Kynurenic Acid Protects against Thioacetamide-Induced Liver Injury in Rats

Apocynin alleviates thioacetamide-induced acute liver injury: Role of NOX1/NOX4/NF-κB/NLRP3 pathways

The liver has a distinctive capacity to regenerate, yet severe acute injury can be life-threatening if not treated appropriately. Inflammation and oxidative stress are central processes implicated in the pathophysiology of acute livery injury. NOX isoforms are important enzymes for ROS generation, NF-κB and NLRP3 activation, its inhibition could be vital in alleviating acute liver injury (ALI). Here in our study, we used apocynin, a natural occurring potent NOX inhibitor, to exploreits potential protective effect against thioacetamide (TAA)-induced ALI through modulating crucial oxidative and inflammatory pathways. Rats were injected once with TAA (500 mg/kg/i.p) and treated with apocynin (10 mg/kg/i.p) twice before TAA challenge. Sera and hepatic tissues were collected for biochemical, mRNA expression, western blot analysis and histopathological assessments. Pretreatment with apocynin improved liver dysfunction evidenced by decreased levels of aminotransferases, ALP, GGT and bilirubin. Apocynin reduced mRNA expression of NOX1 and NOX4 which in turn alleviated oxidative stress, as shown by reduction in MDA and NOx levels, and elevation in GSH levels andcatalase and SOD activities. Moreover, apocynin significantly reduced MPO gene expression. We also demonstrate that apocynin ameliorated inflammation through activating IκBα and suppressing IKKα, IKKβ, NF-κBp65 and p-NF-κBp65, IL-6 andTNF-α. Additionally, apocynin potentiated the gene expression of anti-inflammatory IL-10 and reduced levels of hepatic NLRP3, Caspase-1 and IL-1β. These results suggest that apocynin protects against ALI in association with the inhibition of NOX1 and NOX4 and regulating oxidative and inflammatory pathways.

The Biology and Biochemistry of Kynurenic Acid, a Potential Nutraceutical with Multiple Biological Effects

Kynurenic acid (KYNA) is an antioxidant degradation product of tryptophan that has been shown to have a variety of cytoprotective, neuroprotective and neuronal signalling properties. However, mammalian transporters and receptors display micromolar binding constants; these are consistent with its typically micromolar tissue concentrations but far above its serum/plasma concentration (normally tens of nanomolar), suggesting large gaps in our knowledge of its transport and mechanisms of action, in that the main influx transporters characterized to date are equilibrative, not concentrative. In addition, it is a substrate of a known anion efflux pump (ABCC4), whose in vivo activity is largely unknown. Exogeneous addition of L-tryptophan or L-kynurenine leads to the production of KYNA but also to that of many other co-metabolites (including some such as 3-hydroxy-L-kynurenine and quinolinic acid that may be toxic). With the exception of chestnut honey, KYNA exists at relatively low levels in natural foodstuffs. However, its bioavailability is reasonable, and as the terminal element of an irreversible reaction of most tryptophan degradation pathways, it might be added exogenously without disturbing upstream metabolism significantly. Many examples, which we review, show that it has valuable bioactivity. Given the above, we review its potential utility as a nutraceutical, finding it significantly worthy of further study and development.

Kynurenic acid protects against ischemia/reperfusion injury by modulating apoptosis in cardiomyocytes

Acute myocardial infarction, often associated with ischemia/reperfusion injury (I/R), is a leading cause of death worldwide. Although the endogenous tryptophan metabolite kynurenic acid (KYNA) has been shown to exert protection against I/R injury, its mechanism of action at the cellular and molecular level is not well understood yet. Therefore, we examined the potential involvement of antiapoptotic mechanisms, as well as N-methyl-D-aspartate (NMDA) receptor modulation in the protective effect of KYNA in cardiac cells exposed to simulated I/R (SI/R). KYNA was shown to attenuate cell death induced by SI/R dose-dependently in H9c2 cells or primary rat cardiomyocytes. Analysis of morphological and molecular markers of apoptosis (i.e., membrane blebbing, apoptotic nuclear morphology, DNA double-strand breaks, activation of caspases) revealed considerably increased apoptotic activity in cardiac cells undergoing SI/R. The investigated apoptotic markers were substantially improved by treatment with the cytoprotective dose of KYNA. Although cardiac cells were shown to express NMDA receptors, another NMDA antagonist structurally different from KYNA was unable to protect against SI/R-induced cell death. Our findings provide evidence that the protective effect of KYNA against SI/R-induced cardiac cell injury involves antiapoptotic mechanisms, that seem to evoke independently of NMDA receptor signaling.

