Protective Effect of Lemon Essential Oil and Its Major Active Component, D-Limonene, on Intestinal Injury and Inflammation of E. coli-Challenged Mice

Antioxidant properties of D-limonene and its nanoemulsion form enhance its anticoccidial efficiency in experimentally infected broilers with Eimeria tenella: an in vitro and in vivo study

The excessive use of conventional medications to treat coccidiosis has led to concerns regarding drug residues in tissues and the emergence of multidrug resistance. Essential oils with anti-inflammatory and antioxidant activities may also have anticoccidial effects. The present study investigated the efficacy of D-limonene and its nanoemulsion form against Eimeria tenella in chickens. An in vitro study was conducted to evaluate the sporulation inhibitory effects of D-limonene on Eimeria tenella oocysts. Five D-limonene concentrations (0.625, 1.25, 2.5, 5, and 10% v/v) were tested alongside positive (10% formalin) and negative (2.5% potassium dichromate) controls. Each ELISA plate well was inoculated with 1200 unsporulated oocysts and incubated at 30 °C for 24, 48, and 72 h. Subsequently, samples were microscopically examined to assess sporulation inhibition and calculate the percentage of sporulated oocysts. For the in vivo study, 125 eight-day-old broiler chicks were divided into five groups of 25 birds each. The control negative group remained uninfected and untreated. The control positive group was challenged with 5 × 104 sporulated Eimeria tenella oocysts. The diclazuril group received 0.2 mg/kg diclazuril in their diet two days prior to, and until 10 days post infection. The D-limonene (DL) and D-limonene nanoemulsion (DLN) groups were challenged with 5 × 104 sporulated E. tenella oocysts at 18 days of age and administered 150 mg/L of their respective treatments in drinking water from day eight until the end of the experiment. Results from the in vitro study demonstrated that D-limonene suppressed oocyst sporulation by 50.83% at its highest concentration of 10%. In the in vivo study, both DL and DLN treated groups exhibited a significant reduction in oocyst output per gram of feces (OPG), along with increased body weight and decreased parasite stages in the cecal tissue. Furthermore, these treatments were associated with elevated levels of antioxidant enzymes such as glutathione peroxidase (GPX), catalase (CAT), and superoxide dismutase (SOD), accompanied by a decrease in malondialdehyde (MDA) and nitric oxide (NO) levels. Particularly, DLN treatment remarkably increased the number of goblet cells. In conclusion, D-limonene and its nanoemulsion represent promising alternatives for managing coccidiosis in poultry. They not only effectively control parasites but also promote intestinal health and boost antioxidant defenses.

Ursolic acid improves necroptosis via STAT3 signaling in intestinal ischemia/reperfusion injury

Intestinal ischemia/reperfusion injury (IRI) poses a serious threat to human survival and quality of life with high mortality and morbidity rates. The current absence of effective treatments for intestinal IRI highlights the urgent need to identify new therapeutic targets. Ursolic acid (UA), a pentacyclic triterpene natural compound, has been shown to possess various pharmacological properties including intestinal protection. However, its potential protective efficacy on intestinal IRI remains elusive. This study aimed to investigate the effect of UA on intestinal IRI and explore the underlying mechanisms. To achieve this, we utilized network pharmacology to analyze the mechanism of UA in intestinal IRI and assessed UA's effects on intestinal IRI using a mouse model of superior mesenteric artery occlusion/reperfusion and an in vitro model of oxygen-glucose deprivation and reperfusion-induced IEC-6 cells. Our results demonstrated that UA improved necroptosis through the RIP1/RIP3/MLKL pathway, reduced necroinflammation via the HMGB1/TLR4/NF-κB pathway, attenuated morphological damage, and enhanced intestinal barrier function. Furthermore, UA pretreatment downregulated the phosphorylation level of signal transducer and activator of transcription 3 (STAT3). The effects of UA were attenuated by the STAT3 agonist Colivelin. In conclusion, our study suggests that UA can improve intestinal IRI by inhibiting necroptosis in enterocytes via the suppression of STAT3 activation. These results provide a theoretical basis for UA treatment of intestinal IRI and related clinical diseases.

