Neuroprotective Effects of Zerumbone on H2O2-Induced Oxidative Injury in Human Neuroblastoma SH-SY5Y Cells.

Oxidative stress is recognized as one of the main reasons for cellular damage and neurodegenerative diseases. Zerumbone is one of the sesquiterpenoid compounds in the essential oil of Zingiber zerumbet Smith. Zerumbone exhibits various physiological activities, such as anticancer, antioxidant, and antibacterial effects. However, studies on the neuroprotective efficacy of zerumbone and the mechanism behind it are lacking. In this study, we explored the neuroprotective efficacy of zerumbone and its mechanism in hydrogen peroxide-treated human neuroblastoma SH-SY5Y cells. H2O2 treatment (400 µM) for 24 h enhanced the generation of intracellular reactive oxygen species (ROS) compared to untreated cells. By contrast, zerumbone treatment significantly suppressed the production of intracellular ROS. Zerumbone significantly inhibited H2O2-induced nitric oxide production and expression of inflammation-related genes. Moreover, zerumbone decreased H2O2-induced mitogen-activated protein kinase (MAPK) protein expression. Various hallmarks of apoptosis in H2O2-treated cells were suppressed in a dose-dependent manner through downregulation of the Bax/Bcl-2 expression ratio by zerumbone. Since activation of AMP-activated kinase (AMPK) is a promising therapeutic target for neurodegenerative diseases, we also investigated the mammalian target of rapamycin (mTOR) as part of the autophagy mechanism in H2O2-treated SH-SY5Y cells. In this study, zerumbone upregulated the expression of Sirtuin 1 (SIRT1) and p-AMPK (which were downregulated by the H2O2 treatment) and downregulated p-mTOR. Altogether, our results propose that inhibition of apoptosis and inflammation by autophagy activation plays an important neuroprotective role in H2O2-treated SH-SY5Y cells. Zerumbone may thus be a potent dietary agent that reduces the onset and progression, as well as prevents neurodegenerative diseases.

Phenethyl Isothiocyanate Improves Lipid Metabolism and Inflammation via mTOR/PPARγ/AMPK Signaling in the Adipose Tissue of Obese Mice.

Obesity is defined as excess adipose mass that causes serious health problems. Phenethyl isothiocyanate (PEITC) is a major and relatively nontoxic compound of the isothiocyanates. Although many studies have demonstrated that PEITC is a potent substance with physiological activities, such as anticancer activity, the precise mechanism for the effects of PEITC on inflammation and lipid metabolism in adipose tissue is not clear. Our study aimed to clarify the effects of PEITC supplements on the adipose tissue in obesity induced with a high-fat/cholesterol diet, and the underlying mechanisms. We induced obesity by feeding the mice with high fat with 1% cholesterol diet (HFCD) for 13 weeks. Mice were divided into five groups: normal diet (CON), HFCD, HFCD with 3 mg/(kg·d) gallic acid (HFCD+G), and HFCD with 30 and 75 mg/(kg·d) PEITC (HFCD+P30 and HFCD+P75, respectively). Using western blotting and quantitative polymerase chain reaction (qPCR) analysis of the adipose tissue, we determined the expression of lipid metabolism-related genes and inflammation-related genes. In the HFCD, the expression level of nuclear factor-κB (NF-κB), lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1), and cyclooxygenase-2 (COX-2), was higher compared with that in the CON. Moreover, in the HFCD, the expression of p-mechanical targets of the rapamycin (mTOR) was increased, whereas that of p-AMP-activated protein kinase (AMPK) was decreased compared with that in the CON. Nevertheless, these decreased expression levels of p-AMPK and increased levels of LOX-1, p-mTOR, peroxisome proliferator-activated receptor gamma (PPARγ), NF-κB, and COX-2, were alleviated by PEITC supplementation. Therefore, we suggest that PEITC might be a potential preventive agent for ameliorating obesity-induced inflammation and adipogenesis by modulating the mTOR/AMPK/PPARγ pathway.

Molecular Mechanism of the Protective Effect of Zerumbone on Lipopolysaccharide-Induced Inflammation of THP-1 Cell-Derived Macrophages.

