Identification of kazinol Q, a natural product from Formosan plants, as an inhibitor of DNA methyltransferase

DNA methylation plays a pivotal role in the epigenetic regulation of the transcription of a number of cancer-related genes, thereby representing an important target for cancer prevention and treatment. In our search for DNA methyltransferase (DNMT) inhibitors from Formosan plants, by screening against a library consisting of 12 structurally distinct natural products, we identified kazinol Q {4-[6-(1,1-dimethyl-allyl)-7-hydroxy-chroman-2-yl]-3,6-bis-(3-methyl-but-2-enyl)-benzene-1,2-diol} as an inhibitor of recombinant DNMT1 with IC50 of 7 μM. The effect of kazinol Q on DNMT inhibition was validated by its ability to reactivate the expression of a DNA methylation-silenced gene, E-cadherin, in MDA-MB-231 breast cancer cells. Moreover, kazinol Q suppressed the proliferation of MCF-7 breast and LNCaP prostate cancer cells, in part, through apoptosis induction. The role of DNMT1 inhibition in mediating kazinol Q's antiproliferative effect was supported by the protective effect of ectopic expression of DNMT1 on kazinol Q-induced cell death. Molecular modeling analysis suggests that kazinol Q inhibited DNMT activity by competing with cytosine binding, a mechanism similar to that described for (-)-epigallocatechin-3-gallate (EGCG). Relative to EGCG, kazinol Q exhibits several desirable features for drug development, including chemical stability and increased hydrophobicity, and might have therapeutic relevance to cancer treatment.

Cytotoxic and antioxidant constituents from Garcinia subelliptica

Two new triterpenoids, garcinielliptones Q (1) and S (3), and a new phloroglucinol, garcinielliptone R (2), were isolated from the seed of Garcinia subelliptica. Their structures were established by analysis of their spectroscopic data. Phloroglucinol, garcinielliptone FC (4) from this plant exhibited a significant increase of antiproliferative effect, while 4 combined with cisplatin significantly caused decrease of cell inhibition induced by cisplatin in NTUB1. Exposure of NTUB1 cells to 4 cotreated with cisplatin for significantly decreased the amount of reactive oxygen species (ROS) than that of the total amount generated by 4 and cisplatin. These results suggested that 4 could protect the cisplatin toxicity through reduction of ROS in NTUB1. Phloroglucinols, garcinielliptones, A (5) and F (7), and garsubelline A (6), from this plant, revealed ABTS radical cation scavenging activity and 5 displayed an inhibitory effect on xanthine oxidase. These finding showed that 5-7 may be used as antioxidants.

Assessing nitrate contamination and its potential health risk to Kinmen residents

Kinmen is located in the southwest of Mainland China. Groundwater supplies 50% of the domestic water use on the island. Residents of Kinmen drink groundwater over the long term because surface water resources are limited. Nitrate-N pollution is found and distributed primarily in the western part of groundwater aquifer whereas saline groundwater is distributed to the northeastern Kinmen. This work applied the DRASTIC model to construct the vulnerability map of Kinmen groundwater. MT3D was then used to evaluate the contamination potential of nitrate-N. The health risk associated with the ingestion of nitrate-N contaminated groundwater is also assessed. The results from DRASTIC model showed that the upland crop and grass land have high contamination potential, whereas the forest, reservoir and housing land have low contamination potential. The calibrated MT3D model inversely determined the high strength sources (0.09-2.74 kg/m(2)/year) of nitrate contaminant located in the west to the north west area and required 2-5 years travel time to reach the monitoring wells. Simulated results of MT3D also showed that both the continuous and instantaneous contaminant sources of nitrate-N release may cause serious to moderate nitrate contamination in the western Kinmen and jeopardize the domestic use of groundwater. The chronic health hazard quotient (HQ) associated with the potential non-carcinogenic risk of drinking nitrate-N contaminated groundwater showed that the assessed 95th percentile of HQ is 2.74, indicating that exposure to waterborne nitrate poses a potential non-cancer risk to the residents of the island. Corrective measures, including protecting groundwater recharge zones and reducing the number of agricultural and non-agricultural nitrogen sources that enters the aquifer, should be implemented especially in the western part of Kinmen to assure a sustainable use of groundwater resources.