Kynurenic Acid Plays a Protective Role in Hepatotoxicity Induced by HFPO-DA in Male Mice

Following its introduction as an alternative to perfluorooctanoic acid, hexafluoropropylene oxide dimer acid (HFPO-DA) has been extensively detected in various environmental matrices. Despite this prevalence, limited information is available regarding its hepatotoxicity biomarkers. In this study, toxicokinetic simulations indicated that under repeated treatment, HFPO-DA in mice serum reached a steady state by the 4th day. To assess its subacute hepatic effects and identify potential biomarkers, mice were administered HFPO-DA orally at doses of 0, 0.1, 0.5, 2.5, 12.5, or 62.5 mg/kg/d for 7 d. Results revealed that the lowest observed adverse effect levels were 0.5 mg/kg/d for hepatomegaly and 2.5 mg/kg/d for hepatic injury. Serum metabolomics analysis identified 34, 58, and 118 differential metabolites in the 0.1, 0.5, and 2.5 mg/kg/d groups, respectively, compared to the control group. Based on weighted gene coexpression network analysis, eight potential hepatotoxicity-related metabolites were identified; among them, kynurenic acid (KA) in mouse serum exhibited the highest correlation with liver injury. Furthermore, liver-targeted metabolomics analysis demonstrated that HFPO-DA exposure induced metabolic migration of the kynurenine pathway from KA to nicotinamide adenine dinucleotide, resulting in the activation of endoplasmic reticulum stress and the nuclear factor kappa-B signaling pathway. Notably, pretreatment with KA significantly attenuated liver injury induced by HFPO-DA exposure in mice, highlighting the pivotal roles of KA in the hepatotoxicity of HFPO-DA.

Thioacetamide-Induced Acute Liver Injury Increases Metformin Plasma Exposure by Downregulating Renal OCT2 and MATE1 Expression and Function

Metformin plasma exposure is increased in rats with thioacetamide (TAA)-induced liver failure. The absorption, distribution, and excretion process of metformin is mainly mediated by organic cation transporters (OCTs) and multidrug and toxin extrusion transporters (MATEs). To investigate the mechanisms of the increase in TAA-induced metformin plasma exposure, we employed intestinal perfusion and urinary excretion assays to evaluate the changes in the absorption and excretion of metformin and used Western blotting to investigate the metformin-related transport proteins' expression changes and mechanisms. The results showed that neither intestinal OCT2 expression nor metformin intestinal absorption were significantly altered by TAA-induced liver failure, while significantly decreased expression and function of renal OCT2 and MATE1 as well as impaired metformin excretion were observed in TAA rats. HK-2 cells were used as an in vitro model to explore the mechanism of liver-failure-mediated downregulation in renal OCT2 and MATE1. The results demonstrated that among numerous abnormal substances that changed in acute liver failure, elevated estrogen levels and tumor necrosis factor-α were the main factors mediating the downregulation of OCT2 and MATE1. In conclusion, this study highlights the downregulation of renal OCT2 and MATE1 in liver injury and its regulatory mechanism and reveals its roles in the increase in TAA-mediated metformin plasma exposure.

Effect of Yarrowia lipolytica yeast biomass with increased kynurenic acid content on selected metabolic indicators in mice

Background

The unconventional yeast species Yarrowia lipolytica is a valuable source of protein and many other nutrients. It can be used to produce hydrolytic enzymes and metabolites, including kynurenic acid (KYNA), an endogenous metabolite of tryptophan with a multidirectional effect on the body. The administration of Y. lipolytica with an increased content of KYNA in the diet may have a beneficial effect on metabolism, which was evaluated in a nutritional experiment on mice.

Methods

In the dry biomass of Y. lipolytica S12 enriched in KYNA (high-KYNA yeast) and low-KYNA (control) yeast, the content of KYNA was determined by high-performance liquid chromatography. Then, proximate and amino acid composition and selected indicators of antioxidant status were compared. The effect of 5% high-KYNA yeast content in the diet on the growth, hematological and biochemical indices of blood and the redox status of the liver was determined in a 7-week experiment on adult male mice from an outbred colony derived from A/St, BALB/c, BN/a and C57BL/6J inbred strains.

Results

High-KYNA yeast was characterized by a greater concentration of KYNA than low-KYNA yeast (0.80 ± 0.08 vs. 0.29 ± 0.01 g/kg dry matter), lower content of crude protein with a less favorable amino acid composition and minerals, higher level of crude fiber and fat and lower ferric-reducing antioxidant power, concentration of phenols and glutathione. Consumption of the high-KYNA yeast diet did not affect the cumulative body weight gain per cage, cumulative food intake per cage and protein efficiency ratio compared to the control diet. A trend towards lower mean corpuscular volume and hematocrit, higher mean corpuscular hemoglobin concentration and lower serum total protein and globulins was observed, increased serum total cholesterol and urea were noted. Its ingestion resulted in a trend towards greater ferric-reducing antioxidant power in the liver and did not affect the degree of liver lipid and protein oxidation.

