Evidence for the involvement of ionotropic glutamatergic receptors on the antinociceptive effect of (-)-linalool in mice

Neurophysiological measurements of planarian brain activity: a unique model for neuroscience research

Planarians are well-known model organisms for regeneration and developmental biology research due to their remarkable regenerative capacity. Here, we aim to advocate for the use of planaria as a valuable model for neurobiology, as well. Planarians have most of the major qualities of more developed organisms, including a primal brain. These traits combined with their exceptional regeneration capabilities, allow neurobiological experiments not possible in any other model organism, as we demonstrate by electrophysiological recording from planaria with two heads that controlling a shared body. To facilitate planarian neuroscience research, we developed an extracellular multi-unit recording procedure for the planarians fragile brain (Dugesia japonica). We created a semi-intact preparation restrained with fine dissection pins, enabling hours of reliable recording, via a suction electrode. Here, we demonstrate the feasibility and potential of planarian neurophysiological research by characterizing the neuronal activity during simple learning processes and responses to various stimuli. In addition, we examined the use of linalool as anesthetic agent to allows recordings from an intact, large worm and for fine electrophysiological approaches such as intracellular recording. The demonstrated ability for neurophysiological measurements, along with the inherent advantages of planarians, promotes this exceptional model organism for neuroscience research.

Acute analgesic effect of nicotine vaping using three experimental pain induction tasks: a randomized, placebo-controlled laboratory study

RATIONALE

Pain and nicotine use are co-occurring conditions with a significant impact on health. Experimental evidence supports an acute analgesic effect of nicotine which may reinforce nicotine use among those with chronic pain. Evidence for nicotine analgesia have primarily been gathered in combustible cigarette users and have not been extended to electronic nicotine delivery systems (ENDS or vaping). Furthermore, the mechanisms of nicotine analgesia in humans are not well understood.

OBJECTIVES

Assess the effect of acute vaped nicotine on subjective and behavioral indices of pain sensitivity using three tasks designed to probe distinct mechanisms of analgesia.

METHODS

This study recruited ENDS users (N = 86) to undergo a paced vaping protocol followed by pain tasks in counterbalanced order. Across four sessions, participants vaped e-liquid containing nicotine or placebo, and flavor or no-flavor in a 2 × 2 within-subject design. Assessments included cold pressor, submaximal effort tourniquet to induce ischemic pain, and temporal summation of heat pain, an index of central sensitization.

RESULTS

Compared to placebo, nicotine increased cold pressor pain tolerance (ηp2 = 0.031), ischemic pain threshold (ηp2 = 0.073) and tolerance (ηp2 = 0.056) but had no effect on temporal summation of pain. Flavor did not affect pain sensitivity. Females reported greater ischemic pain sensitivity (ηp2 = 0.027) and greater reductions in craving (ηp2 = 0.086).

CONCLUSIONS

Consistent with research from tobacco smoking, analgesia may be reinforcing and contribute to nicotine dependence among ENDS users. More research on sex differences is warranted.

Discriminative stimulus properties of Cannabis sativa terpenes in rats

Cannabis is a pharmacologically complex plant consisting of hundreds of potentially active compounds. One class of compounds present in cannabis that has received little attention are terpenes. Traditionally thought to impart aroma and flavor to cannabis, it has become increasingly recognized that terpenes might exert therapeutic effects themselves. Several recent reports have also indicated terpenes might behave as cannabinoid type 1 (CB1) receptor agonists. This study aimed to investigate whether several terpenes present in cannabis produce discriminative stimulus effects similar to or enhance the effects of Δ 9 -tetrahydrocannabinol (THC). Subsequent experiments explored other potential cannabimimetic effects of these terpenes. Rats were trained to discriminate THC from vehicle while responding under a fixed-ratio 10 schedule of food presentation. Substitution testing was performed with the CB receptor agonist JWH-018 and the terpenes linalool, limonene, γ-terpinene and α-humulene alone. Terpenes were also studied in combination with THC. Finally, THC and terpenes were tested in the tetrad assay to screen for CB1-receptor agonist-like effects. THC and JWH-018 dose-dependently produced responding on the THC-paired lever. When administered alone, none of the terpenes produced responding predominantly on the THC-paired lever. When administered in combination with THC, none of the terpenes enhanced the potency of THC, and in the case of α-humulene, decreased the potency of THC to produce responding on the THC-paired lever. While THC produced effects in all four tetrad components, none of the terpenes produced effects in all four components. Therefore, the terpenes examined in this report do not have effects consistent with CB1 receptor agonist properties in the brain.

Terpenes from Cannabis sativa induce antinociception in a mouse model of chronic neuropathic pain via activation of adenosine A2A receptors

ABSTRACT

Terpenes are small hydrocarbon compounds that impart aroma and taste to many plants, including Cannabis sativa. A number of studies have shown that terpenes can produce pain relief in various pain states in both humans and animals. However, these studies were methodologically limited and few established mechanisms of action. In our previous work, we showed that the terpenes geraniol, linalool, β-pinene, α-humulene, and β-caryophyllene produced cannabimimetic behavioral effects via multiple receptor targets. We thus expanded this work to explore the potential antinociception and mechanism of these Cannabis terpenes in a mouse model of chronic pain. We first tested for antinociception by injecting terpenes (200 mg/kg, IP) into male and female CD-1 mice with mouse models of chemotherapy-induced peripheral neuropathy (CIPN) or lipopolysaccharide-induced inflammatory pain, finding that the terpenes produced roughly equal antinociception to 10 mg/kg morphine or 3.2 mg/kg WIN55,212. We further found that none of the terpenes produced reward as measured by conditioned place preference, while low doses of terpene (100 mg/kg) combined with morphine (3.2 mg/kg) produced enhanced antinociception vs either alone. We then used the adenosine A2A receptor (A2AR) selective antagonist istradefylline (3.2 mg/kg, IP) and spinal cord-specific CRISPR knockdown of the A2AR to identify this receptor as the mechanism for terpene antinociception in CIPN. In vitro cAMP and binding studies and in silico modeling studies further suggested that the terpenes act as A2AR agonists. Together these studies identify Cannabis terpenes as potential therapeutics for chronic neuropathic pain and identify a receptor mechanism for this activity.

Studies on the Inhibition Mechanism of Linalyl Alcohol against the Spoilage Microorganism Brochothrix thermosphacta

The aim of this study was to investigate the bacterial inhibitory ability and mechanism of action of linalyl alcohol against B. thermosphacta. Linalyl alcohol causes the leakage of intracellular material by disrupting the cell wall and exposing the hydrophobic phospholipid bilayer, which binds to bacterial membrane proteins and alters their structure. In addition, linalyl alcohol causes cell membrane damage by affecting fatty acids and proteins in the cell membrane. By inhibiting the synthesis of macromolecular proteins, the normal physiological functions of the bacteria are altered. Linalyl alcohol binds to DNA in both grooved and embedded modes, affecting the normal functioning of B. thermosphacta, as demonstrated through a DNA interaction analysis.

