market, ground, and the EEO was extracted by using hydro-distillation and then purified and chemically characterized using gas chromatography-mass spectrometry (GC-MS). A disk-diffusion assay showed that Helicobacter pylori is sensitive to EEO, with an inhibition zone ranging from 10 ± 06 to 22 ± 04 mm. The minimum inhibition concentration (MIC) of EEO ranged from 23.0 to 51.0 μg/mL against both Helicobacter pylori clinical isolates and standard strains. In addition, EEO showed antibiofilm activity at 25 µg/mL and 50 µg/mL against various Helicobacter pylori strains, with suppression percentages of 49.32% and 73.21%, respectively. The results obtained from the anti-inflammatory assay revealed that EEO possesses strong anti-inflammatory activity, with human erythrocyte hemolysis inhibition percentages of 53.04, 58.74, 61.07, and 63.64% at concentrations of 4, 8, 16, and 32 μg/L, respectively. GC-MS analysis revealed that EEO is a major component of Syzygium aromaticum when extracted with a hydro-distillation technique, which was confirmed by its purification using a chemical separation process. EEO exhibited antibacterial action against resistant Helicobacter pylori strains, as well as antibiofilm and anti-inflammatory activities, and is a promising natural alternative in clinical therapy.

Novel formulation for co-delivery of cinnamon- and cumin-loaded polymeric nanoparticles to enhance their oral bioavailability

Nanobiotechnology has been an encouraging approach to improving the efficacy of hydrophobic bioactive compounds. The biologically active constituents present in herbal extracts are poorly absorbed, resulting in loss of bioavailability and efficacy. Hence, herbal medicine and nanotechnology are combined to overcome these limitations. The surface-to-volume ratio of nanoparticles is high and as the size is small, the functional properties are enhanced. The present study reports the synthesis of cinnamon and cumin (Ci-Cu) dual drug-loaded poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) to overcome the limitations of oral bioavailability and extend the effect of these drugs for alleviating health problems. The solvent evaporation method was adopted for the synthesis, and the as-prepared nanoparticles were characterized by Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The average size of the formed spherical Ci-Cu nanoparticles ranged between 90 and 120 nm. The encapsulation efficiency of the drug was found to be 79% ± 4.5%. XRD analysis demonstrated that cinnamon and cumin were amorphously scattered in the PLGA matrix. The FTIR bands showed no evident changes suggesting the no direct molecular interactions between the drug and the polymer. At pH 6.9, the release studies in vitro exhibited a burst initially followed by a tendency to obtain a slower steady release. The results indicated that the Cu-Ci dual drug-loaded polymeric NPs has drug release at a slower rate. The time taken for 25% release of drug in Ci-Cu-loaded PLGA NPs was twice as compared to cumin-loaded PLGA Nps, and three times compared to cinnamon-loaded PLGA NPs.

Antioxidant, Cytotoxic, and DNA Damage Protection Activities of Endophytic Fungus Pestalotiopsis neglecta Isolated from Ziziphus spina-christi Medicinal Plant

Fungal endophytes are friendly microorganisms that colonize plants and are important in the interactions between plants and their environment. They generate valuable secondary metabolites that are valuable to both plants and humans. Endophytic fungi with bioactivities were isolated from the leaves of the medicinal plant Ziziphus spina-christi. An efficient isolate was selected and identified as Pestalotiopsis neglecta based on nucleotide sequencing of the internal transcribed spacer region (ITS 1-5.8S-ITS 2) of the 18S rRNA gene (NCBI accession number OP529850); the 564 bp had 99 to 100% similarity with P. neglecta MH860161.1, AY682935.1, KP689121.1, and MG572407.1, according to the BLASTn analysis, following preliminary phytochemical and antifungal screening. The biological activities of this fungus' crude ethyl acetate (EtOAc) extract were assessed. With an efficient radical scavenging activity against 2,2'-diphenyl-1-picrylhydrazyl and an IC₅₀ value of 36.6 µg mL^-1, P. neglecta extract has shown its potential as an antioxidant. Moreover, it displayed notable cytotoxic effects against MCF-7 (breast carcinoma, IC₅₀ = 22.4 µg mL^-1), HeLa (cervical carcinoma, IC₅₀ = 28.9 µg mL^-1) and HepG-2 (liver carcinoma, IC₅₀ = 28.9 µg mL^-1). At 10 µg mL^-1, EtOAc demonstrated significant DNA protection against hydroxyl radical-induced damage. Based on FT-IR and GC-MS spectral analysis, it was detected that the EtOAc of P. neglecta product contains multiple bioactive functional groups. Subsequently, this validated the features of major different potent compounds; tolycaine, 1H-pyrazol, 1,3,5-trimethyl-, eugenol, 2,5-cyclohexadiene-1,4-dione, 2,6-bis(1,1-dimethyl), and bis(2-ethylhexyl) phthalate. Since these compounds are biologically relevant in various aspects, and distinct biological activities of fungal extract were acceptable in vitro, this suggests that endophytic fungus P. neglecta may be a viable source of bioactive natural products. This could be a good starting point for pharmaceutical applications.

