Salting-out effect-mediated size-control of protein nanoparticles towards controllable microstructures for sustained release of eugenol

Size and monodispersity of solid particles are essential to their structuring behaviors at biphasic interfaces. However, delicate control over biomolecular nanoparticle sizes is challenging. In this study, we prepared monodisperse rice protein (RP) nanoparticles by neutralizing RP solutions (pH 12.0) using combined treatments of cationic exchange resins (CERs) and HCl. CERs absorbed Na+ by releasing H+ without producing salt during neutralization. By compromising the usages of CERs and HCl when preparing RPs, the generation of NaCl can be delicately tailored, leading to controllable nanoparticle sizes from 20 nm to 30 nm. By mixing these nanoparticles with eugenol in an aqueous solution, the nanoparticles accommodated eugenol in their cores due to inward diffusion. Furthermore, such eugenol-contained nanoparticles with different sizes demonstrated tunable releases of eugenol due to size-dependent capillary forces, which can be harnessed for suppression of microbial growth on fruit with prolonged effective eugenol concentration.

A Promising Plant-Based Eugenol-Loaded Nano Delivery System (EUG@CMC-PGMA-CS) for Enhanced Antibacterial and Insect Repellent Behavior

Pathogens and pests pose significant threats to global crop productivity and plant immunity, necessitating urgent measures from researchers to prevent pathogen contamination and pest damage to crops. A natural plant-based antibacterial agent, eugenol (EUG), has demonstrated excellent antimicrobial and insect repellent capabilities, but the characteristics of volatilization and poor dissolution limit the practical application. The nanoization of pesticide formulations holds promise in the development of highly effective pesticides for antibacterial and insecticidal purposes. Herein, a eugenol-loaded nano delivery system (EUG@CMC-PGMA-CS) was synthesized using glycidyl methacrylate (GMA) as a functional monomer to connect carrier core structure carboxymethyl cellulose (CMC) with shell structure chitosan (CS), and EUG was encapsulated within the carrier. EUG@CMC-PGMA-CS demonstrated excellent leaf affinity, with minimum contact angles (CAs) of 37.83 and 70.52° on hydrophilic and hydrophobic vegetable leaf surfaces, respectively. Moreover, the maximum liquid holding capacity (LHC) of EUG@CMC-PGMA-CS on both hydrophilic and hydrophobic vegetable leaf surfaces demonstrates a noteworthy 55.24% enhancement compared to the LHC of pure EUG. The in vitro release curve of EUG@CMC-PGMA-CS exhibited an initial burst followed by stable sustained release. It is with satisfaction that the nano delivery system demonstrated exceptional antibacterial properties against S. aureus and satisfactory insecticidal efficacy against Spodoptera litura. The development of this eugenol-loaded nano delivery system holds significant potential for enhanced antibacterial and insect repellents in agriculture, paving the way for the application of volatile bioactive substances.

pH-responsive on-demand release of eugenol from metal-organic frameworks for synergistic bacterial killing

Bacterial infections are a big challenge in clinical treatment, making it urgent to develop innovative antibacterial systems and therapies to combat bacterial infections. In this study, we developed a novel MOF-based synergistic antibacterial system (Eu@B-UiO-66/Zn) by loading a natural antibacterial substance (eugenol) with hierarchically porous MOF B-UiO-66 as a carrier and further complexing it with divalent zinc ions. Results indicate that the system achieved a controlled release of eugenol under pH responsive stimulation, with the complexation ability of eugenol and Zn2+ ions as a switch. Due to the destruction of a coordination bond between eugenol and Zn2+ ions by an acidic medium, the release of eugenol loaded in Eu@B-UiO-66/Zn reached 80% at pH 5.8, which was significantly higher than that under pH 8.0 (51%). Moreover, the inhibitory effect of Eu@B-UiO-66/Zn against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) after 24 h was 96.4% and 99.7%, respectively, owing to the synergistic antibacterial effect of eugenol and Zn2+ ions, which was significantly stronger than free eugenol and Eu@B-UiO-66. We hope that this strategy for constructing responsive MOF-based antibacterial carriers could have potential possibilities for the application of MOF materials in antibacterial fields.

Self-assembly of sophorolipid and eugenol into stable nanoemulsions for synergetic antibacterial properties through alerting membrane integrity

Exploring the natural, safe, and effective antimicrobial is one of the preferable ways to control foodborne bacteria. In this work, novel oil-in-water nanoemulsions were formulated with sophorolipids and eugenol without any co-surfactant using a self-assembling strategy. These nanoemulsions showed high stability with sizes less than 200 nm when exposure to low concentrations of salt ions, various pH values (5.0, 7.0, 10.0), storage temperature and time. The synergistic antibacterial effects against both Gram-negative Escherichia coli and Gram-positive Bacillus cereus were determined with a minimum inhibitory concentration (MIC) value of 0.5 mg/mL and 0.125 mg/mL, respectively. Further microscopy (SEM, TEM, LCSM) examination and ATP/Na+-K+-ATPase assay results showed that the morphological changes, intensive cell membrane permeability, leakage of ATP, and decreased Na+-K+-ATPase contributed to the antibacterial effects. Moreover, the bonding mechanism between nanoemulsions and cell membranes were further evaluated by FTIR and ITC using a DPPC vesicle model, which demonstrated that the nanoemulsions adsorbed on the surface of bilayer, interacted with the hydrophobic chains of DPPC membrane mainly through the hydrophobic interaction, and altered the structural integrity of the lipid bilayer. These results not only provide a facile green strategy for fabricating stable nanoemulsions, but also highlight a new perspective for stabilizing essential oils for their widely application in food industry.

Pharmacodynamic, pharmacokinetic, toxicity, and recent advances in Eugenol's potential benefits against natural and chemical noxious agents: A mechanistic review

The active biological phytochemicals, crucial compounds employed in creating hundreds of medications, are derived from valuable and medicinally significant plants. These phytochemicals offer excellent protection from various illnesses, including inflammatory disorders and chronic conditions caused by oxidative stress. A phenolic monoterpenoid known as eugenol (EUG), it is typically found in the essential oils of many plant species from the Myristicaceae, Myrtaceae, Lamiaceae, and Lauraceae families. One of the main ingredients of clove oil (Syzygium aromaticum (L.), Myrtaceae), it has several applications in industry, including flavoring food, pharmaceutics, dentistry, agriculture, and cosmeceuticals. Due to its excellent potential for avoiding many chronic illnesses, it has lately attracted attention. EUG has been classified as a nonmutant, generally acknowledged as a safe (GRAS) chemical by the World Health Organization (WHO). According to the existing research, EUG possesses notable anti-inflammatory, antioxidant, analgesic, antibacterial, antispasmodic, and apoptosis-promoting properties, which have lately gained attention for its ability to control chronic inflammation, oxidative stress, and mitochondrial malfunction and dramatically impact human wellness. The purpose of this review is to evaluate the scientific evidence from the most significant research studies that have been published regarding the protective role and detoxifying effects of EUG against a wide range of toxins, including biological and chemical toxins, as well as different drugs and pesticides that produce a variety of toxicities, throughout view of the possible advantages of EUG.

Succinylated starch emulsified Eugenol and Carvacrol nanoemulsions improved digestive stability, bio-accessibility and Salmonella typhimurium inhibition

The ultrasonically processed Eugenol (EU) and Carvacrol (CAR) nanoemulsions (NE) were successfully optimized via response surface methodology (RSM) to achieve broad spectrum antimicrobial efficacy. These NE were prepared using 2 % (w/w) purity gum ultra (i.e., succinylated starch), 10 % (v/v) oil phase, 80 % (800 W) sonication power, and 10 min of processing time as determined via RSM. The second order Polynomial method was suitable to RSM with a co-efficient of determination >0.90 and a narrow polydispersity index (PDI) ranging 0.12-0.19. NE had small droplet sizes (135.5-160 nm) and low volatility at high temperatures. The EU & CAR entrapment and heat stability (300 °C) confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Further, the volatility of EU & CAR NE was 18.18 ± 0.13 % and 12.29 ± 0.11 % respectively, being lower than that of bulk/unencapsulated EU & CAR (i.e., 23.48 ± 0.38 % and 19.11 ± 0.08 %) after 2 h at 90 °C. Interestingly, both EU & CAR NE showed sustained release behaviour till 48 h. Their digest could inhibit Salmonella typhimurium (S. typhimurium) via membrane disruption and access to cellular machinery as evident from SEM images. Furthermore, in-vivo bio-accessibility of EU & CAR in mice serum was up to 80 %. These cost-effective and short-processed EU/CAR NE have the potential as green preservatives for food industry.

