BITC and S-Carvone Restrain High-Fat Diet-Induced Obesity and Ameliorate Hepatic Steatosis and Insulin Resistance

Benzyl isothiocyanate ameliorates hepatic insulin resistance in mice with high-fat diet-induced nonalcoholic fatty liver disease

The global prevalence of overweight and obesity has risen sharply over the past few decades as a result of excess calorie intake and sedentary lifestyles. Obesity increases the risk for various metabolic disorders, such as hyperlipidemia, fatty liver disease, and diabetes mellitus. Isothiocyanates, which are abundant in cruciferous vegetables, have been shown to exhibit anti-cancer, anti-inflammatory, and antioxidant properties. However, the efficacy of benzyl isothiocyanate (BITC) in preventing the adverse effects of obesity, such as hepatic steatosis and insulin resistance, remains uncertain. To address this knowledge gap, we assessed whether BITC protects against hepatic insulin resistance by using primary mouse hepatocytes and AML12 cells treated with palmitic acid (PA) and mice fed a high-fat diet supplemented with cholesterol and cholic acid (HFCCD). We found that the impairments in insulin sensitivity caused by PA, such as decreases in the phosphorylation of insulin receptor substrate (IRS) 1 (Tyr608), Akt, glycogen synthase kinase (GSK) 3β, and FOXO1 and increases in the expression of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase 1 (PEPCK) mRNA in hepatocytes, were mitigated by pretreatment with BITC. BITC also attenuated PA-induced hepatic lipid accumulation and reactive oxygen species production. In vivo, BITC significantly reduced blood glucose levels and the HOMA-IR and inhibited hepatic lipid accumulation, IRS1 phosphorylation at Ser307, and G6Pase and PEPCK expression compared with that in mice fed the HFCCD alone. These results show that BITC ameliorates the lipotoxicity associated with insulin resistance by activating the IR/IRS/Akt/FOXO1 and GSK3β pathways, which leads to decreased gluconeogenesis and increased glycogen synthesis.

Enhanced in-vitro bioavailability of curcumin, lutein and isoflavones through interaction with spearmint (Mentha spicata) via its bioactive component (R)-(-)-carvone

Numerous dietary phytochemicals such as curcumin, lutein and isoflavones are associated with health beneficial activities, however their application is often limited by their low bioavailability. Therefore, bioenhancers represent a feasible approach to increase the absorption efficiency of bioactive compounds. Here, we combined uptake and transport studies in differentiated Caco-2 cells with high resolution analytics and fractionation to evaluate the impact of spearmint (Mentha spicata) on the cellular uptake of curcumin. Additionally, we utilized mechanistic studies in native and overexpressing cell systems to assess P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) efflux transporter activity as well as in-silico molecular docking simulations. We found significantly elevated intracellular curcuminoid levels mediated by spearmint. Fractionation and functional assays identified (R)-(-)-carvone as a putative candidate for the biologically active compound mediating increased curcumin uptake via BCRP inhibition. Inhibition of P-gp-mediated efflux might additionally be involved. Molecular docking simulations suggest a common binding site of curcumin and (R)-(-)-carvone in BCRP. Further, spearmint significantly increased cellular uptake of lutein and transintestinal transport of isoflavones in-vitro. In summary, spearmint was identified as a novel bioenhancer for curcumin, lutein and isoflavones. Our findings suggest that spearmint increases bioavailability of a wide range of nutrients and drugs at least partially due to interference with BCRP via its active compound (R)-(-)-carvone.

Biological Properties of Mentha viridis L. Essential Oil and Its Main Monoterpene Constituents

This research aimed to evaluate the antidiabetic, dermatoprotective, and antibacterial activities of Mentha viridis L. essential oil (MVEO) collected in the province of Ouezzane (Northwest Morocco). Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the main constituents of MVEO were carvone (37.26 %), 1,8-cineole (11.82 %), limonene (5.27 %), α-terpineol (4.16 %), and β-caryophyllene (4.04 %). MVEO showed strong inhibitory effects on α-amylase and α-glucosidase activities, exceeding those of acarbose, but weak anti-elastase activity. The main compounds, β-caryophyllene (IC50=79.91±2.24 and 62.08±2.78 μg/mL) and limonene (IC50=90.73±3.47 and 68.98±1, 60 μg/mL), demonstrated the strongest inhibitory effects on both digestive enzymes (α-glucosidase and α-amylase, respectively). In silico investigations, using molecular docking, also showed the inhibitory potential of these bioactive compounds against the enzymes tested. In conclusion, MVEO, due to its main components such as limonene, 1,8-cineole, β-caryophyllene, carvone, and α-terpineol, shows promising prospects for drug discovery and natural therapeutic applications.