Multifaceted Pharmacological Potentials of Curcumin, Genistein, and Tanshinone IIA through Proteomic Approaches: An In-Depth Review

Phytochemicals possess various intriguing pharmacological properties against diverse pathological conditions. Extensive studies are on-going to understand the structural/functional properties of phytochemicals as well as the molecular mechanisms of their therapeutic function against various disease conditions. Phytochemicals such as curcumin (Cur), genistein (Gen), and tanshinone-IIA (Tan IIA) have multifaceted therapeutic potentials and various efforts are in progress to understand the molecular dynamics of their function with different tools and technologies. Cur is an active lipophilic polyphenol with pleiotropic function, and it has been shown to possess various intriguing properties including antioxidant, anti-inflammatory, anti-microbial, anticancer, and anti-genotoxic properties besides others beneficial properties. Similarly, Gen (an isoflavone) exhibits a wide range of vital functions including antioxidant, anti-inflammatory, pro-apoptotic, anti-proliferative, anti-angiogenic activities etc. In addition, Tan IIA, a lipophilic compound, possesses antioxidant, anti-angiogenic, anti-inflammatory, anticancer activities, and so on. Over the last few decades, the field of proteomics has garnered great momentum mainly attributed to the recent advancement in mass spectrometry (MS) techniques. It is envisaged that the proteomics technology has considerably contributed to the biomedical research endeavors lately. Interestingly, they have also been explored as a reliable approach to understand the molecular intricacies related to phytochemical-based therapeutic interventions. The present review provides an overview of the proteomics studies performed to unravel the underlying molecular intricacies of various phytochemicals such as Cur, Gen, and Tan IIA. This in-depth study will help the researchers in better understanding of the pharmacological potential of the phytochemicals at the proteomics level. Certainly, this review will be highly instrumental in catalyzing the translational shift from phytochemical-based biomedical research to clinical practice in the near future.

The Antimicrobial and Toxicity Influence of Six Carrier Oils on Essential Oil Compounds

Essential oil compounds have been identified as alternative antimicrobials; however, their use is limited due to their toxicity on human lymphocytes, skin, and reproduction. Carrier oils can reduce the toxicity of essential oils, which raises the question as to whether such activity would extend to the essential oil compounds. Thus, this study aimed to investigate the antimicrobial and toxicity activity of essential oil compounds in combination with carrier oils. The antimicrobial properties of the essential oil compounds, alone and in combination with carrier oils, were determined using the broth microdilution assay. The toxicity was determined using the brine shrimp lethality assay. Antimicrobial synergy (ΣFIC ≤ 0.50) occurred in 3% of the samples when tested against the ESKAPE pathogens. The compound thymoquinone in combination with the carrier oil Prunus armeniaca demonstrated broad-spectrum synergistic activity and a selectivity index above four, highlighting this combination as the most favorable. The carrier oils reduced the toxicity of several compounds, with Calendula officinalis and P. armeniaca carrier oils being responsible for the majority of the reduced toxicity observed. This study provides insight into the interactions that may occur when adding a carrier oil to essential oil compounds.

Essential oils and their active components applied as: free, encapsulated and in hurdle technology to fight microbial contaminations. A review

Microbial contaminations are responsible for many chronic, healthcare, persistent microbial infections and illnesses in the food sector, therefore their control is an important public health challenge. Over the past few years, essential oils (EOs) have emerged as interesting alternatives to synthetic antimicrobials as they are biodegradable, extracted from natural sources and potent antimicrobials. Through their multiple mechanisms of actions and target sites, no microbial resistance has been developed against them till present. Although extensive documentation has been reported on the antimicrobial activity of EOs, comparisons between the use of whole EOs or their active components alone for an antimicrobial treatment are less abundant. It is also essential to have a good knowledge about EOs to be used as alternatives to the conventional antimicrobial products such as chemical disinfectants. Moreover, it is important to focus not only on planktonic vegetative microorganisms, but to study also the effect on more resistant forms like spores and biofilms. The present article reviews the current knowledge on the mechanisms of antimicrobial activities of EOs and their active components on microorganisms in different forms. Additionally, in this review, the ultimate advantages of encapsulating EOs or combining them with other hurdles for enhanced antimicrobial treatments are discussed.

Mannosylated Systems for Targeted Delivery of Antibacterial Drugs to Activated Macrophages

Macrophages are a promising target for drug delivery to influence macrophage-associated processes in the body, namely due to the presence of resistant microorganisms in macrophages. In this work, a series of mannosylated carriers based on mannan, polyethylenimine (PEI) and cyclodextrin (CD) was synthesized. The molecular architecture was studied using FTIR and ¹H NMR spectroscopy. The particle size, from small 10-50 nm to large 500 nm, depending on the type of carrier, is potentially applicable for the creation of various medicinal forms: intravenous, oral and inhalation. Non-specific capture by cells with a simultaneous increase in selectivity to CD206+ macrophages was achieved. ConA was used as a model mannose receptor, binding galactosylated (CD206 non-specific) carriers with constants of the order of 10⁴ M^-1 and mannosylated conjugates of 10⁶-10⁷ M^-1. The results of such primary "ConA-screening" of ligands are in a good agreement in terms of the comparative effectiveness of the interaction of ligands with the CD206+ macrophages: non-specific (up to 10%) absorption of highly charged and small particles; weakly specific uptake of galactosylated polymers (up to 50%); and high affine capture (more than 70-80%) of the ligands with grafted trimannoside was demonstrated using the cytometry method. Double and multi-complexes of antibacterials (moxifloxacin with its adjuvants from the class of terpenoids) were proposed as enhanced forms against resistant pathogens. In vivo pharmacokinetic experiments have shown that polymeric carriers significantly improve the efficiency of the antibiotic: the half-life of moxifloxacin is increased by 2-3 times in conjugate-loaded forms, bio-distribution to the lungs in the first hours after administration of the drug is noticeably greater, and, after 4 h of observation, free moxifloxacin was practically removed from the lungs of rats. Although, in polymer systems, its content is significant-1.2 µg/g. Moreover, the importance of the covalent crosslinking carrier with mannose label was demonstrated. Thus, this paper describes experimental, scientifically based methods of targeted drug delivery to macrophages to create enhanced medicinal forms.