Conclusions

The improvement of the quality of Y. lipolytica yeast biomass with increased content of KYNA, including its antioxidant potential, would be affected by the preserved level of protein and unchanged amino acid profile. It will be worth investigating the effect of such optimized yeast on model animals, including animals with metabolic diseases.

Gallic acid and metformin co-administration reduce oxidative stress, apoptosis and inflammation via Fas/caspase-3 and NF-κB signaling pathways in thioacetamide-induced acute hepatic encephalopathy in rats

BACKGROUND

Hepatic encephalopathy (HE) is a consequence of chronic or acute liver diseases. This study evaluates the combined effect of gallic acid (GA), and metformin (Met) on the liver and brain damage associated with HE.

METHODS

Acute HE was induced by a single dose of thioacetamide (TAA) (300 mg/kg) as an I.P. injection. Treated groups received GA group (100 mg/kg/day, p.o), Met (200 mg/kg/day, p.o), or their combination for 25 consecutive days before TAA injection.

RESULTS

The administration of TAA induced various biochemical and histopathological alterations. In contrast, treatment with GA either alone or combined with Met resulted in improved liver functions by the significant reduction in serum ALT, AST, and ALP activities, and ammonia levels. Inflammatory mediators; TNF-α, IL-6, and NFkβ levels were decreased by these treatments as well as apoptotic cascade via down-regulation of FAS and caspase-3 (CASP-3) expression in hepatic tissues. Furthermore, GA and Met either alone or combined protected the liver and brain tissues from damage by increased glutathione concentration while decreasing malondialdehyde. In addition, it was accompanied by the improvement of the brain neurotransmitter profile via the restoration of norepinephrine, dopamine, and serotonin levels. Based on our data, this is the first study to report a novel combined hepatoprotective and cognitive enhancing effect of GA and Met against TAA-induced acute liver and brain injury.

CONCLUSION

GA and Met combination resulted in a prominent improvement in HE complications, relative to monotherapy. Both agents potentiated the antioxidant, anti-inflammatory, and anti-apoptotic effects of each other.

Bromelain ameliorates D-galactosamine-induced acute liver injury: role of SIRT1/LKB1/AMPK, GSK3β/Nrf2 and NF-κB p65/TNF-α/caspase-8, -9 signalling pathways

OBJECTIVES

The present research focused on estimating, for the first time, the potential protective effects of bromelain against D-galactosamine-induced acute liver injury in rats as well as identifying the possible underlying mechanisms.

METHODS

Silymarin (100 mg/kg/day, p.o.) as a reference drug or bromelain (20 and 40 mg/kg/day, p.o.) were administered for 10 days, and on the 8th day of the experiment, a single dose of galactosamine (400 mg/kg/i.p.) induced acute liver injury.

KEY FINDINGS

Pretreatment with bromelain improved liver functions and histopathological alterations induced by galactosamine. Bromelain ameliorated oxidative stress by inducing SIRT1 protein expression and increasing LKB1 content. This resulted in phosphorylating the AMPK/GSK3β axis, which stimulated Nrf2 activation in hepatic cells and thus increased the activity of its downstream antioxidant enzymes [HO-1 and NQO1]. Besides, bromelain exerted significant anti-apoptotic and anti-inflammatory effects by suppressing hepatic contents of TNF-α, NF-κB p65, as well as caspase-8 and caspase-9. The protective effects of bromelain40 were proved to be better than silymarin and bromelain20 in most of the assessed parameters.

CONCLUSIONS

Our results highlight the significant hepatoprotective effects of bromelain against acute liver injury through modulation of SIRT1/LKB1/AMPK, GSK3β/Nrf2 signalling in addition to NF-κB p65/TNF-α/ caspase-8 and -9 pathway.

A Review of the Health Benefits of Food Enriched with Kynurenic Acid

Kynurenic acid (KYNA), a metabolite of tryptophan, is an endogenous substance produced intracellularly by various human cells. In addition, KYNA can be synthesized by the gut microbiome and delivered in food. However, its content in food is very low and the total alimentary supply with food accounts for only 1-3% of daily KYNA excretion. The only known exception is chestnut honey, which has a higher KYNA content than other foods by at least two orders of magnitude. KYNA is readily absorbed from the gastrointestinal tract; it is not metabolized and is excreted mainly in urine. It possesses well-defined molecular targets, which allows the study and elucidation of KYNA's role in various pathological conditions. Following a period of fascination with KYNA's importance for the central nervous system, research into its role in the peripheral system has been expanding rapidly in recent years, bringing some exciting discoveries. KYNA does not penetrate from the peripheral circulation into the brain; hence, the following review summarizes knowledge on the peripheral consequences of KYNA administration, presents data on KYNA content in food products, in the context of its daily supply in diets, and systematizes the available pharmacokinetic data. Finally, it provides an analysis of the rationale behind enriching foods with KYNA for health-promoting effects.