An In Silico Approach to Exploring the Antinociceptive Biological Activities of Linalool and its Metabolites

Pain is characterized by the unpleasant sensory and emotional sensation associated with actual or potential tissue damage, whereas nociception refers to the mechanism by which noxious stimuli are transmitted from the periphery to the CNS. The main drugs used to treat pain are nonsteroidal anti-inflammatory drugs (NSAIDs) and opioid analgesics, which have side effects that limit their use. Therefore, in the search for new drugs with potential antinociceptive effects, essential oils have been studied, whose constituents (monoterpenes) are emerging as a new therapeutic possibility. Among them, linalool and its metabolites stand out. The present study aims to investigate the antinociceptive potential of linalool and its metabolites through a screening using an in silico approach. Molecular docking was used to evaluate possible interactions with important targets involved in antinociceptive activity, such as α2-adrenergic, GABAergic, muscarinic, opioid, adenosinergic, transient potential, and glutamatergic receptors. The compounds in the investigated series obtained negative energies for all enzymes, representing satisfactory interactions with the targets and highlighting the multi-target potential of the L4 metabolite. Linalool and its metabolites have a high likelihood of modulatory activity against the targets involved in nociception and are potential candidates for future drugs.

Inhibitory effects of linalool, an essential oil component of lavender, on nociceptive TRPA1 and voltage-gated Ca2+ channels in mouse sensory neurons

Linalool, an essential oil component of lavender is commonly used in fragrances. It is known that linalool has anxiolytic, sedative, and analgesic actions. However, the mechanism of its analgesic action has not yet been fully clarified. Pain signals elicited by the activation of nociceptors on peripheral neurons are transmitted to the central nervous system. In the present study, we investigated the effects of linalool on transient receptor potential (TRP) channels and voltage-gated channels, both of which are important for pain signaling via nociceptors in somatosensory neurons. For detection of channel activity, the intracellular Ca²⁺ concentration ([Ca²⁺]_i) was measured using a Ca²⁺-imaging system, and membrane currents were recorded using the whole-cell patch-clamp technique. Analgesic actions were also examined in vivo. In mouse sensory neurons linalool at concentrations that did not induce [Ca²⁺]_i increases did not affect [Ca²⁺]_i responses to capsaicin and acids, TRPV1 agonists, but suppressed those induced by allyl isothiocyanate (AITC) and carvacrol, TRPA1 agonists. Similar inhibitory effects of linalool were observed in cells that heterologously expressed TRPA1. Linalool attenuated the [Ca²⁺]_i increases induced by KCl and voltage-gated Ca²⁺ currents but only slightly suppressed voltage-gated Na^＋currents in mouse sensory neurons. Linalool diminished TRPA1-mediated nociceptive behaviors. The present data suggest that linalool exerts an analgesic action via the suppression of nociceptive TRPA1 and voltage-gated Ca²⁺ channels.

Linalool: Monoterpene alcohol effectiveness in chronic synovitis through lowering Interleukin-17, spleen and thymus indices

Interleukin-17 has a positive role in the initial induction and late chronic phases of many inflammatory disorders like arthritis. This cytokine has a strong option for therapeutic targeting due to the fact that it was found in the inflamed joints of individual with rheumatoid arthritis (RA) and persuasive evidence from experimental arthritis models indicating its pro-inflammatory actions. IL-17 suppression lessened the asperity of arthritis. The present study aimed to assess the anti-arthritic potential of linalool in a model of chronic joint inflammation (CFA-mediated rheumatoid arthritis) in rats. Linalool markedly lowered spleen and thymus indices as opposed to arthritic control. The over-formation of IL-17, COX-2, TNF-α IL-1β, iNOS and IL-6 were markedly impaired in all linalool treated rats, but IL-10 was raised as compared to arthritic animals in Real time-PCR. There was reduction in associated parameters like paw volume, arthritic index, mobility score, and flexion pain score and a marked increase in stance score in CFA model as compared to the arthritic control group. Furthermore, there was improvement in body weight, hematological, tissue, and radiological parameters in the CFA-model. Molecular docking study exhibited strong binding interaction of linalool with IL-17, PGE-2, iNOS and COX-2, thus providing a good correlation among experimental and theoretical results. The current findings show that linalool reduces adjuvant arthritis by suppressing pro-inflammatory mediators, arthritic development, and spleen and thymus indices. Thus, linalool may be employed therapeutically to alleviate arthritis in humans.

Immunomodulatory effect of Linalool (Lin) against CCl4 -induced hepatotoxicity and oxidative damage in rats

The current study explored the hepatoprotective and immunomodulatory effects of Linalool (Lin) against carbon tetrachloride (CCl₄ )-induced toxicity in mice. Four study groups (n = 8 each) were used: (1) a negative control group and (2) a toxicity control group (single dose of CCl₄ administered on day 14 as 1 mL/kg of CCL₄ in 1% olive oil). Intraperitoneally (i.p.)), and two experimental groups where mice were treated with either (3) Lin (25 mg/kg b.w., orally, daily for 15 days) or (4) pretreated with Lin (25 mg/kg b.w., orally, daily for 14 days) and intoxicated with CCl₄ (1 mL/kg of CCL₄ in 1% olive oil. i.p.) on day 14. The levels of the anti-inflammatory cytokine interleukin 10 (IL-10), the proinflammatory cytokines TNF-α, IL-6, and TGF-1β, and the histopathology of the liver were assessed. According to our findings, IL-10 concentrations were significantly increased in Lin-treated groups, while other cytokine levels were marked by a considerable decrease in the toxicity model group (CCl₄ -treated group). Histopathological examinations of liver tissues showed that the Lin-treated groups had an almost normal structure. The current findings showed that Lin could inhibit CCl₄ -induced liver injury in mice, which warrants further investigation of Lin as a potential protective and therapeutic agent against hepatotoxicity.

Olfactory Stimulation Successfully Modulates the Neurochemical, Biochemical and Behavioral Phenotypes of the Visceral Pain

Visceral pain (VP) is the organ-derived nociception in which increased inflammatory reaction and exaggerated activation of the central nucleus of the amygdala (CeA) may contribute to this deficiency. Considering the amygdala also serves as the integration center for olfaction, the present study aimed to determine whether olfactory stimulation (OS) would effectively depress over-activation and inflammatory reaction in CeA, and successfully relieve VP-induced abnormalities. Adult rats subjected to intraperitoneal injection of acetic acid inhaled lavender essential oil for 2 or 4 h. The potential benefits of OS were determined by measuring the pro-inflammatory cytokine level, intracellular potassium and the upstream small-conductance calcium-activated potassium (SK) channel expression, together with detecting the stress transmitters that participated in the modulation of CeA activity. Results indicated that in VP rats, strong potassium intensity, reduced SK channel protein level, and increased corticotropin-releasing factor, c-fos, and substance P immuno-reactivities were detected in CeA. Enhanced CeA activation corresponded well with increased inflammatory reaction and decreased locomotion, respectively. However, in rats subjected to VP and received OS, all above parameters were significantly returned to normal levels with higher change detected in treating OS of 4h. As OS successfully depresses inflammation and CeA over-activation, application of OS may serve as an alternative and effective strategy to efficiently relieve VP-induced deficiency.

