Inhibitory effect of anethole on T-lymphocyte proliferation and interleukin-2 production through down-regulation of the NF-AT and AP-1

From Natural Sources to Synthetic Derivatives: The Allyl Motif as a Powerful Tool for Fragment-Based Design in Cancer Treatment

Since the beginning of history, natural products have been an abundant source of bioactive molecules for the treatment of different diseases, including cancer. Many allyl derivatives, which have shown anticancer activity both in vitro and in vivo in a large number of cancers, are bioactive molecules found in garlic, cinnamon, nutmeg, or mustard. In addition, synthetic products containing allyl fragments have been developed showing potent anticancer properties. Of particular note is the allyl derivative 17-AAG, which has been evaluated in Phase I and Phase II/III clinical trials for the treatment of multiple myeloma, metastatic melanoma, renal cancer, and breast cancer. In this Perspective, we compile extensive literature evidence with descriptions and discussions of the most recent advances in different natural and synthetic allyl derivatives that could generate cancer drug candidates in the near future.

Evaluation of the Multifunctionality of Soybean Proteins and Peptides in Immune Cell Models

Inflammatory and oxidative processes are tightly regulated by innate and adaptive immune systems, which are involved in the pathology of a diversity of chronic diseases. Soybean peptides, such as lunasin, have emerged as one of the most hopeful food-derived peptides with a positive impact on health. The aim was to study the potential antioxidant and immunomodulatory activity of a lunasin-enriched soybean extract (LES). The protein profile of LES was characterized, and its behavior under simulated gastrointestinal digestion was evaluated. Besides its in vitro radical scavenging capacity, LES and lunasin's effects on cell viability, phagocytic capacity, oxidative stress, and inflammation-associated biomarkers were investigated in both RAW264.7 macrophages and lymphocytes EL4. Lunasin and other soluble peptides enriched after aqueous solvent extraction partially resisted the action of digestive enzymes, being potentially responsible for the beneficial effects of LES. This extract scavenged radicals, reduced reactive oxygen species (ROS) and exerted immunostimulatory effects, increasing nitric oxide (NO) production, phagocytic activity, and cytokine release in macrophages. Lunasin and LES also exerted dose-dependent immunomodulatory effects on EL4 cell proliferation and cytokine production. The modulatory effects of soybean peptides on both immune cell models suggest their potential protective role against oxidative stress, inflammation, and immune response-associated disorders.

Anti-inflammatory effect of trans-anethol in a rat model of myocardial ischemia-reperfusion injury

Myocardial ischemia‑reperfusion injury (MI/R) is considered a main risk factor for global cardiac mortality and morbidity, for which no effective treatment exists. Both inflammation and epigenetic regulation play a pivotal role in the early stage of MI/R. The present study aimed at investigating the prospective anti-inflammatory role of trans-anethole (TNA) in targeting MI/R and its related mechanism in upregulating the expression of the inflammatory and cardiac-related gene (VAV3), and its epigenetic regulators (lncRNA-JRKL-AS1 and miR-1298) that were retrieved from in-silico data analysis in an ischemia/reperfusion (I/R) rat model.

MATERIALS & METHODS

TNA was administered in 3 doses (50, 100, and 200 mg/kg), 15 min prior to coronary ligation in male Wistar rats. The left ventricular end-diastolic pressure and dP/dtmax were assessed. Histopathological, biochemical, and molecular analyses were performed to assess the effects of TNA pre-treatment on the I/R rats model.

RESULTS

TNA alleviated the I/R-induced cardiac injury pathologically and improved the cardiac function tests and enzymes. At the molecular level, TNA upregulated the expression level of the retrieved RNA-based panel (VAV3 mRNA/miR-1298/lncRNA JRKL-AS1). At the protein level, TNA decreased the cardiac content of the pro-inflammatory cytokine TNF-α.

CONCLUSION

TNA has demonstrated a potential ability to alleviate the cardiac injury and attenuate the inflammatory response following ischemia-reperfusion in the rat model through modulation of the expression of RNA panel (VAV3 mRNA/miR-1298/lncRNA JRKL-AS1) and TNF- α protein.

