Arecoline-stimulated placenta growth factor production in gingival epithelial cells: modulation by curcumin.

OBJECTIVE: Placenta growth factor (PlGF) is associated with the progression and prognosis of oral cancer. MATERIALS AND METHODS: This study used ELISA, quantitative polymerase chain reaction, and Western blotting to study the arecoline-stimulated (PlGF) protein or mRNA expression in human gingival epithelial S-G cells. RESULTS: Arecoline, a major areca nut alkaloid and an oral carcinogen, could stimulate PlGF protein synthesis in S-G cells in a dose- and time-dependent manner. The levels of PlGF protein secretion increased about 3.1- and 3.8-fold after 24-h exposure to 0.4 and 0.8 mM arecoline, respectively. Pretreatment with antioxidant N-acetyl-l-cysteine (NAC) and ERK inhibitor PD98059, but not NF-κB inhibitor Bay 11-7082, JNK inhibitor SP600125, p38 MAPK inhibitor SB203580, and PI3-K inhibitor LY294002, significantly reduced arecoline-induced PlGF protein synthesis. ELISA analyses demonstrated that NAC and PD98059 reduced about 43% and 38% of the arecoline-induced PlGF protein secretion, respectively. However, combined treatment with NAC and PD98059 did not show additive effect. Moreover, 10 µM curcumin and 4 mM NAC significantly inhibited arecoline-induced ERK activation. Furthermore, 10 µM curcumin completely blocked arecoline-induced PlGF mRNA expression. CONCLUSION: Arecoline-induced PlGF synthesis is probably mediated by reactive oxygen species/ERK pathways, and curcumin may be an useful agent in controlling oral carcinogenesis.

Chemistry and biological activities of constituents from Morus australis.

A novel constituent named australone B (1) was further isolated from the cortex of Morus australis (Moraceae). The structure of 1 has been elucidated by one- and two-dimension spectra. In human citrated platelet-rich plasma, 1 showed strong inhibition of aggregation induced by adrenaline in a concentration-dependent manner with an IC(50) value of about 33.3 microM. Compound 1 (30 microM) also showed inhibitory effects on superoxide anion formation from rat neutrophils stimulated with formyl-Met-Leu-Phe (fMLP)/cytochalasin B (CB). Morusin (2) inhibited superoxide anion formation from rat neutrophils stimulated with phorbol myristate acetate (PMA) in a concentration-dependent manner with an IC(50) value of 66.9+/-2.5 microM.

Differential regulation of protein tyrosine kinase on free radical production, granule enzyme release, and cytokine synthesis by activated murine peritoneal macrophages.

The present study examined the regulatory effect of tyrosine kinase inhibitors (genistein, tyrphostin, and 2,5-dihydroxycinnamate) on the free radical production, granule enzyme release, and synthesis of interleukin (IL)-8 and granulocyte macrophage-colony stimulating factor (GM-CSF) in murine peritoneal macrophages exposed to different stimulators [10 ng/mL of IL-1, 1 microgram/mL of lipopolysaccharide (LPS), and 1 microM N-formyl-methionyl-leucyl-phenylalanine (fMLP)]. Protein tyrosine kinase (PTK) inhibitors attenuated the stimulated superoxide, hydrogen peroxide, and nitric oxide production in macrophages stimulated with IL-1, LPS, or fMLP. N,N-Dimethylsphingosine (DMS) alone stimulated superoxide and hydrogen peroxide production by intact macrophages, but at 45 microM the stimulatory effect on superoxide production was not found. In contrast, DMS attenuated nitric oxide production by macrophages. High concentrations of DMS, tyrphostin, and 2,5-dihydroxycinnamate showed cytotoxic effects. PTK inhibitors did not exhibit a significant effect on granule enzyme release induced by IL-1, whereas they attenuated the effect of LPS and fMLP on degranulation. Genistein and tyrphostin decreased the production of IL-8 and GM-CSF in macrophages activated by IL-1, whereas 2,5-dihydroxycinnamate did not affect it. The results suggest that tyrosine kinases exposed to IL-1, LPS, and fMLP may exert different modulatory actions on macrophage responses. The IL-1-activated macrophage responses, particularly degranulation, appear to be differently regulated by tyrosine kinases compared with the responses activated by LPS and fMLP.

The changing estrogen content of the nuclear fraction of human myometrium during labor.

The cytosol and nuclear fractions were prepared from 32 pieces of myometrium obtained from 20 elective cesarean sections (regarded as typical of quiescent pregnancy (P)) and 12 emergency cesareans (performed after labor had started and therefore taken as typical of labor (L)). The nuclear fraction was purified by standard procedures. All protein-bound estrogen was released from the nuclear fractions, and the released estrogen simultaneously solubilized by denaturation with ethanol. The estriol (E3) and estradiol (E2) content of the alcohol solutions were assayed by radioimmunoassay with highly specific antisera for E3 and E2. In the L group, average E3 content was slightly (not significantly) lower, and average E2 content was significantly (P less than 0.005) higher, than in the P group. The E3/E2 ratio decreased dramatically (P less than 0.001) during this change from P to L.

Synthesis and antithrombotic effect of xanthone derivatives.

