Emodin targeting the colonic metabolism via PPARγ alleviates UC by inhibiting facultative anaerobe.

BACKGROUND: Emodin is an active ingredient of traditional Chinese medicine Rheum palmatum L. and Polygonum cuspidatum, which possesses anti-inflammatory and intestinal mucosal protection effects. Our previous study found that emodin significantly alleviated ulcerative colitis induced by sodium dextran sulfate (DSS). In this study, we found the underlying mechanism of emodin on ulcerative colitis (UC). PURPOSE: We aimed to further explore the mechanism of emodin in the treatment of ulcerative colitis from the perspective of metabolism and intestinal flora. METHODS: Ulcerative colitis was induced by 3% sodium dextran sulfate (DSS) on mice, and the mice were respectively treated with mesalazine, rosiglitazone, emodin, and emodin combined with GW9662 (PPARγ inhibitor) simultaneously. Weight changes, the disease activity index (DAI), colonic length, and pathologic changes in colon were used to evaluate the efficacy of emodin. LC-MS/MS was performed for metabolomics analysis of colon. In addition, intestinal flora was assessed using 16S rDNA sequencing. A vector-based short hairpin RNA (shRNA) method was used to silence PPARγ gene expression in Caco-2 cells. RESULTS: Emodin binds to the active site of PPARγ protein and forms hydrogen bond interaction with ARG288 and CYS285 amino acids. Furthermore, Emodin significantly promotes the protein expression of PPARγ, while inhibiting iNOS and NF-kB p65 in UC mice, however, this effect is hardly shown when it is combined with GW9662 (the inhibitor of PPARγ). Meanwhile, emodin suppresses the expression of iNOS in Caco-2 cells induced with IFNγ and IL-22, but has no effect on its expression in shPPARγ-Caco-2 cells. In addition, through activating PPARγ signal pathway, emodin is capable of regulating colonic metabolism including oxidative phosphorylation and citrulline metabolism and effecting luminal availability of oxygen and nitrate. This promotes the recovery of anoxic environment of colon epithelial cells, which strains the growth and expansion of Enterobacteriaceae. CONCLUSION: The mechanism of Emodin in the treatment of ulcerative colitis relies on its regulation of PPARγ signal pathway, which could modulate colonic metabolism and restore intestinal homeostasis.

Iron supplementation ameliorates aloin-induced iron deficiency anemia in rats.

Aloin, an anthraquinone glycoside, is one of other C-glycosides found in the leaf exudate of Aloe plant. Aloin possesses several biologic activities, including antitumor activity in vitro and in vivo. However, aloin treatment has shown iron deficiency anemia and erythropoiesis in vivo. The present study was undertaken to verify if iron supplementation could alleviate these perturbations, compared to doxorubicin, an anthracycline analog. Oral iron supplementation (20.56 mg elemental Fe/kg bw) to aloin-treated rats normalized red blood corpuscles count, hemoglobin concentration, and serum levels of total iron binding capacity and saturated transferrin, as well as hepatic iron content, hepcidin level, and mRNA expression of ferritin heavy chain (Ferr-H) and transferrin receptor-1 (TfR-1) genes. Although, serum hyperferremia, and leukocytosis were maintained, yet the spleen iron overload was substantially modulated. However, combined aloin and iron treatment increased iron storage levels in the heart and bone marrow, compared to aloin treatment per se. On other hand, oral iron supplementation to rats treated with doxorubicin (15 mg/kg bw) lessened the increase in the spleen iron content concomitantly with hepatic hepcidin level, rebound hepatic iron content to normal level, and by contrast augmented serum levels of iron and transferrin saturation. Also, activated Ferr-H mRNA expression and repressed TfR-1 mRNA expression were recorded, compared to doxorubicin treatment per se. Histopathological examination of the major body iron stores in rats supplemented with iron along with aloin or doxorubicin showed an increase in extramedullary hematopoiesis. In conclusion, iron supplementation restores the disturbances in iron homeostasis and erythropoiesis induced by aloin treatment.

Enhanced therapeutic efficacy of a novel colon-specific nanosystem loading emodin on DSS-induced experimental colitis.