Trans-anethole ameliorates LPS-induced inflammation via suppression of TLR4/NF-κB pathway in IEC-6 cells

This study was undertaken to investigate the protective role of trans-anethole (TA) in lipopolysaccharide (LPS)-induced rat intestinal epithelial cells (IEC-6) injury and the potential mechanisms. The cells were pretreated with TA (0 and 1 mM) for 24 h, prior to stimulation by LPS (1 mg/mL) for 24 h. Compared with the control group (CON), LPS stimulus resulted in decreased cell viability, intestinal barrier injury, increased cell apoptosis and cell cycle arrest at the G2/M phase. These effects triggered by LPS were reversed by TA. In order to reveal the main genes and pathways involved among the groups, transcriptome analysis was performed to identify the differential expression genes (DEGs) among the treatment groups. There were a total of 493 DEGs (275 upregulated and 218 downregulated) that were identified between the LPS and CON group. Meanwhile, a total of 361 DEGs (103 regulated and 258 downregulated) were identified in the LPS+TA group compared with the LPS group. The results showed that the DEGs were mostly enriched in immune related pathways, such as tumor necrosis factor (TNF) signaling pathway, cytokine-cytokine receptor interaction, complement and coagulation cascades, interleukin-17 (IL-17) signaling pathway, NF-kappa B (NF-κB) signaling pathway, antigen processing and presentation, and NOD-like receptor signaling pathway. Based on the results of RNA-sequencing, further investigation of the signaling pathway involved revealed that TA could inhibit the activation of toll like receptor 4 (TLR4)/NF-κB signaling pathway and NLR family pyrin domain containing 3 (NLRP3) inflammasome in LPS-induced IEC-6 cells. In conclusion, this finding demonstrated a functional role of TA in intestinal epithelial cells injury and indicated that TA may be a potential strategy for treatment of inflammatory intestinal diseases.

Innate Immune Response against Staphylococcus aureus Preincubated with Subinhibitory Concentration of trans-Anethole

The study aimed to analyze morphological and functional changes of Staphylococcus aureus cells due to trans-anethole (a terpenoid and the major constituent of fennel, anise, or star anise essential oils) exposition, and their consequences for human neutrophils phagocytic activity as well as IL-8 production (recognized as the major chemoattractant). The investigation included the evaluation of changes occurring in S. aureus cultures, i.e., staphyloxanthin production, antioxidant activities, cell size distribution, and cells composition as a result of incubation with trans-anethole. It was found that the presence of trans-anethole in the culture medium reduced the level of staphyloxanthin production, as well as decreased antioxidant activities. Furthermore, trans-anethole-treated cells were characterized by larger size and a tendency to diffuse in comparison to the non-treated cells. Several cell components, such as phospholipids and peptidoglycan, were found remarkably elevated in the cultures treated with trans-anethole. As a result of the aforementioned cellular changes, the bacteria were phagocytized by neutrophils more efficiently (ingestion and parameters associated with killing activity were at a higher level as compared to the control system). Additionally, IL-8 production was at a higher level for trans-anethole modified bacteria. Our results suggest that trans-anethole represents a promising measure in combating severe staphylococcal infections, which has an important translational potential for clinical applications.

Anethole reduces oxidative stress and improves in vitro survival and activation of primordial follicles

Primordial follicles, the main source of oocytes in the ovary, are essential for the maintenance of fertility throughout the reproductive lifespan. To the best of our knowledge, there are no reports describing the effect of anethole on this important ovarian follicle population. The aim of the study was to investigate the effect of different anethole concentrations on the in vitro culture of caprine preantral follicles enclosed in ovarian tissue. Randomized ovarian fragments were fixed immediately (non-cultured treatment) or distributed into five treatments: α-MEM⁺ (cultured control), α-MEM⁺ supplemented with ascorbic acid at 50 μg/mL (AA), and anethole at 30 (AN30), 300 (AN300), or 2000 µg/mL (AN2000), for 1 or 7 days. After 7 days of culture, a significantly higher percentage of morphologically normal follicles was observed when anethole at 2000 μg/mL was used. For both culture times, a greater percentage of growing follicles was observed with the AN30 treatment compared to AA and AN2000 treatments. Anethole at 30 and 2000 µg/mL concentrations at days 1 and 7 of culture resulted in significantly larger follicular diameter than in the cultured control treatment. Anethole at 30 µg/mL concentration at day 7 showed significantly greater oocyte diameter than the other treatments, except when compared to the AN2000 treatment. At day 7 of culture, levels of reactive oxygen species (ROS) were significantly lower in the AN30 treatment than the other treatments. In conclusion, supplementation of culture medium with anethole improves survival and early follicle development at different concentrations in the caprine species.

