Chih-Yu Lo

6‐Shogaol is more effective than 6‐gingerol and curcumin in inhibiting 12‐O‐tetradecanoylphorbol 13‐acetate‐induced tumor promotion in mice

We previously reported that 6-shogaol strongly suppressed lipopolysaccharide-induced overexpression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in murine macrophages. In this study, we further compared curcumin, 6-gingerol, and 6-shogaols molecular mechanism of action and their anti-tumor properties. We demonstrate that topical application of 6-shogaol more effectively inhibited 12-O-tetradecanoylphorbol 13-acetate (TPA)-stimulated transcription of iNOS and COX-2 mRNA expression in mouse skin than curcumin and 6-gingerol. Pretreatment with 6-shogaol has resulted in the reduction of TPA-induced nuclear translocation of the nuclear factor-kappaB subunits. 6-Shogaol also reduced TPA-induced phosphorylation of IkappaBalpha and p65, and caused subsequent degradation of IkappaBalpha. Moreover, 6-shogaol markedly suppressed TPA-induced activation of extracellular signal-regulate kinase1/2, p38 mitogen-activated protein kinase, JNK1/2, and phosphatidylinositol 3-kinase/Akt, which are upstream of nuclear factor-kappaB and AP-1. Furthermore, 6-shogaol significantly inhibited 7,12-dimethylbenz[a]anthracene/TPA-induced skin tumor formation measured by the tumor multiplicity of papillomas at 20 wk. Presented data reveal for the first time that 6-shogaol is an effective anti-tumor agent that functions by down-regulating inflammatory iNOS and COX-2 gene expression in mouse skin. It is suggested that 6-shogaol is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

Antitumor Activity of 3,5,4 '-trimethoxystilbene in COLO 205 cells and xenografts in SCID mice

Resveratrol (R‐3), a trihydroxy trans‐stilbene from grape, inhibits multistage carcinogenesis in animal models. Here we report that 3,5,4′‐trimethoxystilbene (MR‐3), the permethylated derivative of R‐3 was more potent against the growth of human cancer cells (HT‐29, PC‐3, COLO 205) with estimated IC50 values of 81.31,42.71, and 6.25 µM, respectively. We further observed that MR‐3 induced apoptosis in COLO 205 cells through modulation of mitochondrial functions regulated by reactive oxygen species (ROS). ROS generation occurs in the early stages of MR‐3‐induced apoptosis, preceding cytochrome‐c release, caspase activation, and DNA fragmentation. Significant therapeutic effects were demonstrated in vivo by treating severe combined immune deficiency (SCID) mice bearing COLO 205 tumor xenografts with MR‐3 (50 mg/kg ip). Assays on DNA fragmentation and caspase activation were performed and demonstrated that apoptosis occurred in tumor tissues treated with MR‐3. The appearance of apoptotic cells, as shown by Hematoxylin and Eosin (H&E) staining, and an increase in p21 and decrease in proliferating cell nuclear antigen (PCNA) protein by immuno‐histochemistry were observed in tumor tissues under MR‐3 treatment. Our study identifies the novel mechanisms of the antitumor effects of MR‐3 and indicates that these results may have significant applications for cancer chemotherapy.

Inhibitory effect of magnolol on TPA-induced skin inflammation and tumor promotion in mice.

Magnolol has been reported to have an anti-inflammatory and antitumor effect in vitro and in vivo. Herein, we report the investigation of the inhibitory effects of magnolol on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in mouse skin. We found that the topical application of magnolol effectively inhibited the transcriptional activation of iNOS and COX-2 mRNA and proteins in mouse skin stimulated by TPA. Pretreatment with magnolol resulted in the reduction of TPA-induced nuclear translocation of the nuclear factor-kappaB (NFkappaB) subunit and DNA binding by blocking the phosphorylation of IkappaBalpha and p65 and subsequent degradation of IkappaBalpha. In addition, magnolol can suppress TPA-induced activation of extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K)/Akt, which are upstream of NFkappaB. Moreover, magnolol significantly inhibited 7,12-dimethylbene[a]anthracene (DMBA)/TPA-induced skin tumor formation by reducing the tumor multiplicity, tumor incidence, and tumor size of papillomas at 20 weeks. All these results revealed that magnolol is an effective antitumor agent and that its inhibitory effect is through the down-regulation of inflammatory iNOS and COX-2 gene expression in mouse skin, suggesting that magnolol is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

Chemoprevention of colonic tumorigenesis by dietary hydroxylated polymethoxyflavones in azoxymethane-treated mice

