Dietary Geraniol by Oral or Enema Administration Strongly Reduces Dysbiosis and Systemic Inflammation in Dextran Sulfate Sodium-Treated Mice

The senotherapeutic potential of phytochemicals for age-related intestinal disease

During the last few decades, life expectancy has increased worldwide along with the prevalence of several age-related diseases. Among aging pathways, cellular senescence and chronic inflammation (or "inflammaging") appear to be connected to gut homeostasis and dysbiosis of the microbiome. Cellular senescence is a state of essentially irreversible cell cycle arrest that occurs in response to stress. Although senescent cells (SC) remain metabolically active, they do not proliferate and can secrete inflammatory and other factors comprising the senescence-associated secretory phenotype (SASP). Accumulation of SCs has been linked to onset of several age-related diseases, in the brain, bones, the gastrointestinal tract, and other organs and tissues. The gut microbiome undergoes substantial changes with aging and is tightly interconnected with either successful (healthy) aging or disease. Senotherapeutic drugs are compounds that can clear senescent cells or modulate the release of SASP factors and hence attenuate the impact of the senescence-associated pro-inflammatory state. Phytochemicals, phenolic compounds and terpenes, which have antioxidant and anti-inflammatory activities, could also be senotherapeutic given their ability to act upon senescence-linked cellular pathways. The aim of this review is to dissect links among the gut microbiome, cellular senescence, inflammaging, and disease, as well as to explore phytochemicals as potential senotherapeutics, focusing on their interactions with gut microbiota. Coordinated targeting of these inter-related processes might unveil new strategies for promoting healthy aging.

Geraniol intake improves age-related malnutrition in mice

AIM

Geraniol is an acyclic monoterpenoid that is abundant in many plants, including rose, lemongrass, and lavender. As geraniol has various beneficial functions, rose oil rich in geraniol is not only used for aromatherapy but also as a supplement to promote health benefits. However, the beneficial effects of geraniol on age-related pathologies are unknown. In this study, we aimed to clarify the effects of geraniol intake on age-related pathologies.

METHODS

We orally administered geraniol to aged mice (age: 24-29 months) five times a week for 4 weeks and sampled their blood and various organs. We investigated age-related changes in the blood and organ samples. Furthermore, we treated HepG2 cells with geraniol and examined the expression level of the ALB gene and the amount of secreted albumin in vitro.

RESULTS

Geraniol significantly increased blood albumin, total cholesterol, and red blood cell counts, indicating an improvement in nutritional markers in aged mice. Geraniol also transcriptionally increased the Alb gene expression in the liver of aged mice. Furthermore, treatment with geraniol significantly upregulated the ALB gene expression and the secretion of albumin in the conditioned medium of HepG2 cells.

CONCLUSION

Geraniol increases serum albumin levels at the transcriptional level. Geraniol intake can be an effective strategy for age-related malnutrition. Geriatr Gerontol Int 2024; 24: 1233-1240.

Antipruritic effects of geraniol on acute and chronic itch via modulating spinal GABA/GRPR signaling

BACKGROUND AND PURPOSE

Itch (pruritus) is a common unpleasant feeling, often accompanied by the urge of scratching the skin. It is the main symptom of many systemic and skin diseases, which can seriously affect the patient's quality of life. Geraniol (GE; trans-3,7-dimethyl-2,6-octadien-1-ol) is a natural monoterpene with diverse effects, including anti-inflammatory, antioxidant, neuroprotective, anti-nociceptive, and anticancer properties. The study aims to examine the effects of GE on acute and chronic itch, and explore the underlying mechanisms.

METHODS

Acute itch was investigated by using Chloroquine and compound 48/80 induced model, followed by manifestation of diphenylcyclopropenone (DCP)-induced allergic contact dermatitis and the acetone-ether-water (AEW)-induced dry skin model in mice. The scratching behavior, skin thickness, c-Fos expression, and GRPR protein expression in the spinal cord were subsequently monitored and evaluated by behavioral tests as well as pharmacological and pharmacogenetic technologies.

RESULTS

Dose-dependent intraperitoneal injection of GE alleviated the acute itch, induced by chloroquine and compound 48/80, as well as increased the spinal c-Fos expression. Intrathecal administration of GE suppressed the GABAA receptor inhibitor bicuculline-induced itch, GRP-induced itch, and the GABAergic neuron inhibition-induced itch. Furthermore, the subeffective dose of bicuculline blocked the anti-pruritic effect of GE on the chloroquine and compound 48/80 induced acute itch. GE also attenuated DCP and AEW-induced chronic itch, as well as the increase of spinal GRPR expression in DCP mice.

CONCLUSION AND IMPLICATIONS

GE alleviates both acute and chronic itch via modulating the spinal GABA/GRPR signaling in mice. Findings of this study reveal that GE may provide promising therapeutic options for itch management. Also, considering the pivotal role of essential oils in aromatherapy, GE has great application potential in aromatherapy for treating skin diseases, and especially the skin with severe pruritus.