The immunoinhibitory and apoptosis-inducing activities of Foeniculum vulgare on human peripheral blood lymphocytes

Foeniculum vulgare (F. vulgare, Apiaceae) is an important plant currently used in folk medicine to treat various diseases including infections and inflammatory conditions. In this study we have investigated the immunomodulatory and apoptosis-inducing activities of the fractions from this plant. We prepared dichloromethane, hexane, butanol, and water fractions from the aerial parts of the plant. We examined the growth inhibitory effects of the fractions on proliferative lymphocytes by the BrdU incorporation assay. Cell viability was determined by the propidium iodide (PI) assay. AnnexinV/PI staining and cell cycle analysis by flow cytometry was performed to investigate the apoptosis-inducing effects of the plant fractions. Cytokine levels were measured by enzyme-linked immunosorbent assay. All fractions reduced cell proliferation of the activated lymphocytes. The dichloromethane fraction with the highest inhibitory effect (IC₅₀, 19.8 μg/mL) significantly reduced cell viability. Although the butanol fraction inhibited cell growth (IC₅₀, 88.2 μg/mL) it did not affect cell viability. Annexin V/PI and cell cycle analysis showed the maximum apoptosis-inducing effect of the dichloromethane fraction at 200 μg/mL. Cytokines, that included interleukin (IL)-4 (22.8 ± 0.9 pg/mL, P < 0.05) and interferon (IFN)-γ (651 ± 37.5 pg/mL, P < 0.01) reduced the activated lymphocyte levels in cultures in the presence of 100 μg/mL concentration of butanol fraction compared to the untreated control. In conclusion, the dichloromethane fraction of F. vulgare had the capability of inducing apoptosis in the activated lymphocytes, whereas the butanol fraction reduced cell activation and cytokine secretion. These data suggested the potential of these examined fractions for more studies in terms of their beneficial effects on immune-mediated diseases.

Hepatotoxicity of illegal home-made alcohols

OBJECTIVE AND AIM

Alcohol-related hepatotoxicity is not only caused by excessive alcohol consumption but also caused and even accelerated by hepatotoxic ingredients other than ethanol. Concentrations of hepatotoxic substances might be significantly high, particularly in illegally produced home-made alcohols. In this study we aim to analyze the hepatotoxic effects of a home-made alcohol traditionally called "bogma raki" in Turkey.

MATERIALS AND METHOD

Fifty Wistar albino male rats were used. Five groups were randomly formed with ten animals in each. Besides laboratory diets, groups were fed as follows: Group 1 (control group) distilled water; Group 2 bogma raki with distilled water (%44 (v/v), 9.2 ml/kg/day); Group 3 bogma raki with distilled water (%44 (v/v), 9.2 ml/kg/day)+walnut (10 g/kg/day); Group 4 whisky with distilled water (%40 (v/v), 9.2 ml/kg/day); Group 5 distilled water + walnut (10 g/kg/day), for 28 days. The toxicological analysis of The spirits were analyzed using Hewlett-Packard (Palo Alto, CA) GC/MS system with HP 6890 gas chromatograph, an HP 5972 mass selective detector (MSD) and an HP 6890 automatic liquid sampler GC/MS; the pressure of the carrier gas helium was 6.0 bar and the split value with a ratio of 1:100. The injection unit temperature set to 250 °C and MS quadrupole temperature set to 280 °C. The MS quadrupole detector ionization energy set to 70 eV. The initial column temperature was 60 °C (for 4 min) programmed by 6 °C/min to final temperature 160 °C and kept for 8 min at 160 °C. Utilized whisky and bogma raki samples were analyzed for the amounts of trans-anethole, ethanol, methanol, 1-propanolol, butanol, 2-butanol, 2-methyl-1-propanolol (isobutanol) and 3-methylbutanol (isoamyl alcohol). Histopathological changes in liver tissues were graded as follows; normal = 0 (<10%), mild = 1 (10%-40%), moderate = 2 (40%-70%), severe = 3 (above 70%).