BACKGROUND: Ulcerative colitis (UC) is an intricate enteric disease with a rising incidence that is closely related to mucosa-barrier destruction, gut dysbacteriosis, and immune disorders. Emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, EMO) is a natural anthraquinone derivative that occurs in many Polygonaceae plants. Its multiple pharmacological effects, including antioxidant, immune-suppressive, and anti-bacteria activities, make it a promising treatment option for UC. However, its poor solubility, extensive absorption, and metabolism in the upper gastrointestinal tract may compromise its anti-colitis effects. PURPOSE: EMO was loaded in a colon-targeted delivery system using multifunctional biomedical materials and the enhanced anti-colitis effect involving mucosa reconstruction was investigated in this study. METHODS: EMO-loaded Poly (DL-lactide-co-glycolide)/EudragitⓇ S100/montmorillonite nanoparticles (EMO/PSM NPs) were prepared by a versatile single-step assembly approach. The colon-specific release behavior was characterized in vitro and in vivo, and the anti-colitis effect was evaluated in dextran sulfate sodium (DSS)-induced acute colitis in mice by weight loss, disease activity index (DAI) score, colon length, histological changes, and colitis biomarkers. The integrity of the intestinal mucosal barrier was evaluated through transwell co-culture model in vitro and serum zonulin-related tight junctions and mucin2 (MUC2) in vivo. RESULTS: EMO/PSM NPs with a desirable hydrodynamic diameter (~ 235 nm) and negative zeta potential (~ -31 mV) could prevent the premature drug release (< 4% in the first 6 h in vitro) in the upper gastrointestinal tract (GIT) and boost retention in the lower GIT and inflamed colon mucosa in vivo. Compared to free EMO-treatment of different doses in UC mice, the NPs could enhance the remedial efficacy of EMO in DAI decline, histological remission, and regulation of colitis indicators, such as myeloperoxidase (MPO), nitric oxide (NO), and glutathione (GSH). The inflammatory factors including induced nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-α, and IL-1ß were suppressed by EMO/PSM NPs at both mRNA and protein levels. The obtained NPs could also promote the regeneration of the mucosal barrier via reduced fluorescein isothiocyanate (FITC)-dextran leakage in the transwell co-culture model and decreased serum zonulin levels, which was demonstrated to be associated with the upregulated tight junctions (TJs)-related proteins (claudin-2, occludin, and zo-1) and MUC2 at mRNA level. Moreover, the NPs could contribute to attenuating the liver injury caused by free EMO under excessive immune inflammation. CONCLUSION: Our results demonstrated that EMO/PSM NPs could specifically release EMO in the diseased colon, and effectively enhance the anti-colitis effects of EMO related to intestinal barrier improvement. It can be considered as a novel potential alternative for oral colon-targeted UC therapy by increasing therapeutic efficacy and reducing side-effects.

Post-transcriptional regulation activity through alternative splicing involved in the effects of Aloe vera on the Wnt/ß-catenin and Notch pathways in colorectal cancer cells.

Aloe vera (L.) Burm.f. is widely used as laxative drugs, cosmetics, and functional food due to a variety of therapeutic effects. However, several studies indicated a colonic carcinogenic activity of Aloe vera. But the underline mechanism has not been well clarified. This study aimed to explore the potential mechanism at the post-transcriptional level. Identification of Differential Expressed Alternative Splicing (DEAS) genes and events and the corresponding functional enrichment analyses were conducted on RKO cells after treated with Aloe vera aqueous extract and its two active components, aloin and aloesin. And RT-qPCR was conducted for validation. Results indicated that they induced 2200, 2342 and 2133 DEAS events, respectively. The GO enrichment and the COG classification results of DEAS genes showed that they were associated with transcription, as well as functions like signal transduction mechanisms. Moreover, DEAS genes related to the two colorectal cancerous pathways, Wnt and Notch pathways, were annotated. In conclusion, aloe extract, aloin and aloesin significantly regulated the DEAS profile of RKO cells. The colonic carcinogenicity of Aloe vera may due to its post-transcriptional regulatory activity through Alternative Splicing (AS) on genes, especially on Wnt-related and Notch-related key genes.

In vitro study of the nephrotoxicity of total Dahuang (Radix Et Rhizoma Rhei Palmati) anthraquinones and emodin in monolayer human proximal tubular epithelial cells cultured in a transwell chamber.

OBJECTIVE: To examine changes in the morphology and physiological functions of human proximal tubular epithelial cells (HK-2 cells) caused by total Dahuang (Radix Et Rhizoma Rhei Palmati) anthraquinones (TDA) and emodin. METHODS: HK-2 cells were cultured on polycarbonate (PCF) membranes to form a complete monolayer of cells. A fluorescein isothiocyanate-dextran (FITC) permeability assay was conducted and secretion of γ-glutamyltranspeptidase (GGT), lactate dehydrogenase (LDH), N-acetyl-ß-D-glucosaminidase (NAG) and kidney injury molecule 1 (KIM-1) was examined. The reabsorption of glucose and the excretion of para-aminohippuric acid (PAH) by HK-2 cells were also examined. The morphology of HK-2 cells was observed using optical microscopy and scanning electron microscopy. The cytoskeleton of HK-2 cells was observed under a fluorescence microscope. RESULTS: Compared with the results for the dimethyl sulfoxide group, treatment of cells with TDA and emodin showed statistically significant differences in the FITC leakage rate, the apical / basolateral ratio of LDH and GGT, and the secretion of GGT, LDH, NAG and KIM-1. At 64 µg/mL, TDA markedly inhibited blood glucose reabsorption and remarkably suppressed PAH excretion by HK-2 cells. Both TDA and emodin caused various degrees of damage to the morphology and cytoskeleton of HK-2 cells with the degree of damage correlating positively with the dosage of the tested substances. CONCLUSION: Both TDA and emodin caused damage to human renal proximal tubular epithelial cells at certain dosages. At the same dosage, TDA caused more severe damage than emodin to the HK-2 cells.

[Emodin worsens methionine-choline-deficient diet-induced non-alcoholic fatty liver disease in mice].