SCOPE Hydroxylated polymethoxyflavones (PMFs), existing exclusively in citrus genus, have been reported to exhibit a broad spectrum of biological activity. Here we investigated the chemopreventive effects and underlying molecular mechanisms of dietary administration of hydroxylated PMFs in an azoxymethane (AOM)-induced colonic tumorigenesis model. METHODS AND RESULTS Male, Institute of Cancer Research (ICR), mice at age of 6 wk were injected with AOM twice weekly at a dose of 5 mg/kg for 2 wk and continuously fed control diet or diets containing 0.01 and 0.05% hydroxylated PMFs, respectively. Mice were then sacrificed at 6 and 20 wk, and colonic tissues were collected and examined. Hydroxylated PMFs feeding dose-dependently decreased the number of aberrant crypt foci in colonic tissues of mice. More importantly, we found that hydroxylated PMFs caused a strong reduction in numbers of large aberrant crypt foci and tumors in colonic tissue. Molecular analysis exhibited the anti-proliferative, anti-inflammatory, anti-angiogenic and pro-apoptotic activities of hydroxylated PMFs by significantly decreasing the levels of inducible nitric oxide synthase, cyclooxygenase, cyclin D1 and vascular endothelial growth factor through interfering with Wnt/β-catenin and epidermal growth factor receptor/Ras/mitogen-activated protein kinase signaling pathways as well as the activation of transcription factors NF-κB and STAT3 in colonic tissue, thus resulting in suppression of colonic tumorigenesis. CONCLUSION Taken together, these results demonstrated for the first time the in vivo chemopreventive efficacy and molecular mechanisms of dietary hydroxylated PMFs against AOM-induced colonic tumorigenesis.

Synthesis and anticancer activity of a novel series of 9-O-substituted berberine derivatives: A lipophilic substitute role

To alter its hydrophobicity, a series of compounds bearing 9-O-alkyl- or 9-O-terpenyl- substituted berberine were synthesized and evaluated for anticancer activity against human cancer HepG2 and HT29 cell lines. We found that the lipophilic substitute of 9-O-alkyl- and 9-O-terpenyl berberine derivatives plays a role in inhibiting the human cancer cell growth and its activity could be maximized with the optimized substitute type and chain length. Most strikingly, nonetheless, of the six compounds prepared, sample 8, a farnesyl 9-O-substituted berberine, showed either comparable or better cytotoxic activity against human cancer HepG2 cell line than that of berberine. Compound 8 had also shown a 104-fold antiproliferation activity in compare with berberine against human hepatoma HepG2 cell lines after 48 incubation hours. Further, in Hoechst 33258 and annexin V-FITC/PI staining analyses it induced apoptosis in HepG2 cells at lower concentration than that of berberine for 24h. Take all; farnesyl 9-O-substituted berberine could be a potential candidate for new anticancer drug development.

Trapping effects of green and black tea extracts on peroxidation-derived carbonyl substances of seal blubber oil.

Green and black tea extracts were employed to stabilize seal blubber oil at 60 degrees C for 140 h. On the basis of the headspace SPME-GC-MS analysis, with the addition of green/black tea extracts, the contents of acetaldehyde, acrolein, malondialdehyde, and propanal, four major lipid peroxidation products, were reduced. The inhibition rates of acrolein formation by green tea and black tea extracts were 98.40 and 96.41% respectively, and were 99.17 and 98.16% for malondialdehyde, respectively, much higher than the inhibition of the formation of acetaldehyde and propanal. Because malondialdehyde and acrolein are reactive carbonyl species (RCS) and recent studies have suggested that phenolics can directly trap RCS, this study also investigated whether green tea polyphenols can trap acrolein or not. Acrolein was reduced by 90.30% in 3 h of incubation with (-)-epigallocatechin-3-gallate (EGCG). Subsequent LC-MS analysis revealed the formation of new adducts of equal molars of acrolein and EGCG. The reaction site for acrolein was elucidated to be the A ring of EGCG as evidenced by LC-MS/MS analysis and by testing of the acrolein-trapping capacities of the analogous individual A, B, and C rings of EGCG. Thus, EGCGs direct trapping of RCS may also contribute to the significant reduction of acrolein and other aldehydes in the peroxidation of seal blubber oil.

Identification and mode of action of 5-hydroxymethyl-2-furfural (5-hmf) and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA) as potent xanthine oxidase inhibitors in vinegars.

Vinegars have been used as an alternative remedy for treating gout, but the scientific basis remains to be elucidated. In this study, seven commercial vinegars and one laboratory-prepared red-koji vinegar were evaluated for the inhibitory activity of xanthine oxidase (XO), a critical enzyme catalyzing uric acid formation. Red-koji vinegar exhibited potent xanthine oxidase inhibitory (XOI) activity and was used for isolating active compounds. The substances under two peaks with XOI activity from HPLC were identified as 5-hydroxymethyl-2-furfural (5-HMF) and 1-methyl-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (MTCA), by LC-MS-MS and NMR. The XO half-maximal inhibitory concentrations (IC(50)) of 5-HMF and MTCA were 168 and 860 μg/mL, respectively. In further mode-of-action analysis, the inhibitory mechanism of each compound was elucidated at the IC(50) level in the presence of various concentrations of xanthine as the substrate. The following Michaelis-Menten kinetics analysis of XO inhibition revealed uncompetitive and competitive patterns for 5-HMF and MTCA, respectively.