Unregulated inflammatory responses lead to massive production of macrophages-activating inflammatory cytokines and chemokines, which may induce diabetes, cancer, and atherosclerosis. Macrophages differentiated from human monocyte (THP-1) have been extensively used in in vitro inflammation models in recent studies. Zerumbone is a major component of the essential oil of Zingiber zerumbet Smith, a type of wild ginger. In this study, we investigated the effects of zerumbone on the secretion of pro-inflammatory cytokines and its underlying mechanistic regulation in lipopolysaccharide (LPS)-activated inflammation of THP-1 cell-derived macrophages. Nuclear factor (NF)-κB and toll-like receptors (TLRs) are known to play important roles in inflammation and immunity. If pathogens enter the host, TLRs recognize the pathogens and signal for the activation of NF-κB to induce inflammatory gene products, such as cytokines. We demonstrated that zerumbone inhibits the secretion of pro-inflammatory cytokines and the induction of NF-κB p65 in LPS-activated inflammation of THP-1 cell-derived macrophages. In addition, zerumbone significantly inhibited mRNA and protein levels of TLR-2/4, and the expression of myeloid differentiation factor 88 (MyD88) adaptor proteins in the LPS-activated inflammation of THP-1 cell-derived macrophages. Moreover, we showed that zerumbone (1-10 µM) regulated histone deacetylase (HDAC) activity and the expression of HDAC genes. H3K9ac, H3K27ac, and H3K4me2 are inducible histone marks that activate gene expression. Treatment with LPS upregulated H3K9ac, H3K27ac, and H3K4me2 in THP-1 cell-derived macrophages; however, this upregulation was decreased by zerumbone treatment. Therefore, these results provide evidence that zerumbone may have therapeutic benefits for chronic inflammatory diseases.

Combination Treatments with Luteolin and Fisetin Enhance Anti-Inflammatory Effects in High Glucose-Treated THP-1 Cells Through Histone Acetyltransferase/Histone Deacetylase Regulation.

Hyperglycemia leads to diabetes and its diabetic complications. In this study, we investigated the synergistic effects of luteolin and fisetin on proinflammatory cytokine secretion and its underlying epigenetic regulation in human monocytes exposed to hyperglycemic (HG) concentrations. Human monocytic cells (THP-1) were cultured under controlled (14.5 mM mannitol), normoglycemic (5.5 mM glucose), or HG (20 mM glucose) conditions in the absence or presence of the two phytochemicals for 48 h. Whereas HG conditions significantly induced histone acetylation, nuclear factor-kappa B (NF-κB) activation, interleukin 6, and tumor necrosis factor-α release from THP-1 cells; combination treatments with the two phytochemicals (500 nM fisetin, and l µM and 500 nM luteolin) suppressed NF-κB activity and inflammatory cytokine release. Fisetin, luteolin, and their combination treatments also significantly decreased the activity of histone acetyltransferase, a known NF-κB coactivator; inhibited reactive oxygen species production; and activated sirtuin (SIRT)1 and forkhead box O3a (FOXO3a) expressions (P < .05). Thus, combination treatments with the two phytochemicals inhibited HG condition-induced cytokine production in monocytes, through epigenetic changes involving NF-κB activation. We, therefore, suggest that combination treatments with luteolin and fisetin may be a potential candidate for the treatment and prevention of diabetes and its complications.

Gallic Acid Decreases Inflammatory Cytokine Secretion Through Histone Acetyltransferase/Histone Deacetylase Regulation in High Glucose-Induced Human Monocytes.

Hyperglycemia contributes to diabetes and several diabetes-related complications. Gallic acid is a polyhydroxy phenolic compound found in various natural products. In this study, we investigated the effects and mechanism of gallic acid on proinflammatory cytokine secretion in high glucose-induced human monocytes (THP-1 cells). THP-1 cells were cultured under normoglycemic or hyperglycemic conditions, in the absence or presence of gallic acid. Hyperglycemic conditions significantly induced histone acetylation, nuclear factor-κB (NF-κB) activation, and proinflammatory cytokine release from THP-1 cells, whereas gallic acid suppressed NF-κB activity and cytokine release. It also significantly reduced CREB-binding protein/p300 (CBP/p300, a NF-κB coactivator) gene expression, acetylation levels, and CBP/p300 histone acetyltransferase (HAT) activity. In addition, histone deacetylase 2 (HDAC2) expression was significantly induced. These results suggest that gallic acid inhibits hyperglycemic-induced cytokine production in monocytes through epigenetic changes involving NF-κB. Therefore, gallic acid may have potential for the treatment and prevention of diabetes and its complications.