Dietary limonene promotes gastrointestinal barrier function via upregulating tight/adherens junction proteins through cannabinoid receptor type-1 antagonistic mechanism and alters cellular metabolism in intestinal epithelial cells

Limonene, a dietary monocyclic monoterpene commonly found in citrus fruits and various aromatic plants, has garnered increasing interest as a gastrointestinal protectant. This study aimed to assess the effects of limonene on intestinal epithelial barrier function and investigate the involvement of cannabinoid receptor type-1 (CB1R) in vitro. Additionally, the study focused on examining the metabolomic changes induced by limonene in the intestinal epithelial cells (Caco-2). Initial analysis of transepithelial electrical resistance (TEER) revealed that both l-limonene and d-limonene, isomers of limonene, led to a dose- and time-dependent increase in TEER in normal cells and those inflamed by pro-inflammatory cytokines mixture (CytoMix). Furthermore, both types of limonene reduced CytoMix-induced paracellular permeability, as demonstrated by a decrease in Lucifer yellow flux. Moreover, d-limonene and l-limonene treatment increased the expression of tight junction molecules (TJs) such as occludin, claudin-1, and ZO-1, at both the transcriptional and translational levels. d-Limonene upregulates E-cadherin, a molecule involved in adherens junctions (AJs). Mechanistic investigations demonstrated that d-limonene and l-limonene treatment significantly inhibited CB1R at the protein, while the mRNA level remained unchanged. Notably, the inhibitory effect of d-limonene on CB1R was remarkably similar to that of pharmacological CB1R antagonists, such as rimonabant and ORG27569. d-limonene also alters Caco-2 cell metabolites. A substantial reduction in β-glucose and 2-succinamate was detected, suggesting limonene may impact intestinal epithelial cells' glucose uptake and glutamate metabolism. These findings suggest that d-limonene's CB1R antagonistic property could effectively aid in the recovery of intestinal barrier damage, marking it a promising gastrointestinal protectant.

Essential oils: a systematic review on revolutionizing health, nutrition, and omics for optimal well-being

Purpose

Essential oils from various plants have diverse therapeutic properties and are researched extensively. They have applications in medicine, aromatherapy, microbiology, agriculture, livestock, and the food industry, benefiting the population.

Methods

This systematic review followed the PRISMA verification protocol. The study focused on the anti-inflammatory effects, nutraceutical properties, antioxidant and antibacterial activity of essential oils in lemon, orange, cumin, cinnamon, coriander, rosemary, thyme, and parsley. We also looked at their presence in the diet, their effect, their mechanism of action on health, and the most important active compounds. The search was conducted in the PubMed database for the last 12 years of publications, including in vitro, in vivo, and online cell model tests.

Results

Essential oils have been shown to have multiple health benefits, primarily due to their antimicrobial and anti-inflammatory effects. The mechanism of action of cinnamon oil alters bacterial membranes, modifies lipid profiles, and inhibits cell division, giving a potential benefit in protection against colitis. On the other hand, a significant improvement was observed in the diastolic pressure of patients with metabolic syndrome when supplementing them with cumin essential oil. The antimicrobial properties of coriander essential oil, especially its application in seafood like tilapia, demonstrate efficacy in improving health and resistance to bacterial infections. Cumin essential oil treats inflammation. Parsley essential oil is an antioxidant. Orange peel oil is antibacterial, antifungal, antiparasitic, and pro-oxidative. Lemon essential oil affects mouse intestinal microbiota. Thyme essential oil protects the colon against damage and DNA methylation. Carnosic acid in rosemary oil can reduce prostate cancer cell viability by modifying the endoplasmic reticulum function.

Conclusion and discussion

Essential oils have many therapeutic and antiparasitic properties. They are beneficial to human health in many ways. However, to understand their potential benefits, more research is needed regarding essential oils such as coriander, parsley, rosemary, cumin, and thyme. These research gaps are relevant since they restrict understanding of the possible benefits of these crucial oils for health-related contexts.

Variation of the essential oil components of Citrus aurantium leaves upon using different distillation techniques and evaluation of their antioxidant, antidiabetic, and neuroprotective effect against Alzheimer's disease