DNA binding peptide CF-14 enhances bactericidal efficacy of eugenol/carvacrol nanoparticles to Escherichia coli

To evaluate the bactericidal action of antimicrobial peptide CF-14, Eugenol (EU) and carvacrol (CAR) nanoparticles (NPs) less than 200 nm were surface-modified with CF14, gaining approximately 200 nm of EU-CF and CAR-CF NPs with swollen morphology. EU-CF and CAR-CF NPs were bactericidal to E. coli at dosage of 0.09% and 0.07% (v/v), respectively; while they were just bacteriostatic to Staphylococcus aureus at 0.10% and 0.08% (v/v). Spectral variations in bacterial carbohydrates (1185-900 cm-1), lipids (3000-2800 cm-1) and DNA (1500-1185 cm-1) were obvious as evident from Fourier transform infrared spectroscopy (FTIR). A higher percentage of membrane damaged (non-revivable) E. coli than S. aureus was found, which indicated electrostatic interactions between Gram-negative E. coli with cationic CF conjugated NPs leading to DNA disintegration. Interestingly, EU-CF and CAR-CF NPs inhibited E. coli growth in orange juice without impacting flavour compounds.

Antioxidant Capacity of Eugenol and Its Effect on Intestinal Flora Under in Vitro Simulated Conditions

In northern China, clove is a common plant. Its extracted eugenol exhibits a variety of biological properties, including antioxidant and antibacterial effects. This study looked at eugenol's antioxidant potential and its impact on the flora in the intestinal tract of humans. Eugenol's ability to scavenge superoxide anions and 2,2-biphenyl-1-picrylhydrazyl (DPPH) radicals, as well as its impact on the growth of common intestinal bacteria Lactobacillus and Escherichia coli, were studied at various eugenol concentrations. The results showed that different optimal antioxidant concentrations of eugenol existed for different free radicals, and the optimal antioxidant concentrations for DPPH and superoxide anion were 0.16 μL/mL and 0.04 μL/mL, respectively. Low concentrations of eugenol had no significant inhibitory effect on Lactobacillus but a significant inhibitory effect on E. coli. This research is anticipated to offer a theoretical reference for the use of eugenol in specialized dietary food applications.

Potential dual inhibition of SE and CYP51 by eugenol conferring inhibition of Candida albicans: Computationally curated study with experimental validation

Ergosterol is the key sterol component in the cell membrane of fungi including moulds and yeasts. Any decrease in the levels of ergosterol in the cell membrane of fungi render them venerable to cell membrane damage and even its death. Majority of antifungal drug targets the key enzymes involved in ergosterol biosynthesis pathway. The biochemical pathway for the synthesis of Ergosterol is a complex one, though the reactions carried by Squalene Epoxidase (SE) and 14α-demethylase (CYP51- a member of Cytochrome P450 family) serves to the key rate limiting reactions that can impact the overall production of Ergosterol. Allylamines class of antifungal drug target SE while Azoles target the CYP51. Currently advancement in the drug development is focused to introduce newer drugs that can simultaneously inhibit both this rate limiting enzymes. However, natural compounds established to possess antifungal activity but the major loophole about their understanding lies in the fact that their mode of action are severely unstudied. One such well-established antifungal natural phytochemical is Eugenol, and in current manuscript we investigated its efficacy to interact with both, SE and CYP51 of Candida albicans using molecular Docking, Free energy change calculations and Molecular Dynamics (MD) simulation, showing promising outcomes. For experimental studies, terbinafine, clotrimazole and eugenol showed 4 μg/ml, 2 μg/ml, and 512 μg/ml MIC₉₀ values, respectively against C. albicans and also showed reduction in Ergosterol production at sub-MIC levels. The obtained result indicates the involvement of eugenol in the inhibition of enzymes require in the ergosterol biosynthesis pathway.

BdorOBP69a is involved in the perception of the phenylpropanoid compound methyl eugenol in oriental fruit fly (Bactrocera dorsalis) males

The oriental fruit fly (Bactrocera dorsalis) is a devastating fruit pest that infests more than 450 plant species. Methyl eugenol (ME) has been used as male attractant to monitor and eradicate B. dorsalis populations for 70 years, but the molecular basis of its activity remains largely unclear. Previously, BdorOBP83b and BdorOBP56f-2 as odorant binding proteins (OBPs) were identified responsible for ME perception. In this study, ME-induced expression profiles and in vitro binding assays revealed that BdorOBP69a is also produced in response to ME and binds directly to it with strong affinity (K_d = 9.54 μM). BdorOBP69a^-/- null mutants generated by CRISPR/Cas9 mutagenesis showed significantly lower electroantennogram and behavioral responses to ME than wild-type controls. Molecular docking analysis followed by site-directed mutagenesis showed that residues Leu89 and Phe145 are essential for the interaction between BdorOBP69a and ME. BdorOBP69a is therefore an important component involved in the perception of ME in B. dorsalis and a promising molecular target for the development of new male attractants. The molecular docking and binding assay data also provide an important reference for future OBP gene manipulation and ME chemical engineering to improve the efficiency of male attractants.

Screening of bioactive ingredients of Tsantan Sumtang in ameliorating H9c2 cells injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tsantan Sumtang (TS), a traditional Tibetan medicine, has been used in the clinic for the treatment of myocardial ischemia (MI) for ages, however, the bioactive ingredients that are responsible for improving MI remain unknown.

AIM OF THE STUDY

This study investigated the chemical components of TS and their medicinal efficacies at cell levels, in order to expound the bioactive ingredients in TS.

MATERIALS AND METHODS

First, a response-surface methodology was employed to determine the optimum ethanol reflux extraction process of polyphenols in TS (PTS) due to their close correlation with MI improvement. Second, a serum pharmacochemistry technique was used to analyze the compounds of PTS absorbed into the blood of rats. Third, hypoxia-, H₂O₂-, and adriamycin (ADM)-induced H9c2 cell injury models were used to investigate the cardioprotective effects of these compounds in vitro. Fourth, protective effects of isovitexin, quercitrin, and isoeugenol on mitochondrial function were further tested.

RESULTS

The optimum extraction conditions for obtaining PTS were an ethanol concentration of 78.22%, an extraction time of 67.4 min, and a material-liquid ratio of 1:72.60 mL/g. Serum pharmacochemistry analysis detected 21 compounds, of which 11 compounds were always present in the blood within 5 h. Cytotoxicity and the protective effect of 11 compounds in hypoxia-, H₂O₂-, and ADM-induced H9c2 cell injury models shown that isovitexin, quercitrin, and isoeugenol had almost no cytotoxicity, and they could elevate the survival rate in injured H9c2 cells. Furthermore, isovitexin, quercitrin, and isoeugenol could decrease mitochondrial reactive oxygen species (ROS) releasion, inhibite mitochondrial permeability transition pore (mPTP) opening, ameliorate the change of mitochondrial membrane potential (MMP) to exert mitochondrial protection effect.

CONCLUSION

Isovitexin, quercitrin, and isoeugenol exhibited cardioprotective effect at cell levles, these three compounds might be the bioactive ingredients in TS. These findings elucidate the pharmacodynamic substances and mechanisms of TS, guiding its clinical use.

