3--4--didemethylnobiletin and nobiletin

Chemoprevention strategies employing the use of multiple dietary bioactive components and their metabolites in combination offer advantages due to their low toxicity and potential synergistic interactions. Herein, for the first time, we studied the combination of curcumin and 3',4'-didemethylnobiletin (DDMN), a primary metabolite of nobiletin, to determine their combinatory effects in inhibiting growth of human colon cancer cells. Isobologram analysis revealed a synergistic interaction between curcumin and DDMN in the inhibition of cell growth of HCT116 colon cancer cells. The combination treatment induced significant G

Topics: Anticarcinogenic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; Curcumin; Drug Synergism; Flavones; Gene Expression Regulation, Neoplastic; HCT116 Cells; Humans

Nobiletin (NBT) is a major citrus flavonoid with various health benefits. Herein, we investigated the colon cancer chemopreventive effects of NBT and its colonic metabolites in a colitis-associated colon carcinogenesis mouse model as well as in human colon cancer cell models.. In azoxymethane/dextran sulfate sodium treated mice, oral administration of NBT effectively decreased both incidence and multiplicity of colonic tumors. NBT showed significant antiproliferative, proapoptotic, and anti-inflammatory effects in the mouse colon. HPLC analysis revealed that oral administration of NBT resulted in high levels of metabolites, i.e. 3'-demethylnobiletin (M1), 4'-demethylnobiletin (M2), and 3',4'-didemethylnobiletin (M3) in the colonic mucosa. In contrast, the colonic level of NBT was about 20-fold lower than the total colonic level of three metabolites. Cell culture studies demonstrated that the colonic metabolites of NBT significantly inhibited the growth of human colon cancer cells, caused cell-cycle arrest, induced apoptosis, and profoundly modulated signaling proteins related with cell proliferation and cell death. All of these effects were much stronger than those produced by NBT alone.. Our results demonstrated that oral administration of NBT significantly inhibited colitis-associated colon carcinogenesis in mice, and this chemopreventive effect was strongly associated with its colonic metabolites.

Topics: Administration, Oral; Animals; Anticarcinogenic Agents; Apoptosis; Cell Line, Tumor; Colitis; Colonic Neoplasms; Cytokines; Flavones; Humans; Male; Mice, Inbred Strains; Neoplasms, Experimental

Posterior capsular opacification (PCO) is the most frequent complication and the primary reason for visual decrease after extracapsular cataract surgery. The proliferation and migration of leftover lens epithelial cells (LECs) after surgery may contribute to the development of PCO. To prevent PCO, a rational approach would be to inhibit both the proliferation and the migration of LECs using nontoxic xenobiotics. Nobiletin, one of the most abundant polymethoxyflavones (PMFs) in citrus peel, and its synthetic congeners displayed a potent inhibition of LEC proliferation. Structural features which enhance anti-proliferative activity have also been discussed.

Topics: Cataract; Cell Line; Cell Movement; Cell Proliferation; Citrus; Epithelial Cells; Flavones; Humans; Lens, Crystalline; Matrix Metalloproteinase 9; Structure-Activity Relationship

Oxidative stress is considered a major cause of neurodegenerative disorders. In this work, we investigated the cytoprotective effects and mechanisms of the citrus flavonoid nobiletin (NOB) and its metabolite, 3',4'-didemethylnobiletin (3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone; DTF), in PC12 cells. Both NOB and DTF exhibited strong potency in attenuating serum withdrawal- and H(2)O(2)-caused cell death and increased intracellular GSH level via upregulation of both catalytic and modifier subunits of glutamate-cysteine ligase (GCL). However, only DTF suppressed intracellular ROS accumulation in H(2)O(2)-treated cells, induced heme oxygenase-1 (HO-1) expression, and enhanced nuclear factor E2-related factor 2 (Nrf2) binding to the ARE. Nevertheless, DTF-mediated HO-1 upregulation was independent of Nrf2 activation because knockdown of Nrf2 expression by siRNA did not affect its expression. DTF suppressed NF-κB activation, and addition of NF-κB inhibitor, pyrrolidine dithiocarbamate or Bay 11-7082, synergistically enhanced DTF-mediated HO-1 expression, indicating that HO-1 induction is associated with NF-κB suppression. NOB and DTF also activated the ERK, JNK, and Akt pathways in PC12 cells that had undergone serum starvation. Addition of pharmacological kinase inhibitors, U0126, SP600125, and LY294002, caused cytotoxicity and the last significantly attenuated NOB- and DTF-mediated antiapoptotic actions, indicating the involvement of PI3K/Akt signaling in their cytoprotective effects. In conclusion, HO-1 and GCL upregulation and intrinsic ROS-scavenging activity may contribute to DTF-mediated cytoprotection. Furthermore, modulation of PI3K/Akt signaling is involved in channeling the DTF stimulus for cell survival against oxidative insults.

Topics: Animals; Antioxidants; Cell Survival; Flavones; Gene Expression; Glutamate-Cysteine Ligase; Heme Oxygenase-1; Hydrogen Peroxide; Metabolic Detoxication, Phase II; NF-E2-Related Factor 2; NF-kappa B; Oxidative Stress; PC12 Cells; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Rats; Reactive Oxygen Species; RNA, Small Interfering; Signal Transduction

A divergent synthesis of nobiletin metabolites was developed through highly oxygenated acetophenone derivative. We used commercially available methyl 3,4,5-trimethoxybenzoate as a starting material for concise preparation of the key intermediate, 2'-hydroxy-3',4',5',6'-tetramethoxyacetophenone (I). These metabolites showed strong inhibitory activity against matrix metalloproteinase-9 production in human lens epithelial cells.