Benzyl isothiocyanate attenuates activation of the NLRP3 inflammasome in Kupffer cells and improves diet-induced steatohepatitis

The NLRP3 inflammasome plays an important role in the pathogenesis of numerous inflammation-related diseases. Benzyl isothiocyanate (BITC) is rich in cruciferous vegetables and possesses potent antioxidant, anti-inflammatory, anti-cancer, and anti-obesogenic properties. In this study, we investigated the role of the NLRP3 inflammasome in the protection by BITC against steatohepatitis and insulin resistance. A mouse model of high-fat/cholesterol/cholic acid diet (HFCCD)-induced steatohepatitis, LPS/nigericin-stimulated primary Kupffer cells, and IL-1β treated primary hepatocytes were used. BITC attenuated LPS/nigericin-induced activation of the NLRP3 inflammasome by enhancing protein kinase A-dependent NLRP3 ubiquitination, which increased the degradation of NLRP3 and reduced IL-1β secretion in Kupffer cells. In hepatocytes, BITC pretreatment reversed the IL-1β-induced decrease in the phosphorylation of IR, AKT, and GSK3β in response to insulin. After 12 weeks of HFCCD feeding, increases in blood alanine aminotransferase (ALT) and glucose levels were ameliorated by BITC. Hepatic IL-1β production, macrophage infiltration, and collagen expression induced by HFCCD were also mitigated by BITC. BITC suppresses activation of the NLRP3 inflammasome in Kupffer cells by enhancing the PKA-dependent ubiquitination of NLRP3, which leads to suppression of IL-1β production and subsequently ameliorates hepatic inflammation and insulin resistance.

Epigenetics and the role of nutraceuticals in health and disease

In the post-genomic era, the data provided by complete genome sequencing could not answer several fundamental questions about the causes of many noninfectious diseases, diagnostic biomarkers, and novel therapeutic approaches. The rapidly expanding understanding of epigenetic mechanisms, as well as widespread acceptance of their hypothesized role in disease induction, facilitated the development of a number of novel diagnostic markers and therapeutic concepts. Epigenetic aberrations are reversible in nature, which enables the treatment of serious incurable diseases. Therefore, the interest in epigenetic modulatory effects has increased over the last decade, so about 60,000 publications discussing the expression of epigenetics could be detected in the PubMed database. Out of these, 58,442 were published alone in the last 10 years, including 17,672 reviews (69 historical articles), 314 clinical trials, 202 case reports, 197 meta-analyses, 156 letters to the editor, 108 randomized controlled trials, 87 observation studies, 40 book chapters, 22 published lectures, and 2 clinical trial protocols. The remaining publications are either miscellaneous or a mixture of the previously mentioned items. According to the species and gender, the publications included 44,589 human studies (17,106 females, 14,509 males, and the gender is not mentioned in the remaining papers) and 30,253 animal studies. In the present work, the role of epigenetic modulations in health and disease and the influencing factors in epigenetics are discussed.

Benzyl isothiocyanate improves the prognosis of Aspergillus fumigatus keratitis by reducing fungal load and inhibiting Mincle signal pathway

Aspergillus fumigatus keratitis is a potential blinding disease associated with A. fumigatus invasion and excessive inflammatory response. Benzyl isothiocyanate (BITC) is a secondary metabolite with broad antibacterial and anti-inflammatory activity extracted from cruciferous species. However, the role of BITC in A. fumigatus keratitis has not been discovered yet. This study aims to explore the antifungal and anti-inflammatory effects and mechanisms of BITC in A. fumigatus keratitis. Our results provided evidences that BITC exerted antifungal effects against A. fumigatus by damaging cell membranes, mitochondria, adhesion, and biofilms in a concentration-dependent manner. In vivo, fungal load and inflammatory response including inflammatory cell infiltration and pro-inflammatory cytokine expression were reduced in BITC-treated A. fumigatus keratitis. Additionally, BITC significantly decreased Mincle, IL-1β, TNF-α, and IL-6 expression in RAW264.7 cells that stimulated by A. fumigatus or Mincle ligand trehalose-6,6-dibehenate. In summary, BITC possessed fungicidal activities and could improve the prognosis of A. fumigatus keratitis by reducing fungal load and inhibiting the inflammatory response mediated by Mincle.

Essential Oil of Carvone Chemotype Lippia alba (Verbenaceae) Regulates Lipid Mobilization and Adipogenesis in Adipocytes

Obesity is characterized by an expansion of adipose tissue due to excessive accumulation of triglycerides in adipocytes, causing hypertrophy and hyperplasia, followed by hypoxia, alterations in adipocyte functionality, and chronic inflammation. However, current treatments require changes in lifestyle that are difficult to achieve and some treatments do not generate sustained weight loss over time. Therefore, we evaluated the effect of the essential oil (EO) of Lippia alba (Verbenaceae) carvone chemotype on viability, lipid mobilization, and adipogenesis of adipocytes in two normal and pathological cellular models in vitro. In 3T3-L1 adipocytes, a normal and a pathological model of obesity were induced, and then the cells were treated with L. alba carvone chemotype EO to evaluate cell viability, lipid mobilization, and adipogenesis. L. alba carvone chemotype EO does not decrease adipocyte viability at concentrations of 0.1, 1, and 5 µg/mL; furthermore, there was evidence of changes in lipid mobilization and adipogenesis, leading to a reversal of adipocyte hypertrophy. These results could be due to effects produced by EO on lipogenic and lipolytic pathways, as well as modifications in the expression of adipogenesis genes. L. alba carvone chemotype EO could be considered as a possible treatment for obesity, using the adipocyte as a therapeutic target.