Therapeutic potential of Litsea cubeba essential oil in modulating inflammation and the gut microbiome

Inflammation, a sophisticated and delicately balanced physiological mechanism, is paramount to the host's immunological defense against pathogens. However, unfettered and excessive inflammation can be instrumental in engendering a plethora of chronic ailments and detrimental health repercussions, notably within the gastrointestinal tract. Lipopolysaccharides (LPS) from bacteria are potent endotoxins capable of instigating intestinal inflammation through the disruption of the intestinal epithelial barrier and the stimulation of a pro-inflammatory immune response. In this study, we sought to investigate the influence of Litsea cubeba essential oil (LCEO) on LPS-induced intestinal inflammation and associated changes in the gut microbiota. We investigated the therapeutic potential of LCEO for gut health, with particular emphasis on its gut protective properties, anti-inflammatory properties and modulation of the gut microbiome. LCEO exhibited protective effects on colonic tissue by protecting crypts and maintaining epithelial integrity, and anti-inflammatory properties by reducing TNF-α, IL-6, and IL-1β levels in the liver and intestine. Citral, a major component of LCEO, showed robust binding to IL-1β, IL-6, and TNF-α, exerting anti-inflammatory effects through hydrogen bonding interactions. Using community barplot and LEfSe analyses, we detected significant variation in microbial composition, identified discrete biomarkers, and highlighted the influence of essential oils on gut microbial communities. Our research suggests that LCEO may be a promising natural compound for ameliorating diarrhea and intestinal inflammation, with potential implications for modulating the gut microbiome. These observations provide invaluable insight into the potential therapeutic role of LCEO as a natural anti-inflammatory agent for treating intestinal inflammatory disorders, particularly in the setting of a dysregulated immune response and altered gut microbiota. Furthermore, our findings highlight the need to understand the complex interplay between the host, the gut microbiome and natural products in the context of inflammatory diseases.

Lentilactobacillus kefiri SGL 13 and Andrographis paniculata alleviate dextran sulfate sodium induced colitis in mice

Introduction

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions that typically involve diarrhea, abdominal pain, fatigue, and weight loss, with a dramatic impact on patients' quality of life. Standard medications are often associated with adverse side effects. Thus, alternative treatments such as probiotics are of great interest. The purpose of the present study was to evaluate the effects of oral administration of Lentilactobacillus kefiri (basonym: Lactobacillus kefiri) SGL 13 and Andrographis paniculata, namely, Paniculin 13™, on dextran sodium sulfate (DSS)- treated C57BL/6J mice.

Methods

Colitis was induced by administering 1.5% DSS in drinking water for 9 days. Forty male mice were divided into four groups, receiving PBS (control), 1.5% DSS, Paniculin 13™ and 1.5% DSS + Paniculin 13™.

Results

The results showed that body weight loss and Disease Activity Index (DAI) score were improved by Paniculin 13™. Moreover, Paniculin 13™ ameliorated DSS-induced dysbiosis, by modulating the gut microbiota composition. The gene expression of MPO, TNFα and iNOS in colon tissue was reduced and these data matched with the histological results, supporting the efficacy of Paniculin 13™ in reducing the inflammatory response. No adverse effects were associated to Paniculin 13™ administration.

Discussion

In conclusion, Paniculin 13™ could be an effective add-on approach to conventional therapies for IBD.

Extract of Laurus nobilis attenuates inflammation and epithelial ulcerations in an experimental model of inflammatory bowel disease

Inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, are classified as chronic inflammatory disorders and typically require anti-inflammatory drug therapies, such as glucocorticoid regimens, non-steroidal anti-inflammatory drugs, and biologics, aimed at reducing inflammation in the bowel wall. However, each of these therapies is accompanied by a list of possible serious side effects. Because of this, there remains an urgent need to identify new pharmacologic options to reduce or prevent the pro-inflammatory events of IBD while minimizing adverse side effects, and to make available more cost-effective treatment modalities. We have previously identified several herbal extracts that demonstrate potent bio-inhibitory activity of the innate immune response. In particular, Laurus nobilis (LN), or more commonly called bay laurel, demonstrated significant anti-inflammatory function by inhibiting nuclear factor-κB activation. Based upon our original in vitro findings, we have now examined the effects of this herbal extract on a murine dextran sodium sulfate (DSS) model of IBD. Hematoxylin and eosin-stained paraffin sections prepared from DSS treated animals show clear epithelial damage, including ulcerations, extensive neutrophil infiltration into the mucosal layer, and granuloma formation. Tissue from DSS treated animals that also received LN extract showed improved tissue morphology more closely resembling that from control animals. In addition, DSS treated mice with co-administration of LN extract showed a significant reduction in CD4+ antibody staining within the mucosal layer in colonic sections indicating reduced lymphocyte infiltration. Based on these findings, we believe that administration of LN extracts may be effective in reducing the intestinal epithelial damage seen in human IBD and warrants further investigation through clinical trials. Lay Summary: Inflammatory bowel diseases (IBD), such as Crohn's disease (CD) and ulcerative colitis (UC), manifest as chronic inflammation and ulceration of tissues lining the digestive tract. CD involves inflammation of the deeper layers of the digestive tract, including both the small and large intestines, and less commonly, the upper digestive tract. UC involves inflammation along the lining of the colon and rectum. Steroid or biologic treatments for IBD are common, however, are limited due to significant side effects and/or prohibitive cost. In the present study, we provide evidence for use of the natural product, Laurus nobilis (bay leaf), as a safe and effective anti-inflammatory therapy for IBD.

Geraniol Treatment for Irritable Bowel Syndrome: A Double-Blind Randomized Clinical Trial

Geraniol is an acyclic monoterpene alcohol with well-known anti-inflammatory and antimicrobial properties which has shown eubiotic activity towards gut microbiota (GM) in patients with irritable bowel syndrome (IBS).