Respiratory Depression as Antibacterial Mechanism of Linalool against Pseudomonas fragi Based on Metabolomics

Linalool showed a broad-spectrum antibacterial effect, but few studies have elucidated the antibacterial mechanism of linalool on Pseudomonas fragi (P. fragi) to date. The present study aimed to uncover the antimicrobial activity and potential mechanism of linalool against P. fragi by determining key enzyme activities and metabolites combined with a high-throughput method and metabolomic pathway analysis. As a result, linalool had excellent inhibitory activity against P. fragi with MIC of 1.5 mL/L. In addition, the presence of linalool significantly altered the intracellular metabolic profile and a total of 346 differential metabolites were identified, of which 201 were up-regulated and 145 were down-regulated. The highlight pathways included beta-alanine metabolism, pantothenic acid and CoA metabolism, alanine, aspartate and glutamate metabolism, nicotinate and nicotinamide metabolism. Overall, linalool could cause metabolic disorders in cells, and the main metabolic pathways involved energy metabolism, amino acid metabolism and nucleic acid metabolism. In particular, the results of intracellular ATP content and related enzymatic activities (ATPase, SDH, and GOT) also highlighted that energy limitation and amino acid disturbance occurred intracellularly. Together, these findings provided new insights into the mechanism by which linalool inhibited P. fragi and theoretical guidance for its development as a natural preservative.

Antinociceptive effects of minor cannabinoids, terpenes and flavonoids in Cannabis

Cannabis has been used for centuries for its medicinal properties. Given the dangerous and unpleasant side effects of existing analgesics, the chemical constituents of Cannabis have garnered significant interest for their antinociceptive, anti-inflammatory and neuroprotective effects. To date, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) remain the two most widely studied constituents of Cannabis in animals. These studies have led to formulations of THC and CBD for human use; however, chronic pain patients also use different strains of Cannabis (sativa, indica and ruderalis) to alleviate their pain. These strains contain major cannabinoids, such as THC and CBD, but they also contain a wide variety of cannabinoid and noncannabinoid constituents. Although the analgesic effects of Cannabis are attributed to major cannabinoids, evidence indicates other constituents such as minor cannabinoids, terpenes and flavonoids also produce antinociception against animal models of acute, inflammatory, neuropathic, muscle and orofacial pain. In some cases, these constituents produce antinociception that is equivalent or greater compared to that produced by traditional analgesics. Thus, a better understanding of the extent to which these constituents produce antinociception alone in animals is necessary. The purposes of this review are to (1) introduce the different minor cannabinoids, terpenes, and flavonoids found in Cannabis and (2) discuss evidence of their antinociceptive properties in animals.

Ethnobotanical and phytochemical aspects of the edible herb Coriandrum sativum L

Coriandrum sativum (coriander) is an edible herb in the family Apiaceae. The leaves, fruits, and stems of C. sativum have long been used as culinary spice due to their favorable odor. Traditional practitioners used this plant for treating different diseases like blepharitis, scabies, aphthous stomatitis, laryngitis, headache, and palpitation. In modern researches, coriander has demonstrated anxiolytic, anticonvulsant, antimigraine, neuroprotective, analgesic, diuretic, hypoglycemic, hypolipidemic, hypotensive, anticancer, and antioxidant activities. Coriander contains a wide range of bioactive phytochemicals among which phenylpropenes, terpenoids, isocoumarins, phytosterols, and fatty acids are the most important. This review provides information about the botanical and ethnobotanical aspects, chemical profile, therapeutic uses in Islamic traditional medicine (ITM), and recent pharmacological studies of coriander effects. The results have shown that coriander and its monoterpenoid compound, linalool, can be considered as potential drug candidates for treating metabolic syndrome and different inflammatory conditions especially neural and CNS diseases.

Potential adjunct therapies for the management of temporomandibular disorders: An evidence-based review

OBJECTIVE

The aim was to review the role of adjuvant therapies that may potentially contribute toward the management of temporomandibular disorders (TMD).

METHODS

The addressed focused question was, "Are there any adjuvant therapies that may contribute toward the management of TMD?". Indexed databases were searched up to June 2021. The eligibility criteria were the following: (a) original clinical studies and (b) randomized controlled clinical trials (RCTs).

RESULTS

Adjuvant therapies were comprised of acupuncture, manual therapy, jaw exercises, dietary modifications, botulinum toxin therapy, and photobiomodulation. Short-term follow-up results from each of these RCTs showed beneficial effects in terms of pain reduction and improvements in jaw movement among patients with TMD. There are no long-term follow-up results in this regard.

CONCLUSION

The most effective adjunct treatment for managing TMD remains unknown, primarily due to a lack of sufficient scientific evidence.

Analgesic Potential of Terpenes Derived from Cannabis sativa

Pain prevalence among adults in the United States has increased 25% over the past two decades, resulting in high health-care costs and impacts to patient quality of life. In the last 30 years, our understanding of pain circuits and (intra)cellular mechanisms has grown exponentially, but this understanding has not yet resulted in improved therapies. Options for pain management are limited. Many analgesics have poor efficacy and are accompanied by severe side effects such as addiction, resulting in a devastating opioid abuse and overdose epidemic. These problems have encouraged scientists to identify novel molecular targets and develop alternative pain therapeutics. Increasing preclinical and clinical evidence suggests that cannabis has several beneficial pharmacological activities, including pain relief. Cannabis sativa contains more than 500 chemical compounds, with two principle phytocannabinoids, Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Beyond phytocannabinoids, more than 150 terpenes have been identified in different cannabis chemovars. Although the predominant cannabinoids, Δ9-THC and CBD, are thought to be the primary medicinal compounds, terpenes including the monoterpenes β-myrcene, α-pinene, limonene, and linalool, as well as the sesquiterpenes β-caryophyllene and α-humulene may contribute to many pharmacological properties of cannabis, including anti-inflammatory and antinociceptive effects. The aim of this review is to summarize our current knowledge about terpene compounds in cannabis and to analyze the available scientific evidence for a role of cannabis-derived terpenes in modern pain management. SIGNIFICANCE STATEMENT: Decades of research have improved our knowledge of cannabis polypharmacy and contributing phytochemicals, including terpenes. Reform of the legal status for cannabis possession and increased availability (medicinal and recreational) have resulted in cannabis use to combat the increasing prevalence of pain and may help to address the opioid crisis. Better understanding of the pharmacological effects of cannabis and its active components, including terpenes, may assist in identifying new therapeutic approaches and optimizing the use of cannabis and/or terpenes as analgesic agents.

Orexinergic descending inhibitory pathway mediates linalool odor-induced analgesia in mice

Linalool odor exposure induces an analgesic effect in mice. This effect disappeared in the anosmic model mice, indicating that olfactory input evoked by linalool odor triggered this effect. Furthermore, hypothalamic orexinergic neurons play a pivotal role in this effect. However, the neuronal circuit mechanisms underlying this effect have not been fully addressed. In this study, we focused on the descending orexinergic projection to the spinal cord and examined whether this pathway contributes to the effect. We assessed the effect of intrathecal administration of orexin receptor antagonists on linalool odor-induced analgesia in the tail capsaicin test. We found that the selective orexin type 1 receptor antagonist, but not the selective orexin type 2 receptor antagonist, prevented the odor-induced analgesic effect. Furthermore, immunohistochemical analyses of c-Fos expression induced by the capsaicin test revealed that neuronal activity of spinal cord neurons was suppressed by linalool odor exposure, which was prevented by intrathecal administration of the orexin 1 receptor antagonist. These results indicate that linalool odor exposure drives the orexinergic descending pathway and suppresses nociceptive information flow at the spinal level.