Citrus fruit essential oil is considered one of the widely studied essential oils while its leaves attract less attention although being rich in nearly the same composition as the peel and flowers. The leaves of bitter orange or sour orange (Citrus aurantium L.) were extracted using three different techniques namely; hydrodistillation (HD), steam distillation (SD), and microwave-assisted distillation (MV) to compare their chemical composition. The three essential oil samples were analyzed through GC/FID and GC/MS analyses. The samples were tested in vitro using different antioxidant techniques (DPPH, ABTS, CUPRAC, FRAP, PBD, and MCA), neuroprotective enzyme inhibitory activities (acetylcholine and butyl choline enzymes), and antidiabetic activities (α-amylase and α-glucosidase). The results showed that thirty-five volatile ingredients were detected and quantified. Monoterpenes represented the most abundant class in the three essential oils followed by sesquiterpenes. C. aurantium essential oil carried potential antioxidant activity where SD exhibited the highest antioxidant activity, with values arranged in the following order: FRAP (200.43 mg TE/g), CUPRAC (138.69 mg TE/g), ABTS (129.49 mg TE/g), and DPPH (51.67 mg TE/g). SD essential oil also presented the most potent α-amylase (0.32) inhibition while the MV essential oil showed the highest α-glucosidase inhibition (2.73 mmol ACAE/g), followed by HD (2.53 mmol ACAE/g), and SD (2.46 mmol ACAE/g). The SD essential oil exhibited the highest BChE and AChE inhibitory activities (3.73 and 2.06 mg GALAE/g), respectively). Thus, bitter orange essential oil can act as a potential source of potent antioxidant, antidiabetic, and neuroprotective activities for future drug leads.

Essential Oil of Matricaria chamomilla Alleviate Psoriatic-Like Skin Inflammation by Inhibiting PI3K/Akt/mTOR and p38MAPK Signaling Pathway

Background

The traditional Matricaria chamomilla L. has been used to treat dermatitis for thousands of years. Due to emerging trends in alternative medicine, patients prefer natural remedies to relieve their symptoms. Therefore, finding safe and effective plant medicines for topical applications on the skin is an important treatment strategy for dermatologists. German chamomile (Matricaria chamomilla L.) from the Compositae family is a famous medicinal plant, often known as the "star of medicinal species."However, the function of Matricaria chamomilla essential oil on skin inflammation has not been thoroughly examined in earlier research.

Methods

GC-MS analyzed the components of MCEO, and this study explored the anti-inflammation effects of MCEO on psoriasis with network pharmacological pathway prediction. Following this, we used clinical samples of psoriasis patients to confirm the secretory characteristic of relative inflammatory markers. The therapeutic effect of MCEO on skin inflammation was detected by examination of human keratinocytes HaCaT. At the same time, we prepared imiquimod-induced psoriatic-like skin inflammation in mice to investigate thoroughly the potential inhibition functions of MCEO on psoriatic skin injury and inflammation.

Results

MCEO significantly reduced interleukin-22/tumor necrosis factor α/lipopolysaccharide-stimulated elevation of HaCaT cell inflammation, which was correlated with downregulating PI3K/Akt/mTOR and p38MAPK pathways activation mediated by MCEO in HaCaT cells treated with IL-22/TNF-α/LPS. Skin inflammation was evaluated based on the PASI score, HE staining, and relative inflammatory cytokine levels. The results showed that MCEO could significantly contribute to inflammatory skin disease treatment.

Conclusion

MCEO inhibited inflammation in HaCaT keratinocytes induced by IL-22/TNF-α/LPS, the potential mechanisms associated with inhibiting excessive activation and crosstalk between PI3K/Akt/mTOR and p38MAPK pathways. MCEO ameliorated skin injury in IMQ-induced psoriatic-like skin inflammation of mice by downregulating the levels of inflammatory cytokines but not IL-17A. Thus, anti-inflammatory plant drugs with different targets with combined applications were a potential therapeutic strategy in psoriasis.

Citral-Enriched Fraction of Lemon Essential Oil Mitigates LPS-Induced Hepatocyte Injuries

Lemon essential oil (LEO) is known for its aromatic and healthy properties; however, less consideration is given to the biological properties of the fractions obtained from LEO. This study aims to evaluate the ability of a citral-enriched fraction obtained from LEO (Cfr-LEO) to counteract lipopolysaccharide (LPS)-mediated inflammation, oxidative stress, and epithelial-mesenchymal transition (EMT) in healthy human hepatocytes. Human immortalized hepatocytes (THLE-2 cell line) were pretreated with Cfr-LEO and subsequently exposed to LPS at various time points. We report that the pretreatment with Cfr-LEO counteracts LPS-mediated effects by inhibiting inflammation, oxidative stress, and epithelial-mesenchymal transition in THLE-2. In particular, we found that pretreatment with Cfr-LEO reduced NF-κB activation and the subsequent proinflammatory cytokines release, ROS production, and NRF2 and p53 expression. Furthermore, the pretreatment with Cfr-LEO showed its beneficial effect in counteracting LPS-induced EMT. Taken together, these results support Cfr-LEO application in the nutraceutical research field not only for its organoleptic properties, conferred by citral enrichment, but also for its biological activity. Our study could lay the basis for the development of foods/drinks enriched with Cfr-LEO, aimed at preventing or alleviating chronic conditions associated with liver dysfunction.