METHODS

Fifty-six IBS patients diagnosed according to Rome III criteria were enrolled in an interventional, prospective, multicentric, randomized, double-blinded, placebo-controlled trial. In the treatment arm, patients received a low-absorbable geraniol food supplement (LAGS) once daily for four weeks.

RESULTS

Patients treated with LAGS showed a significant reduction in their IBS symptoms severity score (IBS-SSS) compared to the placebo (195 vs. 265, p = 0.001). The rate of responders according to IBS-SSS (reduction ≥ 50 points) was significantly higher in the geraniol vs placebo group (52.0% vs. 16.7%, p = 0.009) mainly due to the IBS mixed subtype. There were notable differences in the microbiota composition after geraniol administration, particularly a significant decrease in a genus of Ruminococcaceae, Oscillospira (p = 0.01), a decreasing trend for the Erysipelotrichaceae and Clostridiaceae families (p = 0.1), and an increasing trend for other Ruminococcaceae taxa, specifically Faecalibacterium (p = 0.09). The main circulating proinflammatory cytokines showed no differences between placebo and geraniol arms.

CONCLUSION

LAGS was effective in treating overall IBS symptoms, together with an improvement in the gut microbiota profile, especially for the IBS mixed subtype.

Neuroprotective effect of geraniol on neurological disorders: a review article

BACKGROUND

Neurological disorders are structural, biochemical, and electrical abnormalities that affect the peripheral and central nervous systems. Paralysis, muscle weakness, tremors, spasms, and partial or complete loss of sensation are some symptoms of these disorders. Neurorehabilitation is the main treatment for neurological disorders. Treatments can improve the quality of life of patients. Neuroprotective substances of natural origin are used for the treatments of these disorders.

METHODS AND RESULTS

Online databases, such as Google Scholar, PubMed, ScienceDirect, and Scopus were searched to evaluate articles from 1981-2021 using the Mesh words of geraniol (GER), neurological disorders, epilepsy, spinal cord injury (SCI), Parkinson's diseases (PD), and depression. A total of 87 studies were included in this review. GER with antioxidant, anti-inflammatory, and neuroprotective effects can improve the symptoms and reduce the progression of neurological diseases. GER exhibits neuroprotective effects by binding to GABA and glycine receptors as well as by inhibiting the activation of nuclear factor kappa B (NF-κB) pathway and regulating the expression of nucleotide-binding oligomerization of NLRP3 inflammasome. In this study, the effect of GER was investigated on neurological disorders, such as epilepsy, SCI, PD, and depression.

CONCLUSION

Although the medicinal uses of GER have been reported, more clinical and experimental studies are needed to investigate the effect of using traditional medicine on improving lifethreatening diseases and the quality of life of patients.

Nutraceuticals in the Modulation of the Intestinal Microbiota: Current Status and Future Directions

Pharmaceutical interest in the human intestinal microbiota has increased considerably, because of the increasing number of studies linking the human intestinal microbial ecology to an increasing number of non-communicable diseases. Many efforts at modulating the gut microbiota have been made using probiotics, prebiotics and recently postbiotics. However, there are other, still little-explored opportunities from a pharmaceutical point of view, which appear promising to obtain modifications of the microbiota structure and functions. This review summarizes all in vitro, in vivo and clinical studies demonstrating the possibility to positively modulate the intestinal microbiota by using probiotics, prebiotics, postbiotics, essential oils, fungus and officinal plants. For the future, clinical studies investigating the ability to impact the intestinal microbiota especially by using fungus, officinal and aromatic plants or their extracts are required. This knowledge could lead to effective microbiome modulations that might support the pharmacological therapy of most non-communicable diseases in a near future.

Human Umbilical Cord Mesenchymal Stem Cells Improve Locomotor Function in Parkinson’s Disease Mouse Model Through Regulating Intestinal Microorganisms

Parkinson’s disease (PD) is a progressive neurological disorder characterized by loss of neurons that synthesize dopamine, and subsequent impaired movement. Umbilical cord mesenchymal stem cells (UC-MSCs) exerted neuroprotection effects in a rodent model of PD. However, the mechanism underlying UC-MSC-generated neuroprotection was not fully elucidated. In the present study, we found that intranasal administration of UC-MSCs significantly alleviated locomotor deficits and rescued dopaminergic neurons by inhibiting neuroinflammation in a PD mouse model induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, a toxic agent which selectively destroys nigrostriatal neurons but does not affect dopaminergic neurons elsewhere). Furthermore, UC-MSC treatment altered gut microbiota composition characterized by decreased phylum Proteobacteria, class Gammaproteobacteria, family Enterobacteriaceae, and genus Escherichia-Shigella. In addition, the neurotransmitter dopamine in the striatum and 5-hydroxytryptamine in the colon were also modulated by UC-MSCs. Meanwhile, UC-MSCs significantly maintained intestinal goblet cells, which secrete mucus as a mechanical barrier against pathogens. Furthermore, UC-MSCs alleviate the level of TNF-α and IL-6 as well as the conversion of NF-κB expression in the colon, indicating that inflammatory responses were blocked by UC-MSCs. PICRUSt showed that some pathways including bacterial invasion of epithelial cells, fluorobenzoate degradation, and pathogenic Escherichia coli infection were significantly reversed by UC-MSCs. These data suggest that the beneficial effects were detected following UC-MSC intranasal transplantation in MPTP-treated mice. There is a possible neuroprotective role of UC-MSCs in MPTP-induced PD mice by cross talk between the brain and gut.

