Pharmacokinetics of eugenol and its effects on thermal hypersensitivity in rats

Eugenol as a potential adjuvant therapy for gingival squamous cell carcinoma

Adoption of plant-derived compounds for the management of oral cancer is encouraged by the scientific community due to emerging chemoresistance and conventional treatments adverse effects. Considering that very few studies investigated eugenol clinical relevance for gingival carcinoma, we ought to explore its selectivity and performance according to aggressiveness level. For this purpose, non-oncogenic human oral epithelial cells (GMSM-K) were used together with the Tongue (SCC-9) and Gingival (Ca9-22) squamous cell carcinoma lines to assess key tumorigenesis processes. Overall, eugenol inhibited cell proliferation and colony formation while inducing cytotoxicity in cancer cells as compared to normal counterparts. The recorded effect was greater in gingival carcinoma and appears to be mediated through apoptosis induction and promotion of p21/p27/cyclin D1 modulation and subsequent Ca9-22 cell cycle arrest at the G0/G1 phase, in a p53-independent manner. At these levels, distinct genetic profiles were uncovered for both cell lines by QPCR array. Moreover, it seems that our active component limited Ca9-22 and SCC-9 cell migration respectively through MMP1/3 downregulation and stimulation of inactive MMPs complex formation. Finally, Ca9-22 behaviour appears to be mainly modulated by the P38/STAT5/NFkB pathways. In summary, we can disclose that eugenol is cancer selective and that its mediated anti-cancer mechanisms vary according to the cell line with gingival squamous cell carcinoma being more sensitive to this phytotherapy agent.

Study on mechanism of transdermal administration of eugenol for pain treatment by network pharmacology and molecular docking technology

The objective of this study was to explore the pharmacological mechanism of transdermal administration of eugenol (EUG) for pain treatment. Firstly, network pharmacology techniques were employed to identify the potential targets responsible for the analgesic effect of EUG. Subsequently, molecular docking technology was used to validate interactions between EUG and the crystal structure of the core target protein. Finally, the impact of EUG on the expression and activation of TRPV1 receptors in HaCaT cells was evaluated through in vitro experiments, thus confirming the analysis of network pharmacology. The study suggested that the transdermal administration of EUG for pain treatment might target the TRPV1 receptor. Molecular docking revealed that EUG could spontaneously bind to the TRPV1 receptor with a high binding ability. The analysis of Western blot (WB) and intracellular Ca2+ levels demonstrated that EUG could increase the expression of TRPV1 in HaCaT cells, activating TRPV1 to induce intracellular Ca2+ influx (P < 0.05). These findings suggested that the initial application of EUG would cause a brief stimulation of TRPV1 receptors and upregulation of TRPV1 expression. Upon continued exposure, EUG would act as a TRPV1 agonist, increasing intracellular Ca2+ levels that might be associated with desensitization of pain sensations.

Cardioprotective Effect of Eugenol Against Cd-Induced Inflammation, Oxidative Stress, and Dyslipidemia in Male Rats: An In Vivo and Molecular Docking Study

Cadmium, a highly toxic heavy metal, can cause severe damage to several vital organs including the kidney, liver, and brain. Many of the natural compounds found in aromatic plants have beneficial pharmacological properties. Eugenol is one such compound reported to have anti-inflammatory and antioxidant properties. The aim of this study is to investigate whether eugenol, a natural compound found in aromatic plants known for its anti-inflammatory and antioxidant properties, can mitigate the detrimental effects of cadmium exposure on cardiac inflammation, oxidative stress, and dyslipidemia. Male albino rats were subjected to randomization into four groups, each comprising six animals, to investigate the potential of eugenol in mitigating cadmium-induced toxicity. All groups received oral gavage treatment for 21 days. Following the treatment regimen, cardiac tissue specimens were collected for analysis. The assessment of cardiac antioxidant status entailed the determination of enzymatic activities including catalase, SOD, GST, and GPx. Additionally, levels of lipid peroxidation, reduced glutathione, protein carbonyl oxidation, and thiol levels were quantified in the cardiac tissue samples. To evaluate cardiac damage, marker enzymes such as LDH and CK-MB were measured. Furthermore, the inflammatory response in the cardiac tissue induced by cadmium exposure was assessed through the quantification of NO, TNF-α, and IL-6 levels. Additionally, molecular docking and dynamics studies were conducted utilizing autodock and GLIDE methodologies. Cadmium administration markedly enhanced the activities of LDH and CK-MB, prominent cardiac markers. Furthermore, cadmium treatment also demonstrated a significant decrease in the reduced glutathione levels and antioxidant enzyme activities. Significant elevation of the inflammatory markers was also observed in the cadmium-treated group. Eugenol treatment effectively ameliorates cadmium-induced biochemical changes. This study underscores the potent anti-inflammatory and antioxidant attributes of eugenol. Co-administration of eugenol alongside cadmium exhibited remarkable protective efficacy against cadmium-induced cardio-toxicity. Eugenol demonstrated the capability to reinstate the cellular redox equilibrium of rats subjected to cadmium treatment to levels akin to those of the normal control group.

Assessment of acute and subacute toxicity, pharmacokinetics, and biodistribution of eugenol nanoparticles after oral exposure in Wistar rats

The present study aimed to assess the safety, toxicity, biodistribution, and pharmacokinetics of eugenol nanoparticles (EONs) following oral administration in Wistar rat models. In the acute toxicity study, the rats were given a fixed dose of 50, 300, and 2000 mg/kg body weight per group orally and screened for 2 weeks after administration. In the subacute study, three different doses (500, 1000, and 2000 mg/kg BW) of EON were administered for 28 days. The results indicated no significant differences in food and water consumption, bodyweight change, hematological and biochemical parameters, relative organ weights, gross findings, or histopathology compared to the control. Additionally, no significant changes were observed in the expression profiles of inflammatory cytokines such as IL-1, IL-6, and TNFα in the plasma, confirming the absence of systemic inflammation. Biodistribution analysis revealed rapid absorption of eugenol and improved bioavailability due to gradual and sustained release, leading to a maximum eugenol concentration of 15.05 μg/mL (Cmax) at approximately 8 h (Tmax) in the blood plasma. Thus, the study provides valuable insights into the utilization of EON for enhancing the stability, solubility, and sustained release of eugenol and highlights its promising safety profile in vivo.