Ameliorative Effect of D-Carvone against Hepatic Ischemia-Reperfusion-Induced Injury in Rats

BACKGROUND

D-carvone is a monoterpene that exists in the essential oils of several plant species. Hepatic ischemia-reperfusion (Hep I/R) takes place clinically during different scenarios of liver pathologies. The aim of the current investigation is to disclose the hepato-protective actions of carvone against Hep I/R-induced damage and to reveal the underlying mechanism.

MATERIAL AND METHODS

Rats were assigned into five groups: sham and carvone plus sham groups, in which rats were administered either saline or carvone orally for three weeks prior to the induction of Hep I/R. In the Hep I/R group, rats were administered saline orally prior to the Hep I/R induction operation. The carvone 25 plus Hep I/R and Carvone 50 plus Hep I/R groups were administered carvone (25 and 50 mg/kg, respectively) for three weeks, followed by the induction of Hep I/R.

RESULTS

Liver ischemic animals demonstrated impaired liver function, several histopathological variations, and reduced levels of antioxidant enzyme activities. Furthermore, the Hep I/R groups showed the elevated gene expression of high-mobility group box 1 (HMGB1), toll-like receptors 4 (TLR4), nuclear factor kappa B (NFκB), and LR family pyrin domain containing 3 (NLP3), with subsequent escalated adhesion molecule 1 (ICAM-1), neutrophil infiltration, and several inflammatory mediators, including interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α), as well as apoptotic markers. Pretreatment with D-carvone alleviated ischemia/reperfusion-induced impaired liver function, diminished the histopathological deviations, and augmented the antioxidant enzymes. In addition, D-carvone mitigated the gene expression of HMGB1, TLR4, NFκB, and NLP3, with a subsequent reduction in ICAM-1, neutrophils infiltration, inflammatory mediators, and apoptotic markers.

CONCLUSION

Rats pretreated with D-carvone exhibited hepato-protective actions against Hep I/R-induced damage via the downregulation of HMGB1, TLR4, NFκB, NLP3, associated inflammatory mediators, and apoptotic markers.

D-Carvone Attenuates CCl4-Induced Liver Fibrosis in Rats by Inhibiting Oxidative Stress and TGF-ß 1/SMAD3 Signaling Pathway

D-carvone is a natural monoterpene found in abundance in the essential oil of aromatic medicinal plants with a wide range of pharmacological values. However, the impact of D-carvone on liver fibrosis remains unclear. This study aimed to evaluate the anti-fibrotic potential of D-carvone in a rat model of liver fibrosis and to clarify the possible underlying mechanisms. Liver fibrosis was induced in rats by carbon tetrachloride, CCl₄ (2.5 mL/kg, interperitoneally every 72 h for 8 weeks). Oral treatment of rats with D-carvone (50 mg/kg, daily) started on the 3rd week of CCl₄ administration. D-carvone significantly enhanced liver functions (ALT, AST), oxidant/antioxidant status (MDA, SOD, GSH, total antioxidant capacity; TAC), as well as histopathological changes. Moreover, D-carvone effectively attenuated the progression of liver fibrosis, evident by the decreased collagen deposition and fibrosis score by Masson trichrome staining (MT) and α-SMA protein expression. Moreover, D-carvone administration resulted in a significant downregulation of the pro-fibrogenic markers TGF-β1 and SMAD3 and upregulation of MMP9. These findings reveal the anti-fibrotic effect of D-carvone and suggest regulation of the TGF-β1/SMAD3 pathway, together with the antioxidant activity as a mechanistic cassette, underlines this effect. Therefore, D-carvone could be a viable candidate for inhibiting liver fibrosis and other oxidative stress-related hepatic diseases. Clinical studies to support our hypothesis are warranted.

Protective Effect and Mechanism of Plant-Based Monoterpenoids in Non-alcoholic Fatty Liver Diseases

The protective effect of plant active ingredients against non-alcoholic fatty liver disease (NAFLD) is becoming increasingly prominent, and the terpenoids have always been the main active compounds in Chinese herbal medicine exerting hepatoprotective effects. However, the related pharmacological effects, especially for monoterpenoids or iridoid glycosides, which have obvious effects on improvement of NAFLD, have not been systematically analyzed. The objective of this review is to systematically examine the molecular mechanisms of monoterpenoids in NAFLD. The signaling pathways of peroxisome proliferator-activated receptor, insulin, nuclear factor κB, toll-like receptor, adipocytokine, RAC-α serine/threonine protein kinase, mammalian target of rapamycin, 5'-AMP-activated protein kinase, and autophagy have been proven to mediate this protective effect. We further compared the experimental data from animal models, including the dosage of these monoterpenoids in detail, and demonstrated that they are effective and safe candidate drugs for NAFLD. This review provides a reference for the development of NAFLD drugs as well as a research guideline for the potential uses of plant monoterpenoids.