Antifungal Activity of Natural Compounds vs. Candida spp.: A Mixture of Cinnamaldehyde and Eugenol Shows Promising In Vitro Results

Candida spp. are commensal organisms of the skin, mucous membranes, gastrointestinal tract, blood, and vagina of animals and humans. In recent decades, the incidence of human fungal infections has increased, with Candida spp. (mainly C. albicans) infections being the most frequent, and the treatment of fungal infections is still a clinical challenge. Colonization of the human gastrointestinal tract by Candida spp. is significant because infections (e.g., candidemia and vulvovaginal candidiasis) frequently arise from commensal microorganisms. The aim of this study was to test in vitro the antifungal activity and the eventual synergistic effect of five pure components of essential oils: cinnamaldehyde, α-pinene, limonene, eucalyptol, and eugenol. These compounds were tested on 18 Candida strains (15 C. albicans, 2 C. glabrata, and 1 C. lusitaniae) derived from a culture collection of vaginal clinical strains.

METHODS

Fungistatic activity was evaluated using the disk diffusion method. For fungicidal activity, microdilution and time-kill curve protocols were set up. The checkerboard method was chosen to evaluate a possible synergistic effect of these compounds when mixed.

RESULTS

Cinnamaldehyde and eugenol gave the best results, inhibiting all the Candida strains and showing a highly additive effect (FICI 0.625). The cinnamaldehyde inhibition zone (IZ), MIC, and MFC means were 69 mm, 50.05 mg/L, and 109.26 mg/L respectively. Cinnamaldehyde led to the total loss of viable Candida cells within 4 h. Eugenol IZ, MIC, and MFC means were 35.2 mm, 455.42 mg/L, and 690.09 mg/L, respectively. Eugenol led to the total loss of viable fungal cells within 1 h. Treatment with α-pinene inhibited 88.9% of Candida strains, with an IZ mean of 21.2 mm, a MIC mean of 195.41 mg/L, and a MFC mean of 251.27 mg/L; this compound led to the total loss of viable fungal cells only after 24 h. Limonene inhibited only 33.3% of the tested strains and eucalyptol did not produce an inhibition halo, so these compounds were not tested further.

CONCLUSIONS

These characteristics, together with the well-known safety of cinnamaldehyde and eugenol for human use, make these two natural compounds the perfect candidates for the treatment of candidiasis. This was a pilot study, the purpose of which was to evaluate the best composition of a mixture to be used against intestinal and vulvovaginal candidiasis; in vivo studies are needed to confirm these very encouraging results.

Nasal biocompatible powder of Geraniol oil complexed with cyclodextrins for neurodegenerative diseases: physicochemical characterization and in vivo evidences of nose to brain delivery

Recently, many studies have shown that plant metabolites, such as geraniol (GER), may exert anti-inflammatory effects in neurodegenerative diseases and, in particular, Parkinson's disease (PD) models. Unfortunately, delivering GER to the CNS via nose-to-brain is not feasible due to its irritant effects on the mucosae. Therefore, in the present study β-cyclodextrin (βCD) and its hydrophilic derivative hydroxypropyl-beta-cyclodextrin (HPβCD) were selected as potential carriers for GER nose-to-brain delivery. Inclusion complexes were formulated and the biocompatibility with nasal mucosae and drug bioavailability into cerebrospinal fluid (CSF) were studied in rats. It has been demonstrated by DTA, FT-IR and NMR analyses that both the CDs were able to form 1:1 GER-CD complexes, arising long-term stable powders after the freeze-drying process. GER-HPβCD-5 and GER-βCD-2 complexes exhibited comparable results, except for morphology and solubility, as demonstrated by SEM analysis and phase solubility study, respectively. Even though both complexes were able to directly and safely deliver GER to CNS, GER-βCD-2 displayed higher ability in releasing GER in the CSF. In conclusion, βCD complexes can be considered a very promising tool in delivering GER into the CNS via nose-to-brain route, preventing GER release into the bloodstream and ensuring the integrity of the nasal mucosa.

Molecules Present in Plant Essential Oils for Prevention and Treatment of Colorectal Cancer (CRC)

Essential oils (EOs) are a complex mixture of hydrophobic and volatile compounds synthesized from aromatic plants, commonly present in the human diet. In recent years, many in vitro studies have suggested possible anticancer properties of single EO compounds, on colorectal cancer (CRC) cells. However, the majority of these studies did not compare the effects of these compounds on normal and cancer colon cells. By using NCM-460, a normal human mucosal epithelial cell line, Caco-2, a human colon epithelial adenocarcinoma cell line, and SW-620, colon cancer cells derived from lymph node metastatic site, we identified cinnamaldehyde, derived from cinnamon EO and eugenol, derived from bud clove EO, as compounds with a specific anticancer action selectively targeting the transformed colonic cells. Both cinnamaldehyde (75 µM) and eugenol (800 µM), after 72 h of treatment, were capable to induce apoptosis, necrosis and a cell cycle slowdown in Caco-2 and in SW-620, but not in NCM-460 cells. If associated with a targeted delivery to the colon, these two compounds could prove effective in the prevention or treatment of CRC.