OBJECTIVE: To investigate the influence of emodin on methionine-choline-deficient (MCD) diet-induced non-alcoholic fatty liver disease (NAFLD) in mice. METHODS: C57BL/6J mice were randomly divided into three groups: methionine-choline-supplemented (MCS) diet group, MCD diet plus DMSO injection group (MCD), MCD diet plus emodin injection group (MCD-emodin). The mice were fed with MCS or MCD diet for 10 days, and then peritoneally injected with DMSO or emodin for 20 days consecutively. HE staining was performed to observe pathologic changes of livers. The levels of serum alanine aminotransferase (ALT) and aspartate transaminase (AST), triglyceride (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), alkaline phosphatase (ALP), glucose (GLU) were measured by automatic biochemical analyzer. The mRNA levels of interleukin 1ß (IL-1ß), IL-6 and tumor necrosis factor-α (TNF-α) were determined by real-time quantitative PCR. RESULTS: HE staining showed that there were more lipid accumulation and leukocyte infiltration in the livers of the MCD group compared with the MCS group. The above manifestations were more severe in the MCD-emodin group. Moreover, compared with the MCD group, emodin injection remarkably raised serum AST and ALT levels and greatly increased IL-1ß and IL-6 mRNA levels. CONCLUSION: Emodin worsened MCD diet-induced NAFLD in mice.

Inhibitory effects of herbal constituents on P-glycoprotein in vitro and in vivo: herb-drug interactions mediated via P-gp.

Modulation of drug transporters via herbal medicines which have been widely used in combination with conventional prescription drugs may result in herb-drug interactions in clinical practice. The present study was designed to investigate the inhibitory effects of 50 major herbal constituents on P-glycoprotein (P-gp) in vitro and in vivo as well as related inhibitory mechanisms. Among these herbal medicines, four constituents, including emodin, 18ß-glycyrrhetic acid (18ß-GA), dehydroandrographolide (DAG), and 20(S)-ginsenoside F1 [20(S)-GF1] exhibited significant inhibition (>50%) on P-gp in MDR1-MDCKII and Caco-2 cells. Emodin was the strongest inhibitor of P-gp (IC50=9.42 µM), followed by 18ß-GA (IC50=21.78 µM), 20(S)-GF1 (IC50=76.08 µM) and DAG (IC50=77.80 µM). P-gp ATPase activity, which was used to evaluate the affinity of substrates to P-gp, was stimulated by emodin and DAG with Km and Vmax values of 48.61, 29.09 µM and 71.29, 38.45 nmol/min/mg protein, respectively. However, 18ß-GA and 20(S)-GF1 exhibited significant inhibition on both basal and verapamil-stimulated P-gp ATPase activities at high concentration. Molecular docking analysis (CDOCKER) further elucidated the mechanism for structure-inhibition relationships of herbal constituents with P-gp. When digoxin was co-administered to male SD rats with emodin or 18ß-GA, the AUC(0₋t) and Cmax of digoxin were increased by approximately 51% and 58%, respectively. Furthermore, 18ß-GA, DAG, 20(S)-GF1 and Rh1 at 10 µM significantly inhibited CYP3A4/5 activity, while emodin activated the metabolism of midazolam in human liver microsomes. In conclusion, four herbal constituents demonstrated inhibition of P-gp to specific extents in vitro and in vivo. Taken together, our findings provided the basis for the reliable assessment of the potential risks of herb-drug interactions in humans.

Comparison of laxative and antioxidant activities of raw, processed and fermented Polygoni Multiflori radix.

AIM: To observe the anti-oxidative activity and adverse laxative effect of raw, traditional processed and fermented products of Polygoni Multiflori Radix (PMR), and furthermore, to evaluate the fermentation method used in the processing procedure of PMR. METHODS: In vitro ferric reducing antioxidant power (FRAP) assay was carried out to evaluate the anti-oxidative activity. Modulation of normal defecation and effect on gastrointestinal motility in mice were carried out to investigate their adverse laxative effect. RESULTS: Fermented PMR induced less severe laxative adverse effect than Polygoni Multiflori Radix Praeparata (PMRP). PMR fermented with Rhizopus sp. (FB) could modulate the defecation significantly. The gastrointestinal motility was inhibited by PMRP and PMR fermented with Rhizopus oryzae (FA). FA and FB showed better antioxidant activity than PMRP in 50% and 95% ethanol group. Contents of 2, 3, 5, 4'-tetrahydroxy-stilbene-2-O-ß-D-glucoside (TSG) were reduced significantly after traditional processing but maintained after fermentation. Emodin and physcion were increased after traditional processing and fermented with Rhizopus oryzae. CONCLUSION: All processing procedure, including fermentation, might reduce its anti-oxidative activity. However, most of the processed products could lessen the adverse effect on gastrointestinal tract compared to PMR. Fermentation with Rhizopus oryzae was considered as a promising processing method of PMR.

Hypersensitivity to aloe.

Hypersensitivity, manifested by generalized nummular eczematous and papular dermatitis, and presumably by contact urticaria, developed in a 47-year-old man after four years of using oral and topical aloe. Patch tests for aloe were positive in this patient.