High Performance Liquid Chromatography versus Stacking-Micellar Electrokinetic Chromatography for the Determination of Potentially Toxic Alkenylbenzenes in Food Flavouring Ingredients

Alkenylbenzenes, including eugenol, methyleugenol, myristicin, safrole, and estragole, are potentially toxic phytochemicals, which are commonly found in foods. Occurrence data in foods depends on the quality of the analytical methodologies available. Here, we developed and compared modern reversed-phase high performance liquid chromatography (HPLC) and stacking-micellar electrokinetic chromatography (MEKC) methods for the determination of the above alkenylbenzenes in food flavouring ingredients. The analytical performance of HPLC was found better than the stacking-MEKC method. Compared to other HPLC methods found in the literature, our method was faster (total run time with conditioning of 15 min) and able to separate more alkenylbenzenes. In addition, the analytical methodology combining an optimized methanol extraction and proposed HPLC was then applied to actual food flavouring ingredients. This methodology should be applicable to actual food samples, and thus will be vital to future studies in the determination of alkenylbenzenes in food.

Anticancer Properties of Eugenol: A Review

Conventional cancer treatments have shown several unfavourable adverse effects, as well as an increase in anticancer drug resistance, which worsens the impending cancer therapy. Thus, the emphasis is currently en route for natural products. There is currently great interest in the natural bioactive components from medicinal plants possessing anticancer characteristics. For example, clove (Syzygium aromaticum L.) (Family Myrtaceae) is a highly prized spice that has been historically utilized as a food preservative and for diverse medical uses. It is reckoned amongst the valued sources of phenolics. It is indigenous to Indonesia but currently is cultivated in various places of the world. Among diverse active components, eugenol, the principal active component of S. aromaticum, has optimistic properties comprising antioxidant, anti-inflammatory, and anticancer actions. Eugenol (4-allyl-2-methoxyphenol) is a musky oil that is mainly obtained from clove. It has long been utilized all over the world as a result of its broad properties like antioxidant, anticancer, anti-inflammatory, and antimicrobial activities. Eugenol continues to pique investigators’ interest because of its multidirectional activities, which suggests it could be used in medications to treat different ailments. Anticancer effects of eugenol are accomplished by various mechanisms like inducing cell death, cell cycle arrest, inhibition of migration, metastasis, and angiogenesis on several cancer cell lines. Besides, eugenol might be utilized as an adjunct remedy for patients who are treated with conventional chemotherapy. This combination leads to a boosted effectiveness with decreased toxicity. The present review focuses on the anticancer properties of eugenol to treat several cancer types and their possible mechanisms.

Comparison of Aging Resistance and Antimicrobial Properties of Ethylene-Norbornene Copolymer and Poly(Lactic Acid) Impregnated with Phytochemicals Embodied in Thyme (Thymus vulgaris) and Clove (Syzygium aromaticum)

The effects of plant-based extracts on the solar aging and antimicrobial properties of impregnated ethylene-norbornene (EN) copolymer and poly(lactic acid) (PLA) were investigated. In this study, the impregnation yield of polyolefin, lacking in active centers capable of phytochemical bonding, and polyester, abundant in active sides, was measured. Moreover, two different extracts plentiful in phytochemicals-thyme (TE) and clove (CE)-were employed in the solvent-based impregnation process. The effect of thymol and eugenol, the two main compounds embodied in the extracts, was studied as well. Interestingly, oxidation induction times (OIT) for the impregnation of EN with thyme and clove extracts were established to be, respectively, 27.7 and 39.02 min, which are higher than for thymol (18.4 min) and eugenol (21.1 min). Therefore, an aging experiment, mimicking the full spectrum of sunlight, was carried out to investigate the resistance to common radiation of materials impregnated with antioxidative substances. As expected, the experiment revealed that the natural extracts increased the shelf-life of the polymer matrix by inhibiting the degradation processes. The aging resistance was assessed based on detected changes in the materials' behavior and structure that were examined with Fourier-transform infrared spectroscopy, contact angle measurements, color quantification, tensile tests, and hardness investigation. Such broad results of solar aging regarding materials impregnated with thyme and clove extracts have not been reported to date. Moreover, CE was found to be the most effective modifying agent for enabling material with antimicrobial activity against Escherichia coli to be obtained.

Methoxyeugenol deactivates hepatic stellate cells and attenuates liver fibrosis and inflammation through a PPAR-ɣ and NF-kB mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Studies have shown interest in nutraceuticals for the prevention of liver diseases. Methoxyeugenol, is a molecule found in foods, such as nutmeg (Myristica fragrans Houtt.) and Brazilian red propolis. These two sources of methoxyeugenol, propolis and nutmeg, are used in folk medicine for the treatment of hepatic and gastrointestinal disorders, although little is known about their effects on the prevention of liver fibrosis. Natural PPAR (Peroxisome proliferator-activated receptor) agonists would represent unique molecules for therapy, considering the lack of therapeutics to treat liver fibrosis in chronic liver disease. Thus, investigation on new alternatives are necessary, including the search for natural compounds from renewable and sustainable sources. Liver fibrosis is a pathological process characterized by an exacerbated cicatricial response in the hepatic tissue, which compromises liver function. Therefore, inhibition of HSC (hepatic stellate cell) activation and hepatocyte damage are considered major strategies for the development of new anti-fibrotic treatments.

AIM OF THE STUDY

This study aimed to investigate the effects of methoxyeugenol treatment on HSC phenotype modulation in human and murine cells, hepatocyte damage prevention, and protective effects in vivo, in order to evaluate its therapeutic potential for liver fibrosis prevention.

METHODS

We investigated the effects of methoxyeugenol in (i) in vitro models using human and murine HSC and hepatocytes, and (ii) in vivo models of CCl₄ (carbon tetrachloride) -induced liver fibrosis in mice.

RESULTS

We herein report that methoxyeugenol decreases HSC activation through the activation of PPAR-ɣ, ultimately inducing a quiescent phenotype highlighted by an increase in lipid droplets, loss of contraction ability, and a decrease in the proliferative rate and mRNA expression of fibroblast markers. In addition, methoxyeugenol prevented hepatocytes from oxidative stress damage. Moreover, in mice submitted to chronic liver disease through CCl₄ administration, methoxyeugenol decreased the inflammatory profile, liver fibrosis, mRNA expression of fibrotic genes, and the inflammatory pathway signaled by NF-kB (Nuclear factor kappa B).

CONCLUSION

We propose methoxyeugenol as a novel and potential therapeutic approach to treat chronic liver disease and fibrosis.

Amino Alcohols from Eugenol as Potential Semisynthetic Insecticides: Chemical, Biological, and Computational Insights

A series of β-amino alcohols were prepared by the reaction of eugenol epoxide with aliphatic and aromatic amine nucleophiles. The synthesized compounds were fully characterized and evaluated as potential insecticides through the assessment of their biological activity against Sf9 insect cells, compared with a commercial synthetic pesticide (chlorpyrifos, CHPY). Three derivatives bearing a terminal benzene ring, either substituted or unsubstituted, were identified as the most potent molecules, two of them displaying higher toxicity to insect cells than CHPY. In addition, the most promising molecules were able to increase the activity of serine proteases (caspases) pivotal to apoptosis and were more toxic to insect cells than human cells. Structure-based inverted virtual screening and molecular dynamics simulations demonstrate that these molecules likely target acetylcholinesterase and/or the insect odorant-binding proteins and are able to form stable complexes with these proteins. Encapsulation assays in liposomes of DMPG and DPPC/DMPG (1:1) were performed for the most active compound, and high encapsulation efficiencies were obtained. A thermosensitive formulation was achieved with the compound release being more efficient at higher temperatures.