Targeting cardiovascular risk factors with eugenol: an anti-inflammatory perspective

Inflammation is a multifaceted biological reaction to a wide range of stimuli, and it has been linked to the onset and progression of chronic diseases such as heart disease, cancer, and diabetes. Inflammatory markers found in the blood, including C-reactive protein, serum amyloid A, fibrinogen, plasma viscosity, erythrocyte sedimentation rate, interleukin-6, and soluble adhesion molecules (like intercellular adhesion molecule-1 and vascular cell adhesion molecule-1), are risk factors for cardiovascular diseases such as coronary heart disease, stroke, and peripheral arterial disease. These markers play a crucial role in understanding and assessing cardiovascular health. Due to this complicated relationship between inflammation and cardiovascular disease, anti-inflammatory agents of natural origin have been the subject of many preclinical and clinical studies in recent years. Eugenol is a natural phenolic compound found in clove oil, nutmeg oil, cinnamon oil, and bay leaf oil, as well as other essential oils. Eugenol has been shown to have anti-inflammatory properties in many forms of experimental inflammation. It may scavenge free radicals, which contribute to inflammation and tissue damage. Various studies also suggest that eugenol can limit the production of inflammatory mediators such as prostaglandins, cytokines, and chemokines. Animal models of arthritis, colitis, and lung damage, as well as human clinical studies, have shown that eugenol has phenomenal anti-inflammatory properties. These properties suggest that eugenol may be able to reduce the risk of cardiovascular diseases.

Cannflavins isolated from Cannabis sativa impede Caenorhabditis elegans response to noxious heat

Cannflavins, flavonoids abundantly present in Cannabis sativa, possess a distinct chemical structure comprising a vanillyl group. Notably, the capsaicin structure also contains a vanillyl group, which is considered essential for interacting with the vanilloid receptor. The vanilloid receptor plays a crucial role in the perception of pain, heat, and inflammation and mediates the analgesic effects of capsaicin. Therefore, we postulated that prolonged exposure to cannflavin A (Can A) and cannflavin B (Can B) would provoke vanilloid receptor desensitization and hinder nocifensive responses to noxious thermal stimuli. C. elegans wild-type (N2) and mutants were exposed to Can A and Can B solutions for 60 min and then aliquoted on Petri dishes divided into quadrants for thermal stimulation. We then determined the thermal avoidance index for each C. elegans experimental group. Proteomics was performed to identify proteins and pathways associated with Can A or B treatment. Prolonged exposure to Can A and Can B hindered heat avoidance (32-35 °C) in C. elegans. No antinociceptive effect was observed 6 h post Can A or B exposure. Proteomics and Reactome pathway enrichment analyses identified hierarchical differences between Can A- and B-treated nematodes. However, both treatments were related to eukaryotic translation initiation (R-CEL-72613) and metabolic processes strongly associated with pain development. Our study aids in characterizing the pharmacological activity of cannflavins isolated from Cannabis sativa and outlines a possible application as pain therapy.

Eugenol works synergistically with colistin against colistin-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae isolates by enhancing membrane permeability

Colistin is a potent antibiotic for the treatment of carbapenem-resistant Gram-negative bacteria and is considered a last-resort drug. Unfortunately, the incidence of colistin-resistant bacteria isolated from patients is continuously growing due to clinical reuse of colistin. In this study, we found that the combination of colistin and eugenol has a significant synergistic antibacterial effect and reverses the sensitivity of colistin-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae against colistin, as confirmed by checkerboard and time-kill assays. Crystal violet staining and scanning electron microscopy revealed colistin and eugenol's synergistic antibiofilm action. Concerning the synergy mechanism, the results revealed that the combination of eugenol and colistin increases membrane permeability and causes considerable membrane damage, further inhibiting bacteria synergistically. Meanwhile, up to 500 µg/mL of eugenol is non-toxic to RAW 264.7 cells, and the colistin/eugenol combination is also efficacious in vivo, as demonstrated by the Galleria mellonella infection model. Our findings indicate that the colistin/eugenol combination is a viable treatment option for colistin-resistant P. aeruginosa and K. pneumoniae clinical infections. IMPORTANCE Colistin is used as a last resort for severe infections caused by multidrug-resistant Gram-negative bacteria, however, colistin resistance is increasing. As a result, we investigated the synergistic effect of eugenol/colistin combination, and the results revealed significant antibacterial and antibiofilm action. Eugenol may help clinical colistin-resistant Pseudomonas aeruginosa and Klebsiella pneumoniae recover their susceptibility. These findings suggest that combining eugenol and colistin may be a viable treatment option for colistin-resistant pathogen clinical infections.

Pharmacokinetic and Permeation Studies in Rat Brain of Natural Compounds Led to Investigate Eugenol as Direct Activator of Dopamine Release in PC12 Cells

Eugenol, cinnamaldehyde and D-limonene, the main components of natural essential oils, are endowed with antioxidant and anti-inflammatory properties which allow them to induce beneficial effects on intestinal, cardiac and neuronal levels. In order to characterize their pharmacokinetic profiles and aptitude to permeate in the central nervous system after intravenous and oral administration to rats, new analytical procedures, easily achievable with HPLC-UV techniques, were developed. The terminal half-lives of these compounds range from 12.4 ± 0.9 (D-limonene) and 23.1 ± 1.6 min (cinnamaldehyde); their oral bioavailability appears relatively poor, ranging from 4.25 ± 0.11% (eugenol) to 7.33 ± 0.37% (cinnamaldehyde). Eugenol evidences a marked aptitude to permeate in the cerebrospinal fluid (CSF) of rats following both intravenous and oral administrations, whereas cinnamaldehyde appears able to reach the CSF only after intravenous administration; limonene is totally unable to permeate in the CSF. Eugenol was therefore recruited for in vitro studies of viability and time-/dose-dependent dopamine release in neuronal differentiated PC12 cells (a recognized cellular model mimicking dopaminergic neurons), evidencing its ability to increase cell viability and to induce dopamine release according to a U-shaped time-course curve. Moreover, concentration-response data suggest that eugenol may induce beneficial effects against Parkinson's disease after oral administration.