Intestinal Anti-Inflammatory Activity of Terpenes in Experimental Models (2010-2020): A Review

Inflammatory bowel diseases (IBDs) refer to a group of disorders characterized by inflammation in the mucosa of the gastrointestinal tract, which mainly comprises Crohn’s disease (CD) and ulcerative colitis (UC). IBDs are characterized by inflammation of the intestinal mucosa, are highly debilitating, and are without a definitive cure. Their pathogenesis has not yet been fully elucidated; however, it is assumed that genetic, immunological, and environmental factors are involved. People affected by IBDs have relapses, and therapeutic regimens are not always able to keep symptoms in remission over the long term. Natural products emerge as an alternative for the development of new drugs; bioactive compounds are promising in the treatment of several disorders, among them those that affect the gastrointestinal tract, due to their wide structural diversity and biological activities. This review compiles 12 terpenes with intestinal anti-inflammatory activity evaluated in animal models and in vitro studies. The therapeutic approach to IBDs using terpenes acts basically to prevent oxidative stress, combat dysbiosis, restore intestinal permeability, and improve the inflammation process in different signaling pathways.

One Hundred Faces of Geraniol

Geraniol is a monoterpenic alcohol with a pleasant rose-like aroma, known as an important ingredient in many essential oils, and is used commercially as a fragrance compound in cosmetic and household products. However, geraniol has a number of biological activities, such as antioxidant and anti-inflammatory properties. In addition, numerous in vitro and in vivo studies have shown the activity of geraniol against prostate, bowel, liver, kidney and skin cancer. It can induce apoptosis and increase the expression of proapoptotic proteins. The synergy of this with other drugs may further increase the range of chemotherapeutic agents. The antibacterial activity of this compound was also observed on respiratory pathogens, skin and food-derived strains. This review discusses some of the most important uses of geraniol.

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.

Nasal administration of nanoencapsulated geraniol/ursodeoxycholic acid conjugate: Towards a new approach for the management of Parkinson's disease

The combined use of different therapeutic agents in the treatment of neurodegenerative disorders is a promising strategy to halt the disease progression. In this context, we aimed to combine the anti-inflammatory properties of geraniol (GER) with the mitochondrial rescue effects of ursodeoxycholic acid (UDCA) in a newly-synthesized prodrug, GER-UDCA, a potential candidate against Parkinson's disease (PD). GER-UDCA was successfully synthetized and characterized in vitro for its ability to release the active compounds in physiological environments. Because of its very poor solubility, GER-UDCA was entrapped into both lipid (SLNs) and polymeric (NPs) nanoparticles in order to explore nose-to-brain pathway towards brain targeting. Both GER-UDCA nanocarriers displayed size below 200 nm, negative zeta potential and the ability to increase the aqueous dissolution rate of the prodrug. As SLNs exhibited the higher GER-UDCA dissolution rate, this formulation was selected for the in vivo GER-UDCA brain targeting experiments. The nasal administration of GER-UDCA-SLNs (1 mg/kg of GER-UDCA) allowed to detect the prodrug in rat cerebrospinal fluid (concentration range = 1.1 to 4.65 μg/mL, 30-150 min after the administration), but not in the bloodstream, thus suggesting the direct nose to brain delivery of the prodrug. Finally, histopathological evaluation demonstrated that, in contrast to the pure GER, nasal administration of GER-UDCA-SLNs did not damage the structural integrity of the nasal mucosa. In conclusion, the present data suggest that GER-UDCA-SLNs could provide an effective and non-invasive approach to boost the access of GER and UDCA to the brain with low dosages.

Phytochemical drug candidates for the modulation of peroxisome proliferator-activated receptor γ in inflammatory bowel diseases

Plant-based compounds or phytochemicals such as alkaloids, glycosides, flavonoids, volatile oils, tannins, resins, and polyphenols have been used extensively in traditional medicine for centuries and more recently in Western alternative medicine. Extensive evidence suggests that consumption of dietary polyphenolic compounds lowers the risk of inflammatory diseases. The anti-inflammatory properties of several phytochemicals are mediated through ligand-inducible peroxisome proliferator-activated receptors (PPARs), particularly the PPARγ transcription factor. Inflammatory bowel disease (IBD) is represented by ulcerative colitis, which occurs in the mucosa of the colon and rectum, and Crohn's disease (CD) that can involve any segment of gastrointestinal tract. Because of the lack of cost-effective pharmaceutical treatment options, many IBD patients seek and use alternative and unconventional therapies to alleviate their symptoms. PPARγ plays a role in the inhibition of inflammatory cytokine expression and activation of anti-inflammatory immune cells. The phytochemicals reported here are ligands that activate PPARγ, which in turn modulates inflammatory responses. PPARγ is highly expressed in the gut making it a potential therapeutic target for IBDs. This review summarizes the effects of the currently published phytochemicals that modulate the PPARγ pathway and reduce or eliminate colonic inflammation.

Geraniol targets KV1.3 ion channel and exhibits anti-inflammatory activity in vitro and in vivo

Naturally occurring monoterpenes are known for their various pharmacological activities including anti-inflammation. K_V1.3 ion channel is a voltage-gated potassium channel and has been validated as a drug target for autoimmune and chronic inflammatory diseases like psoriasis. Here we experimentally test the direct interaction between monoterpenes and K_V1.3 ion channel. Our electrophysiological analysis determined that monoterpenes (geraniol, nerol, β-citronellol, citral and linalool) have inhibitory effects on K_V1.3 ion channel. Representatively, geraniol reversibly blocked K_V1.3 currents in a voltage-dependent manner with an IC₅₀ of 490.50 ± 1.04 μM at +40 mV in HEK293T cells. At the effective concentrations, geraniol also inhibited cytokine secretion of activated human T cells, including IL-2, TNF-α and IFN-γ. In an imiquimod-induced psoriasis-like animal model, geraniol administration significantly reduced psoriasis area and severity index scores, ameliorated the deteriorating histopathology and decreased the degree of splenomegaly. Together, our findings not only suggest that monoterpenes may serve as lead molecules for the development of K_V1.3 inhibitors, but also indicate that geraniol could be considered as a promising therapeutic candidate to treat autoimmune diseases.