Gut Microbiota Regulation of AHR Signaling in Liver Disease

Liver health plays a vital role in human health and disease. Emerging evidence has shown the importance of the aryl hydrocarbon receptor (AHR) in liver diseases such as alcoholic liver disease, fatty liver disease, and liver failure. As a ligand-activated transcription factor, AHR can be activated by endogenous ligands of microbial metabolites such as tryptophan (Trp), kynurenine (Kyn) or indole derivatives locally or distantly. However, the therapeutic effects of the gut microbiota-regulated AHR pathway remain to be clarified. In this review, we summarize recent progress and examine the role of AHR signaling as a target for gut microbiota intervention in liver diseases. The focus on AHR signaling will identify a promising target in the gut microbiota for better understanding and therapeutic opportunities in liver diseases.

Ongoing Clinical Trials in Aging-Related Tissue Fibrosis and New Findings Related to AhR Pathways

Fibrosis is a pathological manifestation of wound healing that replaces dead/damaged tissue with collagen-rich scar tissue to maintain homeostasis, and complications from fibrosis contribute to nearly half of all deaths in the industrialized world. Ageing is closely associated with a progressive decline in organ function, and the prevalence of tissue fibrosis dramatically increases with age. Despite the heavy clinical and economic burden of organ fibrosis as the population ages, to date, there is a paucity of therapeutic strategies that are specifically designed to slow fibrosis. Aryl hydrocarbon receptor (AhR) is an environment-sensing transcription factor that exacerbates aging phenotypes in different tissues that has been brought back into the spotlight again with economic development since AhR could interact with persistent organic pollutants derived from incomplete waste combustion. In addition, gut microbiota dysbiosis plays a pivotal role in the pathogenesis of numerous diseases, and microbiota-associated tryptophan metabolites are dedicated contributors to fibrogenesis by acting as AhR ligands. Therefore, a better understanding of the effects of tryptophan metabolites on fibrosis modulation through AhR may facilitate the exploitation of new therapeutic avenues for patients with organ fibrosis. In this review, we primarily focus on how tryptophan-derived metabolites are involved in renal fibrosis, idiopathic pulmonary fibrosis, hepatic fibrosis and cardiac fibrosis. Moreover, a series of ongoing clinical trials are highlighted.

Synthesis and Investigation of the G-Quadruplex Binding Properties of Kynurenic Acid Derivatives with a Dihydroimidazoquinoline-3,5-dione Core

G-quadruplexes are secondary structures originating from nucleic acid regions rich in guanines, which are well known for their involvement in gene transcription and regulation and DNA damage repair. In recent studies from our group, kynurenic acid (KYNA) derivative 1 was synthesized and found to share the structural features typical of G-quadruplex binders. Herein, structural modifications were conducted on this scaffold in order to assist the binding with a G-quadruplex, by introducing charged hydrophilic groups. The antiproliferative activity of the new analogues was evaluated on an IGROV-1 human ovarian cancer cell line, and the most active compound, compound 9, was analyzed with NMR spectrometry in order to investigate its binding mode with DNA. The results indicated that a weak, non-specific interaction was set with duplex nucleotides; on the other hand, titration in the presence of a G-quadruplex from human telomere d(TTAGGGT)4 showed a stable, although not strong, interaction at the 3'-end of the nucleotidic sequence, efficiently assisted by salt bridges between the quaternary nitrogen and the external phosphate groups. Overall, this work can be considered a platform for the development of a new class of potential G-quadruplex stabilizing molecules, confirming the crucial role of a planar system and the ability of charged nitrogen-containing groups to facilitate the binding to G-quadruplex grooves and loops.

Alterations of gut microbiome and metabolite profiles in choledocholithiasis concurrent with cholangitis

BACKGROUND AND AIMS

Gut microbiota and their metabolic products might play important roles in regulating the pathogenesis of choledocholithiasis concurrent with cholangitis (CC). The aim of this study was to explore the characteristic gut dysbiosis, metabolite profiles and the possible roles in patients with CC.

