Acute effect of essential oil of Eugenia caryophyllata on cognition and pain in mice

Clove Essential Oil: Chemical Profile, Biological Activities, Encapsulation Strategies, and Food Applications

Plants have proven to be important sources for discovering new compounds that are useful in the treatment of various diseases due to their phytoconstituents. Clove (Syzygium aromaticum L.), an aromatic plant widely cultivated around the world, has been traditionally used for food preservation and medicinal purposes. In particular, clove essential oil (CEO) has attracted attention for containing various bioactive compounds, such as phenolics (eugenol and eugenol acetate), terpenes (β-caryophyllene and α-humulene), and hydrocarbons. These constituents have found applications in cosmetics, food, and medicine industries due to their bioactivity. Pharmacologically, CEO has been tested against a variety of parasites and pathogenic microorganisms, demonstrating antibacterial and antifungal properties. Additionally, many studies have also demonstrated the analgesic, antioxidant, anticancer, antiseptic, and anti-inflammatory effects of this essential oil. However, CEO could degrade for different reasons, impacting its quality and bioactivity. To address this challenge, encapsulation is viewed as a promising strategy that could prolong the shelf life of CEO, improving its physicochemical stability and application in various areas. This review examines the phytochemical composition and biological activities of CEO and its constituents, as well as extraction methods to obtain it. Moreover, encapsulation strategies for CEO and numerous applications in different food fields are also highlighted.

Comparison of intranasal and intraperitoneal administration of Eugenia caryophyllata (clove) essential oil on spatial memory, anxiety-like behavior and locomotor activity in a pilocarpine-induced status epilepticus rat model

Background

Epilepsy induces behavioral effects and histological changes in the hippocampus. Eugenol, the main component of clove essential oil, has modulatory effects on seizure. We aimed to investigate the effect of intraperitoneal (IP) and intranasal (IN) clove essential oil on cognitive and histological changes during the chronic phase of temporal lope epilepsy.

Methods

Male Wistar rats were divided into eight groups of seven including control, pilocarpine (PLC), clove oil (IP and IN), sesame oil (IP and IN), phenobarbital (positive control) and saline. Rats were injected with 350 mg/kg PLC to induce status epilepticus (SE). We evaluated the effects of 14 days IP (0.1 ml/kg) and IN (0.02 ml/kg) administration of clove essential oil on locomotor/explorative activity, anxiety-like behavior, spatial recognition memory, and hyperexcitability, as well as hippocampal cell survival in PLC-treated rats.

Results

Our findings indicated that clove oil could effectively ameliorate PLC-induced behavioral deficits, and also alleviate neuronal death in the cornu ammonis 1 (CA1) region of the hippocampus. Behavioral results as in the Y-maze, Open field and elevated plus maze featured significant differences between control and treated groups. Post-seizure behavioral battery (PBSS) results explicated that behavioral hyperexcitability were less in clove oil groups (both IN and IP) compared to PLC-treated rats. Moreover, results of this study demonstrated that IN administration of clove oil was more potent in alleviating behavioral impairment at a lower dosage than by IP route. The results of this study, also demonstrated that intranasal administration of clove oil could reduce duration of recurrent seizures.

Conclusion

In summary, clove oil treatment ameliorated histopathological and behavioral consequences of PLC-induced SE.

Anti-inflammatory and anti-nociceptive effects of Cinnamon and Clove essential oils nanogels: an in vivo study

BACKGROUND

Cinnamon (Cinnamomum zeylanicum) and Clove (Syzygium aromaticum) essential oils are two medicinally important plant-derived substances with a wide range of biological properties. Besides, nanoemulsion-based gels have been widely used to increase topical drug delivery and effectiveness.

METHODS

This study aimed to explore the anti-inflammatory effect (paw edema test) and the anti-nociceptive effect (hot plate and formalin test) of nanoemulsion-based gels containing the essential oils in the animal model. Cinnamon and Clove essential oils nanoemulsions with droplet sizes of 28 ± 6 nm and 12 ± 3 nm were first prepared. By adding carboxymethylcellulose (3.5% w/v), the nanoemulsions were then gelified. Finally, the nanogels were characterized by ATR-FTIR analysis and were used as topical pre-treatment before induction of inflammation or pain in acute and chronic analgesic experimental studies.

RESULTS

The paw edema and formalin findings showed that the nanogels formulations possess significant anti-nociceptive and anti-inflammatory effects.

CONCLUSION

The prepared nanogels could be considered as analgesic drugs for inhibiting the inflammation and pain of diseases.

Antinociceptive effects of flower extracts and the active fraction from Styrax japonicus

ETHNOPHARMACOLOGICAL RELEVANCE

Flowers from Styrax japonicus sieb. et Zucc. have been used as a Chinese folk medicine to alleviate pain such as toothache and sore throat.

AIM OF THE STUDY

To testify the analgesic effect of flowers from Styrax japonicus, analyze components of the active fraction, and investigate the mechanism of analgesia.