Eugenol, A Major Component of Clove Oil, Attenuates Adiposity and Modulates Gut Microbiota in High-Fat Diet-fed Mice

SCOPE

Eugenol (EU), the major aromatic compound derived from clove oil, is being focused recently due to its potential in preventing several chronic conditions. Herein, we aimed to evaluate the potential of EU in obesity prevention and to delineate the mechanisms involved.

METHODS AND RESULTS

Five-week-old male C57BL/6J mice were fed with high-fat diet (HFD) or HFD supplemented with EU (0.2%, w/w) for 13 weeks. EU significantly reduced obesity-related indexes including final body weight, body weight gain, adipocyte size, visceral fat-pad weight, and fasting blood glucose. EU prevented HFD-induced gut dysbiosis, as indicated by the increase of Firmicutes and decrease of Desulfobacterota at phylum level, and the increase of Dubosiella, Blautia, unclassified_f_Oscillospiraceae, and unclassified_f_Ruminococcaceae, and the decrease of Alistipes, Alloprevotella, and Bilophila at genus level. Notably, the obesity-related indexes were positively correlated with the relative abundances of Bacteroides, unclassified_f_Lachnospiraceae, Colidextribacter, and Bilophila, and negatively correlated with the relative abundances of norank_f_Muribaculaceae and Lachnospiraceae_NK4A136_group. Moreover, the preventive effects of EU on obesity were accompanied by the transcriptomic reprogramming of white adipose tissue.

CONCLUSION

These findings demonstrated that EU prevents the HFD-induced adiposity and modulates gut dysbiosis, and highlighted the potential of EU in obesity intervention as a functional dietary supplement. This article is protected by copyright. All rights reserved.

HPLC Fluorescence Method for Eugenols in Basil Products Derivatized with DIBI

Eugenols (Eugs) such as eugenol (Eug), methyleugenol (MeEug), and linalool (Lin) in basil product are the main bioactive components of basil products and have a terminal double-bond. A sensitive HPLC-fluorescence method for Eugs derivatized with 4-(4,5-diphenyl-1H-imidazol-2-yl)iodobenzene (DIBI) was developed. Good separation of DIB-Eugs was achieved within 20 min on an Atlantis T3 column (50 × 2.1 mm i.d., 3 µm) with a mobile phase of methanol-water. The calibration curves obtained with Eug standards showed good linearities in the range of 0.1-50 µM (r ≥ 0.999). The limits of detection at a signal-to-noise ratio (S/N) = 3 for Eug, MeEug, and Lin were 1.0, 6.0, and 4.8 nM, respectively. The limits of quantitation (S/N = 10) of the Eugs were lower than 19.9 nM. The accuracies for the Eugs were within 96.8-104.6%. The intra- and inter-day precisions as relative standard deviations for the Eugs were less than 1.2 and 9.6% (n = 3). The recoveries of Eug, MeEug, and Lin were 99.0 ± 0.1, 98.0 ± 0.2, and 96.0 ± 0.4% (n = 3), respectively. The DIB-Eugs were confirmed to be stable for 2 h (>90%) at room temperature and 24 h (>95%) at 4 °C. These parameters of the proposed method were useful for the simultaneous determination of Eugs in basil products. Therefore, the developed method may be a powerful tool for the quality evaluation of dried commercially available basil products.

Resiniferatoxin Hampers the Nocifensive Response of Caenorhabditis elegans to Noxious Heat, and Pathway Analysis Revealed that the Wnt Signaling Pathway is Involved

Resiniferatoxin (RTX) is a metabolite extracted from Euphorbia resinifera. RTX is a potent capsaicin analog with specific biological activities resulting from its agonist activity with the transient receptor potential channel vanilloid subfamily member 1 (TRPV1). RTX has been examined as a pain reliever, and more recently, investigated for its ability to desensitize cardiac sensory fibers expressing TRPV1 to improve chronic heart failure (CHF) outcomes using validated animal models. Caenorhabditis elegans (C. elegans) expresses orthologs of vanilloid receptors activated by capsaicin, producing antinociceptive effects. Thus, we used C. elegans to characterize the antinociceptive properties and performed proteomic profiling to uncover specific signaling networks. After exposure to RTX, wild-type (N2) and mutant C. elegans were placed on petri dishes divided into quadrants for heat stimulation. The thermal avoidance index was used to phenotype each tested C. elegans experimental group. The data revealed for the first time that RTX can hamper the nocifensive response of C. elegans to noxious heat (32 - 35 °C). The effect was reversed 6 h after RTX exposure. Additionally, we identified the RTX target, the C. elegans transient receptor potential channel OCR-3. The proteomics and pathway enrichment analysis results suggest that Wnt signaling is triggered by the agonistic effects of RTX on C. elegans vanilloid receptors.

Pharmacokinetic and tissue distribution study of eight volatile constituents in rats orally administrated with the essential oil of Artemisiae argyi Folium by GC-MS/MS

Artemisia argyi is commonly used as a remedy for gynecological and respiratory disease in traditional Chinese medicine. The essential oil is considered as the major active ingredients of A. argyi, mainly composed of eucalyptol, α-thujone, camphor, borneol, bornyl acetate, eugenol, β-caryophyllene, and caryophyllene oxide, while limited study addresses the in vivo disposition of these volatile ingredients. In present study, a rapid, sensitive and selective GC-MS/MS method has been developed and validated for the quantification of the eight volatile constituents in rat plasma and tissues after orally dosing with the essential oil of Artemisiae Argyi Folium (AAEO) using naphthalene as an internal standard (IS). The analytes were extracted from biosamples by liquid-liquid extraction with hexane/ethyl acetate. The GC separation was achieved on a TG-5SILMS column (30 m × 0.25 mm, 0.25 μm film thickness) and MS detection was performed on selective reaction monitoring (SRM) mode. The assay had a lower limit of quantification (LLOQ) less than 2 ng/ml for the analytes with good linearity (r ≥ 0.9907). Their disposition profile in rat plasma and tissues was characterized after orally giving AAEO, and the data revealed the analytes underwent rapid absorption from GI tract and were mainly transferred to the liver, heart, kidney, lung, and spleen with prompt elimination. The results provided a meaningful basis for guiding the pharmacodynamic study and clinical applications of this herbal medicine.