METHODS

A case-control study was carried out to analyze the alterations in the intestinal microbiota and their metabolites in patients with CC (n = 25) compared with healthy controls (HCs) (n = 25) by metagenomic sequencing to define the gut microbiota community and liquid chromatography/mass spectrometry (LC/MS) analysis to characterize the metabolite profiles.

RESULTS

Significantly reduced Shannon diversity index (p = 0.043) and differential overall fecal microbiota community in CCs were observed. Twelve dominant altered species were identified and analyzed (LDA score > 3.0, p < 0.05) (Q value < 0.05), including unclassified_f_Enterobacteriaceae, Escherichia_coli, Roseburia_faecis and Eubacterium rectale. Moreover, the levels of KEGG pathways related to biofilm formation of Escherichia coli, lipopolysaccharide (LPS) biosynthesis, and the metabolism of propanoate and glutathione in CCs were significantly altered. Finally, 47 markedly changed metabolites (VIP > 1.0 and p < 0.05), including low level of kynurenic acid (KYNA) and high concentration of N-palmitoylsphingosine involving tryptophan metabolism and sphingolipid signaling pathways, were identified to validate aberrant metabolic patterns in CCs, and multiple correlated metabolic modules involving bile inflammation were altered in CCs.

CONCLUSION

Our study provides novel insights into compositional and functional alterations in the gut microbiome and metabolite profiles in CC and the underlying mechanisms between gut microbiota and bile inflammation.

Phytochemical constituents and protective efficacy of Schefflera arboricola L. leaves extract against thioacetamide-induced hepatic encephalopathy in rats

Context: Hepatic encephalopathy (HE) is a severe neuropsychiatric syndrome resulting from liver failure. Objective: To evaluate the protective effect of Schefflera arboricola L. leaves methanol extract against thioacetamide (TAA) induced HE in rats. Materials and methods: GC/MS, LC-ESI-MS and the total phenolic and flavonoid contents were determined. The methanol extract was orally administrated (100 and 200 mg/kg) for 21 days. TAA (200 mg/kg) was given intraperitoneally on day 19 and continued for three days. The evaluation was done by measuring alanine aminotransferases (ALT), alkaline phosphatase (ALP), ammonia, reduced glutathione (GSH), malondialdehyde (MDA), nitric oxide (NO) alpha tumor necrotic factor (TNFα), toll like receptor (TLR4), interleukin 1 beta (IL-1β), interlukin 6 (IL-6), cyclooxygenase 2(COX2), B cell lymphoma (BCL2), alpha smooth muscle actin (α-SMA) and cluster of differentiation 163 (CD163). The histological features of liver and brain were conducted. Results: Forty five compounds were identified from the n-hexane fraction, while twenty nine phenolic compounds were determined from the methanol extract. Pretreatment with the plant extract returned most of the measurements under investigation to nearly normal. Conclusion: Due to its richness with bioactive compounds, Schefflera arboricola L. leaves extract succeeded to exert anti-fibrotic, anti-inflammatory and antioxidants properties in TAA-induced HE in rats with more efficacy to its high protective dose.

Auricularia auricula Melanin Protects against Alcoholic Liver Injury and Modulates Intestinal Microbiota Composition in Mice Exposed to Alcohol Intake

The potential effects of Auricularia auricula melanin (AAM) on the intestinal flora and liver metabolome in mice exposed to alcohol intake were investigated for the first time. The results showed that oral administration of AAM significantly reduced the abnormal elevation of serum total triglyceride (TG), cholesterol (TC), low density lipoprotein cholesterol (LDL-C), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and significantly inhibited hepatic lipid accumulation and steatosis in mice exposed to alcohol intake. Besides, the abnormally high levels of bile acids (BAs) and lactate dehydrogenase (LDH) in the liver of mice with alcohol intake were significantly decreased by AAM intervention, while the hepatic levels of glutathione (GSH) and superoxide dismutase (SOD) were appreciably increased. Compared with the model group, AAM supplementation significantly changed the composition of intestinal flora and up-regulated the levels of Akkermansia, Bifidobacterium, Romboutsia, Muribaculaceae, Lachnospiraceae_NK4A136_group, etc. Furthermore, liver metabolomics demonstrated that AAM had a significant regulatory effect on the composition of liver metabolites in mice with alcohol intake, especially the metabolites involved in phosphatidylinositol signaling system, ascorbate and aldarate metabolism, starch and sucrose metabolism, galactose metabolism, alpha-linolenic acid metabolism, glycolysis/gluconeogenesis, and biosynthesis of unsaturated fatty acids. At the gene level, AAM treatment regulated the mRNA levels of lipid metabolism and inflammatory response related genes in liver, including ACC-1, FASn, CPT-1, CD36, IFN-γ, LDLr and TNF-α. Conclusively, these findings suggest that AAM has potential beneficial effects on alleviating alcohol-induced liver injury and is expected to become a new functional food ingredient.