Topics: Acetophenones; Epithelial Cells; Flavones; Humans; Hydroxybenzoates; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors

Three metabolites and 12 analogues of nobiletin (1) were synthesized. Whereas nobiletin derivatives 2-4 inhibited pro-MMP-9 production similarly in both PMA- and TNF-α-stimulated human lens epithelial cells, the 2'-hydroxylated analogue 5a exerted marked inhibitory effects (IC(50): 0.4 μM) on PMA-treated cells, which were 170-fold more potent than those on TNF-α-treated cells. This activity may be closely related to PKC-mediated transcriptional regulation of pro-MMP-9.

Topics: Cell Line; Enzyme Precursors; Epithelial Cells; Flavones; Humans; Lens, Crystalline; Matrix Metalloproteinase 9; Matrix Metalloproteinase Inhibitors; Protease Inhibitors; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

There is accumulating evidence that LDL oxidation is essential for atherogenesis and antioxidants that prevent oxidation may either decelerate or reduce atherogenesis. Current study focused on the effect and mechanism of 3',4'-dihydroxy-5,6,7,8-tetramethoxyflavone (DTF), a major metabolite of nobiletin (NOB, a citrus polymethoxylated flavone) on atherogenesis. We found DTF had stronger inhibitory activity than alpha-tocopherol on inhibiting Cu2+-mediated LDL oxidation measured by thiobarbituric acid-reactive substances assay (TBARS), conjugated diene formation and electrophoretic mobility. Monocyte-to-macrophage differentiation plays a vital role in early atherogenesis. DTF (10-20 microM) dose-dependently attenuated differentiation along with the reduced gene expression of scavenger receptors, CD36 and SR-A, in both PMA- and oxidized low-density lipoprotein (oxLDL)-stimulated THP-1 monocytes. Furthermore, DTF treatment of monocytes and macrophages led to reduction of fluorescent DiI-acLDL and DiI-oxLDL uptake. In conclusion, at least three mechanisms are at work in parallel: DTF reduces LDL oxidation, attenuates monocyte differentiation into macrophage and blunts uptake of modified LDL by macrophage. The effect is different from that of NOB, from which DTF is derived. This study thus significantly enhanced our understanding on how DTF may be beneficial against atherogenesis.

Topics: Animals; CD11b Antigen; CD36 Antigens; Cell Differentiation; Cells, Cultured; Down-Regulation; Flavones; Flow Cytometry; Lipid Peroxidation; Lipoproteins, LDL; Macrophages; Mice; Monocytes; Oxidation-Reduction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Scavenger Receptors, Class A; Scavenger Receptors, Class E; Tetradecanoylphorbol Acetate; Thiobarbituric Acid Reactive Substances

We reported previously that 3',4'-didemethylnobiletin (DDMN) is the major metabolite of nobiletin in mouse urine. In this study, we examined DDMN's molecular mechanism of action and its anti-inflammatory and antitumor properties. We demonstrated that topical application of DDMN effectively inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated transcription of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2 and ornithine decarboxylase (ODC) messenger RNA and protein expression in mouse skin. Pretreatment with DDMN has resulted in the reduction of TPA-induced nuclear translocation of the nuclear factor-kappa B (NF-kappaB) subunit. DDMN also reduced DNA binding by blocking phosphorylation of inhibitor kappaB (IkappaB) alpha and p65 and caused subsequent degradation of IkappaBalpha. DDMN inhibited TPA-induced phosphorylation and nuclear translocation of the signal transducer and activator of transcription 3. Moreover, DDMN suppressed TPA-induced activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, phosphatidylinositol 3-kinase/Akt and protein kinase C that are upstream of NF-kappaB and activator protien-1. We also found that DDMN significantly inhibited TPA-induced mouse skin inflammation by decreasing inflammatory parameters. Furthermore, DDMN significantly inhibited 7,12-dimethylbenz[a]anthracene/TPA-induced skin tumor formation measured by the tumor multiplicity of papillomas at 20 weeks. Presented data for the first time reveal that DDMN is an effective antitumor agent that functions by downregulating inflammatory iNOS, COX-2 and ODC gene expression in mouse skin. It is suggested that DDMN is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

Topics: Animals; Anti-Inflammatory Agents; Antineoplastic Agents; Benz(a)Anthracenes; Blotting, Western; Carcinogenicity Tests; Cyclooxygenase 2; Electrophoretic Mobility Shift Assay; Female; Flavones; Gene Expression; Immunohistochemistry; Mice; NF-kappa B; Nitric Oxide Synthase Type II; Ornithine Decarboxylase; Proliferating Cell Nuclear Antigen; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Skin Neoplasms; Transcription Factor AP-1

Nobiletin, a major component of polymethoxyflavones in citrus fruits, has a broad spectrum of health beneficial properties including anti-inflammatory and anti-carcinogenic activities. The metabolite identification of nobiletin in mouse urine has concluded that it undergoes mono-demethylation (3'- and 4'-demethylnobiletin) and di-demethylation (3',4'-didemethylnobiletin) metabolic pathway. Biological screening of nobiletin and its metabolites has revealed that the metabolites possess more potent anti-inflammatory activity than their parent compound. Therefore, this letter reports the identification of nobiletin metabolites and their anti-inflammatory activity against LPS-induced NO production and iNOS, COX-2 protein expression in RAW264.7 macrophage.

Topics: Animals; Anti-Inflammatory Agents; Cell Line; Chromatography, High Pressure Liquid; Flavones; Mice; Tandem Mass Spectrometry