Protective effect of eugenol on hepatic inflammation and oxidative stress induced by cadmium in male rats

BACKGROUND

Cadmium is one of the most toxic heavy metals. The prolonged exposure of it can lead to severe alterations and damage in different tissues including blood, liver, kidney and brain. Eugenol, a phenolic compound, is present in various aromatic plants. It acts as a natural antioxidant and anti-inflammatory agent. The aim of this study was to investigate whether the treatment of eugenol is beneficial against the hepatic oxidative stress and inflammation induced by Cd.

METHODS

To study the effect of eugenol in reversal of Cd toxicity, 24 albino rats were equally divided into four different groups: G1 Control (saline), G2 Eugenol (3 mg kg-1), G3 CdCl2 (5 mg kg-1) and G4 CdCl2 + Eugenol (5 mg kg-1 + 3 mg kg-1). All the groups were treated with gavage orally for the period of 21 days. After this treatment period, rats were sacrificed and liver tissues were removed. The hepatic antioxidant status was evaluated by measuring the activities of SOD, Catalase and GST enzymes. The reduced glutathione, lipid peroxidation, protein carbonyl oxidation (PCO) and thiol contents were measured in hepatic tissues. The activities of liver marker enzymes such as ALT, AST, GGT, ALP, TP, albumin, Bilirubin content and LDH were determined to assess the hepatic damage in different groups. Cd induced hepatic inflammation was determined by evaluating the levels of TNF-a, IL-6 and NO.

RESULTS

Oral intoxication of Cd for 21 days significantly elevated the level of hepatic markers including activities of LDH, GGT, ALP, ALT, AST and Bilirubin level. The albumin content, reduced GSH level, and activities of antioxidant enzymes were significantly reduced in Cd treated group. The levels of inflammatory markers were significantly elevated in Cd treated group. The eugenol treatment was very effective and it significantly reversed the Cd induced biochemical alterations almost similar to that of control.

CONCLUSION

The results demonstrated that the eugenol possessed very strong anti-oxidative and anti-inflammatory potential. The co-treatment of eugenol with Cd exhibited protective potential of eugenol against Cd induced toxicity. Eugenol was able to improve the cellular redox system in rats treated with Cd.

Synergistic interaction between 4-allyl-1-hydroxy-2-methoxybenzene (eugenol) and diclofenac: An isobolograpic analysis in Wistar rats

Clinical and preclinical research that contributes pain palliation has suggested that drugs favor the expected effects and minimize the adverse effects. Among the most widely used strategies is the combination of analgesic drugs among those in the same group, with those in another group of analgesics or with co-adjuvants (nonanalgesic drugs or elements of traditional medicine). This work aims to evaluate the interaction between eugenol (EUG) and diclofenac (DFC) on nociception in the presence of a noxious stimulus through the formalin test and isobolographic analysis. The results indicate that EUG, DFC, or the combination of both produce an antinociceptive effect in rodents (p ≤ 0.05). Local co-administration of EUG and DFC gave a theoretical effective dose (Zadd ) 2,936.27 ± 155.33 μg/kg (p ≤ 0.05) significantly higher as compared to the effective experimental doses (Zmix ) of 866.89 ± 0.02 μg/kg in phase 1 and 292.88 ± 0.05 μg/kg in phase 2, with an interaction index of 0.29 and 0.09, respectively. These data allow concluding that the interaction derived from the joint administration of EUG and DFC, in the rodent at a local level, is synergistic.

In vitro and in vivo inhibition of HCT116 cells by essential oils from bark and leaves of Virola surinamensis (Rol. ex Rottb.) Warb. (Myristicaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Virola surinamensis (Rol. ex Rottb.) Warb. (Myristicaceae), popularly known in Brazil as "mucuíba", "ucuúba", "ucuúba-branca" or "ucuúba do igapó", is a medicinal plant used to treat a variety of diseases, including infections, inflammatory processes and cancer.

AIM OF THE STUDY

In the present work, we investigated the chemical constituents and the in vitro and in vivo inhibition of human colon carcinoma HCT116 cells by essential oils obtained from the bark (EOB) and leaves (EOL) of V. surinamensis.

MATERIALS AND METHODS

EOB and EOL were obtained by hydrodistillation and analyzed via gas chromatography with flame ionization detection and gas chromatography coupled to mass spectrometry. In vitro cytotoxic activity was determined in cultured cancer cells HCT116, HepG2, HL-60, B16-F10 and MCF-7 and in a non-cancerous cell line MRC-5 by the Alamar blue assay after 72 h of treatment. Annexin V/propidium iodide staining, mitochondrial transmembrane potential and cell cycle distribution were evaluated by flow cytometry in HCT116 cells treated with essential oils after 24 and 48 h of treatment. The cells were also stained with May-Grunwald-Giemsa to analyze cell morphology. In vivo antitumor activity was evaluated in C.B-17 SCID mice with HCT116 cells.

RESULTS

The main constituents in EOB were aristolene (28.0 ± 3.1%), α-gurjunene (15.1 ± 2.4%), valencene (14.1 ± 1.9%), germacrene D (7.5 ± 0.9%), δ-guaiene (6.8 ± 1.0%) and β-elemene (5.4 ± 0.6%). On the other hand, EOL displayed α-farnesene (14.5 ± 1.5%), β-elemene (9.6 ± 2.3%), bicyclogermacrene (8.1 ± 2.0%), germacrene D (7.4 ± 0.7%) and α-cubebene (5.6 ± 1.1%) as main constituents. EOB showed IC₅₀ values for cancer cells ranging from 9.41 to 29.52 μg/mL for HCT116 and B16-F10, while EOL showed IC₅₀ values for cancer cells ranging from 7.07 to 26.70 μg/mL for HepG2 and HCT116, respectively. The IC₅₀ value for a non-cancerous MRC-5 cell was 34.7 and 38.93 μg/mL for EOB and EOL, respectively. Both oils induced apoptotic-like cell death in HCT116 cells, as observed by the morphological characteristics of apoptosis, externalization of phosphatidylserine, mitochondrial depolarization and fragmentation of internucleosomal DNA. At a dose of 40 mg/kg, tumor mass inhibition rates were 57.9 and 44.8% in animals treated with EOB and EOL, respectively.