Potential Antioxidant and Anti-Inflammatory Function of Gynura procumbens Polyphenols Ligand

The antioxidant and anti-inflammatory potentials of polyphenols contained in Gynura procumbens (GP) extract were systematically analyzed. Polyphenols in GP were analyzed for nine peaks using high-performance liquid chromatography (HPLC) combined with mass spectrometry (MS), and quantitatively determined through each standard. A total of nine polyphenolic compounds were identified in the samples and their MS data were tabulated. To determine the potential of bioactive ingredients targeting DPPH and COX-2, we analyzed them by ultrafiltration combined with LC. The results identified the major compounds exhibiting binding affinity for DPPH and COX-2. Caffeic acid, kynurenic acid, and chlorogenic acid showed excellent binding affinity to DPPH and COX-2, suggesting that they can be considered as major active compounds. Additionally, the anti-inflammatory effect of GP was confirmed in vitro. This study will not only be used to provide basic data for the application of GP to the food and pharmaceutical industries, but will also provide information on effective screening methods for other medicinal plants.

In vivo anticancer effects of Momordica charantia seed fat on hepatocellular carcinoma in a rat model

BACKGROUND

Momordica charantia or bitter melon is a well-known vegetable with a number of therapeutic actions in Ayurvedic medicine. Alpha-eleostearic acid, a conjugated trienoic fatty acid present in bitter melon is proven to have anticancer properties. Crude seed oil from local bitter melon varieties could be an effective and economical anticancer therapy.

OBJECTIVE(S)

The study was conducted to evaluate the anticancer effect of the crude oil from the seeds of Matale green variety of bitter melon on a hepatocellular carcinoma-induced rat model.

MATERIALS AND METHODS

Hepatocellular carcinoma (HCC) was experimentally induced in Wistar rats. Crude seed oil of Matale green bitter melon (MGBM) was supplemented to one treatment group in concurrence with carcinoma induction and to another treatment group after the development of carcinoma. After 168 days, gross morphological, histopathological, biochemical, hematological and gene-expression analysis of treated and control groups were performed.

RESULTS

Oral supplementation of MGBM seed oil showed a statistically significant reduction (p < 0.05) in the average number, diameter and area of hepatic dysplastic nodules and a reduction in the size of histopathological neoplastic lesions in both treatment groups compared to the non-treated control group. The expression of tumor suppressor gene p53 and anti-apoptotic gene Bcl-2 were significantly increased while the expression of apoptotic gene caspase 3 was significantly reduced in the treatment group when MGBM supplementation was in concurrence with carcinogenesis (p < 0.05).

CONCLUSION

Crude seed oil from the MGBM has anticancer effects against experimentally induced HCC in Wistar rats, specially when supplemented in concurrence with carcinoma induction.

Apoptosis-mediated anticancer activity in prostate cancer cells of a chestnut honey (Castanea sativa L.) quinoline-pyrrolidine gamma-lactam alkaloid

Prostate cancer (PCa) is the most common malignancy in men and represents the second leading cause of cancer deaths in Western countries. PCa is initially androgen-dependent, however, this tumor inevitably progresses as castration-resistant prostate cancer (CRPC), which represents the most aggressive phase of the pathology. In this work, in two CRPC cell lines (DU145 and PC3), we studied the in vitro inhibitory properties of the tryptophan-derived endogenous metabolite kynurenic acid (KYNA) and of the lactam form of 3–2′-pyrrilonidinyl-kynurenic acid (3-PKA-L), alkaloids usually present in combination in chestnut honey. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell colony formation assay, and Western blot analysis of the major mediator proteins involved in apoptotic processes. In all experiments, KYNA was scarcely or not active while 3-PKA-L showed anticancer activity in the high concentration range (0.01 mM – 1 mM) from 24 to 72 h. The results obtained showed that cell death was induced by extrinsic apoptotic pathway, by cell morphological changes and reduction of cell colonies number. These novel results represent the first promising step to the accurate description of 3-PKA-L cytotoxic effect, not observed with KYNA, paving the way to the search of new anticancer agents, as well as to the better understanding of the physiopathological role of this interesting natural product.