Rapid characterization of sugar-binding specificity by in-solution proximity binding with photosensitizers

Cell-surface carbohydrates are known to participate in many important physiological and pathological activities by interacting with their corresponding proteins or receptors. Although several methods have been developed for studying carbohydrate-protein interactions, one major problem originates from the weak bindings of carbohydrates/proteins that are often lost during repeating wash steps. Herein, we established a homogeneous solution carbohydrate array in which polyacrylamide-based glycans are used for offering a multivalent environment. The method requires no wash step and can be carried out in a high-throughput manner. We characterized the carbohydrate-binding specificities of 11 lectins and 7 antibodies, the majority of which displayed the binding patterns in consistence with previous reports. These results demonstrate that our developed solution carbohydrate array provides a useful alternative that is better than or comparable with the current available methods.

Xanthine oxidase inhibitory triterpenoid and phloroglucinol from guttiferaceous plants inhibit growth and induced apoptosis in human NTUB1 cells through a ROS-dependent mechanism

A known triterpenoid, β-amyrin (1), and a known and a new phloroglucinol, cohulupone (2) and garcinielliptone P (3), were isolated from the pericarp and heartwood and seed of Garcinia subelliptica, respectively. A new xanthonolignoid, hyperielliptone HF (4), was isolated from the heartwood of Hypericum geminiflorum. The new compounds were established by analysis of their spectroscopic data. Compounds 1-3 showed an inhibitory effect on xanthine oxidase (XO). Treatment of NTUB1, a human bladder cancer cell, with 1 or 1 cotreated with cisplatin for 24 h resulted in a decreased viability of cells. Exposure of NTUB1 to 1 or 1 cotreated with cisplatin for 24 h significantly increased the level of production of reactive oxygen species (ROS). Flow cytometric analysis indicated that treatment of NTUB1 with 1 or 1 cotreated with cisplatin led to the cell cycle arrest, accompanied by an increase in the extent of apoptotic cell death in 1 or 1 combined with cisplatin-treated NTUB1 after 24 h. These data suggested that the presentation of cell cycle arrest and apoptosis in 1 or 1 combined with cisplatin-treated NTUB1 for 24 h was mediated through an increased amount of ROS in cells exposed to 1 or 1 cotreated with cisplatin.

Xanthine oxidase inhibitory terpenoids of Amentotaxus formosana protect cisplatin-induced cell death by reducing reactive oxygen species (ROS) in normal human urothelial and bladder cancer cells

The diterpenoids (+)-ferruginol (1), ent-kaur-16-en-15-one (2), ent-8(14),15-sandaracopimaradiene-2α,18-diol (3), 8(14),15-sandaracopimaradiene-2α,18,19-triol (4), and (+)-sugiol (5) and the triterpenoids 3β-methoxycycloartan-24(24(1))-ene (6), 3β,23β-dimethoxycycloartan-24(24(1))-ene (7), 3β,23β-dimethoxy-5α-lanosta-24(24(1))-ene (8), and 23(S)-23-methoxy-24-methylenelanosta-8-en-3-one (9), isolated from Amentotaxus formosana, showed inhibitory effects on xanthine oxidase (XO). Of the compounds tested, compound 5 was a potent inhibitor of XO activity, with an IC(50) value of 6.8±0.4 μM, while displaying weak ABTS radical cation scavenging activity. Treatment of the bladder cancer cell line, NTUB1, with 3-10 μM of compound 5 and 10 μM cisplatin, and immortalized normal human urothelial cell line, SV-HUC1, with 0.3-1 μM and 10-50 μM of compound 5 and 10 μM cisplatin, respectively, resulted in increased viability of cells compared with cytotoxicity induced by cisplatin. Treatment of NTUB1 with 20 μM cisplatin and 10 or 30 μM of compound 5 resulted in decreased ROS production compared with ROS production induced by cisplatin. These results indicate that 10 or 30 μM of compound 5 in NTUB1 cells may mediate through the suppression of XO activity and reduction of reactive oxygen species (ROS) induced by compound 5 cotreated with 20 μM cisplatin and protection of subsequent cell death.

Generation of a novel factor IX with augmented clotting activities in vitro and in vivo

BACKGROUND

Hemophilia B is an X-linked inherited disorder caused by the lack of functional factor IX (FIX). Currently, treatment of hemophilia B is performed by intravenous infusion of plasma-derived or recombinant FIX.

OBJECTIVE

In an effort to reduce factor usage and cost, we investigated the potential use of FIX variants with enhanced specific clotting activity.