MATERIALS AND METHODS

Flower extracts were obtained by ethanol, petroleum ether and hydrodistillation extraction. Different fractions of ethanol extracts (EE) were isolated by silica gel column chromatography and preparative liquid chromatography. Analgesic effects of EE, petroleum ether extracts (PEE), hydrodistillation extracts (HDE), and fractions of EE were evaluated using hot plate, acetic acid-induced writhing and formalin tests on mice. Components of the active fraction 1 (F1) were determined by the ultrahigh-performance liquid chromatography Q extractive mass spectrometry (UHPLC-QE-MS). Anti-inflammatory and sedative effects involving analgesic mechanisms were evaluated by carrageenan induced hind paw oedema and pentobarbital sodium sleep tests, respectively. In addition, antagonists including naloxone hydrochloride (NXH), flumazenil (FM), SCH23390 (SCH) and WAY100635 (WAY) were used to investigate the possible mechanism of analgesia. Contents of neurotransmitters and relevant metabolites in different brain regions of mice were also quantified by the ultraperformance liquid chromatography with a fluorescence detector (UPLC-FLD).

RESULTS

EE rather than PEE and HDE at medium and high doses (150 mg/kg and 300 mg/kg) significantly prolonged the latency time of the response of mice to the thermal stimulation in the hot plate test. Moreover, EE significantly decreased number of writhes in the acetic acid-induced writhing test, and reduced licking time in both two phases of the formalin test in a dose-dependent manner. The F1 (50 mg/kg) showed effective antinociceptive responses in all mice models. However, fraction 2 (F2) and fraction 3 (F3) at 50 mg/kg performed no analgesic action. Kaempferol-3-O-rutinoside, isorhamnetin-3-O-rutinoside, pinoresinol-4-O-glucoside, forsythin and arctiin were identified from components of the F1. Furthermore, F1 (50 mg/kg) did not significantly affect hind paw oedema of mice induced by carrageenan but significantly shortened sleep latency and increased sleep duration in the pentobarbital sodium sleep test. In addition, the antinociceptive response of F1 was not affected by NXH in two mice models, but significantly blocked by FM and WAY in the hot plate test. In the formalin test, FM avoided the effect of F1 only in the first phase, while the analgesic activity of F1 was totally suppressed by WAY in both two phases. Otherwise, contents of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) increased significantly in hippocampus and striatum of mice in the F1 group.

CONCLUSION

EE from flowers of Styrax japonicus, and F1, the active part isolated from EE, showed significant antinociceptive activities. The analgesic effect of F1 appeared to be related to the sedative effect, partially mediated by the GABAergic system, and highly involved in the serotonergic system. This was the first study confirming the analgesic effect of Styrax japonicus flower, which provided a candidate for the development of non-opioid analgesics.

In vitro inhibition of a multispecies oral cavity biofilm by Syzygium aromaticum essential oil

OBJECTIVE

To evaluate the anti-fungal activity of Syzygium aromaticum essential oil and its inhibition of a multispecies biofilm in patients with oral candidiasis.

BACKGROUND

Inhibiting biofilm formation on the denture surface is an important practice for preventing denture stomatitis.

MATERIALS AND METHODS

The anti-fungal activity against Candida albicans and non-albicans Candida species was evaluated through the microdilution method to define Minimal Inhibitory (MIC) and Fungicidal (MFC) Concentrations. Time-kill assay assessed growth kinetics of C. albicans based on pre-determined time points (0, 1, 2, 4, 6 and 24 hours). A multi-species biofilm was formed using human saliva from patients with oral candidiasis and anti-biofilm activity determined by Colony Forming Units per milliliter (CFU/mL) count, fluorescence microscopy with calcofluor white to observe yeast presence and structure, and metabolic activity by XTT (2,3-Bis-(2Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-carboxanilide) reduction assay.

RESULTS

The essential oil showed an anti-fungal activity against all Candida species (MIC 500-1000 µg/mL, MFC 1000-2000 µg/mL), and the time-kill assay showed that 2000 µg/mL (from 2 hours onward) and 1000 µg/mL (from 4 hours onward) concentrations had substantially lower yeast growth than the negative control. In the biofilm analysis, the essential oil had a lower CFU/mL count and a biofilm metabolic activity (91.4%) than seen with its negative control, and in both analyses, the essential oil was not significantly different from the positive control (chlorhexidine). Morphological analysis showed amorphous and fragmented cellular structures after treatment with the essential oil.

CONCLUSION

Syzygium aromaticum essential oil had anti-fungal activities, reduced the Candida growth kinetics substantially and inhibited the multi-species biofilm formation.

Efficacy of Essential Oils in Pain: A Systematic Review and Meta-Analysis of Preclinical Evidence

Background: The demand for essential oils (EOs) has been steadily growing over the years. This is mirrored by a substantial increase in research concerned with EOs also in the field of inflammatory and neuropathic pain. The purpose of this present systematic review and meta-analysis is to investigate the preclinical evidence in favor of the working hypothesis of the analgesic properties of EOs, elucidating whether there is a consistent rational basis for translation into clinical settings.