Pharmacological Properties and Health Benefits of Eugenol: A Comprehensive Review

The biologically active phytochemicals are sourced from edible and medicinally important plants and are important molecules being used for the formulation of thousands of drugs. These phytochemicals have great benefits against many ailments particularly the inflammatory diseases or oxidative stress-mediated chronic diseases. Eugenol (EUG) is a versatile naturally occurring molecule as phenolic monoterpenoid and frequently found in essential oils in a wide range of plant species. EUG bears huge industrial applications particularly in pharmaceutics, dentistry, flavoring of foods, agriculture, and cosmeceutics. It is being focused recently due to its great potential in preventing several chronic conditions. The World Health Organization (WHO) has declared EUG as a nonmutant and generally recognized as safe (GRAS) molecule. The available literature about pharmacological activities of EUG shows remarkable anti-inflammatory, antioxidant, analgesic, and antimicrobial properties and has a significant effect on human health. The current manuscript summarizes the pharmacological characteristics of EUG and its potential health benefits.

Variability of the Chemical Composition and Bioactivity between the Essential Oils Isolated from Male and Female Specimens of Hedyosmum racemosum (Ruiz & Pav.) G. Don

Hedyosmum racemosum (Ruiz & Pav.) G. is a native species of Ecuador used in traditional medicine for treatment of rheumatism, bronchitis, cold, cough, asthma, bone pain, and stomach pain. In this study, fresh H. racemosum leaves of male and female specimens were collected and subjected to hydrodistillation for the extraction of the essential oil. The chemical composition of male and female essential oil was determined by gas chromatography–gas chromatography equipped with a flame ionization detector and coupled to a mass spectrometer using a non-polar and a polar chromatographic column. The antibacterial activity was assayed against five Gram-positive and two Gram-negative bacteria, and two dermatophytes fungi. The scavenging radical properties of the essential oil were evaluated by DPPH and ABTS assays. The chemical analysis allowed us to identify forty-three compounds that represent more than 98% of the total composition. In the non-polar and polar column, α-phellandrene was the principal constituent in male (28.24 and 25.90%) and female (26.47 and 23.90%) essential oil. Other main compounds were methyl chavicol, germacrene D, methyl eugenol, and α-pinene. Female essential oil presented a strong activity against Klebsiella pneumoniae (ATCC 9997) with an minimum inhibitory concentration (MIC) of 500 μg/mL and a scavenging capacity SC₅₀ of 800 µg/mL.

Anti-oomycetes and immunostimulatory activity of natural plant extract compounds against Saprolegnia spp.: Molecular docking and in-vitro studies

This study aimed to investigate the effectiveness of five natural plant extract compounds Curcumin (CUR); Eugenol (EUG), Cinnamaldehyde (CIN), Stigmasterol (ST) and Morin (MOR), on two species of Saprolegnia; Saprolegnia parasitica and S. australis. Selective compounds were screened for the minimum inhibitory concentration, first for anti-oomycetes activity and then mycelium growth inhibition, spore germination inhibition and colonisation test. Nitric oxide production and myeloperoxidase activity of the compounds were tested in head kidney leukocytes of rainbow trout, Oncorhynchus mykiss to assess the immunostimulatory potential. Molecular docking of effective compounds was carried out with effector proteins of S. parasitica to investigate the target binding sites. Among all, CUR could completely inhibit zoospore production and significantly (p ≤ .05) inhibit hyphal growth at 16 mg l^-1 against S. parasitica and S. australis. CIN at the concentration of 50 mg l^-1 completely inhibited hyphal growth of both Saprolegnia spp., although the zoospore production of S. parasitica and S. australis was reduced at 25 mg l^-1 and 10 mg l^-1. In the case of EUG, significant inhibition of the hyphal growth and germination of S. parasitica zoospores was observed at 50 mg l^-1. ST and MOR did not show antioomycetes activity. The molecular docking results were consistent with in vitro studies, possibly due to the binding with the vital proteins (Plasma membrane ATPase, V-type proton ATPase, TKL protein kinase, Host targeting protein 1) of S. parasitica and ultimately inhibiting their activity. CUR and CIN showed increased nitric oxide production at the highest concentration of 250 and 256 mg l^-1 but the value was not significant (p ≤ .05) with control. CUR showed significantly higher peroxidase activity (p ≤ .05) at a concentration of 256 mg l^-1 though values were significantly similar with concentration from 16 to 128 mg l^-1. The nitric oxide and total peroxidase activity of rainbow trout leukocytes in the case of CIN showed a significant difference only at 250 mg l^-1 against the control. The results conclude that CUR, CIN showed the better anti-Saprolegnia activity and could be used as phyto-additives in aquaculture. Among all, the inclusion of CUR as phyto-additives will provide additional immunostimulatory activity.

Suggestions on the Contribution of Methyl Eugenol and Eugenol to Bay Laurel (Laurus nobilis L.) Essential Oil Preservative Activity through Radical Scavenging

The present study examined the radical scavenging potential of the two benzene derivatives found in the bay laurel essential oil (EO), namely methyl eugenol (MEug) and eugenol (Eug), theoretically and experimentally to make suggestions on their contribution to the EO preservative activity through such a mechanism. Calculation of appropriate molecular indices widely used to characterize chain-breaking antioxidants was carried out in the gas and liquid phases (n-hexane, n-octanol, methanol, water). Experimental evidence was based on the DPPH^• scavenging assay applied to pure compounds and a set of bay laurel EOs chemically characterized with GC-MS/FID. Theoretical calculations suggested that the preservative properties of both compounds could be exerted through a radical scavenging mechanism via hydrogen atom donation. Eug was predicted to be of superior efficiency in line with experimental findings. Pearson correlation and partial least square regression analyses of the EO antioxidant activity values vs. % composition of individual volatiles indicated the positive contribution of both compounds to the radical scavenging activity of bay laurel EOs. Eug, despite its low content in bay laurel EOs, was found to influence the most the radical scavenging activity of the latter.

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.

Pharmacokinetic Study of Safrole and Methyl Eugenol after Oral Administration of the Essential Oil Extracts of Asarum in Rats by GC-MS

Asarum is a traditional medicine and has been widely used as remedies for inflammatory diseases, toothache, headache, local anesthesia, and aphthous stomatitis in China, Japan, and Korea. Our previous research found that safrole and methyl eugenol were vital compounds that contribute to distinguish the different species and raw Asarum and its processed products apart. The pharmacokinetics of safrole and methyl eugenol after oral administration of Asarum extract has not been reported yet. In this study, a rapid and simple gas chromatography-mass spectroscopy (GC-MS) method that has a complete run time of only 4.5 min was developed and validated for the simultaneous determination and pharmacokinetic study of safrole and methyl eugenol in rat plasma after administration of Asarum extracts. The chromatographic separation was realized on a DB-17 column (30 m × 0.25 mm × 0.25 μm). And detection was carried out under selected ion monitoring (SIM) mode. Plasma samples were pretreated by n-hexane. The pharmacokinetic parameters provided by this study will be beneficial for further developments and clinical applications of Asarum.

OBP2 in the Midlegs of the Male Bactrocera dorsalis Is Involved in the Perception of the Female-Biased Sex Pheromone 4-Allyl-2,6-dimethoxyphenol

Short-range semiochemicals convey individual-specific information, which is important for final successful courtship and copulation. In this study, an electroantennography (EAG) instrument was used to determine the legs of male Bactrocera dorsalis that might participate in the perception of 4-allyl-2,6-dimethoxyphenol (4-DMP), a female-biased cuticular hydrocarbon (CHC) component. By performing comparative RNA-seq analysis, nine differentially expressed OBPs between 4-DMP-stimulated (M_4-DMP) and unstimulated (M) male flies were screened out. Among the four downregulated OBPs, BdorOBP2 exhibited the strongest binding to 4-DMP than BdorOBP4, BdorOBP19a, and BdorOBP56h. Functional analyses confirmed that the reduction in transcript abundance of BdorOBP2 led to a significant decrease in behavioral responses of male flies to 4-DMP. In silico simulation revealed dramatic changes in the key residues and conformation between the two complexes, implying that BdorOBP2 might activate different receptors after binding to 4-DMP or methyl eugenol (ME). The results of this study suggest that BdorOBP2 mediates behavioral responses to 4-DMP and could be a promising molecular target for strategies of pest control.