The pinene scaffold: its occurrence, chemistry, synthetic utility, and pharmacological importance

Plant-based secondary metabolites have been a major source of drug discovery and inspiration for new generations of drugs. Plants offer a wide variety of compound classes, including alkaloids, terpenes, flavonoids, and glycosides, with different molecular architectures (fused bridgehead, bi- and polycyclic, spirocyclic, polycyclic, and acyclic). The diversity, abundance, and accessibility of plant metabolites make plants an attractive source of human and animal medicine. Even though the pinene scaffold is abundant in nature and has historical use in traditional medicine, pinene and pinene-derived compounds have not been comprehensively studied for medicinal applications. This review provides insight into the utility of the pinene scaffold as a crucial building block of important natural and synthetic products and as a chiral reagent in the asymmetric synthesis of important compounds.

Carvone and its pharmacological activities: A systematic review

Natural products from plants have gained prominence in the search for therapeutic alternatives. Monoterpenes, such as carvone, are suggested as candidates for the treatment of several diseases. Therefore, the objective of this study is to review the pharmacological activities of carvone in experimental models in vitro and in vivo. For this, the searches were carried out in May 2020 (upgraded in July 2021) in the databases of PubMed, Web of Science and Scopus and gathered studies on the pharmacological activities of carvone. Two independent reviewers performed the selection of articles using the Rayyan application, extracted the relevant data and assessed the methodological quality of the selected studies using Syrcle's risk of bias tool. Ninety-one articles were selected that described 10 pharmacological activities of carvone, such as antimicrobial, antispasmodic, anti-inflammatory, antioxidant, antinociceptive, anticonvulsant, among others. The evaluation of the methodological quality presented an uncertain risk of bias for most studies. In light of that, carvone stands out as a viable and promising alternative in the treatment of several pathological conditions. However, carrying out studies to evaluate possible mechanisms of action and the safety of this monoterpene is recommended.

Conversion of Limonene over Heterogeneous Catalysis: An Overview

The natural terpene limonene is widely found in nature. The (R)-limonene (the most abundant enantiomer) is present in the essential oils of lemon, orange, and other citrus fruits, while the (S)- limonene is found in peppermint and the racemate in turpentine oil. Limonene is a low-cost, low toxicity biodegradable terpene present in agricultural wastes derived from citrus peels. The products obtained from the conversion of limonene are valuable compounds widely used as additives for food, cosmetics, or pharmaceuticals. The conversion of limonene to produce different products has been the subject of intense research, mainly with the objective of improving catalytic systems. This review focused on the application of heterogeneous catalysts in the catalytic conversion of limonene.

Bioactive properties of the aromatic molecules of spearmint (Mentha spicata L.) essential oil: a review

Spearmint belongs to the genus Mentha in the family Labiateae (Lamiaceae), which is wildly cultivated worldwide for its remarkable aroma and commercial value. The aromatic molecules of spearmint essential oil,...

Exploring the Critical Components and Therapeutic Mechanisms of Perilla frutescens L. in the Treatment of Chronic Kidney Disease via Network Pharmacology

Chronic kidney disease (CKD) is a chronic progressive disease that seriously threatens human health. Some patients will continue to progress into the CKD stage 3–5 (also called chronic renal failure), which is mainly manifested by a decline in renal function and multi-system damage. Perilla frutescens (L.) Britton. (Lamiaceae) is one of the most widely used traditional Chinese medicine (TCM) herbs in CKD, especially in CKD stage 3–5. But its active components and mechanisms are still unclear. In this study, we used network pharmacology to analyze the active components of P. frutescens and the main therapeutic targets for intervention in CKD stage 3–5. Then, the key components were selected for enrichment analysis and identified by high performance liquid chromatograph (HPLC). Finally, we verified the critical components through molecular docking, and in vitro experiments. The results show that 19 main active components of P. frutescens were screened, and 108 targets were intersected with CKD stage 3–5. The PPI network was constructed and found that the core nodes AKT1, TP53, IL6, TNF, and MAPK1 may be key therapeutic targets. Enrichment analysis shows that related targets may be involved in regulating various biological functions, and play a therapeutic role in CKD stage 3–5 by regulating apoptosis, T cell receptor, and PI3K-AKT signaling pathways. Molecular docking indicates that the key active components were well docked with its corresponding targets. Five active components were identified and quantified by HPLC. According to the results, luteolin was selected as the critical component for further verification. In vitro experiments have shown that luteolin can effectively alleviate adriamycin (ADR)-induced renal tubular apoptosis and suppress AKT and p53 phosphorylation. The effects of luteolin to reduce apoptosis may be mediated by inhibiting oxidative stress and downregulating the mitogen-activated protein kinase (MAPK) and p53 pathways. In general, we screened and analyzed the possible active components, therapeutic targets and pathways of P. frutescens for treating CKD. Our findings revealed that luteolin can reduce renal tubular epithelial cell apoptosis and may be the critical component of P. frutescens in the treatment of CKD. It provides references and direction for further research.