The Beneficial Effects of Edible Kynurenic Acid from Marine Horseshoe Crab (Tachypleus tridentatus) on Obesity, Hyperlipidemia, and Gut Microbiota in High-Fat Diet-Fed Mice

The marine horseshoe crab (Tachypleus tridentatus) has been considered as food and traditional medicine for many years. Kynurenic acid (KA) was isolated from horseshoe crab in this study for the first time in the world. A previous study in 2018 reported that intraperitoneal administration of KA prevented high-fat diet- (HFD-) induced body weight gain. Now, we investigated the effects of intragastric gavage of KA on HFD mice and found that KA (5 mg/kg/day) inhibited both the body weight gain and the increase of average daily energy intake. KA reduced serum triglyceride and increased serum high-density lipoprotein cholesterol. KA inhibited HFD-induced the increases of serum low-density lipoprotein cholesterol, coronary artery risk index, and atherosclerosis index. KA also suppressed HFD-induced the increase of the ratio of Firmicutes to Bacteroidetes (two dominant gut microbial phyla). KA partially reversed HFD-induced the changes in the composition of gut microbial genera. These overall effects of KA on HFD mice were similar to that of simvastatin (positive control). But the effects of 1.25 mg/kg/day KA on HFD-caused hyperlipidemia were similar to the effects of 5 mg/kg/day simvastatin. The pattern of relative abundance in 40 key genera of gut microbiota from KA group was closer to that from the normal group than that from the simvastatin group. In addition, our in vitro results showed the potential antioxidant activity of KA, which suggests that the improvement effects of KA on HFD mice may be partially associated with antioxidant activity of KA. Our findings demonstrate the potential role of KA as a functional food ingredient for the treatment of obesity and hyperlipidemia as well as the modulation of gut microbiota.

Drug-induced-acute liver failure: A critical appraisal of the thioacetamide model for the study of hepatic encephalopathy

Hepatic encephalopathy (HE) following acute and chronic liver failure is defined as a complex of neuropsychiatric abnormalities, such as discrete personal changes, sleep disorder, forgetfulness, confusion, and decreasing the level of consciousness to coma. The use and design of suitable animal models that represent clinical features and pathological changes of HE are valuable to map the molecular mechanisms that result in HE. Among different types of animal models, thioacetamide (TAA) has been used extensively for the induction of acute liver injury and HE. This agent is not directly hepatotoxic but its metabolites induce liver injury through the induction of oxidative stress and produce systemic inflammation similar to that seen in acute HE patients. In this short review article, we shortly review the most important pathological findings in animal models of acute HE following the administration of TAA.

Synthesis and biological evaluation of new 3(2H)-pyridazinone derivatives as non-toxic anti-proliferative compounds against human colon carcinoma HCT116 cells

Novel 3(2H)-pyridazinone derivatives were designed, synthesised in satisfactory yields and evaluated in different experimental assays to assess their preliminary toxicity in vivo and anti-proliferative effects against HCT116 cell lines in vitro. Artemia salina lethality test provided LC50 values >100 µg/mL for all compounds. Successive assays revealed that some compounds were endowed with a promising anti-proliferative effect against HCT116 cells, alone or stimulated by serotonin as a pro-inflammatory factor in order to mimick an inflamed model in vivo of cancer cell microenvironment. Moreover, the kinurenic acid level after treatment with these newly synthesised compounds was monitored as a marker of anti-proliferation in colon carcinoma models. The IC50 values obtained for the best-in-class compounds were comparable to that of daunorubicin as a reference drug. Conversely, these compounds were not able to counteract the spontaneous migration of human cancer HCT116 cell line in the wound healing paradigm.

Integrated analysis of transcriptomic and proteomic analyses reveals different metabolic patterns in the livers of Tibetan and Yorkshire pigs

Objective

Tibetan pigs, predominantly originating from the Tibetan Plateau, have been subjected to long-term natural selection in an extreme environment. To characterize the metabolic adaptations to hypoxic conditions, transcriptomic and proteomic expression patterns in the livers of Tibetan and Yorkshire pigs were compared.

Methods

RNA and protein were extracted from liver tissue of Tibetan and Yorkshire pigs (n = 3, each). Differentially expressed genes and proteins were subjected to gene ontology and Kyoto encyclopedia of genes and genomes functional enrichment analyses.

Results

In the RNA-Seq and isobaric tags for relative and absolute quantitation analyses, a total of 18,791 genes and 3,390 proteins were detected and compared. Of these, 273 and 257 differentially expressed genes and proteins were identified. Evidence from functional enrichment analysis showed that many genes were involved in metabolic processes. The combined transcriptomic and proteomic analyses revealed that small molecular biosynthesis, metabolic processes, and organic hydroxyl compound metabolic processes were the major processes operating differently in the two breeds. The important genes include retinol dehydrogenase 16, adenine phosphoribosyltransferase, prenylcysteine oxidase 1, sorbin and SH3 domain containing 2, ENSSSCG00000036224, perilipin 2, ladinin 1, kynurenine aminotransferase 1, and dimethylarginine dimethylaminohydrolase 1.