Sweet Basil Has Distinct Synthases for Eugenol Biosynthesis in Glandular Trichomes and Roots with Different Regulatory Mechanisms

Production of a volatile phenylpropene; eugenol in sweet basil is mostly associated with peltate glandular trichomes (PGTs) found aerially. Currently only one eugenol synthase (EGS), ObEGS1 which belongs to PIP family is identified from sweet basil PGTs. Reports of the presence of eugenol in roots led us to analyse other EGSs in roots. We screened for all the PIP family reductase transcripts from the RNA-Seq data. In vivo functional characterization of all the genes in E. coli showed their ability to produce eugenol and were termed as ObEGS2-8. Among all, ObEGS1 displayed highest expression in PGTs and ObEGS4 in roots. Further, eugenol was produced only in the roots of soil-grown plants, but not in roots of aseptically-grown plants. Interestingly, eugenol production could be induced in roots of aseptically-grown plants under elicitation suggesting that eugenol production might occur as a result of environmental cues in roots. The presence of ObEGS4 transcript and protein in aseptically-grown plants indicated towards post-translational modifications (PTMs) of ObEGS4. Bioinformatics analysis showed possibility of phosphorylation in ObEGS4 which was further confirmed by in vitro experiment. Our study reveals the presence of multiple eugenol synthases in sweet basil and provides new insights into their diversity and tissue specific regulation.

In Vitro and In Vivo Evidence for RNA Adduction Resulting from Metabolic Activation of Methyleugenol

Methyleugenol (ME) is a ubiquitous component in spices and other culinary herbal products. A prevailing theory in ME toxicity is its ability to be metabolically activated by P450 enzymes and sulfotransferases, which initiates sequential reactions of the resulting metabolites with functional biomolecules. The present study aimed at a potential interaction between the reactive metabolites of ME and RNA. Cultured mouse primary hepatocytes were incubated with ME followed by RNA extraction and NaOH and alkaline phosphatase-based RNA hydrolysis. Three adenosine adducts were detected in the hydrolytic mixture by LC-MS/MS. The same adenosine adducts were also detected in hepatic tissues harvested from ME-treated mice. These three adducts were chemically synthesized and structurally characterized by ¹H NMR. Additionally, two guanosine adducts and one cytidine adduct were detected in the in vivo samples. These results provided solid evidence that the reactive metabolites of ME attacked RNA, resulting in RNA adduction.

Evaluation of Antioxidant and Anti-α-glucosidase Activities of Various Solvent Extracts and Major Bioactive Components from the Seeds of Myristica fragrans

Myristica fragrans is a well-known species for flavoring many food products and for formulation of perfume and medicated balm. It is also used to treat indigestion, stomach ulcers, liver disorders, and, as emmenagogue, diaphoretic, diuretic, nervine, and aphrodisiac. We examined antioxidant properties and bioactive compounds in various solvent extracts from the seeds of M. fragrans. Methanol, ethanol, and acetone extracts exhibited relatively strong antioxidant activities by 2,2-diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), superoxide radical, and hydroxyl radical scavenging tests. Furthermore, methanol extracts also displayed significant anti-α-glucosidase activity. Examined and compared to the various solvent extracts for their chemical compositions using HPLC analysis, we isolated the ten higher content compounds and analyzed antioxidant and anti-α-glucosidase activities. Among the isolates, dehydrodiisoeugenol, malabaricone B and malabaricone C were main antioxidant components in seeds of M. fragrans. Malabaricone C exhibited stronger antioxidant capacities than others based on lower half inhibitory concentration (IC₅₀) values in DPPH and ABTS radical scavenging assays, and it also showed significant inhibition of α-glucosidase. These results shown that methanol was found to be the most efficient solvent for extracting the active components from the seeds of M. fragrans, and this material is a potential good source of natural antioxidant and α-glucosidase inhibitor.

Effects of Cinnamon (Cinnamomum spp.) in Dentistry: A Review

Dental medicine is one of the fields of medicine where the most common pathologies are of bacterial and fungal origins. This review is mainly focused on the antimicrobial effects of cinnamon essential oil (EO), cinnamon extracts, and pure compounds against different oral pathogens and the oral biofilm and the possible effects on soft mouth tissue. Basic information is provided about cinnamon, as is a review of its antimicrobial properties against the most common microorganisms causing dental caries, endodontic and periodontal lesions, and candidiasis. Cinnamon EO, cinnamon extracts, and pure compounds show significant antimicrobial activities against oral pathogens and could be beneficial in caries and periodontal disease prevention, endodontics, and candidiasis treatment.

Eugenol and liposome-based nanocarriers loaded with eugenol protect against anxiolytic disorder via down regulation of neurokinin-1 receptors in mice

Anxiety disorder is a psychiatric disorder characterized by extreme fear or worry. It is highly prevalent worldwide which affects daily life and is also an enormous health burden. Neurokinin 1 receptor (NK1R) is a G protein coupled receptor, expressed in both central and peripheral nervous system, involved in affective behaviors. NK1R has established role in anxiety and it is also an important target for pathogenesis of anxiety disorder. Therefore, it has been hypothesized in previous studies that the blockades of NK1R may have antidepressant and anxiolytic effects. The present study deals with the molecular mechanism of protective activity of eugenol against anxiolytic disorder. A pre-clinical animal study was performed on 42 BALB/c mice. Animals were given stress through conventional restrain model. The mRNA expression of NK1R was analyzed by real time RT-PCR. Moreover, the NK1R protein expression was also examined by immunohistochemistry in whole brain and mean density was calculated. The mRNA and protein expressions were found to be increased in animals given anxiety as compared to the normal control. Whereas, the expressions were decreased in the animals treated with eugenol and its liposome-based nanocarriers in a dose dependent manner. However, the results were better in animals treated with nanocarriers as compared to the compound alone. It is concluded that the eugenol and its liposome-based nanocarriers exert anxiolytic activity by down-regulating NK1R protein expression in mice.

Photoinduced Polymerization of Eugenol-Derived Methacrylates

Biobased monomers have been used to replace their petroleum counterparts in the synthesis of polymers that are aimed at different applications. However, environmentally friendly polymerization processes are also essential to guarantee greener materials. Thus, photoinduced polymerization, which is low-energy consuming and solvent-free, rises as a suitable option. In this work, eugenol-, isoeugenol-, and dihydroeugenol-derived methacrylates are employed in radical photopolymerization to produce biobased polymers. The polymerization is monitored in the absence and presence of a photoinitiator and under air or protected from air, using Real-Time Fourier Transform Infrared Spectroscopy. The polymerization rate of the methacrylate double bonds was affected by the presence and reactivity of the allyl and propenyl groups in the eugenol- and isoeugenol-derived methacrylates, respectively. These groups are involved in radical addition, degradative chain transfer, and termination reactions, yielding crosslinked polymers. The materials, in the form of films, are characterized by differential scanning calorimetry, thermogravimetric, and contact angle analyses.

Surfactantless Emulsions Containing Eugenol for Imidacloprid Solubilization: Physicochemical Characterization and Toxicity against Insecticide-Resistant Cimex lectularius

Synthetic insecticides have been used for a long time as one of the most effective tools for insect pest control. However, the re-emergence of insect pests and their fast development of resistance, as has occurred for pyrethroid-resistant bed bugs Cimex lectularius L., make it necessary to develop new and safe strategies for effective pest control. This has fostered the research on new eco-sustainable formulations based on essential oils, which allows reducing the impact associated with the intensive use of synthetic insecticides on the environment and their effects on human health. This research explores the stability of water/eugenol/ethanol surfactantless emulsions loaded with imidacloprid (0.003 wt%), and their toxicity against a resistant bed bug strain. The results have shown that these emulsions enable the solubilization of a poorly water-soluble drug, such as the imidacloprid, without any significant modification of their stability. Furthermore, the application of the obtained formulations against the pyrethroid-resistant bed bug results in mortality in the 50-85% range upon topical and spray applications, with the increase of the eugenol content enhancing the effectiveness of the formulations. It may be expected that the ternary water/eugenol/ethanol mixtures could be further developed in the preparation of ready to use formulations, enabling the dispersion of insecticides for pest control.