Nanoscopic study on carvone-terpene based natural deep eutectic solvents

Terpene-based natural deep eutectic solvents (NADES) formed by using carvone as the hydrogen bond acceptor and a series of organic acids including tartaric, succinic, malic, and lactic acids as hydrogen bond donors are studied using a combination of molecular simulation methods. Density functional theory was used to study small molecular clusters and the topological characterization of the intermolecular forces using the atoms-in-a-molecule approach. Close-range interactions between the optimized carvone bases eutectic solvents between carbon dioxide have been studied for potential utilization of these solvents for gas capture purposes. Furthermore, COSMO-RS calculations have been carried out for the carbon dioxide solubilization performance of NADES compounds and to obtain s-profiles to infer the polarity and H-bond forming ability of the studied solvents. On the other hand, molecular dynamics simulations were carried out to analyze the bulk liquid properties and their relationship with relevant macroscopic properties (e.g., density or thermal expansion). Last but not least, relevant toxicity properties of the studied systems were predicted and reported in this work. The reported results provide the characterization of environmentally friendly NADES and show the suitability of carvone for advanced applications as carbon dioxide solubilizers.

Health Benefits and Pharmacological Properties of Carvone

Carvone is a monoterpene ketone contained in the essential oils of several aromatic and medicinal plants of the Lamiaceae and Asteraceae families. From aromatic plants, this monoterpene is secreted at different concentrations depending on the species, the parts used, and the extraction methods. Currently, pharmacological investigations showed that carvone exhibits multiple pharmacological properties such as antibacterial, antifungal, antiparasitic, antineuraminidase, antioxidant, anti-inflammatory, and anticancer activities. These studies were carried out in vitro and in vivo and involved a great deal of knowledge on the mechanisms of action. Indeed, the antimicrobial effects are related to the action of carvone on the cell membrane and to ultrastructural changes, while the anti-inflammatory, antidiabetic, and anticancer effects involve the action on cellular and molecular targets such as inducing of apoptosis, autophagy, and senescence. With its multiple mechanisms, carvone can be considered as natural compounds to develop therapeutic drugs. However, other investigations regarding its precise mechanisms of action as well as its acute and chronic toxicities are needed to validate its applications. Therefore, this review discusses the principal studies investigating the pharmacological properties of carvone, and the mechanism of action underlying some of these properties. Moreover, further investigations of major pharmacodynamic and pharmacokinetic studies were also suggested.

Role of ectopic olfactory receptors in glucose and lipid metabolism

The metabolic syndrome has become one of the major public health challenges in the world, and adjusting glucose and lipid levels to their normal values is crucial for treating the metabolic syndrome. Olfactory receptors (ORs) expressed in extra-nasal tissues participate in diverse biological processes, including the regulation of glucose and lipid metabolism. Ectopic ORs can regulate a variety of metabolic events including insulin secretion, glucagon secretion, fatty acid oxidation, lipogenesis and thermogenesis. Understanding the physiological function and deciphering the olfactory recognition code by suitable ligands make ectopic ORs potential targets for the treatment of the metabolic syndrome. In this review, we delineate the roles and mechanisms of ectopic ORs in the regulation of glucose and lipid metabolism, summarize the corresponding natural ligands, and discuss existing problems and the therapeutic potential of targeting ORs in the metabolic syndrome.

Elucidation of the Mechanism Underlying the Anti-Inflammatory Properties of (S)-(+)-Carvone Identifies a Novel Class of Sirtuin-1 Activators in a Murine Macrophage Cell Line

The signaling pathways involved in age-related inflammation are increasingly recognized as targets for the development of preventive and therapeutic strategies. Our previous study elucidated the structure-activity relationship of monoterpene compounds derived from p-menthane as potential anti-inflammatory drugs and identified (S)-(+)-carvone as the most potent among the compounds tested. This study aims at identifying the molecular mechanism underlying the anti-inflammatory properties of (S)-(+)-carvone. The murine macrophage cell line, Raw 264.7, was stimulated with bacterial lipopolysaccharide (LPS) to simulate inflammation. Western blot was used to assess protein levels and post-translational modifications. The subcellular localization of NF-κB/p65 was visualized by immunocytochemistry. An in vitro fluorometric assay was used to measure Sirtuin-1 (SIRT1) activity. (S)-(+)-carvone inhibited LPS-induced JNK1 phosphorylation, but not that of p38 and ERK1/2 and also did not affect the phosphorylation and degradation of the NF-κB inhibitor, IκB-α. Accordingly, (S)-(+)-carvone did not affect LPS-induced phosphorylation of NF-κB/p65 on Ser536 and its nuclear translocation, but it significantly decreased LPS-induced IκB-α resynthesis, a NF-κB-dependent process, and NF-κB/p65 acetylation on lysine (Lys) 310. Deacetylation of that Lys residue is dependent on the activity of SIRT1, which was found to be increased by (S)-(+)-carvone, while its protein levels were unaffected. Taken together, these results show that (S)-(+)-carvone is a new SIRT1 activator with the potential to counteract the chronic low-grade inflammation characteristic of age-related diseases.