Luteolin inhibits hyperglycemia-induced proinflammatory cytokine production and its epigenetic mechanism in human monocytes.

Hyperglycemia is a key feature in diabetes. Hyperglycemia has been implicated as a major contributor to several complications of diabetes. High glucose levels induce the release of proinflammatory cytokines. Luteolin is a flavone isolated from celery, green pepper, perilla leaf, and chamomile tea. Luteolin has been reported to possess antimutagenic, antitumorigenic, antioxidant, and anti-inflammatory properties. In this study, we investigated the effects of luteolin on proinflammatory cytokine secretion and its underlying epigenetic regulation in high-glucose-induced human monocytes. Human monocytic (THP-1) cells were cultured under controlled (14.5 mM mannitol), normoglycemic (NG, 5.5 mM glucose), or hyperglycemic (HG, 20 mM glucose) conditions, in the absence or presence of luteolin. Luteolin (3-10 µM) was added for 48 h. While hyperglycemic conditions significantly induced histone acetylation, NF-κB activation, and proinflammatory cytokine (IL-6 and TNF-α) release from THP-1 cells, luteolin suppressed NF-κB activity and cytokine release. Luteolin also significantly reduced CREB-binding protein/p300 (CBP/p300) gene expression, as well as the levels of acetylation and histone acetyltransferase (HAT) activity of the CBP/p300 protein, which is a known NF-κB coactivator. These results suggest that luteolin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB. We therefore suggest that luteolin may be a potential candidate for the treatment and prevention of diabetes and its complications.

Fisetin Inhibits Osteoclast Differentiation via Downregulation of p38 and c-Fos-NFATc1 Signaling Pathways.

The prevention or therapeutic treatment of loss of bone mass is an important means of improving the quality of life for patients with disorders related to osteoclast-mediated bone loss. Fisetin, a flavonoid dietary ingredient found in the smoke tree (Continus coggygria), exhibits various biological activities, but its effect on osteoclast differentiation is unknown. In this study, fisetin dose-dependently inhibited the RANKL-induced osteoclast differentiation with downregulation of the activity or expression of p38, c-Fos, and NFATc1 signaling molecules. The p38/c-Fos/NFATc1-regulated expression of genes required for cell fusion and bone resorption, such as DC-STAMP and cathepsin K, was also inhibited by fisetin. Considering the rescue of fisetin's inhibitory action by NFATc1 over-expression, the cascade of p38-c-Fos-NFATc1 could be strongly involved in the inhibitory effect of fisetin on osteoclast differentiation. Furthermore, fisetin inhibited the bone-resorbing activity of mature osteoclasts. In conclusion, fisetin may be of use in the treatment of osteoclast-related disorders, including osteoporosis.

Fisetin inhibits hyperglycemia-induced proinflammatory cytokine production by epigenetic mechanisms.

Diabetes is characterized by a proinflammatory state, and several inflammatory processes have been associated with both type 1 and type 2 diabetes and the resulting complications. High glucose levels induce the release of proinflammatory cytokines. Fisetin, a flavonoid dietary ingredient found in the smoke tree (Cotinus coggygria), and is also widely distributed in fruits and vegetables. Fisetin is known to exert anti-inflammatory effects via inhibition of the NF-κB signaling pathway. In this study, we analyzed the effects of fisetin on proinflammatory cytokine secretion and epigenetic regulation, in human monocytes cultured under hyperglycemic conditions. Human monocytic (THP-1) cells were cultured under control (14.5 mmol/L mannitol), normoglycemic (NG, 5.5 mmol/L glucose), or hyperglycemic (HG, 20 mmol/L glucose) conditions, in the absence or presence of fisetin. Fisetin was added (3-10 µM) for 48 h. While the HG condition significantly induced histone acetylation, NF-κB activation, and proinflammatory cytokine (IL-6 and TNF-α) release from THP-1 cells, fisetin suppressed NF-κB activity and cytokine release. Fisetin treatment also significantly reduced CBP/p300 gene expression, as well as the levels of acetylation and HAT activity of the CBP/p300 protein, which is a known NF-κB coactivator. These results suggest that fisetin inhibits HG-induced cytokine production in monocytes, through epigenetic changes involving NF-κB. We therefore propose that fisetin supplementation be considered for diabetes prevention.