CONCLUSIONS

These data indicate V. surinamensis as possible herbal medicine in the treatment of colon cancer.

Eugenol and Other Vanilloids Hamper Caenorhabditis elegans Response to Noxious Heat

Eugenol, a known vanilloid, was frequently used in dentistry as a local analgesic in addition, antibacterial and neuroprotective effects were also reported. Eugenol, capsaicin and many vanilloids are interacting with the transient receptor potential vanilloid 1 (TRPV1) in mammals and the TRPV1 is activated by noxious heat. The pharmacological manipulation of the TRPV1 has been shown to have therapeutic value. Caenorhabditis elegans (C. elegans) express TRPV orthologs (e.g. OCR-2, OSM-9) and it is a commonly used animal model system to study nociception as it displays a well-defined and reproducible nocifensive behavior. After exposure to vanilloid solutions, C. elegans wild type (N2) and mutants were placed on petri dishes divided in quadrants for heat stimulation. Thermal avoidance index was used to phenotype each tested C. elegans experimental groups. The results showed that eugenol, vanillin and zingerone can hamper nocifensive response of C. elegans to noxious heat (32-35 °C) following a sustained exposition. Also, the effect was reversed 6 h post exposition. Furthermore, eugenol and vanillin did not target specifically the OCR-2 or OSM-9 but zingerone did specifically target the OCR-2 similarly to capsaicin. Further structural and physicochemical analyses were performed. Key parameters for quantitative structure-property relationships (QSPR), quantitative structure-activity relationships (QSAR) and frontier orbital analyses suggest similarities and dissimilarities amongst the tested vanilloids and capsaicin in accordance with the relative anti-nociceptive effects observed.

Natural Macromolecules as Carriers for Essential Oils: From Extraction to Biomedical Application

Essential oils (EOs) and their main constituents, the terpenes, are widely studied, mostly relating to their antioxidant ability and bioactivity, such as antimicrobial, anticancer, anti-inflammatory, and range of other actions in the living systems. However, there is limited information on their bioavailability, especially upon clinical studies. Having in mind both strong biological effects and health benefits of EOs and their specific physicochemical properties (volatility, lipophilic character, low water solubility or insolubility, viscosity, expressed odor, concentration-dependent toxicity, etc.), there is a need for their encapsulation for target delivery. Encapsulation of EOs and their constituents is the prerequisite for enhancing their oxidative stability, thermostability, photostability, shelf life, and biological activity. We considered various carrier types such a (1) monophase and polyphase polysaccharide hydrogel carriers, (2) polysaccharide-protein carriers, and (3) lipid carriers in the context of physicochemical and engineering factors. Physicochemical factors are encapsulation efficiency, chemical stability under gastric conditions, mechanical stability, and thermal stability of carrier matrices. Choice of carrier material also determines the encapsulation technique. Consequently, the engineering factors are related to the advantage and disadvantage of various encapsulation techniques frequently used in the literature. In addition, it was intended to address the interactions between (1) main carrier components, such as polysaccharides, proteins, and lipids themselves (in order to form chemically and mechanically stable structure); (2) main carrier components with pepsin under gastric conditions (in order to form resistant material under gastric conditions); and (3) main carrier components with EOs (in order to enhance encapsulation efficiency), as a necessary precondition for whole process optimization. Finally, different sources for obtaining natural carrier macromolecules are surveyed, especially the agro-waste materials and agricultural and food by-products. This review article highlights the bioavailability aspects of encapsulated EOs and physicochemical and engineering factors concerning natural macromolecule carriers for their target delivery and application.

A flexible and physically transient electrochemical sensor for real-time wireless nitric oxide monitoring

Real-time sensing of nitric oxide (NO) in physiological environments is critically important in monitoring neurotransmission, inflammatory responses, cardiovascular systems, etc. Conventional approaches for NO detection relying on indirect colorimetric measurement or built with rigid and permanent materials cannot provide continuous monitoring and/or require additional surgical retrieval of the implants, which comes with increased risks and hospital cost. Herein, we report a flexible, biologically degradable and wirelessly operated electrochemical sensor for real-time NO detection with a low detection limit (3.97 nmol), a wide sensing range (0.01-100 μM), and desirable anti-interference characteristics. The device successfully captures NO evolution in cultured cells and organs, with results comparable to those obtained from the standard Griess assay. Incorporated with a wireless circuit, the sensor platform achieves continuous sensing of NO levels in living mammals for several days. The work may provide essential diagnostic and therapeutic information for health assessment, treatment optimization and postsurgical monitoring.

Antioxidant, Anti-Inflammatory, and Microbial-Modulating Activities of Essential Oils: Implications in Colonic Pathophysiology

Essential oils (EOs) are a complex mixture of hydrophobic and volatile compounds synthesized from aromatic plants, most of them commonly used in the human diet. In recent years, many studies have analyzed their antimicrobial, antioxidant, anti-inflammatory, immunomodulatory and anticancer properties in vitro and on experimentally induced animal models of colitis and colorectal cancer. However, there are still few clinical studies aimed to understand their role in the modulation of the intestinal pathophysiology. Many EOs and some of their molecules have demonstrated their efficacy in inhibiting bacterial, fungi and virus replication and in modulating the inflammatory and oxidative processes that take place in experimental colitis. In addition to this, their antitumor activity against colorectal cancer models makes them extremely interesting compounds for the modulation of the pathophysiology of the large bowel. The characterization of these EOs is made difficult by their complexity and by the different compositions present in the same oil having different geographical origins. This review tries to shift the focus from the EOs to their individual compounds, to expand their possible applications in modulating colon pathophysiology.