Cannabis sativa terpenes are cannabimimetic and selectively enhance cannabinoid activity

Limited evidence has suggested that terpenes found in Cannabis sativa are analgesic, and could produce an "entourage effect" whereby they modulate cannabinoids to result in improved outcomes. However this hypothesis is controversial, with limited evidence. We thus investigated Cannabis sativa terpenes alone and with the cannabinoid agonist WIN55,212 using in vitro and in vivo approaches. We found that the terpenes α-humulene, geraniol, linalool, and β-pinene produced cannabinoid tetrad behaviors in mice, suggesting cannabimimetic activity. Some behaviors could be blocked by cannabinoid or adenosine receptor antagonists, suggesting a mixed mechanism of action. These behavioral effects were selectively additive with WIN55,212, suggesting terpenes can boost cannabinoid activity. In vitro experiments showed that all terpenes activated the CB1R, while some activated other targets. Our findings suggest that these Cannabis terpenes are multifunctional cannabimimetic ligands that provide conceptual support for the entourage effect hypothesis and could be used to enhance the therapeutic properties of cannabinoids.

Review of aromatherapy essential oils and their mechanism of action against migraines

ETHNOPHARMACOLOGICAL RELEVANCE

Migraines have become a major threat to human health, as they significantly affect human health and quality of life due to a high prevalence rate, attack rate and pain intensity. Aromatherapy, with its comfortable and pleasant natural characteristics and rapid and efficient characteristics, is widely favored by patients in the folk. Chinese folk also have the application history and related records of aromatic plants in the treatment of migraine.

AIM OF THE STUDY

This study was conducted to review the pathogenesis of migraine, the application of plant essential oils in the treatment of migraine, and further explore the material basis and mechanism of action of plant essential oils against migraine.

MATERIALS AND METHODS

Search the electronic literature of essential oils with anti-migraine effect in Google Scholar, PubMed and China National Knowledge Infrastructure, and further search the research situation of the monomer components of essential oils in migraine, inflammation, pain and other aspects.

RESULTS

studies show that there are 10 types of plant essential oils that could relieve migraine symptoms, and that 16 monomers may play a role in migraine treatment by effectively inhibiting neurogenic inflammation, hyperalgesia and balancing vasorelaxation.

CONCLUSION

Aromatic plant essential oils can relieve migraine effectively, these findings can be used as an important part of the development of anti-migraine drugs.

Protection of CCl4-induced hepatic and renal damage by linalool

The aim of the current study is to determine the protective and therapeutic effects of linalool against carbon tetrachloride (CCl₄)-induced hepatoxicity and nephrotoxicity. Six-week-old male Wistar rats were divided into five groups: Control group (a regular diet); CCl₄ group (1 ml/kg dissolved in olive oil, intraperitoneally at 14th day); pretreatment group (25 mg/kg linalool daily + CCl₄ 14thday); post-treatment group (25 mg/kg linalool 2, 6, 24, and 48 h after the injection of CCl₄ at 14^th day); and linalool group (25 mg/kg linalool daily, orally). All animals were sacrificed, tissue and blood samples were collected to analysis. Administration of CCl₄ resulted in a marked increase in hepatic (aspartate aminotransferase, alanine transaminase, and alkaline phosphatase) and renal (blood urea nitrogen and creatinine) markers. Also, CCl₄ resulted in pathological damages, a significant increase in the concentration of malondialdehyde , tumor necrosis factor-alpha, and Interleukin 6 , expression of nuclear factor kappa-light-chain-enhancer of activated B cells and a significant decrease in the levels of serum total protein, serum albumin, and antioxidants. However, in pretreatment and post treatment groups, linalool significantly inhibited CCl4- induced hepatic and nephric damages. These results demonstrate that linalool has protective and therapeutic effects in an in vitro model of CCL₄-induced hepatic and nephric damage, proposing linalool as a potential therapeutic agent against chemical and drug induced hepatotoxicity and nephrotoxicity.

History repeats itself: Role of characterizing flavors on nicotine use and abuse

The popularity of e-cigarettes has skyrocketed in recent years, and most vapers use flavored e-cigarette products. Consumption of flavored e-cigarettes exceeds that of combustible cigarettes and other tobacco products among adolescents, who are particularly vulnerable to becoming nicotine dependent. Flavorings have been used by the tobacco industry since the 17th century, but the use of flavors by the e-cigarette industry to create products with "characterizing" flavors (i.e. flavors other than tobacco or menthol) has sparked a public health debate. This review addresses the possibility that characterizing flavors make nicotine more appealing, rewarding and addictive. It also discusses ways in which preclinical and clinical studies could improve our understanding of the mechanisms by which flavors may alter nicotine reward and reinforcement. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Putative Mode of Action of the Monoterpenoids Linalool, Methyl Eugenol, Estragole, and Citronellal on Ligand-Gated Ion Channels

Essential oil has been used as sedatives, anticonvulsants, and local anesthetics in traditional medical remedies; as preservatives for food, fruit, vegetable, and grain storage; and as bio-pesticides for food production. Linalool (LL), along with a few other major components such as methyl eugenol (ME), estragole (EG), and citronellal, are the active chemicals in many essential oils such as basil oil. Basil oil and the aforementioned monoterpenoids are potent against insect pests. However, the molecular mechanism of action of these chemical constituents is not well understood. It is well-known that the γ-aminobutyric acid type A receptors (GABAARs) and nicotinic acetylcholine receptor (nAChR) are primary molecular targets of the synthetic insecticides used in the market today. Furthermore, the GABAAR-targeted therapeutics have been used in clinics for many decades, including barbiturates and benzodiazepines, to name just a few. In this research, we studied the electrophysiological effects of LL, ME, EG, and citronellal on GABAAR and nAChR to further understand their versatility as therapeutic agents in traditional remedies and as insecticides. Our results revealed that LL inhibits both GABAAR and nAChR, which may explain its insecticidal activity. LL is a concentration-dependent, non-competitive inhibitor on GABAAR, as the half-maximal effective concentration (EC50) values of γ-aminobutyric acid (GABA) for the rat α1β3γ2L GABAAR were not affected by LL: (36.2 ± 7.9) μmol·L-1 and (36.1 ± 23.8) μmol·L-1 in the absence and presence of 5 mmol·L-1 LL, respectively. The half-maximal inhibitory concentration (IC50) of LL on GABAAR was approximately 3.2 mmol·L-1. Considering that multiple monoterpenoids are found within the same essential oil, it is likely that LL has a synergistic effect with ME, which has been previously characterized as both a GABAAR agonist and a positive allosteric modulator, and with other monoterpenoids, which offers a possible explanation for the sedative and anticonvulsant effects and the insecticidal activities of LL.