Valorization of Pimenta racemosa Essential Oils and Extracts: GC-MS and LC-MS Phytochemical Profiling and Evaluation of Helicobacter pylori Inhibitory Activity

Pimenta racemosa is a commonly known spice used in traditional medicine to treat several ailments. In this study, comprehensive phytochemical profiling of the essential oils and methanol extracts of P. racemosa leaves and stems was performed, alongside assessing their potential Helicobacter pylori inhibitory activity in vitro and in silico. The essential oils were chemically profiled via GC-MS. Moreover, the methanol extracts were profiled using HPLC-PDA-ESI-MS/MS. The antibacterial activity of the essential oils and methanol extracts against H. pylori was determined by adopting the micro-well dilution method. GC-MS analysis unveiled the presence of 21 constituents, where eugenol represented the major component (57.84%) and (59.76%) in both leaves and stems of essential oils, respectively. A total of 61 compounds were annotated in both leaves and stems of P. racemosa methanolic extracts displaying richness in phenolic compounds identified as (epi)catechin and (epi)gallocatechin monomers and proanthocyanidins, hydrolyzable tannin derivatives (gallotannins), flavonoids, and phenolic acids. The stem essential oil showed the most promising inhibitory effects on H. pylori, exhibiting an MIC value of 3.9 µg/mL, comparable to clarithromycin with an MIC value of 1.95 µg/mL. Additionally, in silico molecular modeling studies revealed that decanal, eugenol, terpineol, delta-cadinene, and amyl vinyl showed potential inhibitory activity on H. pylori urease as demonstrated by high-fitting scores indicating good binding to the active sites. These findings indicate that P. racemosa comprises valuable phytochemical constituents with promising therapeutic effects, particularly the stem, an economic agro-industrial waste.

In-vitro anti-Mycobacterium tuberculosis effect of Eugenol

BACKGROUND/OBJECTIVES

Mycobacterium tuberculosis, the causative agent of tuberculosis has developed resistance to most of the available antimicrobials. Therefore research on the detection of new antimicrobials against Mycobacterium tuberculosis is needed urgently. Essential oils extracted from plants have been shown to have anti-Mycobacterium tuberculosis effect in in-vitro experiments. Essential oil contains many chemicals and any one or more than one chemical may have the anti-Mycobacterium tuberculosis effect. Eugenol is one such chemical in the essential oil and the anti-Mycobacterium tuberculosis effect of eugenol is investigated.

METHODS

The anti-Mycobacterium tuberculosis effect of eugenol was evaluated against H37Rv and twelve clinical isolates of Mycobacterium tuberculosis in the BD BACTEC MGIT instrument using different volumes of eugenol.

RESULTS

H37Rv and all the twelve clinical isolates of Mycobacterium tuberculosis were inhibited by eugenol. The minimal inhibitory concentration of H37Rv was 2.5 μl (2.67 mg) and those of the clinical isolates of Mycobacterium tuberculosis ranged from to 2.5 μl (2.67 mg) to 10 μl (10.68 mg).

CONCLUSION

Eugenol has anti-Mycobacterium tuberculosis effect in the in-vitro BD BACTEC MGIT method.

Harnessing the Role of Bacterial Plasma Membrane Modifications for the Development of Sustainable Membranotropic Phytotherapeutics

Membrane-targeted molecules such as cationic antimicrobial peptides (CAMPs) are amongst the most advanced group of antibiotics used against drug-resistant bacteria due to their conserved and accessible targets. However, multi-drug-resistant bacteria alter their plasma membrane (PM) lipids, such as lipopolysaccharides (LPS) and phospholipids (PLs), to evade membrane-targeted antibiotics. Investigations reveal that in addition to LPS, the varying composition and spatiotemporal organization of PLs in the bacterial PM are currently being explored as novel drug targets. Additionally, PM proteins such as Mla complex, MPRF, Lpts, lipid II flippase, PL synthases, and PL flippases that maintain PM integrity are the most sought-after targets for development of new-generation drugs. However, most of their structural details and mechanism of action remains elusive. Exploration of the role of bacterial membrane lipidome and proteome in addition to their organization is the key to developing novel membrane-targeted antibiotics. In addition, membranotropic phytochemicals and their synthetic derivatives have gained attractiveness as popular herbal alternatives against bacterial multi-drug resistance. This review provides the current understanding on the role of bacterial PM components on multidrug resistance and their targeting with membranotropic phytochemicals.

Mannosylated Polymeric Ligands for Targeted Delivery of Antibacterials and Their Adjuvants to Macrophages for the Enhancement of the Drug Efficiency

Bacterial infections and especially resistant strains of pathogens localized in macrophages and granulomas are intractable diseases that pose a threat to millions of people. In this paper, the theoretical and experimental foundations for solving this problem are proposed due to two key aspects. The first is the use of a three-component polymer system for delivering fluoroquinolones to macrophages due to high-affinity interaction with mannose receptors (CD206). Cytometry assay determined that 95.5% macrophage-like cells were FITC-positive after adding high-affine to CD206 trimannoside conjugate HPCD-PEI1.8-triMan, and 61.7% were FITC-positive after adding medium-affine ligand with linear mannose label HPCD-PEI1.8-Man. The second aspect is the use of adjuvants, which are synergists for antibiotics. Using FTIR and NMR spectroscopy, it was shown that molecular containers, namely mannosylated polyethyleneimines (PEIs) and cyclodextrins (CDs), load moxifloxacin (MF) with dissociation constants of the order of 10⁻⁴–10⁻⁶ M; moreover, due to prolonged release and adsorption on the cell membrane, they enhance the effect of MF. Using CLSM, it was shown that eugenol (EG) increases the penetration of doxorubicin (Dox) into cells by an order of magnitude due to the creation of defects in the bacterial wall and the inhibition of efflux proteins. Fluorescence spectroscopy showed that 0.5% EG penetrates into bacteria and inhibits efflux proteins, which makes it possible to increase the maximum concentration of the antibiotic by 60% and maintain it for several hours until the pathogens are completely neutralized. Regulation of efflux is a possible way to overcome multiple drug resistance of both pathogens and cancer cells.