METHODS

Seven recombinant FIX variants using alanine replacement were generated and assayed for their activity in vitro and in vivo.

RESULTS

One variant containing three substitutions (V86A/E277A/R338A, FIX-Triple) exhibited 13-fold higher specific clotting activity and a 10-fold increased affinity for human FVIIIa compared with FIX-wild-type (FIX-WT) and was thus investigated systematically in vivo. Liver-specific FIX-Triple gene expression following hydrodynamic plasmid delivery revealed a 3.5-fold higher specific clotting activity compared with FIX-WT. Human FIX-Triple and FIX-WT knock-in mice were generated and it was confirmed that FIX-Triple has 7-fold higher specific clotting activity than FIX-WT under normal physiological conditions. Protein infusion of FIX-Triple into hemophilia B mice resulted in greater improvement of hemostasis than that achieved with FIX-WT. Moreover, tail-vein administration of a serotype 8 recombinant Adeno-associated vector (AAV8) expressing either FIX-WT or FIX-Triple in hemophilia B mice demonstrated a 7-fold higher specific clotting activity of FIX-Triple than FIX-WT.

CONCLUSIONS

Our results indicate that the FIX-Triple variant exhibits significantly enhanced clotting activity relative to FIX-WT due to tighter binding to FVIIIa, as demonstrated both in vitro and in vivo. Therefore, FIX-Triple is a good candidate for further evaluation in protein replacement therapy as well as gene-based therapeutic strategies.

Terpenoids induce cell cycle arrest and apoptosis from the stems of Celastrus kusanoi associated with reactive oxygen species

Bioguided fractionation of the CHCl(3) extracts obtained from Celastrus kusanoi stems led to isolation of two new terpenoids, 3beta-hydroxy-11,14-oxo-abieta-8,12-diene (1) and 3beta-trans-(3,4-dihydroxycinnamoyloxy)-11alpha-methoxy-12-ursene (2), and four known compounds characterized by spectroscopic methods. Compounds 1 and 2 and known triterpenoid erythrodiol (3) exhibited cytotoxic activity against bladder cancer cells (NTUB1) with IC(50) values of 58.2 +/- 2.3, 160.1 +/- 60.9, and 18.3 +/- 0.5 microM, respectively. Exposure of NTUB1 to 3 (5 and 10 microM) for 24 h significantly increased the level of production of reactive oxygen species (ROS). Flow cytometric analysis showed that treatment of NTUB1 with 3 led to the cell cycle arrest at G0/G1 accompanied by an increase in the extent of apoptotic cell death after 24 h. These data suggest that the presentation of G1 phase arrest and apoptosis in 3-treated NTUB1 for 24 h was mediated through an increased amount of ROS in cells exposed to 3.

Structure-activity relationship studies on chalcone derivatives: potent inhibition of platelet aggregation

In an effort to develop potent antiplatelet agents with anti-inflammatory action, a novel series of anti-inflammatory chalcones was screened to evaluate their antiplatelet effects. Structure-activity relationships and mode of action were investigated and characterized. The antiplatelet effects of the chalcones on washed rabbit platelets and human platelet-rich plasma were evaluated. Arachidonic acid-induced platelet aggregation was potently inhibited by almost all the chalcone derivatives. Collagen-induced platelet aggregation was potently inhibited by all the chalcone derivatives at 300 μm, except for compound 4 at 100 μm. Compounds 6, 7 and 9 significantly inhibited the aggregation of washed rabbit platelets induced by platelet-activating factor at 300 μm. Of the compounds tested in human platelet-rich plasma, compounds 2, 8 and 9 showed significant inhibition of secondary aggregation induced by adrenaline. It is concluded that the antiplatelet effect of 2, 8 and 9 is mainly owing to an inhibitory effect on thromboxane formation. The inhibitory effect of 6, 7 and 9 on platelet aggregation induced by platelet-activating factor could be owing to a calcium antagonizing effect or inhibition of intracellular calcium mobilization.

Improving rubber concrete by waste organic sulfur compounds

In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C-S-H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C-S-H. In the present study, a colloid probe of C-S-H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly.