Cecropin A Alleviates Inflammation Through Modulating the Gut Microbiota of C57BL/6 Mice With DSS-Induced IBD

The present study is undertaken to assess the alleviating effects of antimicrobial peptide cecropin A on inflammatory bowel disease (IBD) in C57BL/6 mice and changes in the gut microbiota, compared to an antibiotic gentamicin. Different doses of cecropin A were intraperitoneally injected into C57BL/6 mice for 5 days to determine the safe doses. The injection doses at ≤ 15 mg/kg showed no negative impact on the liver, heart, spleen, and kidney. The severe and moderate IBD mice model was successfully established via supplementation of 4 or 2.5% dextran sulfate sodium (DSS) in drinking water for 5 days. The severe IBD model was used to ensure the optimal therapeutic dose of cecropin A. Survival rate, body weight and disease activity index (DAI) scores were measured. Administration of 15 mg/kg, not 5 mg/kg cecropin A, for 5 days increased survival rate and decreased body weight loss of mice. The moderate IBD model was applied to investigate the mechanisms for cecropin A to alleviate inflammation in comparison to gentamicin. The mice were treated with 15 mg/kg cecropin A or 5 mg/kg gentamicin for 3 days. The levels of cytokines and related proteins in the colon were detected by ELISA and Western blotting. The microbiota in cecum contents were analyzed using 16S rRNA gene sequencing. The results showed that cecropin A and gentamicin relieved body weight loss, DAI, and gut mucosa disruption, while decreasing tumor necrosis factor-α (TNF-α), interlukin-1β (IL-1β), and interlukin-6 (IL-6) induced by DSS. In addition, cecropin A and gentamicin showed different effects on the gut microbiota structure. Both cecropin A and gentamicin decreased DSS-induced enrichment of Bacteroidaceae and Enterobacteriaceae. However, cecropin A showed a selective enrichment of Lactobacillus in contrast to gentamicin, which demonstrated a selective effect on Desulfovibrionaceae and Ruminococcaceae. Cecropin A alleviates IBD through decreasing harmful gut microflora and specifically enhancing beneficial gut microflora. The mechanism of this effect is different from gentamicin.

Uptake in the Central Nervous System of Geraniol Oil Encapsulated in Chitosan Oleate Following Nasal and Oral Administration

The pharmacological activities of geraniol include anticancer and neuroprotective properties. However, its insolubility in water easily induces separation from aqueous formulations, causing administration difficulties. Here we propose new emulsified formulations of geraniol by using the amphiphilic polymer chitosan-oleate (CS-OA) as surfactant to combine mucoadhesive and absorption enhancer properties with stabilization effects on the oil dispersion. The formulation based on CS-OA 2% (w/w) (G-CS-OA-2.0%) showed viscosity values compatible with oral and nasal administration to rats, and mean diameter of the dispersed phase of 819 ± 104 nm. G-CS-OA-2.0% oral administration sensibly increases the geraniol bioavailability with respect to coarse emulsions obtained without CS-OA (AUC values in the bloodstream were 42,713 ± 1553 µg∙mL⁻¹∙min and 2158 ± 82 µg∙mL⁻¹∙min following administration of 50 mg/kg or 1 mg/kg, respectively), and enhances the aptitude of geraniol to reach the central nervous system from the bloodstream (AUC values in the cerebrospinal fluid were 7293 ± 408 µg∙mL⁻¹∙min and 399 ± 25 µg∙mL⁻¹∙min after oral administration of 50 mg/kg or 1 mg/kg, respectively). Moreover, relevant geraniol amounts were detected in the cerebrospinal fluid following the G-CS-OA-2% nasal administration (AUC values in the cerebrospinal fluid were 10,778 ± 477 µg∙mL⁻¹∙min and 5571 ± 290 µg∙mL⁻¹∙min after nasal administration of 4 mg/kg or 1 mg/kg, respectively).

In vivo protective effect of geraniol on colonization of Staphylococcus epidermidis in rat jugular vein catheter model

Staphylococcal infections associated with indwelling medical devices are difficult to eradicate owing to its recalcitrant nature of biofilms to conventional antibiotics. In our earlier study, we reported the efficacy of geraniol (GE) in inhibiting the in vitro biofilm formation of Staphylococcus epidermidis and adaptive resistant development. To examine the in vivo potential of GE in eradicating the in vivo colonization of S. epidermidis, an implanted rat jugular vein catheter model was developed. Oral supplementation of GE (GE at 200 mg/kg bw for three days) in rats infected with S. epidermidis exhibited a significant reduction of the bacterial burden in catheter, blood, heart and kidney, when compared to the untreated infection control. In addition, GE supplemented animals showed significantly reduced level of inflammatory markers such as nitric oxide and malondialdehyde in heart and kidney tissues. Furthermore, in contrast to the infection control, histopathology analysis of the heart and kidney tissues of the GE-treated group showed a normal histoarchitecture similar to animal control. Thus, the outcome of the present study exhibits the potential of GE as antibiofilm and anti-inflammatory agent against S. epidermidis infections. Furthermore, elucidating the molecular mechanism of GE is important to exploit the therapeutic efficacy of GE.