Antibacterial, Antibiofilm, and Antioxidant Activity of 15 Different Plant-Based Natural Compounds in Comparison with Ciprofloxacin and Gentamicin

Plant-based natural compounds (PBCs) are comparatively explored in this study to identify the most effective and safe antibacterial agent/s against six World Health Organization concern pathogens. Based on a contained systematic review, 11 of the most potent PBCs as antibacterial agents are included in this study. The antibacterial and antibiofilm efficacy of the included PBCs are compared with each other as well as common antibiotics (ciprofloxacin and gentamicin). The whole plants of two different strains of Cannabis sativa are extracted to compare the results with sourced ultrapure components. Out of 15 PBCs, tetrahydrocannabinol, cannabidiol, cinnamaldehyde, and carvacrol show promising antibacterial and antibiofilm efficacy. The most common antibacterial mechanisms are explored, and all of our selected PBCs utilize the same pathway for their antibacterial effects. They mostly target the bacterial cell membrane in the initial step rather than the other mechanisms. Reactive oxygen species production and targeting [Fe-S] centres in the respiratory enzymes are not found to be significant, which could be part of the explanation as to why they are not toxic to eukaryotic cells. Toxicity and antioxidant tests show that they are not only nontoxic but also have antioxidant properties in Caenorhabditis elegans as an animal model.

Plant Alkylbenzenes and Terpenoids in the Form of Cyclodextrin Inclusion Complexes as Antibacterial Agents and Levofloxacin Synergists

Allylpolyalkoxybenzenes (APABs) and terpenoids from plant essential oils exhibit a range of remarkable biological effects, including analgesic, antibacterial, anti-inflammatory, antioxidant, and others. Synergistic activity with antibiotics of different classes has been reported, with inhibition of P-glycoprotein and impairment of bacterial cell membrane claimed as probable mechanisms. Clearly, a more detailed understanding of APABs’ biological activity could help in the development of improved therapeutic options for a range of diseases. However, APABs’ poor solubility in water solutions has been a limiting factor for such research. Here, we found that complex formation with β-cyclodextrins (CD) is an efficient way to transform the APABs into a water-soluble form. Using a combination of spectroscopic (FTIR, NMR, UV) methods, we have estimated the binding constants, loading capacity, and the functional groups of both APABs and monoterpenes involved in complex formation with CD: ethylene, aromatic, methoxy and hydroxy groups. In the presence of a molar excess of CD (up to 5 fold) it was possible to achieve the complete dissolution of APABs and terpenoids in an aqueous medium (at 90–98% encapsulation) higher by 10–1000 times. Further, we have demonstrated that CD-APABs, if used in combination with levofloxacin (Lev), can be antagonistic, indifferent, additive, or synergistic, mostly depending on the concentration ratio: at high Lev concentration with the addition of APAB is typically neutral or even antagonistic; while at a Lev concentration below MIC, the addition of CD-APAB is either additive or synergistic (according to FICI criteria). An over three-fold increase in Lev antibacterial activity was observed in combination with eugenol (EG), as per the growth inhibition diameter measurement in agar. Interestingly, a synergistic effect could be observed with both Gram-positive and Gram-negative bacteria. So, obviously, the APAB-CD and terpenoid-CD mechanism of action is not limited to their interaction with the bacterial membrane, which has been shown earlier for CDs. Further research may open new prospects for the development of adjuvants to improve the therapeutic regimens with existing, as well as with new anti-infective drugs.

Tackling Multiple-Drug-Resistant Bacteria With Conventional and Complex Phytochemicals

Emerging antibiotic resistance in bacteria endorses the failure of existing drugs with chronic illness, complicated treatment, and ever-increasing expenditures. Bacteria acquire the nature to adapt to starving conditions, abiotic stress, antibiotics, and our immune defense mechanism due to its swift evolution. The intense and inappropriate use of antibiotics has led to the development of multidrug-resistant (MDR) strains of bacteria. Phytochemicals can be used as an alternative for complementing antibiotics due to their variation in metabolic, genetic, and physiological fronts as well as the rapid evolution of resistant microbes and lack of tactile management. Several phytochemicals from diverse groups, including alkaloids, phenols, coumarins, and terpenes, have effectively proved their inhibitory potential against MDR pathogens through their counter-action towards bacterial membrane proteins, efflux pumps, biofilms, and bacterial cell-to-cell communications, which are important factors in promoting the emergence of drug resistance. Plant extracts consist of a complex assortment of phytochemical elements, against which the development of bacterial resistance is quite deliberate. This review emphasizes the antibiotic resistance mechanisms of bacteria, the reversal mechanism of antibiotic resistance by phytochemicals, the bioactive potential of phytochemicals against MDR, and the scientific evidence on molecular, biochemical, and clinical aspects to treat bacterial pathogenesis in humans. Moreover, clinical efficacy, trial, safety, toxicity, and affordability investigations, current status and developments, related demands, and future prospects are also highlighted.