Benzyl Isothiocyanate Ameliorates High-Fat Diet-Induced Hyperglycemia by Enhancing Nrf2-Dependent Antioxidant Defense-Mediated IRS-1/AKT/TBC1D1 Signaling and GLUT4 Expression in Skeletal Muscle

Obesity caused lipotoxicity, which results in insulin resistance. We studied whether benzyl isothiocyanate (BITC) improved insulin resistance in muscle. BITC was studied in vivo in mice fed a high-fat diet (HFD) and in vitro in C2C12 myotubes treated with palmitic acid (PA). In C2C12 cells, BITC mitigated PA inhibition of glucose uptake and phosphorylation of IRS-1, AKT, and TBC1D1 in response to insulin. BITC upregulated the expression of HO-1, GSTP, and GCLM mRNA and protein as well as GSH contents, which suppressed oxidative damage. Knockdown of Nrf2 abrogated BITC enhancement of antioxidant defense and subsequently reversed BITC protection against PA-induced insulin resistance. Moreover, BITC upregulated the expression of GLUT4, PPARγ, and C/EBPα. In HFD-fed mice, plasma total cholesterol, nonesterified fatty acid, and glucose levels and HOMA-IR were dose-dependently decreased with 0.05 or 0.1% BITC administration. In gastrocnemius muscle, compared with the HFD group, BITC increased the phosphorylation of AKT and TBC1D1, GSH contents, and the expression of antioxidant enzymes as well as GLUT4. These results indicate that BITC ameliorates obesity-induced hyperglycemia by enhancing insulin sensitivity in muscle. This is partly attributed to its inhibition of lipotoxicity-induced oxidative insult and upregulation of GLUT4 expression.

Carvone suppresses oxidative stress and inflammation in the liver of immobilised rats

OBJECTIVE

The investigation of the effect of carvone (a natural monoterpene) on liver damage caused by chronic immobilisation.

METHODS

Male Wistar rats were divided into four groups: control, carvone, stress, and stress-carvone. To induce stress, rats were placed in a restrainer (6 h/21 day) and carvone was treated by gavage at a dose of 20 mg/kg.

RESULTS

Alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase activities were significantly increased in sera of immobilised rats. Chronic immobilisation also increased malondialdehyde levels and decreased reduced glutathione content, as well as increased TNF-α, IL-1β, IL-6, and NF-κB mRNA expression and also led to the infiltration of inflammatory cells in the liver parenchyma. Carvone's 21-day treatment prevented all of these changes in immobilised rats.

CONCLUSION

It is concluded that carvone has effectively prevented chronic immobilisation-induced liver injury, most probably through its antioxidant and anti-inflammatory capabilities.

Involvement of CYP2E1-ROS-CD36/DGAT2 axis in the pathogenesis of VPA-induced hepatic steatosis in vivo and in vitro

Valproic acid (VPA) is a widely prescribed antiepileptic drug, which may cause steatosis in the liver. Oxidative stress is associated with the progression of VPA-induced hepatic steatosis. However, the potential mechanisms are not fully understood. In this study, we demonstrated the involvement of CYP2E1-ROS-CD36/DGAT2 axis in the pathogenesis of VPA-induced hepatic steatosis in vitro and in vivo. First, VPA treatment (500 mg/kg in mice, 5 mM in LO₂ cells) induced hepatic steatosis and enhanced reactive oxidative stress (ROS) level, and ROS scavenger, N-acetyl-L-cysteine (NAC, 200 mg/kg in mice, 1 mM in LO₂ cells) reversed the changes. Next, we observed the enhanced expression and enzymatic activity of cytochrome P450 2E1 (CYP2E1) in VPA-treated mice and LO₂ cells. Importantly, VPA-induced ROS accumulation and hepatic steatosis were attenuated when CYP2E1 was inhibited using CYP2E1 inhibitor, diallyl sulfide (DAS, 100 mg/kg in mice, 1 mM in LO₂ cells) or in CYP2E1-knockdown cell line, suggesting that CYP2E1 plays a potential role in ROS production following hepatic steatosis. Furthermore, gene expression analysis showed that the mRNA levels of cluster of differentiation 36 (CD36), a fatty acid translocase protein and distinct diacylglycerol acyltransferase 2 (DGAT2) were significantly upregulated in mice and LO₂ cells after VPA treatment, while the change was alleviated by NAC and DAS. Meanwhile, time course experiments demonstrated that the increase of CYP2E1 level occurred earlier than that of ROS, CD36 and DGAT2, and ROS generation preceded the onset of hepatic steatosis. Taken together, VPA treatment enhances the expression and enzymatic activity of CYP2E1, which promotes ROS production and then causes CD36 and DGAT2 overproduction and hepatic steatosis in mice and LO₂ cells, which provides a novel insight into VPA-induced hepatic steatosis.