RESULTS

Chemical composition of illegally produced raki sample (%v/v) was as follows: trans-anethole %1.93, ethanol %95.70, 2-methyl-1-propanolol (isobutanol) %0.19, asetic acid %0.25, 3-methylbutanol (isoamyl alcohol) %0.77, and others %1.16. Chemical composition of commercial whisky sample (%v/v) was as follows: ethanol %97.72, 2-methyl-1-propanolol (isobutanol) %0.57, asetic acid %0.23, 3-methylbutanol (isoamyl alcohol) %1.28, and others %0.2. No traces of trans-anethole were detected in whisky. Normal liver morphology was recorded in control and walnut groups. However, bogma raki caused significant congestion and inflammatory cell infiltration compared to control and walnut group. On the other hand, whisky administration caused mild degeneration including inflammation in a limited area.

CONCLUSION

Obtained findings suggest that trans-anethole containing alcoholic beverages are more hepatotoxic compared to commercial alcoholic beverages.

Conformational Equilibrium and Internal Dynamics of E-Anethole: A Rotational Study

The rotational spectra of the two conformers of E-anethole have been investigated using the free jet broadband millimeter-wave spectroscopic technique combined with theoretical calculations. Anti and syn conformers differ for the relative orientation of the propenyl and methoxy chains, with all heavy atoms coplanar to the benzene ring. Relative intensity measurements prove that the anti form is the global minimum, about 2.0(5) kJ mol(-1) lower in energy with respect to the syn conformer, solving the contrasting results supplied by different theoretical methods. For both conformers, the barriers to internal rotation of the propenyl -CH3 group are low enough to generate fully resolved A-E splittings of the rotational transitions. The corresponding V3 barriers have been determined to be 7.080(5) and 6.978(4) kJ mol(-1), respectively.

Nutrigenomics of Essential Oils and their Potential Domestic Use for Improving Health

The use of essential oils as industrial food additives is notorious, like their medicinal properties. However, their use in household food spicing is for now limited. In this work, we have made a review to reveal the nutrigenomic actions exerted by their bioactive components, to promote awareness of their modulating gene expression ability and the potential that this implies. Also considered is how essential oils can be used as flavoring and seasoning after cooking and before consumption, such as diet components which can improve human health. Genetic mechanisms involved in the medicinal properties of essential oils for food use are identified from literature. These genetic mechanisms reveal nutrigenomic actions. Reviews on the medicinal properties of essential oils have been particularly considered. A wide diversity of nutrigenomic effects from essential oils useful potentially for food spicing is reviewed. General ideas are discussed about essential oils and their properties, such as anti-inflammatory, analgesic, immunomodulatory, anticancer, hepatoprotective, hypolipidemic, anti-diabetic, antioxidant, bone-reparation, anti-depressant and mitigatory for Alzheimer's disease. The essential oils for food use are potentially promoting health agents, and, therefore, worth using as flavoring and condiments. Becoming aware of the modulating gene expression actions from essential oils is important for understanding their potential for use in household dishes as spices to improve health.