Spectroscopy Approach for Highly-Efficient Screening of Lectin-Ligand Interactions in Application for Mannose Receptor and Molecular Containers for Antibacterial Drugs

Rational search of a ligand for a specific receptor is a cornerstone of a typical drug discovery process. However, to make it more “rational” one would appreciate having detailed information on the functional groups involved in ligand-receptor interaction. Typically, the 3D structure of a ligand-receptor complex can be built on the basis of time-consuming X-ray crystallography data. Here, a combination of FTIR and fluorescence methods, together with appropriate processing, yields valuable information about the functional groups of both the ligand and receptor involved in the interaction, with the simplicity of conventional spectrophotometry. We have synthesized the “molecular containers” based on cyclodextrins, polyethyleneimines (PEI) or spermine with mannose-rich side-chains of different molecular architecture (reticulated, star-shaped and branched) with variable parameters to facilitate delivery to alveolar macrophages. We have shown that synthetic mannose-rich conjugates are highly affine to the model mannose receptor ConA: K_d ≈ 10⁻⁵–10⁻⁷ M vs. natural ligand trimannoside (10⁻⁵ M). Further, it was shown that molecular containers effectively load levofloxacin (dissociation constants are 5·10⁻⁴–5·10⁻⁶ M) and the eugenol adjuvant (up to 15–80 drug molecules for each conjugate molecule) by including them in the cyclodextrins cavities, as well as by interacting with polymer chains. Promising formulations of levofloxacin and its enhancer (eugenol) in star-shaped and polymer conjugates of high capacity were obtained. UV spectroscopy demonstrated a doubling of the release time of levofloxacin into the external solution from the complexes with conjugates, and the effective action time (time of 80% release) was increased from 0.5 to 20–70 h. The synergy effect of antibacterial activity of levofloxacin and its adjuvants eugenol and apiol on Escherichia coli was demonstrated: the minimum effective concentration of the antibiotic was approximately halved.

Chemical Composition, Antibacterial and Anti-Quorum Sensing Activities of Pimenta dioica L. Essential Oil and Its Major Compound (Eugenol) against Foodborne Pathogenic Bacteria

The Pimenta dioica essential oil and its main compound (eugenol) were tested for their antibacterial potency against eight Gram-negative and Gram-positive bacteria implicated in food intoxication. This essential oil and its main component were evaluated for their ability in inhibiting Quorum sensing (QS)-dependent mechanisms such as motility in Pseudomonas aeruginosa PAO1, production of violacein by Chromobacterium violaceum and biofilm formation on stainless steel and glass surfaces. Our results demonstrated that P. dioica essential oil and eugenol were active against all tested strains with a maximum of inhibition against Listeria monocytogenes CECT 933 (26.66 ± 0.57 mm). The minimal inhibitory concentration (MIC) value of the tested essential oil and eugenol was about 0.048 mg/mL for all strains. The obtained results demonstrated that 4CMI eugenol inhibited foodborne strains biofilm formation on the glass strips by 73.79% and by 75.90% on polystyrene. Moreover, 0.048 mg/mL (MIC) of P. dioica essential oil inhibited the violacein production by 69.30%. At 100 µg/mL, P. dioica oil and eugenol affected the motility of PAO1 by 42.00% and 29.17%, respectively. Low concentrations of P. dioica essential oil are active against the quorum sensing phenomena and biofilm potency. Thus, this essential oil could be further investigated for new molecules useful for the treatment of toxi-alimentary infections.

Exploring the potential of Cinnamomum zeylanicum oil against drug resistant Helicobacter pylori-producing cytotoxic genes

Thirty-one of sixty dyspeptic patients tested positive for Helicobacter pylori colonization in this study, as determined by histopathology and 16S rRNA. The cytotoxin-associated gene A (cagA) and vacuolating cytotoxin A (vacA) genes were found in 67.7 and 93.5% of H. pylori patients, respectively. The cagA gene was found to be associated with 100% of patients with duodenal erosion and ulceration identified via endoscopy examination. In addition, 86.7% of patients with cancerous and precancerous lesions, glandular atrophy, and intestinal metaplasia identified via histopathology examination. The vacA s1m1 mutation was associated with more severe forms of gastric erosion and ulceration, as well as the presence of precancerous and cancerous lesions. Eighteen (64.3%) of the twenty-eight isolates were classified as multi-drug resistant (MDR) or pan-drug resistant (PDR) H. pylori. Due to a resurgence of interest in alternative therapies derived from plants as a result of H. pylori resistance to the majority of commonly used antibiotics, the inhibitory activity of five essential oils extracted from some commonly used medicinal plants was evaluated in vitro against drug-resistant H. pylori clinical isolates. Cinnamomum zeylanicum essential oil demonstrated the highest anti-H. pylori activity when compared to the other essential oils tested. Cinnamaldehyde was the most abundant compound in C. zeylanicum (65.91%). The toxicological evaluation established the safety of C. zeylanicum oil for human use. As a result, C. zeylanicum essential oil may represent a novel antibacterial agent capable of combating drug-resistant H. pylori carrying cytotoxin genes.

Persistent susceptibility of Aedes aegypti to eugenol

Botanical insecticides are preferred for their environment and user-friendly nature. Eugenol is a plant-based monoterpene having multifarious biocidal activities. To understand whether eugenol would persistently work against Aedes aegypti, we performed larvicidal bioassays on thirty successive generations and determined median lethal concentration (LC50) on each generation. Results showed no apparent differences between LC50 at F0 (63.48 ppm) and F30 (64.50 ppm) indicating no alteration of susceptibility toward eugenol. To analyze, if eugenol has any effect on metabolic detoxification-associated enzymes, we measured esterases (alpha and beta), cytochrome P450, and GST activities from the survived larvae exposed to LC50 concentration from F0–F30. Results revealed a decrease of esterases, GST, and cytochrome P450 activities at the initial 4–8 generations and then a gradual increase as the generations progressed. GST activity remained significantly below the control groups. Synergists (TPP, DEM, and PBO) were applied along with eugenol at F30 and LC50 concentration, and the said enzyme activities were recorded. Results showed a noticeable decrease in LC50 and enzyme activities indicating effective inhibitions of the respective enzymes. Overall, present results inferred that eugenol would effectively work as a larvicide for a longer period in successive generations without initiating rapid resistance and therefore could be advocated for controlling A. aegypti.