Full-Length Transcriptome Sequencing and Different Chemotype Expression Profile Analysis of Genes Related to Monoterpenoid Biosynthesis in Cinnamomum porrectum

Leaves of C. porrectum are rich in essential oils containing monoterpenes, sesquiterpenes and aromatic compounds, but the molecular mechanism of terpenoid biosynthesis in C. porrectum is still unclear. In this paper, the differences in the contents and compositions of terpenoids among three chemotypes were analyzed using gas chromatography mass spectrometry (GC/MS). Furthermore, the differential expression of gene transcripts in the leaf tissues of the three C. porrectum chemotypes were analyzed through a comparison of full-length transcriptomes and expression profiles. The essential oil of the three C. porrectum chemotypes leaves was mainly composed of monoterpenes. In the full-length transcriptome of C. porrectum, 104,062 transcripts with 306,337,921 total bp, an average length of 2944 bp, and an N50 length of 5449 bp, were obtained and 94025 transcripts were annotated. In the eucalyptol and linalool chemotype, the camphor and eucalyptol chemotype, and the camphor and linalool chemotype comparison groups, 21, 22 and 18 terpene synthase (TPS) unigenes were identified respectively. Three monoterpene synthase genes, CpTPS3, CpTPS5 and CpTPS9, were upregulated in the eucalyptol chemotype compared to the linalool chemotype and camphor chemotype. CpTPS1 was upregulated in the camphor chemotype compared to the linalool chemotype and the eucalyptol chemotype. CpTPS4 was upregulated in the linalool chemotype compared to the camphor chemotype and the eucalyptol chemotype. Different unigenes had different expression levels among the three chemotypes, but the unigene expression levels of the 2-C-methyl-D-erythritol 4phosphate (MEP) pathway were generally higher than those of the mevalonate acid (MVA) pathway. Quantitative reverse transcription PCR(qRT-PCR) further validated these expression levels. The present study provides new clues for the functional exploration of the terpenoid synthesis mechanism and key genes in different chemotypes of C. porrectum.

Medicinal Properties of Cannabinoids, Terpenes, and Flavonoids in Cannabis, and Benefits in Migraine, Headache, and Pain: An Update on Current Evidence and Cannabis Science

BACKGROUND

Comprehensive literature reviews of historical perspectives and evidence supporting cannabis/cannabinoids in the treatment of pain, including migraine and headache, with associated neurobiological mechanisms of pain modulation have been well described. Most of the existing literature reports on the cannabinoids Δ⁹ -tetrahydrocannabinol (THC) and cannabidiol (CBD), or cannabis in general. There are many cannabis strains that vary widely in the composition of cannabinoids, terpenes, flavonoids, and other compounds. These components work synergistically to produce wide variations in benefits, side effects, and strain characteristics. Knowledge of the individual medicinal properties of the cannabinoids, terpenes, and flavonoids is necessary to cross-breed strains to obtain optimal standardized synergistic compositions. This will enable targeting individual symptoms and/or diseases, including migraine, headache, and pain.

OBJECTIVE

Review the medical literature for the use of cannabis/cannabinoids in the treatment of migraine, headache, facial pain, and other chronic pain syndromes, and for supporting evidence of a potential role in combatting the opioid epidemic. Review the medical literature involving major and minor cannabinoids, primary and secondary terpenes, and flavonoids that underlie the synergistic entourage effects of cannabis. Summarize the individual medicinal benefits of these substances, including analgesic and anti-inflammatory properties.

CONCLUSION

There is accumulating evidence for various therapeutic benefits of cannabis/cannabinoids, especially in the treatment of pain, which may also apply to the treatment of migraine and headache. There is also supporting evidence that cannabis may assist in opioid detoxification and weaning, thus making it a potential weapon in battling the opioid epidemic. Cannabis science is a rapidly evolving medical sector and industry with increasingly regulated production standards. Further research is anticipated to optimize breeding of strain-specific synergistic ratios of cannabinoids, terpenes, and other phytochemicals for predictable user effects, characteristics, and improved symptom and disease-targeted therapies.

The Mechanism of Compound Anshen Essential Oil in the Treatment of Insomnia Was Examined by Network Pharmacology

The active component-target network and protein-protein interaction network of Compound Anshen essential oil were constructed. The target functions and related pathways were analyzed to explore the mechanism of Compound Anshen essential oil in the treatment of insomnia. GC-MS was used to detect the chemical composition of Compound Anshen essential oil, and the TCMSP, STITCH, TTD, and DrugBank databases were searched to predict and screen the targets of Compound Anshen essential oil in the treatment of insomnia. Cytoscape software was used to construct the network diagrams of the active component-action target and protein-protein interaction networks, ClueGO software was used to analyze the GO enrichment and KEGG pathway of the target, and the systemsDock website database was used for molecular docking. The analysis of the network results showed that the activity of Compound Anshen essential oil mainly involves biological processes such as the phospholipase C-activating G protein-coupled receptor signaling pathway, response to ammonium ions, calcium ion transport into the cytosol, and chloride transport. The results of molecular docking showed that linalool, caryophyllene, dibutyl phthalate, (-)-4-terpineol, and (-)-α-terpineol have good binding activity with ADRB2, DRD2, ESR1, KCNH2, NR1H4, NR1I2, NR1I3, and TRPV1 targets. This study demonstrates the multicomponent, multitarget, and multichannel characteristics of Compound Anshen essential oil and provides a new therapeutic idea and method for further research on the mechanism of Compound Anshen essential oil in the treatment of insomnia.

Linalool Odor-Induced Anxiolytic Effects in Mice

In folk medicine, it has long been believed that odorous compounds derived from plant extracts can have anxiolytic effects. Among them, linalool, one of the terpene alcohols in lavender extracts, has been reported to have the anxiolytic effects. However, the anxiolytic nature of the linalool odor itself as well as its potential action through the olfactory system has not been thoroughly examined. In this study, we examined the anxiolytic effects of linalool odor with light/dark box test and with elevated plus maze (EPM), and found that linalool odor has an anxiolytic effect without motor impairment in mice. The effect was not observed in anosmic mice, indicating that it was triggered by olfactory input evoked by linalool odor. Furthermore, the effect was antagonized by flumazenil, indicating that the linalool odor-induced anxiolytic effect was mediated by γ-aminobutyric acid (GABA)ergic transmission via benzodiazepine (BDZ)-responsive GABA_A receptors. These results provide information about the potential central neuronal mechanisms underlying the odor-induced anxiolytic effects and the foundation for exploring clinical application of linalool odor in anxiety treatments.

Patterns of medicinal cannabis use, strain analysis, and substitution effect among patients with migraine, headache, arthritis, and chronic pain in a medicinal cannabis cohort

BACKGROUND

Medicinal cannabis registries typically report pain as the most common reason for use. It would be clinically useful to identify patterns of cannabis treatment in migraine and headache, as compared to arthritis and chronic pain, and to analyze preferred cannabis strains, biochemical profiles, and prescription medication substitutions with cannabis.