Cytisus scoparius and Ulex europaeus Produce Volatile Organic Compounds with Powerful Synergistic Herbicidal Effects

New herbicides based on natural products are claimed to address weed resistance and environmental concerns related to synthetic herbicides. In our previous studies, certain volatile organic compounds (VOCs) produced by Ulex europaeus and Cytisus scoparius were argued to be responsible for the phytotoxicity of both shrub species. Interactions among VOCs were hypothesized to explain the inconsistency between the effects of the identified pure compounds and those naturally emitted from fresh plant material. In this work, eugenol, verbenone, terpinen-4-ol, α-terpineol, and linalool were assayed as binary mixtures of Amaranthus retroflexus and Digitaria sanguinalis. Powerful synergistic inhibitory effects were revealed for germination and early growth. Only 3.1 ppm of verbenone was enough to inhibit A. retroflexus germination when paired to other VOCs. Eugenol was capable of exacerbating the effects of terpinen-4-ol on A. retroflexus, even though it was innocuous when acting alone at 12.5 ppm. The verbenone and linalool pair produced very significant synergistic effects in terms of D. sanguinalis germination. The synergistic effects were predominantly irreversible for D. sanguinalis, since seeds exposed to paired VOCs were unable to recover their germination capacity after removing the phytotoxins or produced damaged seedlings. Both shrub species have been revealed as sources of natural herbicide molecules, with promising synergistic modes of action that deserve to be studied in depth.

Discovery of novel West Nile Virus protease inhibitor based on isobenzonafuranone and triazolic derivatives of eugenol and indan-1,3-dione scaffolds

The West Nile Virus (WNV) NS2B-NS3 protease is an attractive target for the development of therapeutics against this arboviral pathogen. In the present investigation, the screening of a small library of fifty-eight synthetic compounds against the NS2-NB3 protease of WNV is described. The following groups of compounds were evaluated: 3-(2-aryl-2-oxoethyl)isobenzofuran-1(3H)-ones; eugenol derivatives bearing 1,2,3-triazolic functionalities; and indan-1,3-diones with 1,2,3-triazolic functionalities. The most promising of these was a eugenol derivative, namely 4-(3-(4-allyl-2-methoxyphenoxy)-propyl)-1-(2-bromobenzyl)-1H-1,2,3-triazole (35), which inhibited the protease with IC50 of 6.86 μmol L-1. Enzyme kinetic assays showed that this derivative of eugenol presents competitive inhibition behaviour. Molecular docking calculations predicted a recognition pattern involving the residues His51 and Ser135, which are members of the catalytic triad of the WNV NS2B-NS3 protease.

Hybrid Ofloxacin/eugenol co-loaded solid lipid nanoparticles with enhanced and targetable antimicrobial properties

In the global context of an imminent emergence of multidrug-resistant microorganisms, the present work combined the use of nanotechnology and the therapeutic benefits of natural compounds as a strategy to potentiate antimicrobial action of the wide-spectrum antibiotic Ofloxacin (Ofx). Hybrid solid lipid nanoparticles (SLN) were synthesized by incorporation of chitosan (Chi, a cationic biopolymer with antimicrobial activity) and eugenol (Eu, a phenolic compound that interferes with bacterial quorum sensing) into a lipid matrix by hot homogenization/ultrasonication method. The developed SLN/Chi/Eu sustainably released the encapsulated Ofx for 24 h. Characterization by DLS, TEM, DSC, TGA and XRD revealed the presence of positively charged spherical nanoparticles with diameters around 300 nm and Ofx entrapped in amorphous state. The SLN exhibited an enhanced bactericidal activity against Pseudomonas aeruginosa and Staphylococcus aureus. The minimum inhibitory concentration (MIC) for free and nanoencapsulated Ofx formulations was below 1.0 µg/ml. The MIC values decreased by 6.1- to 16.1-fold when Ofx was encapsulated in SLN/Chi/Eu. Fluorescent-labeled nanoparticles had the ability to interact with the bacterial cell membrane. Selective toxicity of SLN/Chi/Eu-Ofx was tested in the range of 0.3-30.0 µg/ml and showed no toxicity up to 3.0 µg/ml Ofx in human cell models (A549 and Wi-38) at 24 h and 48 h exposure. It was proved that the administration of hybrid SLN to mice by dry powder inhalation reached therapeutic Ofx levels in lungs.

Mechanochemical Synthesis of CuO/MgAl2O4 and MgFe2O4 Spinels for Vanillin Production from Isoeugenol and Vanillyl Alcohol

CuO/MgAl₂O₄ and CuO/MgFe₂O₄ catalysts were successfully synthesized with the use of spinel supports by a very simple and low-cost mechanochemical method. High-speed ball-milling was used to synthesize these catalyst supports for the first time. Materials were subsequently characterized by using XRD, FESEM, TEM, EDS-Dot mapping, XPS, BET-BJH, and Magnetic Susceptibility to investigate the physical-chemical characteristics of the catalysts. Acidity evaluation results indicated that the catalyst with the Mg-Al spinel support had more acid sites. XRD results showed a successful synthesis of the catalysts with large crystal sizes. Both catalysts were used in isoeugenol oxidation and vanillyl alcohol to vanillin reactions, with the CuO/MgAl₂O₄ showing optimum results. This catalyst provided 67% conversion (74% selectivity) after 2 h and this value improved to 81% (selectivity 100%) with the second reaction after 8 h. The CuO/MgFe₂O₄ catalyst in the first reaction after five hours revealed 53% conversion (47% selectivity) and after eight hours with the second reaction, the conversion value improved to 64% (100% selectivity). In terms of reusability, CuO/MgAl₂O₄ showed better results than the CuO/MgFe₂O₄ catalyst, for both reactions.

Association of zein nanoparticles with botanical compounds for effective pest control systems

BACKGROUND

Botanical compounds from plant species are known to have pesticidal activity and have been used in integrated pest management programs. The varied spectrum of the pesticidal action of these compounds can also avoid selection of resistance in pest populations. In this study, mixtures of the botanical compounds geraniol, eugenol and cinnamaldehyde were encapsulated in zein nanoparticles to improve their stability and efficiency. Biological effects of the nano-scale formulations of the botanical compounds were evaluated against two agricultural pests: the two-spotted spider mite (Tetranychus urticae) and the soybean looper (Chrysodeixis includes).

RESULTS

The formulations were stable over time (120 days) with a high encapsulation efficiency (>90%). Nanoencapsulation also provided protection against degradation of the compounds during storage and led to a decrease in toxicity to non-target organisms. The release of the compounds (especially eugenol and cinnamaldehyde) from the nanoparticles was directly influenced by temperature, and the main mechanism of release was through a diffusion-based process. Nanoencapsulated compounds also showed superior efficiency compared to the emulsified compounds in terms of repellency and insecticidal activity.

CONCLUSION

The findings of this study indicate that the convergence of botanical compounds with nano-scale formulation has the potential to improve efficacy for their sustainable use in integrated pest management in agriculture. © 2019 Society of Chemical Industry.

Cardanol and Eugenol Based Flame Retardant Epoxy Monomers for Thermostable Networks

Epoxy materials have attracted attention for many applications that require fireproof performance; however, the utilization of hazardous reagents brings about potential damage to human health. Eugenol and cardanol are renewable, harmless resources (according to ECHA) that allow the achievement of synthesis of novel phosphorylated epoxy monomers to be used as reactive flame retardants. These epoxy building blocks are characterized by ¹H NMR and ³¹P NMR (nuclear magnetic resonance) and reacted with a benzylic diamine to give bio-based flame-retardant thermosets. Compared to DGEBA (Bisphenol A Diglycidyl Ether)-based material, these biobased thermosets differ by their cross-linking ratio, the nature of the phosphorylated function and the presence of an aliphatic chain. Eugenol has led to thermosets with higher glass transition temperatures due to a higher aromatic density. The flame-retardant properties were tested by thermogravimetric analyses (TGA), a pyrolysis combustion flow calorimeter (PCFC) and a cone calorimeter. These analyses demonstrated the efficiency of phosphorus by reducing significantly the peak heat release rate (pHRR), the total heat release (THR) and the effective heat of combustion (EHC). Moreover, the cone calorimeter test exhibited an intumescent phenomenon with the residues of phosphorylated eugenol thermosets. Lastly, the higher flame inhibition potential was highlighted for the phosphonate thermoset.