Bioactivity-Guided Identification of Anti-Adipogenic Isothiocyanates in the Moringa (Moringa oleifera) Seed and Investigation of the Structure-Activity Relationship

Due to the side effects of obesity medications, many studies have focused on the natural products used in the daily diet to control weight. Moringa seed pods and leaves are widely used as vegetables or diet supplements due to the high nutrition value. However, no bioactivity-guided anti-adipogenic study was previously conducted. Therefore, a preadipocyte cell line was adopted as the bioactivity assay to identify the anti-adipogenic compounds in the peeled Moringa seed. Two known sulphur-containing compounds (1 and 2) were isolated and identified. Compound 2, 4-(α-l-rhamnosyloxy) benzyl isothiocyanate, showed a great anti-adipogneic effect with an IC₅₀ value of 9.2 μg/mL. The isothiocyanate (ITC) group in compound 2 could be responsible for the inhibitory activity. In addition, a series of compounds with the ITC group were used to further investigate the structure-activity relationship, indicating foods containing ITC derivatives have the potential of being used to control weight.

Benzyl isothiocyanate ameliorates high-fat/cholesterol/cholic acid diet-induced nonalcoholic steatohepatitis through inhibiting cholesterol crystal-activated NLRP3 inflammasome in Kupffer cells

Incidence of nonalcoholic fatty liver disease is increasing worldwide. Activation of the NLRP3 inflammasome is central to the development of diet-induced nonalcoholic steatohepatitis (NASH). We investigated whether benzyl isothiocyanate (BITC) ameliorates diet-induced NASH and the mechanisms involved. C57BL/6 J mice fed a high-fat diet containing cholesterol and cholic acid (HFCCD) and Kupffer cells stimulated with LPS and cholesterol crystals (CC) were studied. LPS/CC increased the expression of the active form of caspase 1 (p20) and the secretion of IL-1β by Kupffer cells, and these changes were reversed by MCC950, an NLRP3 inflammasome inhibitor. LPS/CC-induced NLRP3 inflammasome activation and IL-1β production were dose-dependently attenuated by BITC. BITC decreased cathepsin B release from lysosomes and binding to NLRP3 induced by LPS/CC. Compared with a normal diet, the HFCCD increased serum levels of ALT, AST, total cholesterol, and IL-1β and hepatic contents of triglycerides and total cholesterol. BITC administration (0.1% in diet) reversed the increase in AST and hepatic triglycerides in the HFCCD group. Moreover, BITC suppressed lipid accumulation, macrophage infiltration, fibrosis, crown-like structure formation, and p20 caspase 1 and p17 IL-1β expression in liver in the HFCCD group. These results suggest that BITC ameliorates HFCCD-induced steatohepatitis by inhibiting the activation of NLRP3 inflammasome in Kupffer cells and may protect against diet-induced NASH.

Benzyl Isothiocyanate and Phenethyl Isothiocyanate Inhibit Adipogenesis and Hepatosteatosis in Mice with Obesity Induced by a High-Fat Diet

Benzyl isothiocyanate (BITC) and phenethyl isothiocyanate (PEITC) are organosulfur phytochemicals rich in cruciferous vegetables. We investigated the antiobesity and antihepatosteatosis activities of BITC and PEITC and the working mechanisms involved. C57BL/6J mice were fed a low-fat diet (LFD), a high-fat diet (HFD), or a HFD supplemented with 0.5 (L) or 1 g/kg (H) BITC or PEITC for 18 weeks. Compared with the HFD group, BITC or PEITC decreased the final body weight of mice in a dose-dependent manner [39.0 ± 3.1 (HFD), 34.4 ± 3.2 (BITC-L), 32.4 ± 2.8 (BITC-H), 36.2 ± 4.4 (PEITC-L), and 32.8 ± 2.9 (PEITC-H) g, p < 0.05], relative weight of epididymal fat [5.7 ± 0.4 (HFD), 4.7 ± 0.7 (BITC-L), 3.7 ± 0.3 (BITC-H), 4.4 ± 1.0 (PEITC-L), and 3.2 ± 0.6 (PEITC-H) %, p < 0.05], hepatic triglycerides [98.4 ± 6.0 (HFD), 81.0 ± 8.9 (BITC-L), 63.5 ± 5.6 (BITC-H), 69.3 ± 5.6 (PEITC-L), and 49.4 ± 2.9 (PEITC-H) mg/g, p < 0.05], and plasma total cholesterol [140 ± 21.3 (HFD), 109 ± 5.6 (BITC-L), 101 ± 11.3 (BITC-H), 126 ± 8.3 (PEITC-L), and 91.8 ± 12.7 (PEITC-H) mg/dL, p < 0.05]. Q-PCR and immunoblotting assays revealed that BITC and PEITC suppressed the expression of liver X receptor α, sterol regulatory element-binding protein 1c, stearoyl-CoA desaturase 1, fatty acid synthase, and acetyl-CoA carboxylase in both epididymal adipose and liver tissues. After a single oral administration of 85 mg/kg BITC or PEITC, the maximum plasma concentrations ( C_max) of BITC and PEITC were 5.8 ± 2.0 μg/mL and 4.3 ± 1.9 μg/mL, respectively. In 3T3-L1 adipocytes, BITC and PEITC dose-dependently reduced adipocyte differentiation and cell cycle was arrested in G0/G1 phase. These findings indicate that BITC and PEITC ameliorate HFD-induced obesity and fatty liver by down-regulating adipocyte differentiation and the expression of lipogenic transcription factors and enzymes.