Ursolic acid derivatives induce cell cycle arrest and apoptosis in NTUB1 cells associated with reactive oxygen species

Twenty-three ursolic acid (1) derivatives 2-24 including nine new 1 derivatives 5, 7-11, 20-22 were synthesized and evaluated for cytotoxicities against NTUB1 cells (human bladder cancer cell line). Compounds 5 and 17 with an isopropyl ester moiety at C-17-COOH and a succinyl moiety at C-3-OH showed potent inhibitory effect on growth of NTUB1 cells. Compounds 23 and 24 with seco-structures prepared from 1 also showed the increase of the cytotoxicity against NTUB1 cells. Exposure of NTUB1 to 5 (40 microM) and 23 (20 and 50 microM) for 24h significantly increased the production of reactive oxygen species (ROS) while exposure of NTUB1 to 5 (20 and 40 microM) and 23 (20 and 50 microM) for 48 h also significantly increased the production of ROS while exposure of cells to 17 did not increase the amount of ROS. Flow cytometric analysis exhibited that treatment of NTUB1 with 5 or 17 or 23 led to the cell cycle arrest accompanied by an increase in apoptotic cell death after 24 or 48 h. These data suggest that the presentation of G1 phase arrest and apoptosis in 5- and 23-treated NTUB1 for 24 h mediated through increased amount of ROS in cells exposed with 5 and 23, respectively, while the presence of G2/M arrest before accumulation of cells in sub-G1 phase in 5-treated cells for 48 h also due to increased amount of ROS in cells exposed with 5. The inhibition of tubulin polymerization and cell cycle arrest at G2/M following by apoptosis presented in the cell cycle of 23 also mediates through the increase amount of ROS induced by treating NTUB1 with 23 for 48 h.

Phloroglucinols inhibit chemical mediators and xanthine oxidase, and protect cisplatin-induced cell death by reducing reactive oxygen species in normal human urothelial and bladder cancer cells

Phloroglucinols, garcinielliptones HA-HE (1-5), and C (6) were studied in vitro for their inhibitory effects on chemical mediators released from mast cells, neutrophils, and macrophages. Compound 6 revealed significant inhibitory effect on release of lysozyme from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Compounds 3, 4, and 6 showed significant inhibitory effects on superoxide anion generation in rat neutrophils stimulated with (fMLP)/(CB), while compounds 1 and 5 revealed inhibitory effects on tumor necrosis factor-alpha (TNF-alpha) formation in macrophages stimulated with lipopolysaccharide (LPS). Compounds 1 and 3-6 showed inhibitory effects on xanthine oxidase (XO) and could inhibit the DNA breakage caused by O2(-*). Treatment of NTUB1 with 2 to 60 microM compound 3 and 5 microM cisplatin and SV-HUC1 with 9 to 60 microM 3 and 5 microM cisplatin, respectively, resulted in an increase of viability of cells. These results indicated that compounds 1 and 3-6 showed anti-inflammatory effects and antioxidant activities. Compound 3 mediates through the suppression of XO activity and reduction of reactive oxygen species (ROS), and protection of subsequent cell death.

2'-Ethoxy-5'-methoxy-2-(5-methylthienyl)chalcone inhibits collagen-induced protein tyrosine phosphorylation and thromboxane formation during platelet aggregation and adhesion

Subendothelial collagen supports platelet adhesion, activation, and thrombus growth at sites of vascular damage. Previous studies have shown that chalcones possess antiplatelet activity, but their mechanism of action is not fully understood. In this study, a recently synthesized chalcone, 2'-ethoxy-5'-methoxy-2-(5-methylthienyl)chalcone (EMMTC), was used to investigate chalcone effects on platelet aggregation and adhesion. We found that EMMTC potently inhibited collagen-induced platelet aggregation with an IC(50) of 1.01 micromol/l. In contrast, it did not inhibit thrombin- and ADP-induced platelet aggregation. EMMTC could inhibit arachidonic acid (AA)-induced platelet aggregation and collagen- and AA-induced thromboxane B(2) (TXB(2)) formation, suggesting that cyclooxygenase and/or thromboxane synthase were affected during this process. Moreover, EMMTC suppressed collagen-induced protein tyrosine phosphorylation, including phospholipase C-gamma2 (PLC-gamma2), phosphatidylinositol-3 kinase (PI-3K), Src, Fyn and LAT. Strikingly, EMMTC also blocked platelet adhesion to immobilized collagen and convulxin (a snake venom-derived protein that activates platelet glycoprotein VI receptor). The attenuation of phosphorylation of focal adhesion kinase (FAK) was observed during adhesion. Taken together, our results presented here demonstrate that the chalcone derivative EMMTC affects collagen-induced protein tyrosine phosphorylation and TXB(2) formation and functionally blocks collagen-induced platelet aggregation and adhesion.