Effect of estragole on leukocyte behavior and phagocytic activity of macrophages

Estragole, a chemical constituent of the essential oils of many aromatic plants, is used as flavoring in beverage and food industries. In vivo and in vitro experimental assays have shown that EST has sedative, anticonvulsant, antioxidant, antimicrobial, and anesthetic activity. In this work, we evaluate the effect of EST on leukocyte behavior and phagocytic activity of macrophages. In the peritonitis model, EST (500 and 750 mg/kg) decreased the infiltration of peritoneal exudate leukocytes. In vitro chemotaxis assay showed that EST (3, 10, 30, and 60 μg/mL) inhibited neutrophil migration toward fMLP. In the in vivo microcirculation assay, EST at doses of 250, 500, and 750 mg/kg significantly reduced the number of rolling and adherent leukocytes and at doses of 250 and 500 mg/kg decreased number of leukocyte migrated to perivascular tissue. The results showed that EST (3, 10, and 30 μg/mL) was able to stimulate the macrophages phagocytosis but only at concentration of 10 μg/mL promoted an increase in nitric oxide (NO) production. In conclusion, this study showed that EST had potential anti-inflammatory effects, likely by inhibiting leukocyte migration and by stimulating macrophages phagocytosis.

5-Lipoxygenase Inhibition of the Fructus of Foeniculum vulgare and Its Constituents

The fruits of Foeniculum vulgare (Foeniculi Fructus) have been widely used in Chinese medicine as an antiemetic, ameliorating stomach ailments and as an analgesic. In order to establish its potential for antiallergic use, inhibitory actions of the fruiton 5-lipoxgenase (5-LOX) and β-hexosaminidase release were evaluated. The 70% ethanol extract of this plant material (FR) considerably inhibited 5-LOX-catalyzed leukotriene production from A23187-induced rat basophilic leukemia (RBL)-1 cells. The IC₅₀ was 3.2 μg/ml. From this extract, 12 major compounds including sabinene, fenchone, γ-terpinene, α-pinene, limonene, p-anisylacetone, p-anisylaldehyde, estragole (4-allylanisole), trans-anethole, scopoletin, bergapten and umbelliferone were isolated. And it was found that several terpene derivatives including γ-terpinene and fenchone as well as phenylpropanoid, trans-anethole, showed considerable inhibitory action of 5-LOX. In particular, the IC₅₀ of trans-anethole was 51.6 μ M. In contrast, FR and the isolated compounds did not show considerable inhibitory activity on the degranulation reaction of β-hexosaminidase release from antigen-treated RBL-2H3 cells. Against arachidonic acid-induced ear edema in mice, FR and trans-anethole showed significant inhibition by oral administration at doses of 100-400 mg/kg. In conclusion, FR and several major constituents are 5-LOX inhibitors and they may have potential for treating 5-LOX-related disorders.

Inhibitory effect of anethole in nonimmune acute inflammation

Anethole [1-methoxy-4-(1-propenyl)benzene] occurs naturally as a major component of the essential oil of star anise (Illicium verum Hook.f., family Illiciaceae), comprising more than 90 % of its volatile components. Studies showed that this substance has antioxidant, antibacterial, antifungal, and anesthetic properties. In this study, the anti-inflammatory properties of anethole in animal models of nonimmune acute inflammation such as croton oil-induced ear edema and carrageenan-induced pleurisy were investigated. The investigated parameters were edema formation, leukocyte migration, and inflammatory mediators involved. Oral administration of anethole at a dose of 250 and 500 mg/kg reduced both the volume of pleural exudates and the number of migrated leukocytes. Levels of nitric oxide (NO) and prostaglandins (PGE2) in the inflammatory exudate were reduced by treatment with anethole, but levels of tumor necrosis factor-α and interleukin-1β were not significantly altered. In ear edema, the oral treatment with anethole inhibited the formation of exudate and the activity of myeloperoxidase, but not after topical administration. These results suggest that the anethole may be effective in controlling some nonimmune acute inflammation-related disease, probably by an inhibitory action on production and/or release of PGE2 and NO.

Macrophages, rather than T and B cells are principal immunostimulatory target cells of Lycium barbarum L. polysaccharide LBPF4-OL

AIM OF THE STUDY

Lycium barbarum L. is a renowned Yin strengthening agent in traditional Chinese medicine. Lycium barbarum L. polysaccharide-protein complex is well-known for its immunoregulatory and antitumor effects. LBPF4-OL is the glycan part of Lycium barbarum L. polysaccharide-protein complex fraction 4 (LBPF4). LBPF4-OL's active contribution in LBPF4 is still blank. In the study, we enrich the polysaccharide part of Lycium barbarum L. polysaccharide-protein complex, and investigate its immunostimulatory effects on mouse spleen cells, T cells, B cells and macrophages.