Conclusion

The findings of this study provide novel insight into the high-altitude metabolic adaptation of Tibetan pigs.

Kynurenic acid and cancer: facts and controversies

Kynurenic acid (KYNA) is an endogenous tryptophan metabolite exerting neuroprotective and anticonvulsant properties in the brain. However, its importance on the periphery is still not fully elucidated. KYNA is produced endogenously in various types of peripheral cells, tissues and by gastrointestinal microbiota. Furthermore, it was found in several products of daily human diet and its absorption in the digestive tract was evidenced. More recent studies were focused on the potential role of KYNA in carcinogenesis and cancer therapy; however, the results were ambiguous and the biological activity of KYNA in these processes has not been unequivocally established. This review aims to summarize the current views on the relationship between KYNA and cancer. The differences in KYNA concentration between physiological conditions and cancer, as well as KYNA production by both normal and cancer cells, will be discussed. The review also describes the effect of KYNA on cancer cell proliferation and the known potential molecular mechanisms of this activity.

Biopotential of Bersama abyssinica Fresen Stem Bark Extracts: UHPLC Profiles, Antioxidant, Enzyme Inhibitory, and Antiproliferative Propensities

In this study, ethyl acetate, methanol, and water extracts of Bersama abyssinica (Melianthaceae) stem bark were screened for enzyme inhibitory and antioxidant properties. The water extract possessed the highest concentration of phenols (230.83 mg gallic acid equivalent/g extract), while the methanol extract was rich in flavonoids (75.82 mg rutin equivalent/g extract), and the ethyl acetate extract possessed the highest amount of saponins (97.37 mg quillaja equivalent/g). The aim of this study was to investigate the antiproliferative effects against the human colon cancer HCT116 cell line challenged with serotonin (5-HT) as a stimulating-proliferation factor. The level of HCT116 cell-deriving pool of kynurenic acid (KA) was also assessed. The UHPLC results confirmed the presence of 58, 68, and 63 compounds in the ethyl acetate, methanol, and water extracts, respectively. Mangiferin, vitexin and its isomer isovitexin were tentatively identified in all extracts and KA (m/z 190.05042 [M−H]⁺) was also tentatively identified in the methanol and water extracts. The methanol extract (1464.08 mg Trolox equivalent [TE]/g extract) showed the highest activity in the CUPRAC assay, whereas the water extract (1063.70 mg TE/g extract) showed the highest activity with the FRAP technique. The ethyl acetate extract was the most active acetylcholinesterase (4.43 mg galantamine equivalent/g extract) and α-glucosidase (mmol acarbose equivalent /g extract) inhibitor. The water extract was able to inhibit 5-HT-stimulated viability of HCT116 cells, and blunt 5-HT-induced reduction of cell-deriving KA. The scientific data generated in this study provide baseline data regarding the biological properties of B. abyssinica stem bark, highlighting its potential use for the development of new pharmaceutic and cosmetic agents.

Neuroprotective and Neuromodulatory Effects Induced by Cannabidiol and Cannabigerol in Rat Hypo-E22 cells and Isolated Hypothalamus

BACKGROUND

Cannabidiol (CBD) and cannabigerol (CBG) are non-psychotropic terpenophenols isolated from Cannabis sativa, which, besides their anti-inflammatory/antioxidant effects, are able to inhibit, the first, and to stimulate, the second, the appetite although there are no studies elucidating their role in the hypothalamic appetite-regulating network. Consequently, the aim of the present research is to investigate the role of CBD and CBG in regulating hypothalamic neuromodulators. Comparative evaluations between oxidative stress and food intake-modulating mediators were also performed.

METHODS

Rat hypothalamic Hypo-E22 cells and isolated tissues were exposed to either CBD or CBG, and the gene expressions of neuropeptide (NP)Y, pro-opiomelanocortin (POMC) and fatty acid amide hydrolase were assessed. In parallel, the influence of CBD on the synthesis and release of dopamine (DA), norepinephrine (NE), and serotonin (5-HT) was evaluated. The 3-hydroxykinurenine/kinurenic acid (3-HK/KA) ratio was also determined.

RESULTS

Both CBD and CBG inhibited NPY and POMC gene expression and decreased the 3-HK/KA ratio in the hypothalamus. The same compounds also reduced hypothalamic NE synthesis and DA release, whereas the sole CBD inhibited 5-HT synthesis.

CONCLUSION

The CBD modulates hypothalamic neuromodulators consistently with its anorexigenic role, whereas the CBG effect on the same mediators suggests alternative mechanisms, possibly involving peripheral pathways.