Effects of dietary essential oil supplementation on growth performance, carcass yield, meat quality, and intestinal tight junctions of broilers with or without Eimeria challenge

The effects of dietary supplementation of essential oil on growth performance, carcass yield, meat quality, serum antioxidant capacity, and intestinal tight junctions of broilers with or without Eimeria challenge were investigated. A total of 576 one-day-old male broilers were randomly separated into 8 treatments (6 replication floor-pens per treatment, 12 broilers per pen) in a 4 × 2 factorial design. The 4 diets consisted of 1) a corn and soybean meal basal diet, 2) an anticoccidial diet (60 g nicarbazin and 60 g narasin per ton of feed), 3) an oregano oil diet (500 ppm oregano oil), and 4) a clove oil diet (500 ppm clove oil). On d 10, half chicks were challenged with 1 × 104 sporulated oocysts of E. tenella, E. acervulina, and E. maxima per chick, whereas the others were inoculated with an equal amount of dilution (0.5 mL). The Eimeria challenge induced a higher fecal oocyst output on d 18, a lower duodenum Occludin expression level on d 28, a lower serum catalase level, and a higher cook loss and protein loss in thigh muscle on d 42. The anticoccidial diet lowered fecal Eimeria output and increased d 1 to 42 BW gain as compared to the control diet. The clove oil treatment enhanced duodenum ZO-1 expression level in nonchallenged birds, increased BW gain from d 1 to 14 and breast yield on d 42. The oregano oil treatment enhanced ZO-1 expression of challenged birds, reduced feed intake from 15 to 28 d, and helped broilers gain more tender meat. For those Eimeria-challenged broilers, both clove and oregano oil treatments recovered drip loss in breast muscle. Our results suggested that Eimeria challenge in broiler early age could interrupt later serum antioxidant capacity and damage meat quality. The dietary supplementation of clove or oregano essential oils could improve broiler growth performance and partially relieve the coccidial damage in gut integrity and meat quality.

Protective Effect of Citrus Medica limonum Essential Oil against Escherichia coli K99-Induced Intestinal Barrier Injury in Mice

Citrus Medica limonum essential oil (LEO) has been reported to have antibacterial and anti-inflammatory activities, but its protective effect in the intestine remains unknown. In this study, we researched the protective effects of LEO in relation to intestinal inflammation induced by E. coli K99. The mice were pretreated with 300, 600, and 1200 mg/kg LEO and then stimulated with E. coli K99. The results showed that E. coli K99 caused immune organ responses, intestinal tissue injury, and inflammation. LEO pretreatment dose-dependently alleviated these changes by maintaining a low index in the thymus and spleen and producing a high content of immunoglobulin A, G, and M (IgA, IgG, and IgM) and low content of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6). Intestinal integrity as a consequence of the LEO pretreatment may be related to the high mRNA expression of intestinal trefoil factor (ITF) and the low mRNA expression of transforming growth factor-β1 (TGF-β1). Conclusively, an LEO pretreatment can alleviate E. coli K99-induced diarrhea, immune organ response, and body inflammation in mice by reducing the levels of inflammatory cytokines and improving the levels of immunoglobulin, and the intestinal integrity remained highest when maintaining the high mRNA expression of ITF and keeping the mRNA expression of TGF-β1 low in the intestinal tissue.

Linalool controls the viability of Escherichia coli by regulating the synthesis and modification of lipopolysaccharide, the assembly of ribosome, and the expression of substrate transporting proteins

Escherichia coli (E. coli) is a Gram-negative bacterium and some pathogenic types may cause serious diseases, foods or food environments were the primary routes for its infection. Citrus aurantium L. var. amara Engl., a variety of sour orange, were used as a kind of non-conventional edible plant in China, but its antimicrobial activity and mechanisms were not well studied. Thus, in this study, EO from the flower of Citrus aurantium L. var. amara Engl. (CAEO) were studied as a kind of natural antimicrobial agent to control E. coli, our results showed that both of CAEO and its main component (linalool) exhibited strong antibacterial efficacy. Further, transcriptomic and proteomic analysis were carried out to explore cell response under linalool treatment and the main results included: (1) The synthesis and modification of lipopolysaccharide (LPS) was significantly influenced. (2) Ribosomal assembly and protein synthesis were significantly inhibited. (3) The expression of proteins related to the uptake of several essential substances was significantly changed. In all, our results would supply a theoretical basis for the proper use of CAEO and linalool as a promising antimicrobial agent to prevent and control E. coli infection in the future.