Progress in Alternative Strategies to Combat Antimicrobial Resistance: Focus on Antibiotics

Antibiotic resistance, and, in a broader perspective, antimicrobial resistance (AMR), continues to evolve and spread beyond all boundaries. As a result, infectious diseases have become more challenging or even impossible to treat, leading to an increase in morbidity and mortality. Despite the failure of conventional, traditional antimicrobial therapy, in the past two decades, no novel class of antibiotics has been introduced. Consequently, several novel alternative strategies to combat these (multi-) drug-resistant infectious microorganisms have been identified. The purpose of this review is to gather and consider the strategies that are being applied or proposed as potential alternatives to traditional antibiotics. These strategies include combination therapy, techniques that target the enzymes or proteins responsible for antimicrobial resistance, resistant bacteria, drug delivery systems, physicochemical methods, and unconventional techniques, including the CRISPR-Cas system. These alternative strategies may have the potential to change the treatment of multi-drug-resistant pathogens in human clinical settings.

Beneficial effects of eugenol supplementation on gut microbiota and hepatic steatosis in high-fat-fed mice

Due to the increase in the prevalence of obesity, new therapies have emerged and Eugenol has been shown to be beneficial in metabolic changes and gut microbiota. This study aimed...

Cinnamaldehyde and eugenol protect against LPS-stimulated oxidative stress and inflammation in Raw 264.7 cells

Macrophages are leukocytes that play a strategic role in immune response and can be associated with various diseases due to their effects on the inflammation process and oxidative events. The current study was evaluated the anti-inflammatory and antioxidant properties of cinnamaldehyde and eugenol, which are phyto-compounds with numerous bioactive properties, on lipopolysaccharide (LPS)-induced macrophage cells. For this purpose, Raw 264.7 cells were incubated with cinnamaldehyde or eugenol (15, 25, and 50 μM) then stimulated with LPS. After 24 hr, tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and IL-6 levels (as inflammatory mediators), and malondialdehyde (MDA) and nitric oxide (NOx) levels as well as superoxide dismutase (SOD) and catalase (CAT) activities (as oxidative status markers) were determined in cell cultures. Cinnamaldehyde and eugenol pre-treatments decreased TNF-α, IL-1β, and IL-6 levels as compared to LPS group at all concentrations. Furthermore, these pre-treatments increased SOD activity while decreased MDA and NOx levels as well as CAT activity at different concentrations. Our results demonstrated that these phyto-compounds have potential for the treatment of various diseases as protective agents against chronic inflammation and oxidative stress. PRACTICAL APPLICATIONS: Chronic inflammation and oxidative stress are complications that play a detrimental role in the pathophysiology of many diseases. Alternative treatment methods have been investigated to prevent them. Cinnamaldehyde and eugenol are phyto-compounds with high bioactivity that can be obtained from foods and spices. In this study, the protective effects of cinnamaldehyde and eugenol on lipopolysaccharide-induced oxidative stress and inflammation in macrophage cells were investigated. According to the obtained results, cinnamaldehyde and eugenol pre-treatments decreased inflammation and also reduced oxidative stress. Cinnamaldehyde and eugenol may be a better natural alternative protective agent for the chronic inflammation- and oxidative stress-related diseases.

Revisiting Therapeutic Strategies for H. pylori Treatment in the Context of Antibiotic Resistance: Focus on Alternative and Complementary Therapies

The prevalence of Helicobacter pylori infection remains significant worldwide and it depends on many factors: gender, age, socio-economic status, geographic area, diet, and lifestyle. All successful infectious diseases treatments use antibiotic-susceptibility testing, but this strategy is not currently practical for H. pylori and the usual cure rates of H. pylori are lower than other bacterial infections. Actually, there is no treatment that ensures complete eradication of this pathogen. In the context of an alarming increase in resistance to antibiotics (especially to clarithromycin and metronidazole), alternative and complementary options and strategies are taken into consideration. As the success of antibacterial therapy depends not only on the susceptibility to given drugs, but also on the specific doses, formulations, use of adjuvants, treatment duration, and reinfection rates, this review discusses the current therapies for H. pylori treatment along with their advantages and limitations. As an alternative option, this work offers an extensively referenced approach on natural medicines against H. pylori, including the significance of nanotechnology in developing new strategies for treatment of H. pylori infection.

Characterization of Four Piper Essential Oils (GC/MS and ATR-IR) Coupled to Chemometrics and Their anti-Helicobacter pylori Activity

Background: Essential oils represent a major class of natural products which are known for their antimicrobial activity. This study aimed to determine the composition of four Piper essential oils by gas chromatography mass spectrometry, attenuated total reflection infrared, and chemometric analysis. Results: Monoterpene was the most predominant class in Piper nigrum and white pepper (87.6 and 80%, respectively) with the dominance of α-pinene, β-pinene, 3-carene, limonene, and β-caryophyllene. Sesquiterpenes represented 50, 19.6, and 12.3% of the essential oils of Piper longum, white pepper, and P. nigrum, respectively. Unlike other species, Piper cubeba oil was found to be rich in aromatics (59%), with eugenol (10.7%) and methyl eugenol (47.4%) representing the major components along with β-myrcene (21.2%) and 1,8-cineole (6.4%). Only P. longum essential oil comprised about 18.2% of alkanes and 13.6% of alkenes. Application of chemometric analysis utilizing GC/MS and ATR-IR data displayed the same segregation pattern where both principal component analysis and hierarchal cluster analysis revealed that white pepper was most closely related to P. nigrum while being completely discriminated from other Piper species. The Piper oils showed promising inhibitory effects on Helicobacter pylori. P. longum oil recorded the most efficient anti-Helicobacter activity [minimum inhibitory concentration (MIC) value of 1.95 μg/ml, which is the same as the MIC of clarithromycin], followed by the oil of white pepper (MIC = 3.90 μg/ml), while P. cubeba and P. nigrum produced the lowest activity (MIC value of 7.81 μg/ml). Conclusion: Piper essential oils can be used as nutritional supplements or therapeutic drugs to protect against H. pylori infection.