EPOX inhibits angiogenesis by degradation of Mcl-1 through ERK inactivation

PURPOSE

Antiangiogenic therapy is considered as an effective strategy for controlling the growth and metastasis of tumors. Among a myriad of biological activities described for xanthone derivatives, the anticancer activity is quite remarkable, but the molecular mechanism is not clearly resolved. In the present study, we investigated the antiangiogenic mechanism of 3,6-di(2,3-epoxypropoxy)xanthone (EPOX), a novel Mcl-1 targeting drug.

EXPERIMENTAL DESIGN

To evaluate the antiangiogenic activity of EPOX, we did cell viability, cell cycle, tube formation assay in vitro, and Matrigel plug assay in vivo. To evaluate the effect of EPOX on the endothelial signaling pathway, we did immunoblotting, immunoprecipitation, and immunofluorescence analysis. Intracellular glutathione levels were determined with the use of monochlorobimane, a glutathione-specific probe.

RESULTS

EPOX induced endothelial cell apoptosis in association with proteasome-dependent Mcl-1 degradation. Down-regulation of Mcl-1 resulted in an increase in Mcl-1-free Bim, activation of Bax, and then signaling of mitochondria-mediated apoptosis. Additionally, glutathione depletion and extracellular signal-regulated kinase (ERK) inactivation was observed in EPOX-treated cells. Glutathione supplementation reversed the inhibitory effects of EPOX on ERK, which increases the phosphorylation of Mcl-1 at T(163.) Overexpression of mitogen-activated protein/ERK kinase (MEK) partially reversed the effect of EPOX on Mcl-1 dephosphorylation, ubiquitination, and degradation, further implicating ERK in the regulation of Mcl-1 stability.

CONCLUSIONS

This study provides evidence that EPOX induces glutathione depletion, ERK inactivation, and Mcl-1 degradation on endothelial cells, which leads to inhibition of angiogenesis. Our results suggest that EPOX is a novel antiangiogenic agent, making it a promising lead compound for further development in the treatment of angiogenesis-related pathologies.

Involvement of caspases and apoptosis-inducing factor in bufotalin-induced apoptosis of Hep 3B cells

Bufotalin is one of the bufadienolides isolated from Formosan Ch'an Su, which is made of the skin and parotid glands of toads. Ingestion of toad venom results in severe morbidity and high mortality. Although Ch'an Su is clinically toxic, it has been used as an important traditional Chinese medicine for heart failure and pains. In this study, bufotalin-induced apoptosis in human hepatocellular carcinoma Hep 3B cells was investigated. The results indicate that externalization of phosphatidylserine, accumulation of sub-G(1) cells, fragmentation of DNA, and formation of apoptotic bodies were observed in bufotalin-treated Hep 3B cells. The signaling pathway might be via the activation of caspase-8, increase in mitochondrial tBid, disruption of mitochondrial membrane potential, and translocation of apoptosis-inducing factor (AIF). Active caspase-8 might activate caspase-9 and caspase-3 leading to the cleavage of nuclear PARP. Presence of AIF and cleaved PARP in the nuclei might lead to DNA fragmentation. Caspase-8 inhibitor (Z-IETD) or wide-ranging caspase inhibitor (Z-VAD) significantly suppressed the bufotalin-induced apoptosis, while the anti-Fas neutralization antibody had no effect. These data suggest that bufotalin-induced apoptosis in Hep 3B cells might involve caspases and AIF.

Phloroglucinols with antioxidant activity and xanthonolignoids from the heartwood of Hypericum geminiflorum

A new phloroglucinol, hyperielliptone HA (1/1a), a new spirophloroglucinol possessing an unprecedented skeleton, hyperielliptone HB (2/2a), and two new xanthonolignoids, hyperielliptones HC (3) and HD (4), were isolated from the heartwood of Hypericum geminiflorum. Compounds 1/1a and 2/2a were obtained as tautomeric pairs. The structures and relative configurations of these compounds were elucidated by spectroscopic methods. In biological testing, compound 2/ 2a revealed significant inhibition of oxidative DNA damage and an inhibitory effect on xanthine oxidase.