METHODS

Via electronic survey in medicinal cannabis patients with headache, arthritis, and chronic pain, demographics and patterns of cannabis use including methods, frequency, quantity, preferred strains, cannabinoid and terpene profiles, and prescription substitutions were recorded. Cannabis use for migraine among headache patients was assessed via the ID Migraine™ questionnaire, a validated screen used to predict the probability of migraine.

RESULTS

Of 2032 patients, 21 illnesses were treated with cannabis. Pain syndromes accounted for 42.4% (n = 861) overall; chronic pain 29.4% (n = 598;), arthritis 9.3% (n = 188), and headache 3.7% (n = 75;). Across all 21 illnesses, headache was a symptom treated with cannabis in 24.9% (n = 505). These patients were given the ID Migraine™ questionnaire, with 68% (n = 343) giving 3 "Yes" responses, 20% (n = 102) giving 2 "Yes" responses (97% and 93% probability of migraine, respectively). Therefore, 88% (n = 445) of headache patients were treating probable migraine with cannabis. Hybrid strains were most preferred across all pain subtypes, with "OG Shark" the most preferred strain in the ID Migraine™ and headache groups. Many pain patients substituted prescription medications with cannabis (41.2-59.5%), most commonly opiates/opioids (40.5-72.8%). Prescription substitution in headache patients included opiates/opioids (43.4%), anti-depressant/anti-anxiety (39%), NSAIDs (21%), triptans (8.1%), anti-convulsants (7.7%), muscle relaxers (7%), ergots (0.4%).

CONCLUSIONS

Chronic pain was the most common reason for cannabis use, consistent with most registries. The majority of headache patients treating with cannabis were positive for migraine. Hybrid strains were preferred in ID Migraine™, headache, and most pain groups, with "OG Shark", a high THC (Δ9-tetrahydrocannabinol)/THCA (tetrahydrocannabinolic acid), low CBD (cannabidiol)/CBDA (cannabidiolic acid), strain with predominant terpenes β-caryophyllene and β-myrcene, most preferred in the headache and ID Migraine™ groups. This could reflect the potent analgesic, anti-inflammatory, and anti-emetic properties of THC, with anti-inflammatory and analgesic properties of β-caryophyllene and β-myrcene. Opiates/opioids were most commonly substituted with cannabis. Prospective studies are needed, but results may provide early insight into optimizing crossbred cannabis strains, synergistic biochemical profiles, dosing, and patterns of use in the treatment of headache, migraine, and chronic pain syndromes.

Antinociceptive and anticonvulsant effects of the monoterpene linalool oxide

CONTEXT

Linalool oxide (OXL) (a monoterpene) is found in the essential oils of certain aromatic plants, or it is derived from linalool. The motivation for this work is the lack of psychopharmacological studies on this substance.

OBJECTIVE

To evaluate OXL's acute toxicity, along with its anticonvulsant and antinociceptive activities in male Swiss mice.

MATERIAL AND METHODS

OXL (50, 100 and 150 mg/kg, i.p.) was investigated for acute toxicity and in the Rota-rod test. Antinociceptive activity was evaluated by the acetic acid-induced writhing test, and by formalin testing. Anticonvulsant effects were demonstrated by testing for pentylenetetrazol (PTZ)-induced seizures and by Maximum Electroshock headset (MES) test. OXL was administered to the animals intraperitoneally 30 min before for pharmacological tests.

RESULTS

OXL showed an LD₅₀ of ∼721 (681-765) mg/kg. In the Rota-rod test, it was observed that OXL caused no damage to the animal's motor coordination. OXL significantly reduced (p < .001) the number of writhings. OXL also significantly decreased (p < .05, p < .01 or p < .001) paw-licking time in the two phases of the formalin test. OXL significantly reduced (p < .01 or p < .001) the duration of tonic seizures in the MES test, and at the dose 150 mg/kg, significantly increased (p < .01) the latency to first seizure in the PTZ test.

CONCLUSION

The tested doses of OXL were safe, with no motor impairment, and show clear antinociceptive and anticonvulsant potential. Future investigations with this monoterpene may lead to the development of a new molecule with even higher potency and selectivity.

Coriander (Coriandrum sativum): A promising functional food toward the well-being

Coriandrum sativum (C. sativum) or coriander is one of the most popularly used spices in culinary worldwide, and its medicinal values has been recognized since ancient time. C. sativum contains bioactive phytochemicals that are accounted for a wide range of biological activities including antioxidant, anticancer, neuroprotective, anxiolytic, anticonvulsant, analgesic, migraine-relieving, hypolipidemic, hypoglycemic, hypotensive, antimicrobial, and antiinflammatory activities. The major compound, linalool, abundantly found in seeds is remarked for its abilities to modulate many key pathogenesis pathways of diseases. Apart from the modulating effects, the potent antioxidant property of the C. sativum provides a key mechanism behind its protective effects against neurodegenerative diseases, cancer, and metabolic syndrome. This review shed light on comprehensive aspects regarding the therapeutic values of the C. sativum, which indicate its significance of being a promising functional food for promoting the well-being in the era of aging and lifestyle-related diseases.

Essential Oils and Compounds against Pains in Animal Studies

The positive impact of essential oils and compounds has been known for a long time. Essential oils are multicomponent mixtures and obtained by steam distillation of leaves or flowers or simply by pressing orange peels for example. Due to the broad-spectrum activity, essential oils can be used for a variety of disorders like sleeping problems, colds or gastrointestinal complaints. The focus of this paper is the use of essential oils against pain in animal studies. The broad use of analgesics like NSAIDs against headaches or menstrual cramps for example, is often associated with unpleasant side effects. Essential oils may help to reduce the analgesic doses.

D-limonene exhibits superior antihyperalgesic effects in a β-cyclodextrin-complexed form in chronic musculoskeletal pain reducing Fos protein expression on spinal cord in mice

Chronic musculoskeletal pain is one of the main symptoms found in Fibromyalgia with unclear etiology and limited pharmacological treatment. The aim of this study was to complex LIM in β-cyclodextrin (LIM-βCD) and then evaluate its antihyperalgesic effect in an animal model of chronic musculoskeletal pain. Differential scanning calorimetry and scanning electron microscopy was used for the characterization of the inclusion complex. Male Swiss mice were used for experimental procedures where mechanical hyperalgesia, thermal hyperalgesia, muscular strength, Fos immunofluorescence was studied after induction of hyperalgesia. Mechanism of action was also investigated through tail flick test and capsaicin-induced nociception. Endothermic events and morphological changes showed that the slurry complex method was the best method for the complexation. After induction of hyperalgesia, the oral administration of LIM-βCD (50mg/kg) significantly increased the paw withdrawal threshold compared to uncomplexed limonene. Fos immunofluorescence showed that both compounds significantly decreased the number of Fos-positive cells in the dorsal horn. In nociceptive tests, FLU was able to reverse the antinociceptive effect of LIM-βCD. After intraplantar administration of capsaicin, LIM was able to significantly decrease time to lick. LIM-βCD has antihyperalgesic action superior to its uncomplexed form, with possible action in the dorsal horn of the spinal cord. These results suggest the possible applicability of LIM, uncomplexed or complexed with βCD, in conditions such as FM and neuropathic pain, for which there are currently only limited pharmacological options.