Volatile phenolics: A comprehensive review of the anti-infective properties of an important class of essential oil constituents

Historically, essential oils and their lead molecules have been extensively recognised for their anti-infective properties. In this context, certain volatile phenolics (VPs) have emerged as important antimicrobial compounds with excellent inhibitory activity against pathogenic bacteria and fungi, which further extends to drug-resistant and biofilm-forming micro-organisms. In this review, we aim to collate and discuss a number of published papers on the anti-infective activities of naturally occurring VPs with special emphasis on eugenol, isoeugenol, thymol and carvacrol, using Scopus Web of Science and PubMed databases. The biosynthesis and extraction of these VPs are discussed, while particular attention is given to their broad-spectrum antimicrobial activity and the mechanisms of action. We highlight combinational studies of the VPs with other phytocompounds and with commercially available drugs, which may be a promising and a rewarding future approach to combat antimicrobial resistance. These VPs alone, or concomitantly with other compounds or drugs, have the potential to be incorporated into different formulations for biomedical applications. An in-depth assessment of 2310 articles retrieved from the Scopus database spanning a 35-year period indicated 23.1% increase in global publication growth in VPs anti-infective research, with authors from Italy, Portugal and Austria dominating the research landscape. The dominant areas of investigations are identified as antimicrobial activity, antibacterial mechanism of action, antifungal mechanism of action, extraction methods and phytochemistry, use in the food industry, and for oral and dental anti-infective activity. Specific research areas, which require future attention include; antituberculosis research, nanoparticle formulation of antimicrobial active VP molecules, preclinical and clinical trials. The antimicrobial testing of isoeugenol was found to be the least studied of the VPs and this requires further attention.

Towards Advances in Medicinal Plant Antimicrobial Activity: A Review Study on Challenges and Future Perspectives

The increasing incidence of drug- resistant pathogens raises an urgent need to identify and isolate new bioactive compounds from medicinal plants using standardized modern analytical procedures. Medicinal plant-derived compounds could provide novel straightforward approaches against pathogenic bacteria. This review explores the antimicrobial activity of plant-derived components, their possible mechanisms of action, as well as their chemical potential. The focus is put on the current challenges and future perspectives surrounding medicinal plants antimicrobial activity. There are some inherent challenges regarding medicinal plant extracts and their antimicrobial efficacy. Appropriate and optimized extraction methodology plant species dependent leads to upgraded and selective extracted compounds. Antimicrobial susceptibility tests for the determination of the antimicrobial activity of plant extracts may show variations in obtained results. Moreover, there are several difficulties and problems that need to be overcome for the development of new antimicrobials from plant extracts, while efforts have been made to enhance the antimicrobial activity of chemical compounds. Research on the mechanisms of action, interplay with other substances, and the pharmacokinetic and/or pharmacodynamic profile of the medicinal plant extracts should be given high priority to characterize them as potential antimicrobial agents.

Discovery of the signal pathways and major bioactive compounds responsible for the anti-hypoxia effect of Chinese cordyceps

ETHNOPHARMACOLOGICAL RELEVANCE

Hypoxia will cause an increase in the rate of fatigue and aging. Chinese cordyceps, a parasitic Thitarodes insect-Ophiocordyceps sinensis fungus complex in the Qinghai-Tibet Plateau, has long been used to ameliorate human conditions associated with aging and senescence, it is principally applied to treat fatigue, night sweating and other symptoms related to aging, and it may play the anti-aging and anti-fatigue effect by improving the body's hypoxia tolerance.

AIMS OF THE STUDY

The present study investigated the anti-hypoxia activity of Chinese cordyceps and explore the main corresponding signal pathways and bioactive compounds.

MATERIALS AND METHODS

In this study, network pharmacology analysis, molecular docking, cell and whole pharmacodynamic experiments were hired to study the major signal pathways and the bioactive compounds of Chinese cordyceps for anti-hypoxia activity.

RESULTS

17 pathways which Chinese cordyceps acted on seemed to be related to the anti-hypoxia effect, and "VEGF signal pathway" was one of the most important pathway. Chinese cordyceps improved the survival rate and regulated the targets related VEGF signal pathway of H9C2 cells under hypoxia, and also had significant anti-hypoxia effects to mice. Chorioallantoic membrane model experiment showed that Chinese cordyceps and the main constituents of (9Z,12Z)-octadeca-9,12-dienoic acid and cerevisterol had significant angiogenic activity in hypoxia condition.

CONCLUSION

Based on the results of network pharmacology and molecular docking analysis, cell and whole pharmacodynamic experiments, promoting angiogenesis by regulating VEGF signal pathway might be one of the mechanisms of anti-hypoxia effect of Chinese cordyceps, (9Z, 12Z)-octadeca-9,12-dienoic acid and cerevisterol were considered as the major anti-hypoxia bioactive compounds in Chinese cordyceps.

Eugenol, a Promising Building Block for Biobased Polymers with Cutting-Edge Properties

Biobased materials, derived from biomass building blocks, are essential in the pursuit of sustainable materials. Eugenol, a natural phenol obtained from clove oil, but also from lignin depolymerization, possesses a chemical structure that allows its easy modification to obtain a broad and versatile platform of biobased monomers. In this Perspective, an overview of the variety of reactions that have been executed on the allylic double bond, phenol hydroxyl group, aromatic ring, and methoxy group is given, focusing our attention on those to obtain monomers suitable for different polymerization reactions. Furthermore, possible applications and perspectives on the eugenol-derived materials are provided.