MATERIALS AND METHODS

Balb/C mice were used in vitro and in vivo studies. In in vitro study, lymphocyte proliferations were analyzed with (3)H-TdR incorporation method. Miltenyi MicroBeads were used in the purification of lymphocytes. Activation of T and B cells was analyzed by flow cytometry. In order to obtain the peritoneal macrophages, mice were injected i.p. with 1mL of sodium thioglycollate 3 days prior to killing. Spleen cells were stimulated with LBPF4-OL and cytokine concentrations in the supernatants were determined by multiplex bead analysis. In in vivo study, mice were injected i.p. with 1 mL of normal saline or 100 μg/mL LBPF4-OL daily for 6 days. Peritoneal macrophage functions were analyzed by enzyme-linked immunosorbent assay and flow cytometry assay.

RESULTS

Spleen cells and lymphocyte proliferation assay indicated that LBPF4-OL markedly induced the spleen cell proliferation, but could not induce proliferation of purified T and B lymphocytes. Further research revealed that B cell proliferation took place in the presence of activated macrophages or LPS. Multiplex bead analysis showed that LBPF4-OL can obviously induce IL-6, IL-8, IL-10 and TNF-α production of the spleen cells in a concentration-dependent manner. Flow cytometric analysis showed that LBPF4-OL (i.p.) prompts CD86 and MHC-II molecules expression on macrophages. ELISA assay showed that LBPF4-OL can greatly strengthen macrophage releasing of TNF-α and IL-1β.

CONCLUSION

These results suggested that glycan LBPF4-OL plays an important role in the immunopharmacological activity of Lycium barbarum L. polysaccharide-protein complex, and primary mouse macrophages, rather than T and B cells, are the principal target cells of it.

Inhibition of macrophage activation and suppression of graft rejection by DTCM-glutarimide, a novel piperidine derived from the antibiotic 9-methylstreptimidone

OBJECTIVE

We have previously synthesized a novel piperidine compound, 3-[(dodecylthiocarbonyl)methyl]glutarimide (DTCM-glutarimide), that inhibits LPS-induced NO production, and in the present research we studied further the anti-inflammatory activity of DTCM-glutarimide in a macrophage cell line and in mice bearing transplanted hearts.

MATERIALS AND METHODS

Mouse macrophage-like RAW264.7 cells were employed for the evaluation of cellular inflammatory activity. DTCM-glutarimide was synthesized in our laboratory. The AP-1 activity was measured by nuclear translocation and phosphorylation. For the heart transplantation experiment, male C57BL/6 (H-2b) and BALB/c (H-2d) mice were used as donor and recipient, respectively. DTCM-glutarimide was administered intraperitoneally.

RESULTS

DTCM-glutarimide inhibited the LPS-induced expression of iNOS and COX-2 in macrophages; but, unexpectedly, it did not inhibit LPS-induced NF-κB activation. Instead, it inhibited the nuclear translocation of both c-Jun and c-Fos. It also inhibited LPS-induced c-Jun phosphorylation. Moreover, it inhibited the mixed lymphocyte reaction in primary cultures of mouse spleen cells; and furthermore, in mice it prolonged the graft survival in heart transplantation experiments.

CONCLUSION

The novel piperidine compound, DTCM-glutarimide, was found to be a new inhibitor of macrophage activation, inhibiting AP-1 activity. It also inhibited graft rejection in mice, and thus may be a candidate for an anti-inflammatory agent.