Cannabis Pharmacology: The Usual Suspects and a Few Promising Leads

The golden age of cannabis pharmacology began in the 1960s as Raphael Mechoulam and his colleagues in Israel isolated and synthesized cannabidiol, tetrahydrocannabinol, and other phytocannabinoids. Initially, THC garnered most research interest with sporadic attention to cannabidiol, which has only rekindled in the last 15 years through a demonstration of its remarkably versatile pharmacology and synergy with THC. Gradually a cognizance of the potential of other phytocannabinoids has developed. Contemporaneous assessment of cannabis pharmacology must be even far more inclusive. Medical and recreational consumers alike have long believed in unique attributes of certain cannabis chemovars despite their similarity in cannabinoid profiles. This has focused additional research on the pharmacological contributions of mono- and sesquiterpenoids to the effects of cannabis flower preparations. Investigation reveals these aromatic compounds to contribute modulatory and therapeutic roles in the cannabis entourage far beyond expectations considering their modest concentrations in the plant. Synergistic relationships of the terpenoids to cannabinoids will be highlighted and include many complementary roles to boost therapeutic efficacy in treatment of pain, psychiatric disorders, cancer, and numerous other areas. Additional parts of the cannabis plant provide a wide and distinct variety of other compounds of pharmacological interest, including the triterpenoid friedelin from the roots, canniprene from the fan leaves, cannabisin from seed coats, and cannflavin A from seed sprouts. This chapter will explore the unique attributes of these agents and demonstrate how cannabis may yet fulfil its potential as Mechoulam's professed "pharmacological treasure trove."

Anti-hyperalgesic effect of Lippia grata leaf essential oil complexed with β-cyclodextrin in a chronic musculoskeletal pain animal model: Complemented with a molecular docking and antioxidant screening

BACKGROUND

Due to its unclear pathophysiology, the pharmacological treatment of fibromyalgia is a challenge for researchers. Studies using medicinal plants, such as those from the genus Lippia, complexed with cyclodextrins (CDs) have shown innovative results.

OBJECTIVE

The present research intended to evaluate the effect of an inclusion complex containing β-cyclodextrin (βCD) inclusion complex with Lippia grata (LG) essential oil in a chronic musculoskeletal pain model, its central activity and its possible interaction with neurotransmitters involved in pain.

METHODS

After acid saline-induced chronic muscle pain, male mice were evaluated for primary and secondary hyperalgesia and muscle strength. Moreover, an antagonist assay was performed to assess the possible involvement of the opioidergic, serotonergic and noradrenergic pathways. In addition, Fos protein in the spinal cord was assessed, and a docking study and antioxidant assays were performed.

RESULTS

The treatment with LG-βCD, especially in the dose of 24mg/kg, was able to significantly decrease (p<0.05) the paw withdrawal and muscle threshold. Furthermore, LG-βCD was shown to affect the opioidergic and serotonergic pathways. There were no significant changes in muscle strength. Fos protein immunofluorescence showed a significant decrease in expression in the dorsal horn of the spinal cord. The main compounds of LG showed through the docking study interaction energies with the alpha-adrenergic and μOpioid receptors. In all antioxidant assays, LG exhibited stronger antioxidant activities than LG-βCD.

CONCLUSION

This study suggested that LG-βCD could be considered as a valuable source for designing new drugs in the treatment of chronic pain, especially musculoskeletal pain.

Nanoemulsion Thermoreversible Pluronic F127-Based Hydrogel Containing Hyptis pectinata (Lamiaceae) Leaf Essential Oil Produced a Lasting Anti-hyperalgesic Effect in Chronic Noninflammatory Widespread Pain in Mice

We evaluated if a nanostructured thermoreversible Pluronic F127-based hydrogel incorporated with Hyptis pectinata leaf essential oil (NE-EOH) produces a long-lasting anti-hyperalgesic effect on chronic muscle pain in an animal model. We induced chronic muscle pain by injecting the gastrocnemius with saline injections. Paw and muscle withdrawal thresholds and motor performance were evaluated after treatment and compared with morphine, diazepam, or vehicle. Naloxone and methysergide administration tested the involvement of opioid and serotonin receptors, respectively. Sites of action in the central nervous system for the NE-EOH were examined by measuring substance P (SP) levels in the spinal cord and Fos protein in the brainstem. NE-EOH increased paw and muscle withdrawal thresholds when compared with vehicle but had no effect on motor function. This analgesic effect was reversed by both naloxone and methysergide. NE-EOH decreased elevated substance P levels and reduced Fos-labeled neurons in the spinal cord and increased the number of Fos-labeled neurons in the periaqueductal gray (PAG), nucleus raphe magnus (NRM), and locus coeruleus (LC). NE-EOH was shown to produce a lasting anti-hyperalgesic effect. It uses opioid and serotonin receptors, activates brainstem inhibitory pathways, and reduces the release of excitatory neurotransmitters in the spinal cord and is a substance with potential to be used in the treatment of noninflammatory pain conditions. Graphical Abstract.

Sesquiterpene lactone! a promising antioxidant, anticancer and moderate antinociceptive agent from Artemisia macrocephala jacquem

Background

Sesquiterpene lactones (STLs) make a diverse and huge group of bio-active constituents that have been isolated from several plant families. However, the greatest numbers are present in Asteraceae family having more than 3000 different reported structures. Recently several researchers have reported that STLs have significant antioxidant and anticancer potentials.

Methods

To investigate the antioxidant, anticancer and antinociceptive potentials of STLs, gravity column chromatography technique was used for isolation from the biologically rich chloroform fraction of Artemisia macrocephala Jacquem. The antioxidant activity of the isolated STLs was determined by DPPH and ABTS free radical scavenging activity, anticancer activity was determined on 3 T3, HeLa and MCF-7 cells by MTT assay while the antinociceptive activity was determined through acetic acid induced writhings, tail immersion method and formalin induced nociception method.

Results

The results showed that the STLs of Artemisia macrocephala possesses promising antioxidant activity and also it decreased the viability of 3 T3, HeLa and MCF-7 cells and mild to moderate antinociceptive activity.

Conclusion

Sesquiterpenes lactones (STLs) are widely present in numerous genera of the family Asteraceae (compositae). They are described as the active constituents used in traditional medicine for the treatment of various diseases. The present study reveals the significant potentials of STL and may be used as an alternative for the management of cancer. Anyhow, the isolated compound is having no prominent antinociceptive potentials.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1517-y) contains supplementary material, which is available to authorized users.