Naturally Occurring PCSK9 Inhibitors

Genetic, epidemiological and pharmacological data have led to the conclusion that antagonizing or inhibiting Proprotein convertase subtilisin/kexin type 9 (PCSK9) reduces cardiovascular events. This clinical outcome is mainly related to the pivotal role of PCSK9 in controlling low-density lipoprotein (LDL) cholesterol levels. The absence of oral and affordable anti-PCSK9 medications has limited the beneficial effects of this new therapeutic option. A possible breakthrough in this field may come from the discovery of new naturally occurring PCSK9 inhibitors as a starting point for the development of oral, small molecules, to be used in combination with statins in order to increase the percentage of patients reaching their LDL-cholesterol target levels. In the present review, we have summarized the current knowledge on natural compounds or extracts that have shown an inhibitory effect on PCSK9, either in experimental or clinical settings. When available, the pharmacodynamic and pharmacokinetic profiles of the listed compounds are described.

Syzygium aromaticum L. (Myrtaceae): Traditional Uses, Bioactive Chemical Constituents, Pharmacological and Toxicological Activities

Herbal medicinal products have been documented as a significant source for discovering new pharmaceutical molecules that have been used to treat serious diseases. Many plant species have been reported to have pharmacological activities attributable to their phytoconstituents such are glycosides, saponins, flavonoids, steroids, tannins, alkaloids, terpenes, etc. Syzygium aromaticum (clove) is a traditional spice that has been used for food preservation and possesses various pharmacological activities. S. aromaticum is rich in many phytochemicals as follows: sesquiterpenes, monoterpenes, hydrocarbon, and phenolic compounds. Eugenyl acetate, eugenol, and β-caryophyllene are the most significant phytochemicals in clove oil. Pharmacologically, S. aromaticum has been examined toward various pathogenic parasites and microorganisms, including pathogenic bacteria, Plasmodium, Babesia, Theileria parasites, Herpes simplex, and hepatitis C viruses. Several reports documented the analgesic, antioxidant, anticancer, antiseptic, anti-depressant, antispasmodic, anti-inflammatory, antiviral, antifungal, and antibacterial activity of eugenol against several pathogenic bacteria including methicillin-resistant Staphylococcus epidermidis and S. aureus. Moreover, eugenol was found to protect against CCl_4-induced hepatotoxicity and showed a potential lethal efficacy against the multiplication of various parasites including Giardia lamblia, Fasciola gigantica, Haemonchus contortus, and Schistosoma mansoni. This review examines the phytochemical composition and biological activities of clove extracts along with clove essential oil and the main active compound, eugenol, and implicates new findings from gas chromatography-mass spectroscopy (GC-MS) analysis.

Effects of Eugenol on Pain Response to the Formalin Test and Plasma Antioxidant Activity in High Fructose Drinking Water in Male Rats

Background:

Increased consumption of fructose in recent years has increased the risk of developing metabolic syndrome. In this syndrome, induction of oxidative stress, cellular dysfunction, and decrease of antioxidant capacity can change response to pain. Therefore, this study aims to investigate the antinociceptive and antioxidant effects of eugenol on metabolic syndrome induced by a fructose-rich diet in rats.

Methods:

The rats were randomly assigned to five groups, to be under experiment for eight weeks. The first, control group, the second fructose 10% plus tween 0.5% (Fr + veh), the third fructose 10% (Fr), and the fourth fructose 10% plus a single dose of eugenol 100 mg/kg (Fr + EoS). However, the fifth obtained fructose 10% plus a continuous dose of eugenol 20 mg/kg/day (Fr + EoC) for the last 10 days of the experiment. After formalin test, blood samples were taken from the animals’ hearts followed by analysis for biochemical factors.

Results:

This study shows that fructose administration does not change any pain response and there are not any changes in pain response between Fr group and control group. However, treatment with single and continuous dose of eugenol in Fr + EoS and Fr + EoC groups significantly decreases response to pain in the first and second phase of formalin test in comparison with Fr group (P<0.05). Continuous does of eugenol improved serum malondialdehyde and total antioxidant capacity levels in Fr + Eoc group in comparison with Fr group.

Conclusions:

In the present work, new findings suggest the beneficial effects of eugenol in pain relief, improved serum glucose, insulin levels, and improved antioxidant activity in metabolic syndrome.

Systematic Overview of Bacopa monnieri (L.) Wettst. Dominant Poly-Herbal Formulas in Children and Adolescents

Background: The Ayurvedic medicinal system employs a holistic approach to health, utilising the synergistic properties of organic resources. Research into the Ayurvedic herb Bacopa monnieri (L.) Wettst. (B.monnieri) has reported improvements in cognitive outcomes in child and adult populations. The aim of current review is to systematically assess and critically summarize clinical trials investigating B.monnieri-dominant poly-herbal formulas and their effects on the cognition, memory, learning, and behaviour in children and adolescents. Methods: Key word searches were performed using PubMed, Scopus, Cochrane Library, DHARA, and CINAHL for publications meeting inclusion criteria up to November 2017. There were no restrictions in study design. Effect sizes were calculated for all significant findings to allow for direct comparisons, and each study was evaluated on design quality. Cognitive and behavioural outcomes were grouped into validated constructs for cross-study comparison. Results: Nine trials met inclusion criteria. Five studies reported sufficient data for effect size analysis with most improvements reported in behavioural outcomes. True cognitive abilities and behavioural constructs were reviewed in six studies, with visual perception, impulsivity, and attention demonstrating the greatest improvements. The veracity of the evidence for the formulations reviewed is weakened by inconsistent statistical design and under-reporting of safety and tolerability data (44%). Conclusions: The current review extends research supporting B.monnieri as a cognitive enhancer and provides modest evidence for the use of B.monnieri in poly-herbal preparations for improving cognitive and behavioural outcomes in child and adolescent populations. Greater emphasis on statistical vigour and the reporting of tolerability data are essential for future trials to adequately document poly-herbal treatment efficacy.

Pharmacological and Toxicological Properties of Eugenol

Eugenol is a volatile phenolic constituent of clove essential oil obtained from Eugenia caryophyllata buds and leaves. It is a functional ingredient of numerous products which have been used in the pharmaceutical, food and cosmetic industry in restricted concentrations. Its derivatives have been used in medicine as a local antiseptic and anesthetic. The wide range of eugenol activities includes antimicrobial, anti-inflammatory, analgesic and antioxidant. Although eugenol is considered safe as a product, due to the vast range of different applications and extensive use, there has been a great concern about its toxicity in recent years. However, studies about cytotoxicity and genotoxicity of eugenol are very limited and controversial. The pharmacological and toxicological properties of eugenol will be discussed in this review.