Methods: A literature search has been conducted on databases relevant for medical scientific literature, i.e., PubMed/MEDLINE, Scopus, and Web of Science from database inception until November 2, 2020, following the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) criteria for systematic reviews and meta-analyses.

Results: The search was conducted in order to answer the following PICOS (participants/population, interventions, comparisons, outcomes, and study design) question: are EOs efficacious in reducing acute nociceptive pain and/or neuropathic pain in mice experimental models? The search retrieved 2,491 records, leaving 954 studies to screen after the removal of duplicates. The title and abstract of all 954 studies were screened, which left 127 records to evaluate in full text. Of these, 30 articles were eligible for inclusion.

Conclusion: Most studies (27) assessed the analgesic properties of EOs on acute nociceptive pain models, e.g. the acetic acid writhings test, the formalin test, and the hot plate test. Unfortunately, efficacy in neuropathic pain models, which are a more suitable model for human conditions of chronic pain, had fewer results (only three studies). Moreover, some methodologies raised concerns in terms of the risk of bias. Therefore, EOs with proven efficacy in both types of pain were corroborated by methodologically consistent studies, like the EO of bergamot, which should be studied in clinical trials to enhance the translational impact of preclinical modeling on clinical pain research.

Emulsions containing essential oils, their components or volatile semiochemicals as promising tools for insect pest and pathogen management

Most of the traditional strategies used for facing the management of insect pest and diseases have started to fail due to different toxicological issues such as the resistance of target organism and the impact on environment and human health. This has made mandatory to seek new effective strategies, which minimize the risks and hazards without compromising the effectiveness of the products. The use of essential oils, their components and semiochemicals (pheromones and allelochemicals) has become a promising safe and eco-sustainable alternative for controlling insect pest and pathogens. However, the practical applications of this type of molecules remain rather limited because their high volatility, poor solubility in water and low chemical stability. Therefore, it is required to design strategies enabling their use without any alteration of their biological and chemical properties. Oil-in-water nano/microemulsions are currently considered as promising tools for taking advantage of the bioactivity of essential oils and their components against insects and other pathogens. Furthermore, these colloidal systems also allows the encapsulation and controlled release of semiochemicals, which enables their use in traps for monitoring, trapping or mating disruption of insects, and in push-pull strategies for their behavioral manipulation. This has been possible because the use of nano/microemulsions allows combining the protection provided by the hydrophobic environment created within the droplets with the enhanced dispersion of the molecules in an aqueous environment, which favors the handling of the bioactive molecules, and limits their degradation, without any detrimental effect over their biological activity. This review analyzes some of the most recent advances on the use of emulsion-like dispersions as a tool for controlling insect pest and pathogens. It is worth noting that even though the current physico-chemical knowledge about these systems is relatively poor, a deeper study of the physico-chemical aspects of nanoemulsions/microemulsions containing essential oils, their components or semiochemicals, may help for developing most effective formulations, enabling the generalization of their use.

Analgesic Potential of Essential Oils

Pain is an unpleasant sensation associated with a wide range of injuries and diseases, and affects approximately 20% of adults in the world. The discovery of new and more effective drugs that can relieve pain is an important research goal in both the pharmaceutical industry and academia. This review describes studies involving antinociceptive activity of essential oils from 31 plant species. Botanical aspects of aromatic plants, mechanisms of action in pain models and chemical composition profiles of the essential oils are discussed. The data obtained in these studies demonstrate the analgesic potential of this group of natural products for therapeutic purposes.

Endogenous opiates and behavior: 2012

This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Effects of different extracts of Eugenia caryophyllata on pentylenetetrazole-induced seizures in mice

OBJECTIVE

To investigate the possible anticonvulsant effect of different extracts of Eugenia caryophyllata (clove) on pentylenetetrazole (PTZ)-induced seizures in mice.

METHODS

The animals were divided into saline, 50, 100, 250 and 500 mg/kg of aqueous extract, 50, 100, 250 and 500 mg/kg of ethanolic extract, and 50, 100, 250 and 500 mg/kg of chloroformic extract of clove groups. The extracts or saline were injected 60 min before each PTZ injection. Latency to the first minimal clonic seizure (MCS) and generalized tonic-clonic seizure (GTCS) and the percent of mortality were recorded.

RESULTS

Aqueous extract of clove at doses of 50, 100, 250 and 500 mg/kg significantly extended the MCS and GTCS latency (P<0.05). The MCS latency in mice treated with 50, 100 and 250 mg/kg of the ethanolic extract was significantly increased (P<0.05). The GTCS latency in mice treated with 50, 100, 250 and 500 mg/kg of ethanolic extract was significantly higher than that of the saline-treated group (P<0.05). There were no significant differences in MCS and GTCS latency between mice treated with different chloroformic extract of clove or saline.

CONCLUSION

The aqueous and ethanolic extracts of clove could inhibit the PTZ-induced convulsion, and this plant has the potential to be used as a new therapeutic agent for control of seizures. The exact mechanisms and the active compounds that are responsible for the anticonvulsive effect need to be clarified in future studies.