A high-fat diet impacts memory and gene expression of the head in mated female Drosophila melanogaster

Obesity predisposes humans to a range of life-threatening comorbidities, including type 2 diabetes and cardiovascular disease. Obesity also aggravates neural pathologies, such as Alzheimer's disease, but this class of comorbidity is less understood. When Drosophila melanogaster (flies) are exposed to high-fat diet (HFD) by supplementing a standard medium with coconut oil, they adopt an obese phenotype of decreased lifespan, increased triglyceride storage, and hindered climbing ability. The latter development has been previously regarded as a potential indicator of neurological decline in fly models of neurodegenerative disease. Our objective was to establish the obesity phenotype in Drosophila and identify a potential correlation, if any, between obesity and neurological decline through behavioral assays and gene expression microarray. We found that mated female w1118 flies exposed to HFD maintained an obese phenotype throughout adult life starting at 7 days, evidenced by increased triglyceride stores, diminished life span, and impeded climbing ability. While climbing ability worsened cumulatively between 7 and 14 days of exposure to HFD, there was no corresponding alteration in triglyceride content. Microarray analysis of the mated female w1118 fly head revealed HFD-induced changes in expression of genes with functions in memory, metabolism, olfaction, mitosis, cell signaling, and motor function. Meanwhile, an Aversive Phototaxis Suppression assay in mated female flies indicated reduced ability to recall an entrained memory 6 h after training. Overall, our results support the suitability of mated female flies for examining connections between diet-induced obesity and nervous or neurobehavioral pathology, and provide many directions for further investigation.

Olfactory receptor 43 reduces hepatic lipid accumulation and adiposity in mice

Olfactory receptors are primarily expressed in nasal olfactory epithelium, but these receptors are also ectopically expressed in diverse tissues. In this study, we investigated the biological functions of Olfr43, a mouse homolog of human OR1A1, in cultured hepatocytes and mice to assess its functionality in lipid metabolism. Olfr43 was expressed in mouse hepatocytes, and Olfr43 activation by a known ligand, (-)-carvone, stimulated cAMP response element-binding protein (CREB) activity. In ligand-receptor binding studies using site-directed mutagenesis, (-)-carvone binding required two residues, M257 and Y258, in Olfr43. In the mouse study, oral administration of (-)-carvone for 5 weeks in high-fat diet-fed mice improved energy metabolism, including reductions in hepatic steatosis and adiposity, and improved glucose and insulin tolerance. In mouse livers and cultured mouse hepatocytes, Olfr43 activation simulated the CREB-hairy and enhancer of split 1 (HES1)-peroxisome proliferator-activated receptor (PPAR)-γ signaling axis, leading to a reduction in hepatic triglyceride accumulation in the mouse liver. Thus, long-term administration of (-)-carvone reduces hepatic steatosis. The knockdown of Olfr43 gene expression in cultured hepatocytes negated these effects of (-)-carvone. In conclusion, an ectopic olfactory receptor, hepatic Olfr43, regulates energy metabolism via the CREB-HES1-PPARγ signaling axis.

Benzyl isothiocyanate ameliorates lipid accumulation in 3T3-L1 preadipocytes during adipocyte differentiation

Benzyl isothiocyanate (BITC) is an organosulfur compound derived from cruciferous vegetables and papaya seeds. In this study, we investigated the effect of BITC on the lipid accumulation in 3T3-L1 preadipocytes during adipocyte differentiation. The treatment of BITC during the differentiation-inducing stage significantly ameliorated the lipid accumulation, whereas it had no inhibitory effect during the differentiation-maintaining stage. BITC also significantly suppressed the mRNA expression of the adipocyte-specific markers, such as CCAAT/enhancer-binding protein α (C/EBPα), C/EBPβ, C/EBPδ and peroxisome proliferator-activated receptor γ. BITC significantly inhibited the phosphorylation of extracellular signal-regulated kinase phosphorylation, whereas it enhanced that of AMP-activated protein kinase. Furthermore, BITC significantly suppressed the intracellular 2-deoxyglucose uptake as well as glucose transporter 4 expression. These results suggest that inhibition of the adipocyte differentiation and glucose uptake may mainly contribute to the inhibitory effect of BITC on the lipid accumulation in 3T3-L1 preadipocytes. Abbreviations: PPARγ: peroxisome proliferator-activated receptor γ; CEBP: CCAAT/enhancer-binding protein; GLUT4: glucose transporter 4; AMPK: AMP-activated protein kinase; ERK1/2: extracellular signal-regulated kinase 1/2; MAPK: a mitogen-activated protein kinase; ITCs: isothiocyanates; BITC: benzyl isothiocyanate; FBS: fetal bovine serum; CS: calf serum; AITC: allyl ITC; IBMX: 3-isobutyl-1-methylxanthine; LDH: lactate dehydrogenase; KRH: Krebs-Ringer-Hepes-bicarbonate; 2-DG: 2-deoxy-d-glucose.