Effects of epigallocatechin gallate on regulatory T cell number and function in obese v. lean volunteers.

Obesity predisposes to an increased incidence of diabetes and CVD. Also, obesity is a pro-inflammatory state. Regulatory T cells (Tregs) are essential negative regulators of inflammation and are down-regulated in pro-inflammatory states. Animal models of obesity are associated with decreased Tregs. The dietary modulation of Tregs could be used as a therapeutic strategy to control inflammation. Epigallocatechin gallate (EGCG) is a potent anti-inflammatory agent and an active ingredient of green tea and is suggested to have a role as a preventive agent in obesity, diabetes and CVD. The role of EGCG in the modulation of Tregs has, however, not been studied. Thus, the aim of the present study was to determine the effect of EGCG on the number and function of Tregs in obese and lean human subjects in vitro, and to delineate its specific regulation mechanisms. Tregs were isolated from normal-weight and obese subjects. Tregs were cultured in the absence or presence of EGCG (20 mum) for 24 h. Foxp3-expressing Tregs were enumerated using flow cytometry. Histone deacetylase (HDAC) activity and nuclear NF-kappaBp65 level were measured by ELISA and Western blots. Obese subjects had lower Tregs and IL-10 production than lean subjects. EGCG treatment significantly enhanced the number of Foxp3-expressing Tregs and IL-10 production in vitro (P < 0.05) in both groups. Also, EGCG decreased NF-kappaB activity and increased HDAC activity and HDAC-2 expression in Tregs (P < 0.05) in both groups. Thus, in part, EGCG enhances the functionality of Tregs, i.e. IL-10 production and number by suppressing the NF-kappaB signalling pathway via inducing epigenetic changes.

A randomized placebo-controlled crossover trial of aloe vera on bioavailability of vitamins C and B(12), blood glucose, and lipid profile in healthy human subjects.

Several factors limit the absorption and bioavailability of vitamins. Vitamin C, a commonly used water-soluble supplement reduces the risk of disease. Vitamin B(12) is necessary for the development of RBC, growth, and nervous system. Vitamin B(12) deficiency is common among elderly. Thus, agents that improve bioavailability of vitamin C and B(12), especially in older individuals would be important. Aloe Vera is a botanical with immunomodulatory properties. Aloe is processed using the hand-filleted technique or whole leaf procedure. The aim of this study is to examine the effect of two different aloe vera preparations (aloe inner leaf gel, [AG] and aloe whole leaf decolorized gel, [AL]) compared to placebo on the bioavailability of vitamins, C and B(12), in healthy human volunteers in a randomized crossover trial. Subjects (n = 15) received in a random fashion either aloe whole leaf extract (AL with vitamins B(12), 1 mg and vitamin C 500 mg) or aloe fillet gel (AG with B(12) 1 mg and vitamin C 500 mg) or water (with vitamin B(12) 1 mg and vitamin C 500 mg). Blood was obtained fasting, followed by 1, 2, 4, 6, 8, and 24 hours postingestion of aloe/water. When given with vitamins C and B(12), AG significantly increased plasma oxygen radical absorbance capacity (ORAC) at both 4 and 24 hours and AL at 4 hours compared to baseline and placebo. AG significantly increased plasma vitamin C at 4, 6, 8, and 24 hours and AL at 4 and 6 hours compared to baseline and placebo (p <.01). Also, both aloes significantly increased serum vitamin B(12) levels at 1 and 2 hours compared to baseline and placebo (p <.01). Thus, AG and AL preparations are safe, well tolerated, and enhance the bioavailability of vitamins C and B(12) and antioxidant potential.

Induction of apoptosis and cell cycle arrest by a chalcone panduratin A isolated from Kaempferia pandurata in androgen-independent human prostate cancer cells PC3 and DU145.