Mechanistic study of saikosaponin-d (Ssd) on suppression of murine T lymphocyte activation

Saikosaponin-d (Ssd) is a triterpene saponin derived from the medicinal plant, Bupleurum falcatum L. (Umbelliferae). Previous findings showed that Ssd exhibits a variety of pharmacological and immunomodulatory activities including anti-inflammatory, anti-bacterial, anti-viral and anti-cancer effects. In the current study we have investigated the effects of Ssd on activated mouse T lymphocytes through the NF-kappaB, NF-AT and AP-1 signaling pathways, cytokine secretion, and IL-2 receptor expression. The results demonstrated that Ssd not only suppressed OKT3/CD28-costimulated human T cell proliferation, it also inhibited PMA, PMA/Ionomycin and Con A-induced mouse T cell activation in vitro. The inhibitory effect of Ssd on PMA-induced T cell activation was associated with down-regulation of NF-kappaB signaling through suppression of IKK and Akt activities. In addition, Ssd suppressed both DNA binding activity and the nuclear translocation of NF-AT and activator protein 1 (AP-1) of the PMA/Ionomycin-stimulated T cells. The cell surface markers like IL-2 receptor (CD25) were also down-regulated together with decreased production of pro-inflammatory cytokines of IL-6, TNF-alpha and IFN-gamma. These results indicate that the NF-kappaB, NF-AT and AP-1 (c-Fos) signaling pathways are involved in the T cell inhibition evoked by Ssd, so it can be a potential candidate for further study in treating T cell-mediated autoimmune conditions.

Suppression of interleukin-2 gene expression by isoeugenol is mediated through down-regulation of NF-AT and NF-κB

Isoeugenol is a naturally occurring methoxyphenol found in a variety of foods and essential oils. We investigated the effect of isoeugenol on T-cell function and the regulatory mechanism underlying its effect. Isoeugenol and its structural analog eugenol suppressed the lymphoproliferative response to concanavalin A stimulation in B6C3F1 mouse splenocyte cultures. Isoeugenol inhibited phorbol 12-myristate 13-acetate (PMA) plus ionomycin (Io)-induced IL-2 mRNA expression and protein secretion in B6C3F1 mouse splenocytes, and in EL4.IL-2 mouse T-cells, as determined by real-time RT-PCR and ELISA, respectively. To further characterize the inhibitory mechanism of isoeugenol at the transcriptional level, we examined the DNA binding activity of the transcription factors for IL-2 using an electrophoretic mobility shift assay. Isoeugenol decreased the binding activity of NF-AT and NF-kappaB in PMA/Io-stimulated EL4.IL-2 cells, but no significant effect was observed for AP-1 or Oct binding activity. Western blot analysis showed that isoeugenol also decreased the nuclear translocation of cytoplasmic NF-AT and NF-kappaB. These results suggest that isoeugenol suppresses IL-2 production through a decrease of IL-2 mRNA expression and that the inhibition is mediated, at least in part, through the down-regulation of NF-AT and NF-kappaB.

Isoeugenol suppression of inducible nitric oxide synthase expression is mediated by down-regulation of NF-kappaB, ERK1/2, and p38 kinase

Isoeugenol, which is a naturally occurring o-methoxyphenol in a variety of foods and essential oils, is known to have anti-inflammatory effects, although the mechanism is not clear. In the present study, we investigated the effect of isoeugenol on NF-kappaB signaling leading to inducible nitric oxide synthase (iNOS) expression in RAW 264.7 murine macrophages stimulated with lipopolysaccharide (LPS). Isoeugenol markedly inhibited nitric oxide (NO) production in dose- and time-dependent manners. The decrease in NO production was found to correlate with a decrease in iNOS expression, as determined by Western blot analysis and real-time RT-PCR. To characterize further the inhibitory mechanisms of isoeugenol at the transcriptional level, we examined the DNA-binding and transcriptional activities of NF-kappaB. Isoeugenol inhibited NF-kappaB-dependent transcriptional activity and DNA-binding activity by decreasing the nuclear translocation of p65, which is a component of NF-kappaB. In addition, isoeugenol blocked signaling upstream of NF-kappaB activation, such as degradation of I-kappaBalpha and the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK), in LPS-stimulated RAW 264.7 cells. The isoeugenol analogues eugenol and allylbenzene also inhibited LPS-induced NF-kappaB signaling and iNOS expression, albeit with less potency than isoeugenol. These results suggest that isoeugenol and its analogues inhibit NO production and iNOS expression in LPS-stimulated RAW 264.7 cells, and that these effects are mediated, at least in part, by blocking the phosphorylation of ERK1/2 and p38 kinase, degradation of I-kappaBalpha, and activation of NF-kappaB.