Novel eugenol bearing oxypropanolamines: Synthesis, characterization, antibacterial, antidiabetic, and anticholinergic potentials

Five oxypropanol amine derivatives that four of them are novel have been synthesized with high yields and practical methods. in vitro antibacterial susceptibility of Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus strains to synthesized substances were evaluated with agar well-diffusion method by comparison with commercially available drugs. Most of the bacteria were multidrug resistant. It was concluded that these compounds are much more effective than reference drugs. These eugenol bearing oxypropanolamine derivatives were also effective inhibitors against α-glycosidase, cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) enzymes with K_i values in the range of 0.80 ± 0.24-3.52 ± 1.01 µM for hCA I, 1.08 ± 0.15-3.64 ± 0.92 µM for hCA II, 5.18 ± 0.84-12.46 ± 2.08 µM for α-glycosidase, and 11.33 ± 2.83-32.81 ± 9.73 µM for AChE, respectively.

Antifungal Activity of Eugenol Derivatives against Botrytis Cinerea

Botrytis cinerea is a worldwide spread fungus that causes the grey mold disease, which is considered the most important factor in postharvest losses in fresh fruit crops. Consequently, the control of gray mold is a matter of current and relevant interest for agricultural industries. In this work, a series of phenylpropanoids derived from eugenol were synthesized and characterized. Their effects on the mycelial growth of a virulent and multi-resistant isolate of B. cinerea (PN2) have been evaluated and IC₅₀ values for the most active compounds range between 31⁻95 ppm. The antifungal activity exhibited by these compounds is strongly related to their chemical structure, i.e., increasing activity has been obtained by isomerization of the double bond or introduction of a nitro group on the aromatic ring. Based on the relationship between the fungicide activities and chemical structure, a mechanism of action is proposed. Finally, the activity of these compounds is higher than that reported for the commercial fungicide BC-1000 that is currently employed to combat this disease. Thus, our results suggest that these compounds are potential candidates to be used in the design of new and effective control with inspired natural compounds of this pathogen.

Evaluation of cytotoxicity, genotoxicity and ecotoxicity of nanoemulsions containing Mancozeb and Eugenol

Mancozeb is a fungicide widely used in agriculture, mostly against the pathogen Glomerella cingulata responsible for the rot of ripe grape, but presents high toxicity. Strategies are sought to reduce the toxicity of this fungicide and alternative treatments are welcome. An alternative could be the use of clove oil, which has Eugenol as its major compound, and has antifungal potential against G. cingulata, however, Eugenol is susceptible to degradation processes which may compromise its efficacy. The nanoencapsulation of Mancozeb and Eugenol is a possible strategy to overcome the limitations of toxicity, solubility and instability of these compounds. Therefore, the objective of this study is to develop nanoemulsions containing Mancozeb (0.1 mg/mL) and Eugenol (33 mg/mL), isolated or associated, and evaluate the safety of these formulations through cytotoxicity, genotoxicity and ecotoxicity tests. Nanoemulsions were developed by the spontaneous emulsification method, cytotoxicity and genotoxicity were evaluated in healthy human cells through MTT, Dichlorofluorescein diacetate and Picogreen tests, and ecotoxicity assessment was carried out using the chronic toxicity test in springtails. After preparation, the physicochemical characterization of the nanoemulsions were performed which presented mean particle size between 200 and 300 nm, polydispersity index less than 0.3, negative zeta potential and acid pH. The nanoencapsulation was able to avoid the reduction of the cell viability caused by Mancozeb, while Eugenol was shown to be safe for cell use in both free and nanostructured forms, however the association of the two active compounds showed toxicity in the higher doses of Mancozeb. In the ecotoxicity tests, both free Mancozeb and Eugenol forms presented high toxic potential for soil, whereas the nanoencapsulation of these compounds did not cause a reduction in number of springtails. Therefore, from the tests performed, it was possible to observe that nanoencapsulation of Mancozeb and Eugenol is a safe alternative for the application of these compounds mainly in agriculture.

Determination of kinetic parameters of the enzymatic reaction between soybean peroxidase and natural antioxidants using chemometric tools

The oxidation of eugenol, isoeugenol and vanillin natural antioxidants catalyzed by the soybean peroxidase enzyme was studied using uv-vis spectroscopy. An experimental design was used to optimize the different variables. The multivariate curve resolution method was used to obtain the profiles of antioxidant absorbance's as a function of time due to uv-vis absorption bands of both antioxidants and the enzymatic reaction product/s show a strong overlap. From these results, apparent Michaelis-Menten constants as well as the kinetic parameters k1 and k3 involved in the catalytic cycle of peroxidases were calculated. The antioxidant apparent acidity constants were also determined at different pH's from uv-vis spectrophotometric measurements. Values of k1 were (0.6 ± 0.1) × 105 M-1 s-1, (2.0 ± 0.2) × 105 M-1 s-1 and (7.0 ± 0.5) × 106 M-1 s-1 and k3 (4.0 ± 0.2) × 105 M-1 s-1, (6.0 ± 0.6) × 105 M-1 s-1 and (6.0 ± 0.9) × 106 M-1 s-1 for eugenol, isoeugenol and vanillin, respectively.

Enhancement in Antibacterial Activities of Eugenol-Entrapped Ethosome Nanoparticles via Strengthening Its Permeability and Sustained Release

The antibacterial efficiency and synergistic mechanisms of novel formulated eugenol entrapped ethosome nanoparticles (ELG-NPs) against fruit anthracnose were investigated. The results showed that concentrations of eugenol and ethanol significantly influenced the particle size and entrapment efficiency of nanoethosome, and the particle size significantly influenced the antibacterial effect. Superior ELG-NPs with optimized process (0.5% eugenol, 2% lecithin, and 30% ethanol) were obtained with a size of 44.21 nm and entrapment efficiency of 82%. ELG-NPs exhibited an antibacterial activity (>93%) against fruit pathogens that was greater than that of free eugenol and showed 100% inhibition of the anthracnose incidence in postharvest loquat after 6 d. The permeability study, first visualized in banana cortex with fluorescent indicators, demonstrated that eugenol delivered to the interior with ELG-NPs was 6-fold higher than that of free eugenol. ELG-NPs showed a satisfactory slow-release and prolonged antibacterial action. This work provides a promising strategy for disease controls in agricultural, food, cosmetic, and medical areas.

Antimicrobial, antioxidant and sensory features of eugenol, carvacrol and trans-anethole in active packaging for organic ready-to-eat iceberg lettuce

In this study, bio-based emitting sachets containing eugenol (EUG), carvacrol (CAR) and trans-anethole (ANT) were inserted into cellulose (CE) and polypropylene (PP) pillow packages of organic ready-to-eat (RTE) iceberg lettuce to investigate their functional features. EUG, CAR and ANT sachets in CE; and CAR in PP packages showed antimicrobial activities against coliforms (Δlog CFU g-1 of -1.38, -0.91, -0.93 and -0.93, respectively). EUG and ANT sachets in both packages reduced discoloration (ΔE of 9.5, 1.8, 9.4 and 5.6, respectively). ANT in both, and EUG only in PP packages induced biosynthesis of caffeoyl derivatives (CaTA, DiCaTA, DiCaQA), total phenolics and antioxidant activity (FRAP). Also, ANT and EUG in both packages improved overall freshness and odor. Principal component analysis separated ANT and EUG from CAR in both packages. The Pearson correlation confirmed that overall quality improvements were more pronounced by ANT inside the packages in comparison to EUG and CAR.