Because of unsatisfactory treatment options for prostate cancer (CaP) there is a need to develop novel preventive approaches for this malignancy. One such strategy is through chemoprevention by the use of non-toxic dietary substances and botanical products. We have shown previously that panduratin A isolated from the extract of Kaempferia pandurata (Zingiberaceae) is a strong inhibitor of cyclooxygenase-2 in RAW264.7 cells and induces apoptosis in HT-29 cells. In the present study, we provide evidence that panduratin A treatment to androgen-independent human CaP cells PC3 and DU145 result in a time and dose-dependent inhibition of cell growth with an IC50 of 13.5-14 microM and no to little effect on normal human prostate epithelial cells. To define the mechanism of these anti-proliferative effects of panduratin A, we determined its effect on critical molecular events known to regulate the cell cycle and the apoptotic machinery. Annexin V/propidium iodide staining provided the evidence for the induction of apoptosis which was further confirmed by the observation of cleavage of poly (ADP-ribose) polymerase and degradation of acinus. Panduratin A treatment to cells was found to result in inhibition of procaspases 9, 8, 6 and 3 with significant increase in the ratio of Bax:Bcl-2, suggesting the involvement of a mitochondrial-dependent apoptotic pathway. Panduratin A-mediated apoptosis was accompanied with upregulation of Fas death receptor and TNF-related apoptosis-inducing ligand (TRAIL). Furthermore, cell cycle analysis using flow cytometry showed that panduratin A treatment of cells resulted in a G2/M arrest in a dose-dependent manner. The immunoblot analysis data revealed that in both cell lines panduratin A treatment resulted in a dose-dependent (i) induction of p21WAF1/Cip1 and p27Kip1, (ii) downregulation of cdks 2, 4 and 6 and (iii) decrease in cyclins D1 and E. These findings suggest that panduratin A may be an effective chemopreventive or therapeutic agent against CaP.

Induction of apoptosis by Panduratin A isolated from Kaempferia pandurata in human colon cancer HT-29 cells.

We previously showed that panduratin A isolated from an extract of Kaempferia pandurata (Zingiberaceae) was a strong inhibitor of cyclooxygenase-2 (COX-2) in RAW264.7 cells, suggesting a potential use of panduratin A as an anti-inflammatory agent. In the present study, we have investigated the effects of panduratin A on cytoplasmic levels of COX-2, as well as proliferation and apoptosis in human colon cancer cells HT-29. Cell proliferation and induction of apoptosis was determined by the MTT assay, DNA fragmentation measurement, flow cytometric analysis, nuclear staining and Western blotting. The MTT assay indicated that panduratin A exhibited cytotoxicity with an IC50 value of 28 microM. The cytotoxic effects of panduratin A were found to be accompanied by the dose-dependent induction of apoptosis as assessed by DNA fragmentation and apoptotic bodies. In addition, treatment with an apoptosis-inducing concentration of panduratin A resulted in cleavage of poly(ADP-ribose) polymerase (PARP) with a concomitant decrease in procaspase-3 protein. Our study provides evidence for cell growth inhibition and induction of apoptosis by panduratin A in human colon cancer cells, suggesting its potential use as a cancer chemopreventive and therapeutic agent.

In vitro anti-inflammatory activity of panduratin A isolated from Kaempferia pandurata in RAW264.7 cells.

An active compound identified as panduratin A was isolated from a methanol extract of Kaempferia pandurata (Zingiberaceae). We examined the effect of panduratin A on nitric oxide (NO) and prostaglandin E (2) (PGE (2)) production induced by lipopolysaccharide (LPS) in RAW264.7 cells. Modulations of iNOS and COX-2 enzyme expression were evaluated by Western blotting. Panduratin A strongly inhibited both NO (IC (50): 0.175 microM) and PGE (2) (IC (50): 0.0195 microM) production and suppressed both iNOS and COX-2 enzyme expression without any appreciable cytotoxic effect on RAW264.7 cells in a dose-dependent manner. Panduratin A also suppressed the phosphorylation of inhibitor kappaBalpha (IkappaBalpha) and degradation of IkappaBalpha associated with nuclear factor kappaB (NF-kappaB) activation. Furthermore, panduratin A inhibited LPS-induced NF-kappaB transcriptional activity in a dose-dependent manner. These results suggest that panduratin A could exert its inhibitory effects on the production of NO and PGE (2) through the suppression of NF-kappaB activation, indicating its potential for use as an anti-inflammatory agent.