Simultaneous analysis of six polymethoxyflavones and six 5-hydroxy-polymethoxyflavones by high performance liquid chromatography combined with linear ion trap mass spectrometry.

Polymethoxyflavones (PMFs) and monohydroxylated polymethoxyflavones (OH-PMFs) exist exclusively in the citrus genus, particularly in citrus peels. Currently, due to the broad application of PMFs and OH-PMFs in nutraceuticals, pharmaceuticals, and functional foods, their identification and quantification will be of great significance and the first criteria to meet. We have developed a validated method with high performance liquid chromatography coupled with linear ion trap mass spectrometry. The method was fully validated in linearity, precision, accuracy, and recovery. Six PMFs and their monohydroxyl counterparts, six 5-OH-PMFs, were simultaneous analyzed within 20 min for the first time. The LOD (limit of detection) and LOQ (limit of quantitation) were calculated as 0.02-0.23 and 0.05-0.76 μg/mL, respectively. The method was performed on the samples of acid treated citrus peel extracts. The citrus peel extracts with high content of PMFs and 5-OH PMFs may provide reliable and economical resources in biological activity studies and development of health beneficial products.

Synthesis and Biological Evaluation of Lipophilic 1,4-Naphthoquinone Derivatives against Human Cancer Cell Lines

To examine the effect of hydrophobicity on the anticancer activity of 1,4-naphthoquinone derivatives, a series of compounds bearing a 2-O-alkyl-, 3-C-alkyl- or 2/3-N-morpholinoalkyl group were synthesized and evaluated for their anticancer activity against five human cancer cell lines in vitro. The cytotoxicity of these derivatives was assayed against HT-29, SW480, HepG2, MCF-7 and HL-60 cells by the MTT assay. Among them, 2-hydroxy-3-farnesyl-1,4-naphthoquinone (11a) was found to be the most cytotoxic against these cell lines. Our results showed that the effectiveness of compound 11a may be attributed to its suppression of the survival of HT-29. Secondly, in the Hoechst 33258 staining test, compound 11a-treated cells exhibited nuclear condensation typical of apoptosis. Additionally, cell cycle analysis by flow cytometry indicated that compound 11a arrested HT-29 cells in the S phase. Furthermore, cell death detected by Annexin V-FITC/propidium iodide staining showed that compound 11a efficiently induced apoptosis of HT-29 in a concentration-dependent manner. Taken together, compound 11a effectively inhibits colon cancer cell proliferation and may be a potent anticancer agent.

Tetrahydrocurcumin ameliorates free fatty acid-induced hepatic steatosis and improves insulin resistance in HepG2 cells

Elevated levels of free fatty acids (FFAs) in the liver, resulting from either increased lipolysis or imbalanced FFAs flux, is a key pathogenic factor of hepatic steatosis. This study was conducted to examine the therapeutic effect of tetrahydrocurcumin (THC), a naturally occurring curcuminoid and a metabolite of curcumin, on oleic acid (OA)-induced steatosis in human hepatocellular carcinoma cells and to elucidate the underlying mechanism. HepG2 cells were incubated with OA to induce steatosis, and then treated with various concentrations of THC. The results showed that THC treatment significantly decreased lipid accumulation in OA-treated HepG2 cells, possibly, by inhibiting the expression of the lipogenic proteins, sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FAS), and fatty acid-binding protein 4 (FABP4). Moreover, THC attenuated OA-induced hepatic lipogenesis in an adenosine monophosphate-activated protein kinase (AMPK)-dependent manner, which was reversed by pretreatment with an AMPK inhibitor. THC promoted lipolysis and upregulated the expression of genes involved in β-oxidation. Glucose uptake and insulin signaling impaired in HepG2 cells incubated with OA were abated by THC treatment, including phosphorylation of the insulin receptor substrate 1 (IRS-1)/phosphoinositide 3-kinase (PI3K)/Akt and downstream signaling pathways, forkhead box protein O1 (FOXO1) and glycogen synthase kinase 3 β (GSK3β), which are involved in gluconeogenesis and glycogen synthesis, respectively. Altogether, these results demonstrated the novel therapeutic benefit of THC against hepatic steatosis and, consequently, a potential treatment for non-alcoholic fatty liver disease (NAFLD).