Dietary geraniol ameliorates intestinal dysbiosis and relieves symptoms in irritable bowel syndrome patients: a pilot study

Background

(Trans)-3,7-Dimethyl-2,6-octadien-1-ol, commonly called geraniol (Ge-OH), is an acyclic monoterpene alcohol with well-known anti-inflammatory and antimicrobial properties. Ge-OH is a non-toxic compound classified as Generally Recognized As Safe (GRAS) by the US Food and Drug Administration and the European Food Security Agency.

Methods

Ge-OH was orally administered at a maximum daily dose of 8 mg kg^(− 1) body weight for four weeks in a delayed release formulation capable of reaching the colon. Fecal microbiota and blood cytokines were analyzed before and after Ge-OH treatment, as well as IBS symptomatology by using Visual Analogue Scale (VAS-IBS).

Results

The results show that orally administered Ge-OH is a powerful modulator of the intestinal microbial ecosystem, capable of leading to increased relative abundances of Collinsella and especially Faecalibacterium, a well-known health-promoting butyrate producer consistently found to be decreased in IBS patients. Moreover, Ge-OH strongly improved the clinical symptoms of colitis by significantly reducing the score recorded by the VAS-IBS questionnaire. Clinical improvement was associated with a significant reduction in the circulating MIP-1β, a chemokine found to be increased in several IBS patients.

Conclusion

Ge-OH could be a powerful component for food supplement targeted to the treatment of IBS patients.

Trial registration

ISRCTN47041881, retrospectively registered on 19th July 2018.

Monoterpenes modulating cytokines - A review

Inflammatory response can be driven by cytokine production and is a pivotal target in the management of inflammatory diseases. Monoterpenes have shown that promising profile as agents which reduce the inflammatory process and also modulate the key chemical mediators of inflammation, such as pro and anti-inflammatory cytokines. The main interest focused on monoterpenes were to develop the analgesic and anti-inflammatory drugs. In this review, we summarized current knowledge on monoterpenes that produce anti-inflammatory effects by modulating the release of cytokines, as well as suggesting that which monoterpenoid molecules may be most effective in the treatment of inflammatory disease. Several different inflammatory markers were evaluated as a target of monoterpenes. The proinflammatory and anti-inflammatory cytokines were found TNF-α, IL-1β, IL-2, IL-5, IL-4, IL-6, IL-8, IL-10, IL-12 IL-13, IL-17A, IFNγ, TGF-β1 and IFN-γ. Our review found evidence that NF-κB and MAPK signaling are important pathways for the anti-inflammatory action of monoterpenes. We found 24 monoterpenes that modulate the production of cytokines, which appears to be the major pharmacological mechanism these compounds possess in relation to the attenuation of inflammatory response. Despite the compelling evidence supporting the anti-inflammatory effect of monoterpenes, further studies are necessary to fully explore their potential as anti-inflammatory compounds.

Medicinal properties of terpenes found in Cannabis sativa and Humulus lupulus

Cannabaceae plants Cannabis sativa L. and Humulus lupulus L. are rich in terpenes - both are typically comprised of terpenes as up to 3-5% of the dry-mass of the female inflorescence. Terpenes of cannabis and hops are typically simple mono- and sesquiterpenes derived from two and three isoprene units, respectively. Some terpenes are relatively well known for their potential in biomedicine and have been used in traditional medicine for centuries, while others are yet to be studied in detail. The current, comprehensive review presents terpenes found in cannabis and hops. Terpenes' medicinal properties are supported by numerous in vitro, animal and clinical trials and show anti-inflammatory, antioxidant, analgesic, anticonvulsive, antidepressant, anxiolytic, anticancer, antitumor, neuroprotective, anti-mutagenic, anti-allergic, antibiotic and anti-diabetic attributes, among others. Because of the very low toxicity, these terpenes are already widely used as food additives and in cosmetic products. Thus, they have been proven safe and well-tolerated.

Mice with Inflammatory Bowel Disease are Susceptible to Clostridium difficile Infection With Severe Disease Outcomes

Background

Over the past several decades, there has been a significant increase in the incidence of Clostridium difficile infection (CDI) in patients suffering from inflammatory bowel disease (IBD). However, a wild-type animal model is not available to study these comorbid diseases.

Methods

We evaluated the susceptibility to CDI of mice with dextran sulfate sodium salt (DSS)-induced colitis (IBD mice) with or without antibiotic exposure; we examined the histopathology and cytokine response in the concomitant diseases after the model was created.

Results

No CDI occurs in healthy control mice, wherease the incidence of CDI in IBD mice is 40%; however, in IBD mice that received antibiotics, the incidence of CDI is 100% and the disease is accompanied by high levels of toxins in the mouse feces and sera. Compared to IBD and CDI alone, those IBD mice infected with C. difficile have more severe symptoms, toxemia, histopathological damage, and higher mortality. Moreover, several proinflammatory cytokines and chemokines are significantly elevated in the colon tissues from IBD mice infected with C. difficile.

Conclusions

We, for the first time, demonstrate in an animal model that mice with dextran sulfate sodium induced-inflammatory bowel disease are significantly more susceptible to C. difficile infection, and that the bacterial infection led to more severe disease and death. These findings are consistent with clinical observations, thus, the animal model will permit us to study the pathogenesis of these concurrent diseases and to develop therapeutic strategies against the comorbidity of IBD and CDI.