Heck Transformations of Biological Compounds Catalyzed by Phosphine-Free Palladium

The development and optimization of synthetic methods leading to functionalized biologically active compounds is described. Two alternative pathways based on Heck-type reactions, employing iodobenzene or phenylboronic acid, were elaborated for the arylation of eugenol and estragole. Cinnamyl alcohol was efficiently transformed to saturated arylated aldehydes in reaction with iodobenzene using the tandem arylation/isomerization sequential process. The arylation of cinnamyl alcohol with phenylboronic acid mainly gave unsaturated alcohol, while the yield of saturated aldehyde was much lower. Catalytic reactions were carried out using simple, phosphine-free palladium precursors and water as a cosolvent, following green chemistry rules as much as possible.

Theoretical Study of the β-Cyclodextrin Inclusion Complex Formation of Eugenol in Water

The interaction between eugenol and β-cyclodextrin in the presence of water is studied by molecular mechanics and dynamics simulations. A force field model is used in molecular mechanics to determine the interaction energy and the complex configuration at the absolute minimum. The van der Waals term is the main contribution to the total energy, and so directly determines the configuration of the inclusion complex. The formation of inclusion complexes is simulated by molecular dynamics, in which their configurations are deduced from the position probability density that represents the preferred location and orientation of the guest in the simulation. When eugenol approaches from the rims of β-cyclodextrin, it tends to enter the cavity, remain inside for a short period and then exit from it. The guest tends to include the phenyl ring inside the cavity in the most probable configurations. Two inclusion complex configurations are proposed, each with the hydroxyl and methoxyl groups pointing towards one different rim of β-cyclodextrin. The initial guest orientation is the main factor determining these configurations. The model presented in this study reproduces the experimental findings on inclusion complex formation and proposes two possible complex configurations, one previously suggested by different authors.

Identification and Quantitation of Potent Odorants in Spearmint Oils

Potent odorants in Native spearmint, Scotch spearmint, and Macho mint oils were determined by the combined use of gas chromatography-olfactometry (GCO), gas chromatography-mass spectrometry (GC-MS), and aroma extract dilution analysis (AEDA). Of the 85 odorants detected, ( R)-(-)-carvone was the most potent odorant in all three spearmint oils. Additional predominant odorants in all spearmint oils included eugenol, ethyl ( S)-(+)-2-methylbutanoate, ( E)-β-damascenone, and (3 E,5 Z)-1,3,5-undecatriene. Forty-six compounds were quantitated using various methods, including 19 by gas chromatography with flame ionization detection (GC-FID), 20 by stable isotope dilution analysis (SIDA), and 14 by GCO dilution analysis. Concentrations were used to calculate the odor activity values (OAVs) for predominant odorants in the oils. Among the compounds quantitated, those with the highest OAVs were ( R)-(-)-carvone, 1,8-cineole, ( E, Z)-2,6-nonadienal, ( E)-β-damascenone, and (3 E,5 Z)-1,3,5-undecatriene.

Influence of Eugenol on the Organization and Dynamics of Lipid Membranes: A Phase-Dependent Study

Eugenol is known for its antimicrobial effects against microorganisms responsible for infectious diseases in humans, food-borne pathogens, and oral pathogens. In spite of several reports on the antimicrobial function of eugenol by modulating the structural properties of cell membranes, there is limited information on the influence of eugenol in the lipid membrane. In this work, we explored the effect of eugenol on the organization and dynamics of large unilamellar vesicles (LUVs) of DMPC using the intrinsic fluorescence of eugenol and an extrinsic hydrophobic probe, DPH, in varying phases. The organization and dynamics of the bilayers of DMPC vesicles were monitored by utilizing varieties of steady-state and time-resolved fluorescence measurements. Our results show that eugenol stabilizes the gel phase and elevates the phase-transition temperature of DMPC in a concentration-dependent fashion. Fluorescence lifetime measurements demonstrate that higher eugenol-induced water penetration was observed in fluid-phase membranes. Time-resolved anisotropy measurements demonstrate that eugenol reduces the semiangle of DPH wobbling-in-a-cone in gel-phase membranes, whereas the semiangle remains unaffected in fluid-phase membrane. This implies that the eugenol further orders the gel-phase membrane, and this could be a plausible reason for the eugenol-dependent elevation of the phase-transition temperature of DMPC. We envisage that these results will contribute important information to understand the interaction of eugenol with biological membranes.

Continuous-Flow Synthesis of Supported Magnetic Iron Oxide Nanoparticles for Efficient Isoeugenol Conversion into Vanillin

This work presents the synthesis of iron oxide nanocatalysts supported on mesoporous Al-SBA-15 by using a continuous-flow setup. The magnetic nanomaterials were tested as catalysts in the oxidative disruption of isoeugenol by using hydrogen peroxide as a green oxidant, featuring high activities (63-88 % conversion) and good selectivities to vanillin (44-68 %). The catalytic systems exhibited good magnetic properties when synthesized under continuous-flow conditions at temperatures not exceeding 190 °C. The use of microwave irradiation significantly reduced times of reaction drastically but exerted negative effects on catalyst reusability.

Fabrication of Electrospun Eugenol/Cyclodextrin Inclusion Complex Nanofibrous Webs for Enhanced Antioxidant Property, Water Solubility, and High Temperature Stability

In this study, inclusion complexes (IC) of three cyclodextrin derivatives (HP-β-CD, HP-γ-CD, and M-β-CD) with eugenol (essential oil compound) were formed in highly concentrated aqueous solutions and then transformed into self-standing functional nanofibrous webs by electrospinning. The improved aqueous solubility of eugenol was confirmed by phase solubility diagrams, in addition, the phase solubility tests also revealed 1:1 molar ratio complexation between host:guest molecules; CD:eugenol. Even though eugenol has a volatile nature, a large amount of eugenol (∼70-95%) was preserved in eugenol/cyclodextrin inclusion complex nanofibrous webs (eugenol/CD/IC-NW). Moreover, enhanced thermal stability of eugenol was recorded for eugenol/CD/IC-NW (up to ∼310 °C) when compared to pure form of eugenol (up to ∼200 °C). The eugenol/CD/IC-NW exhibited fast dissolving behavior in water, contrary to poorly water-soluble eugenol. It was observed that the complexation between M-β-CD and eugenol was the strongest when compared to other two host CD molecules (HP-β-CD and HP-γ-CD) for eugenol/CD/IC-NW samples. The electrospun eugenol/CD/IC-NW samples have shown enhanced antioxidant activity compared to pure form of eugenol. In summary, cyclodextrin inclusion complexes of essential oil compounds, such as eugenol, in the form of self-standing nanofibrous webs may have potentials for food and oral-care applications due to their particularly large surface area along with fast-dissolving character, improved water solubility, high temperature stability, and enhanced antioxidant activity.

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by ¹H NMR, ¹³C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL^-1. Most of the tested compounds presented MIC values ≤220 μg mL^-1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

In vitro and in vivo activities of eugenol against tobacco black shank caused by Phytophthora nicotianae

Phytophthora nicotianae causes serious black shank disease in tobacco. Syringa oblata essential oil and its main components were evaluated to develop an effective and environmentally friendly biocontrol agent. Eugenol, which exhibited the strongest activity, was intensively investigated in vitro and in vivo. The mycelial growth of P. nicotianae was inhibited by eugenol at a minimum inhibitory concentration of 200μgmL-1, and inhibition occurred in a dose-dependent manner. Extracellular pH and extracellular conductivity results indicated that eugenol increased membrane permeability. Flow cytometry and fluorescent staining results further showed that eugenol disrupted mycelial membranes but did not affect spore membrane integrity. The in vivo results confirmed that treatment of tobacco with various concentrations of eugenol formulations reduced disease incidence and better controlled against the disease. Our results suggested that the ability of eugenol to control tobacco black shank depended on its ability to damage mycelial membranes and that eugenol formulations have potential as an eco-friendly antifungal agent for controlling tobacco blank shank.