Antibiofilm and Antifungal Activities of Laurelia sempervirens (Chilean laurel) Essential Oil

Background: Laurelia sempervirens, better known as Chilean laurel, is endemic to Chile. For many years, the leaves and branches of this plant have been popularly used as medicinal agents. However, its antifungal properties and antibiofilm activity against bacterial strains have not been studied. Objectives: To determine antibiofilm and antimicrobial properties of Chilean laurel essential oil on human pathogenic strains. Methods: The antifungal and antibacterial activities of Chilean laurel essential oil were evaluated through the agar diffusion method, and its minimum inhibitory concentration was determined using the standard microdilution method. Antibiofilm activity was examined based on the formation and disruption of bacterial biofilms and evidenced by the crystal violet technique. Results: The results showed important antimicrobial activity against human pathogenic yeast strains, and the minimum inhibitory concentration of Chilean laurel essential oil was 64 µg mL-1 against Candida albicans. The essential oil also showed an important inhibitory effect against the formation of biofilms produced by Staphylococcus aureus, since it inhibited the formation of biofilms by over 50% at the concentration of 64 µg mL-1. With increasing the essential oil’s concentration to 128 µg mL-1, its antibiofilm activity increased by 60%. Conclusions: These results approve the domestic use of Chilean laurel essential oil as an antimicrobial agent and provide knowledge about the antibiofilm and antifungal properties of L. sempervirens.

Eugenol-Functionalized Magnetite Nanoparticles Modulate Virulence and Persistence in Pseudomonas aeruginosa Clinical Strains

Efficient antibiotics to cure Pseudomonas aeruginosa persistent infections are currently insufficient and alternative options are needed. A promising lead is to design therapeutics able to modulate key phenotypes in microbial virulence and thus control the progression of the infectious process without selecting resistant mutants. In this study, we developed a nanostructured system based on Fe₃O₄ nanoparticles (NPs) and eugenol, a natural plant-compound which has been previously shown to interfere with microbial virulence when utilized in subinhibitory concentrations. The obtained functional NPs are crystalline, with a spherical shape and 10-15 nm in size. The subinhibitory concentrations (MIC 1/2) of the eugenol embedded magnetite NPs (Fe₃O₄@EUG) modulate key virulence phenotypes, such as attachment, biofilm formation, persister selection by ciprofloxacin, and the production of soluble enzymes. To our knowledge, this is the first report on the ability of functional magnetite NPs to modulate P. aeruginosa virulence and phenotypic resistance; our data highlights the potential of these bioactive nanostructures to be used as anti-pathogenic agents.

4-chloro eugenol interacts synergistically with artesunate against drug resistant P. falciparum inducing oxidative stress

4-chloro eugenol (4CE), a semisynthetic analog of phytomolecule eugenol exhibited potent antiplasmodial activity with IC₅₀ in the range of 1.5-5 μM against sensitive as well as drug resistant strain of P. falciparum. This analog also showed synergy with a clinically used antimalarial drug artesunate and was able to curtail the IC₅₀ of artesunate up to 4-5 folds. Although, 4CE did not show any effect on heme polymerization, the most common drug target in the malaria parasite, it could increase the level of reactive oxygen species (ROS) and reactive nitrogen species (RNS) alone as well as in combination with artesunate. Further, 4CE induced oxidative stress was observed to affect the macromolecules in terms of DNA damage, protein carbonylation and lipid peroxidation. At the physiological level, cellular organelles like mitochondria and endoplasmic reticulum were observed to be get affected by 4CE in terms of membrane depolarization and calcium ion leakage respectively. These observations could be validated by expression analysis of oxidative stress responsive genes and proteins. Further, in in vivo assay, 4CE showed significant chemo-suppression of parasitemia as well as an increase in mean survival time in the murine malaria model. Interestingly, in combination with artesunate, 4CE showed higher chemo-suppression as well as enhanced mean survival time at a much lower concentrations of both the partners as compared to an individual dose of artesunate and 4CE. A combination of 4CE and artesunate was also observed to attenuate cerebral malaria pathogenesis.

Inhibitory Activity of Essential Oils against Vibrio campbellii and Vibrio parahaemolyticus

Vibriosis, caused by Vibrio strains, is an important bacterial disease and capable of causing significant high mortality in aquatic animals. Essential oils (EOs) have been considered as an alternative approach for the treatment of aquatic bacterial diseases. In this study, we evaluated the antibacterial activity of essential oils (n = 22) or essential oil components (EOCs, n = 12) against Vibrio strains belonging to the harveyi clade. It was verified by three different approaches, e.g., (i) a bacterial growth assay, comparing Vibrio growth with or without EO(C)s at various concentrations; (ii) a vapor-phase-mediated susceptibility assay, comparing the effect of EO(C)s on bacterial growth through the vapor phase; and (iii) a quorum sensing-inhibitory assay, based on specific inhibition of quorum sensing-regulated bioluminescence. The results showed that, in the bacterial growth assay, EOs of Melaleuca alternifolia and Litsea citrata at 0.0001%, Eucalyptus citriodora at 0.01% can inhibit the growth of Vibrio campbellii BB120. These EOs can also prevent the growth of V. parahaemolyticus strains but need to be present at a higher concentration (0.1%). Moreover, in the vapor-phase-mediated susceptibility assay, EOs of M. alternifolia, L. citrata and E. citriodora can inhibit the growth of V. campbellii BB120 through their vapor phase. However, V. parahaemolyticus strains (CAIM170, LMG2850 and MO904) cannot be inhibited by these EOs. Additionally, in the quorum sensing-inhibitory assay, EOs of Mentha pulegium, Cuminum cyminum, Zingiber officinalis, and E. citriodora, all at 0.001%, have quorum sensing-inhibitory activity in V. campbellii BB120. Taken together, our study provides substantial evidence that usage of the major components, individually or in combination, of the tested commercial EOs (extracted from M. alternifolia, L. citrata, and E. citriodora) could be a promising approach to control V. campbellii BB120.