Geraniol Pharmacokinetics, Bioavailability and Its Multiple Effects on the Liver Antioxidant and Xenobiotic-Metabolizing Enzymes

Geraniol is a natural monoterpene showing anti-inflammatory, antioxidant, neuroprotective and anticancer effects. No pharmacokinetic and bioavailability data on geraniol are currently available. We therefore performed a systematic study to identify the permeation properties of geraniol across intestinal cells, and its pharmacokinetics and bioavailability after intravenous and oral administration to rats. In addition, we systematically investigated the potential hepatotoxic effects of high doses of geraniol on hepatic phase I, phase II and antioxidant enzymatic activities and undertook a hematochemical analysis on mice. Permeation studies performed via HPLC evidenced geraniol permeability coefficients across an in vitro model of the human intestinal wall for apical to basolateral and basolateral to apical transport of 13.10 ± 2.3 × 10^-3 and 2.1 ± 0.1⋅× 10^-3 cm/min, respectively. After intravenous administration of geraniol to rats (50 mg/kg), its concentration in whole blood (detected via HPLC) decreased following an apparent pseudo-first order kinetics with a half-life of 12.5 ± 1.5 min. The absolute bioavailability values of oral formulations (50 mg/kg) of emulsified geraniol or fiber-adsorbed geraniol were 92 and 16%, respectively. Following emulsified oral administration, geraniol amounts in the cerebrospinal fluid of rats ranged between 0.72 ± 0.08 μg/mL and 2.6 ± 0.2 μg/mL within 60 min. Mice treated with 120 mg/kg of geraniol for 4 weeks showed increased anti-oxidative defenses with no signs of liver toxicity. CYP450 enzyme activities appeared only slightly affected by the high dosage of geraniol.

Geraniol alleviates LPS-induced acute lung injury in mice via inhibiting inflammation and apoptosis

Geraniol (GOH), a special type of acyclic monoterpene alcohol, has been widely used to treat many diseases associated with inflammation and apoptosis. Acute lung injury (ALI) is a common clinical disease in humans characterized by pulmonary inflammation and apoptosis. In the present study, we investigated the protective effects of GOH in a mouse model of ALI induced by the intranasal administration of lipopolysaccharide (LPS) and elucidated the underlying molecular mechanisms in RAW 264.7 cells. In vivo, GOH treatment markedly ameliorated pathological injury and pulmonary cell apoptosis and reduced the wet/dry (W/D) weight ratio of lungs, myeloperoxidase (MPO) activity and the production of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α). In vitro, the levels of pro-inflammatory cytokines, iNOS and COX-2 were significantly increased in LPS-stimulated RAW 264.7 cells, an effect that was decreased by GOH treatment. Moreover, GOH treatment dramatically reduced the expression of Toll-like receptor 4 (TLR4) and then prevented the nuclear factor-κB (NF-κB) activation. GOH treatment also promoted anti-apoptotic Bcl-2 expression and inhibited pro-apoptotic Bax and Caspase-3 expression. Furthermore, knockdown of TLR4 expression exerted a similar effect and inhibited the phosphorylation of p65, as well as the Bax and Caspase-3 expression. Taken together, these results suggest that GOH treatment alleviates LPS-induced ALI via inhibiting pulmonary inflammation and apoptosis, a finding that might be associated with the inhibition of TLR4-mediated NF-κB and Bcl-2/Bax signalling pathways.

Translating nutritional immunology into drug development for inflammatory bowel disease

PURPOSE OF REVIEW

To highlight recent advances in the understanding of nutritional immunology and in the development of novel therapeutics for inflammatory bowel disease (IBD).

RECENT FINDINGS

We highlight the variety of factors that contribute to the interaction of the immune system and nutrition including the microbiome and the nervous system stimulation of the gut. We describe the potential for therapeutic development in IBD. Further, we review the cellular metabolic effects on immune activation and promising therapeutic targets. Finally, we show how the progression of understanding the role of lanthionine synthetase C-like 2 has encompassed both nutritional and therapeutic advances and led to the development of novel oral small molecule therapeutics for IBD.

SUMMARY

Nutritional immunology and drug development research centered around immunoregulatory pathways can provide safer and more effective drugs while accelerating the path to cures.

Inhibition of the NorA multi-drug transporter by oxygenated monoterpenes

The aim of this study was to investigate intrinsic antimicrobial activity of three monoterpenes nerol, dimethyl octanol and estragole, against bacteria and yeast strains, as well as, investigate if these compounds are able to inhibit the NorA efflux pump related to fluoroquinolone resistance in Staphylococcus aureus. Minimal inhibitory concentrations (MICs) of the monoterpenes against Staphylococcus aureus, Escherichia coli and Candida albicans strains were determined by micro-dilution assay. MICs of the norfloxacin against a S. aureus strain overexpressing the NorA protein were determined in the absence or in the presence of the monoterpenes at subinhibitory concentrations, aiming to verify the ability of this compounds act as efflux pump inhibitors. The monoterpenes were inactive against S. aureus however the nerol was active against E. coli and C. albicans. The addition of the compounds to growth media at sub-inhibitory concentrations enhanced the activity of norfloxacin against S. aureus SA1199-B. This result shows that bioactives tested, especially the nerol, are able to inhibit NorA efflux pump indicating a potential use as adjuvants of norfloxacin for therapy of infections caused by multi-drug resistant S. aureus strains.