Odour-induced analgesia mediated by hypothalamic orexin neurons in mice

Various folk remedies employ certain odorous compounds with analgesic effects. In fact, linalool, a monoterpene alcohol found in lavender extracts, has been found to attenuate pain responses via subcutaneous, intraperitoneal, intrathecal, and oral administration. However, the analgesic effects of odorous compounds mediated by olfaction have not been thoroughly examined. We performed behavioural pain tests under odourant vapour exposure in mice. Among six odourant molecules examined, linalool significantly increased the pain threshold and attenuated pain behaviours. Olfactory bulb or epithelium lesion removed these effects, indicating that olfactory sensory input triggered the effects. Furthermore, immunohistochemical analysis revealed that linalool activated hypothalamic orexin neurons, one of the key mediators for pain processing. Formalin tests in orexin neuron-ablated and orexin peptide-deficient mice showed orexinergic transmission was essential for linalool odour-induced analgesia. Together, these findings reveal central analgesic circuits triggered by olfactory input in the mammalian brain and support a potential therapeutic approach for treating pain with linalool odour stimulation.

Preparation, characterization and pharmacokinetic studies of linalool-loaded nanostructured lipid carriers

Context Linalool (LL) is associated with numerous pharmacological activities. However, its poor solubility usually results in poor bioavailability, and further limited its applications. Objective To reduce volatilization and improve bioavailability of LL, linalool-loaded nanostructured lipid carriers (LL-NLCs) were prepared. Materials and methods LL-NLCs were prepared using high-pressure homogenization method and optimized via response surface methodology-central composite design, followed by characterization, including particle size (PS), zeta potential (ZP), transmission electron microscope (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and in vitro release study. Rats were administered 300 mg × kg (-) (1) LL with each preparation (LL-NLCs or LL) via oral gavage. Results LL-NLCs had a PS of 52.72 nm with polydispersity index of 0.172, and ZP of -16.0 mV. The encapsulation efficiency and drug loading gave 79.563 and 7.555%, respectively. The cumulative release of LL from free LL reached 51.414% at 180 min, while LL from LL-NLCs was 15.564%. All the pharmacokinetics parameters of LL-NLCs were better than those of LL, including Cmax (from 1915.45 to 2182.45 ng × mL (-) (1)), AUC0-t (from 76003.40 to 298948.46 ng × min × mL (-) (1)) and relative bioavailability (393.34%). The t1/2, MRT and tmax of LL-NLCs (110.50, 146.66 and 60 min) were also longer than that of LL (44.72, 45.66 and 40 min). Discussion and conclusion LL-NLCs were for the first time prepared and its oral administration in rats thoroughly investigated. LL-NLCs exhibited sustained release effect and increased absorption of LL. Therefore, these findings might provide a potential possibility for clinical application of LL.

Essential Oil of Ocimum basilicum L. and (-)-Linalool Blocks the Excitability of Rat Sciatic Nerve

The racemate linalool and its levogyrus enantiomer [(−)-LIN] are present in many essential oils and possess several pharmacological activities, such as antinociceptive and anti-inflammatory. In this work, the effects of essential oil obtained from the cultivation of the Ocimum basilicum L. (EOOb) derived from Germplasm Bank rich in (−)-LIN content in the excitability of peripheral nervous system were studied. We used rat sciatic nerve to investigate the EOOb and (−)-LIN effects on neuron excitability and the extracellular recording technique was used to register the compound action potential (CAP). EOOb and (−)-LIN blocked the CAP in a concentration-dependent way and these effects were reversible after washout. EOOb blocked positive amplitude of 1st and 2nd CAP components with IC₅₀ of 0.38 ± 0.2 and 0.17 ± 0.0 mg/mL, respectively. For (−)-LIN, these values were 0.23 ± 0.0 and 0.13 ± 0.0 mg/mL. Both components reduced the conduction velocity of CAP and the 2nd component seems to be more affected than the 1st component. In conclusion EOOb and (−)-LIN inhibited the excitability of peripheral nervous system in a similar way and potency, revealing that the effects of EOOb on excitability are due to the presence of (−)-LIN in the essential oil.

Biologically Active Compounds from Hops and Prospects for Their Use

Although female cones of the hop plant (Humulus lupulus) are known primarily as raw material supplying characteristic bitterness and aroma to beer, their equally significant health-promoting effects have been known to mankind for several thousand years and hop is a plant traditionally utilized in folk medicine. This paper summarizes the scientific knowledge on the effects of all 3 major groups of secondary metabolites of hops; polyphenols, essential oils, and resins. Because of their chemical diversity, it is no coincidence that these compounds exhibit a wide range of pharmacologically important properties. In addition to antioxidant, anti-inflammatory, and anticancer-related properties, particular attention is being paid to prenylflavonoids that occur almost exclusively in hops and are considered to be some of the most active phytoestrogens known. Hop oils and resins are well known for their sedative and other neuropharmacological properties, but in addition, these compounds exhibit antibacterial and antifungal effects. Recently, alpha bitter acids have been shown to block the development of a number of complex lifestyle diseases that are referred to by the collective name "metabolic syndrome." Information presented in this review confirms the significant potential for the use of hops in the pharmaceutical industry and provides an understanding of beer as a natural drink that, although moderately consumed, may become a source of many health-promoting compounds.

Enhanced analgesic activity by cyclodextrins - a systematic review and meta-analysis

INTRODUCTION

Analgesics can be ineffective in treating some types of pain, hence, improved drug delivery systems could optimize their efficacy.

AREA COVERED

The authors conducted a systematic review to evaluate the analgesic activity of compounds complexed in cyclodextrins, analyzing whether these complexes improved analgesic efficacy. The search terms 'analgesics', 'cyclodextrins' and 'drug effects' were used to retrieve articles in SCOPUS, PUBMED and EMBASE. A total of 22 papers were identified. In the clinical studies, there was greater efficacy in the complexed drug when compared with control groups, with differences ranging from 25 to 83%. Through a meta-analysis, the preclinical studies showed that the complexed drug had a significantly (p < 0.01) greater effect than the non-complexed drug.

EXPERT OPINION

The use of cyclodextrins can improve the efficacy of analgesic compounds, and they are an important tool in the search for greater analgesic effect. They may also be a way to reduce the therapeutic doses, and hence increasing the potential of the drug.

Involvement of Cholinergic and Opioid System in γ-Terpinene-Mediated Antinociception

The literature shows that the monoterpenes are great candidates for the development of new drugs for the treatment of various pathological processes, including painful conditions. The gamma terpinene (γ-TPN) is a monoterpene present in plant species that have multiple pharmacological properties and has structural similarity to antinociceptive monoterpenes, such as limonene and alpha-phellandrene. The γ-TPN molecular mass was evaluated by mass spectrometry and showed a pseudomolecular ion with m/z 137.0 Da. The animals did not present any signs of acute toxicity at 2 g/kg, p.o. γ-TPN (1.562 to 50 mg/kg, p.o.) showed an antinociceptive effect in the formalin, capsaicin, and glutamate tests. γ-TPN has antinociceptive action when administered by others routes in glutamate test. To eliminate a possible sedative effect of γ-TPN, the open field and rota-rod test were conducted and the γ-TPN did not show muscle relaxant activity or central depressant effect. To investigate the mechanisms of action, the animals were pretreated with naloxone, glibenclamide, atropine, mecamylamine, or L-arginine in the glutamate test. γ-TPN antinociception was inhibited in the presence of naloxone, glibenclamide, atropine, and mecamylamine. The results suggest that the γ-TPN (p.o.) produced antinociceptive effect in models of chemical nociception through the cholinergic and opioid systems involvement.