The Role of Eugenol in the Prevention of Acute Pancreatitis-Induced Acute Kidney Injury: Experimental Study

Aim. Acute pancreatitis is an inflammatory intra-abdominal disease, which takes a severe form in 15–20% of patients and can result in high mortality especially when complicated by acute renal failure. The aim of this study is to assess the possible reduction in the extent of acute kidney injury after administration of eugenol in an experimental model of acute pancreatitis. Materials and Methods. 106 male Wistar rats weighing 220–350 g were divided into 3 groups: (1) Sham, with sham surgery; (2) Control, with induction of acute pancreatitis, through ligation of the biliopancreatic duct; and (3) Eugenol, with induction of acute pancreatitis and eugenol administration at a dose of 15 mg/kg. Serum urea and creatinine, histopathological changes, TNF-α, IL-6, and MPO activity in the kidneys were evaluated at predetermined time intervals. Results. The group that was administered eugenol showed milder histopathological changes than the Control group, TNF-α activity was milder in the Eugenol group, and there was no difference in activity for MPO and IL-6. Serum urea and creatinine levels were lower in the Eugenol group than in the Control group. Conclusions. Eugenol administration was protective for the kidneys in an experimental model of acute pancreatitis in rats.

Antifungal activity and chemical composition of twenty essential oils against significant indoor and outdoor toxigenic and aeroallergenic fungi

Health affecting, loss-inducing or otherwise harmful fungal pathogens (molds) pose a serious challenge in many areas of human activities. On the contrary, frequent use of synthetic fungicides is undesirable in some cases and may be equally problematic. Moreover, the ever more increasing fungal resistance against commercial synthetic fungicides justifies development of rising efforts to seek new effective, while environmentally friendly alternatives. Botanical fungicides based on Essential oils (EOs) undoubtedly provide such an alternative. The study explores the efficacy of 20 EOs against Alternaria alternata, Stachybotrys chartarum, Cladosporium cladosporioides and Aspergillus niger, related to abundance of majority active substances. Minimum inhibitory concentration (MIC100 and MIC50) was evaluated. GC-MS analysis revealed high abundance of highly effective phenolic compounds whose different molecular structures correlates with differences in EOs efficacy. The efficacy of some EOs, observed in our study, can be similar to the levels of some synthetic fungicides used in medicine and agriculture e.g. sometimes problematic azole-based formulations. Thanks to the EOs environmental safety and natural origin, they offer the potential to become an alternative where the use of synthetic fungicides is impossible for various reasons.

Clove (Syzygium aromaticum): a precious spice

Clove (Syzygium aromaticum) is one of the most valuable spices that has been used for centuries as food preservative and for many medicinal purposes. Clove is native of Indonesia but nowadays is cultured in several parts of the world including Brazil in the state of Bahia. This plant represents one of the richest source of phenolic compounds such as eugenol, eugenol acetate and gallic acid and posses great potential for pharmaceutical, cosmetic, food and agricultural applications. This review includes the main studies reporting the biological activities of clove and eugenol. The antioxidant and antimicrobial activity of clove is higher than many fruits, vegetables and other spices and should deserve special attention. A new application of clove as larvicidal agent is an interesting strategy to combat dengue which is a serious health problem in Brazil and other tropical countries. Pharmacokinetics and toxicological studies were also mentioned. The different studies reviewed in this work confirm the traditional use of clove as food preservative and medicinal plant standing out the importance of this plant for different applications.

Essential oils loaded in nanosystems: a developing strategy for a successful therapeutic approach

Essential oils are complex blends of a variety of volatile molecules such as terpenoids, phenol-derived aromatic components, and aliphatic components having a strong interest in pharmaceutical, sanitary, cosmetic, agricultural, and food industries. Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, and other medicinal properties such as analgesic, sedative, anti-inflammatory, spasmolytic, and locally anaesthetic remedies. In this review their nanoencapsulation in drug delivery systems has been proposed for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano- and microemulsions. Furthermore, molecular complexes such as cyclodextrin inclusion complexes also represent a valid strategy to increase water solubility and stability and bioavailability and decrease volatility of essential oils.

TRP Channels Involved in Spontaneous L-Glutamate Release Enhancement in the Adult Rat Spinal Substantia Gelatinosa

The spinal substantia gelatinosa (SG) plays a pivotal role in modulating nociceptive transmission through dorsal root ganglion (DRG) neurons from the periphery. TRP channels such as TRPV1 and TRPA1 channels expressed in the SG are involved in the regulation of the nociceptive transmission. On the other hand, the TRP channels located in the peripheral terminals of the DRG neurons are activated by nociceptive stimuli given to the periphery and also by plant-derived chemicals, which generates a membrane depolarization. The chemicals also activate the TRP channels in the SG. In this review, we introduce how synaptic transmissions in the SG neurons are affected by various plant-derived chemicals and suggest that the peripheral and central TRP channels may differ in property from each other.

Targeted liquid chromatography quadrupole ion trap mass spectrometry analysis of tachykinin related peptides reveals significant expression differences in a rat model of neuropathic pain

Animal models are widely used to perform basic scientific research in pain. The rodent chronic constriction injury (CCI) model is widely used to study neuropathic pain. Animals were tested prior and after CCI surgery using behavioral tests (von Frey filaments and Hargreaves test) to evaluate pain. The brain and the lumbar enlargement of the spinal cord were collected from neuropathic and normal animals. Tachykinin related peptides were analyzed by high performance liquid chromatography quadrupole ion trap mass spectrometry. Our results reveal that the β-tachykinin₅₈₋₇₁, SP and SP₃₋₁₁ up-regulation are closely related to pain behavior. The spinal β-tachykinin₅₈₋₇₁, SP and SP₃₋₁₁ concentrations were significantly up-regulated in neuropathic animals compared with normal animals (p<0.001; p<0.001 and p<0.05, respectively). In contrast, the spinal SP5₅₋₁₁ concentration in neuropathic animals revealed a significant down-regulation compared with normal animals (p<0.05). The brain β-tachykinin₅₈₋₇₁ and SP concentrations were significantly up-regulated (p<0.05 and p<0.001, respectively). Interestingly, no significant concentration differences were observed in the spinal cord and brain for NKA, β-tachykinin₅₈₋₇₁, SP₁₋₇ and SP₆₋₁₁ (p>0.05). The β-tachykinin₅₈₋₇₁, SP and C-terminal SP metabolites could potentially serve as biomarkers in early drug discovery.

Fractionation of a herbal antidiarrheal medicine reveals eugenol as an inhibitor of Ca2+-Activated Cl- channel TMEM16A

The Ca²⁺-activated Cl⁻ channel TMEM16A is involved in epithelial fluid secretion, smooth muscle contraction and neurosensory signaling. We identified a Thai herbal antidiarrheal formulation that inhibited TMEM16A Cl⁻ conductance. C18-reversed-phase HPLC fractionation of the herbal formulation revealed >98% of TMEM16A inhibition activity in one out of approximately 20 distinct peaks. The purified, active compound was identified as eugenol (4-allyl-2-methoxyphenol), the major component of clove oil. Eugenol fully inhibited TMEM16A Cl⁻ conductance with single-site IC₅₀∼150 µM. Eugenol inhibition of TMEM16A in interstitial cells of Cajal produced strong inhibition of intestinal contraction in mouse ileal segments. TMEM16A Cl⁻ channel inhibition adds to the list of eugenol molecular targets and may account for some of its biological activities.

Presynaptic enhancement by eugenol of spontaneous excitatory transmission in rat spinal substantia gelatinosa neurons is mediated by transient receptor potential A1 channels

Eugenol, which is contained in several plants including clove, has been widely used as an analgesic and anti-inflammatory drug in the dental clinic. Eugenol also has anesthetic effects and produces sedation and the reduction of convulsion threshold. These benefits have been partly attributed to the effects of eugenol on neural tissues, such as inhibition of voltage-gated ion channels. As expected from the fact that eugenol is a vanilloid compound, this drug activates transient receptor potential (TRP) V1 channels in the peripheral nervous system (PNS). Although eugenol affects synaptic transmission in the central nervous system (CNS), this has not yet been fully examined. We investigated how eugenol affects spontaneous glutamatergic excitatory transmission in substantia gelatinosa (SG; lamina II of Rexed) neurons of adult rat spinal cord slices by use of the blind whole-cell patch-clamp technique. Bath-applied eugenol reversibly enhanced spontaneous excitatory transmission and produced an outward current at -70 mV in SG neurons. The former action was due to a large increase in the frequency of spontaneous excitatory postsynaptic current (sEPSC) with a small increase in the amplitude. These actions of eugenol were seen by its repeated application and resistant to a voltage-gated Na(+) channel blocker tetrodotoxin. The effect of eugenol on sEPSC frequency was concentration-dependent with an EC(50) value of 3.8 mM and unaffected by a TRPV1 antagonist capsazepine, whereas inhibited by a nonspecific TRP antagonist ruthenium red and a TRPA1 antagonist HC-030031. On the other hand, the eugenol-induced outward current was not affected by these TRP antagonists. It is concluded that eugenol activates TRPA1 channels in the SG, leading to an increase in the spontaneous release of L-glutamate to SG neurons, and that eugenol also produces a membrane hyperpolarization that is not mediated by TRP channels. Eugenol is suggested to activate different types of TRP channel between the PNS and CNS.

Antinociceptive effects of eugenol evaluated in a monoiodoacetate-induced osteoarthritis rat model

The aim of the present study was to evaluate whether eugenol, the main constituent of clove oil, has the capacity to provide analgesia in the monoiodoacetate-induced rat model of osteoarthritis. Animals (n = 6/group) received either eugenol (20 or 40 mg/kg) or a vehicle by gavage. Daily administrations were initiated 2 days post osteoarthritis induction and continued for the duration of the study (4 weeks). Gait analysis was performed using the CatWalk method and secondary mechanical allodynia was assessed with von Frey filaments. Selected spinal cord peptides (substance P, calcitonin gene-related peptide and dynorphin) were quantified by mass spectrometry. Significant changes were identified in dynamic gait parameters (swing speed, swing phase duration and duty cycle) of the affected limb following 40 mg/kg eugenol treatment compared with the vehicle (p < 0.05). Von Frey results revealed significant differences between the 40 mg/kg treatment and the vehicle group during the first and the third week of the study (p < 0.02). Spinal pain-related peptide analysis revealed a decreased content of substance P and CGRP accompanied by an increase of dynorphin in animals treated with 40 mg/kg eugenol. These results suggest a therapeutic potential of eugenol to alleviate osteoarthritis-related pain.

Eugenol attenuates pulmonary damage induced by diesel exhaust particles

Environmentally relevant doses of inhaled diesel particles elicit pulmonary inflammation and impair lung mechanics. Eugenol, a methoxyphenol component of clove oil, presents in vitro and in vivo anti-inflammatory and antioxidant properties. Our aim was to examine a possible protective role of eugenol against lung injuries induced by diesel particles. Male BALB/c mice were divided into four groups. Mice received saline (10 μl in; CTRL group) or 15 μg of diesel particles DEP (15 μg in; DIE and DEUG groups). After 1 h, mice received saline (10 μl; CTRL and DIE groups) or eugenol (164 mg/kg; EUG and DEUG group) by gavage. Twenty-four hours after gavage, pulmonary resistive (ΔP1), viscoelastic (ΔP2) and total (ΔPtot) pressures, static elastance (Est), and viscoelastic component of elastance (ΔE) were measured. We also determined the fraction areas of normal and collapsed alveoli, amounts of polymorpho- (PMN) and mononuclear cells in lung parenchyma, apoptosis, and oxidative stress. Est, ΔP2, ΔPtot, and ΔE were significantly higher in the DIE than in the other groups. DIE also showed significantly more PMN, airspace collapse, and apoptosis than the other groups. However, no beneficial effect on lipid peroxidation was observed in DEUG group. In conclusion, eugenol avoided changes in lung mechanics, pulmonary inflammation, and alveolar collapse elicited by diesel particles. It attenuated the activation signal of caspase-3 by DEP, but apoptosis evaluated by TUNEL was avoided. Finally, it could not avoid oxidative stress as indicated by malondialdehyde.