A series of xanthone derivatives was synthesized and tested in-vitro for their ability to inhibit aggregation of rabbit washed platelets and human platelet-rich plasma (PRP) induced by various inducers. 2-Prenyloxyxanthone showed the most potent inhibition of rabbit washed platelet aggregation induced by arachidonic acid (1C50 = 10.2 microM). Of the compounds tested in human PRP, 2-[3 (propylamino)-2-hydroxypropoxy]xanthone (4) hydrochloride salt exhibited the most potent inhibition of platelet aggregation induced by adrenaline (IC50 = 4.4 microM), whereas in evaluation of mouse antithrombotic activity, compound 4 exhibited the most potent protection of mice from thrombotic challenge. Compound 4, 2-[3-(isopropylamino)-2-hydroxypropoxylxanthone hydrochloride salt and 2,5 dihydroxyxanthone suppressed the secondary aggregation induced by adrenaline in human PRP. We conclude that the antiplatelet effects of these compounds are mainly due to an inhibitory effect on thromboxane formation.

Synthesis, antiplatelet and vasorelaxing effects of monooxygenated flavones and flavonoxypropanolamines.

A series of flavones and flavonoxypropanolamines were synthesized and tested in-vitro for their ability to inhibit aggregation of washed rabbit platelets and human platelet-rich plasma (PRP), and for vasoconstriction of rat thoracic aorta. The various substituted positions of the hydroxyl group in flavone ring B and the various oxypropanolamine side chains substituted at position C-2' of flavone modified the antiplatelet effects. All the compounds tested in human PRP showed significant inhibition of secondary aggregation induced by adrenaline (epinephrine), suggesting that the antiplatelet effect of these compounds is mainly due to an inhibitory effect on thromboxane formation. Compounds 11 and 12 also had potent vasorelaxant effects in rat thoracic aorta. Phenylephrine- and high-K+-induced 45Ca2+ influx in aorta were both inhibited by the selected compound 11. This result indicates that the inhibitory effect of 11 on the contractile response caused by high-K+ medium and noradrenaline (norepinephrine) in rat thoracic aorta is mainly due to inhibition of Ca2+ influx through both voltage-dependent and receptor-operated Ca2+ channels.

Modulation of 1-methyl-4-phenylpyridinium-induced mitochondrial dysfunction and cell death in PC12 cells by K(ATP) channel block.

The present study investigated the effect of 5-hydroxydecanoate, a selective mitochondrial K(ATP) channel blocker, on the cytotoxicity of neurotoxin 1-methyl-4-phenylpyridinium (MPP(+)) in differentiated PC12 cells. 5-Hydroxydecanoate and glibenclamide (a cell surface and mitochondrial K(ATP) channel inhibitor) reduced the MPP(+)-induced cell death and GSH depletion and showed a maximal inhibitory effect at 5 and 10 microM, respectively. Addition of 5-hydroxydecanoate attenuated the MPP(+)-induced nuclear damage, changes in the mitochondrial membrane permeability and increase in the reactive oxygen species formation in PC12 cells. The results show that 5-hydroxydecanote may prevent the MPP(+)-induced viability loss in PC12 cells by suppressing formation of the mitochondrial permeability transition, leading to the cytochrome c release and caspase-3 activation. This effect appears to be accomplished by the inhibitory action on the formation of reactive oxygen species and the depletion of GSH. The blockade of mitochondrial K(ATP) channels seems to prevent the MPP(+)-induced neuronal cell damage.

Interferon-based combination anti-viral therapy for hepatitis C virus after liver transplantation: a review and quantitative analysis.

Recurrence of hepatitis C virus (HCV) infection after liver transplantation (LT) is universal. However, the efficacy, tolerability and safety of combination interferon and ribavirin (IFN-RIB) or peginterferon and ribavirin (PEG-RIB) anti-viral therapies post-LT are uncertain. We performed a comprehensive search of major medical databases (1980-2005) and conference proceedings (1996-2005). The main outcome measure was sustained virological response (SVR, undetectable HCV RNA) at 6 months. Summary estimates were calculated using random-effects models. Twenty-seven IFN-RIB and 21 PEG-RIB studies were included. IFN-RIB was associated with a pooled SVR rate of 24% (95% CI, 20-27%), while PEG-RIB was associated with an SVR rate of 27% (23-31%). Pooled discontinuation rates were 24% (21-27%) with IFN-RIB and 26% (20-32%) with PEG-RIB. The pooled rate of acute graft rejection was 2% (1-3%) with IFN-RIB and 5% (3-7%) with PEG-RIB. IFN-RIB and PEG-RIB therapies in HCV infection post-LT were associated with similar but overall low SVR and were poorly tolerated. The rate of acute rejection was small. The therapeutic advantage of PEG-RIB therapy observed in non-transplant chronic HCV infection appears to be attenuated post-LT. Clinical trials are needed to evaluate reasons for this post-transplant therapeutic disadvantage and to find strategies to ameliorate them.

Trans-resveratrol modulates the catalytic activity and mRNA expression of the procarcinogen-activating human cytochrome P450 1B1.

The present study was performed to determine if trans-resveratrol (3,5,4'-trihydroxy-trans-stilbene) modulates the catalytic activity and gene expression of cytochrome P450 1B1 (CYP1B1). In vitro, trans-resveratrol decreased human recombinant CYP1B1-catalyzed 7-ethoxyresorufin O-dealkylation activity, with an IC50 value of 1.4 +/- 0.2 microM (mean +/- SEM). Enzyme kinetic analysis indicated that trans-resveratrol inhibited CYP1B1 enzyme activity by a mixed-type inhibition and the apparent Ki was 0.75 +/- 0.06 microM. To determine if trans-resveratrol modulates constitutive CYP1B1 gene expression, cultured MCF-7 human breast carcinoma cells were treated with trans-resveratrol. As indicated by RT-PCR analysis, treatment of MCF-7 cells with 10 microM trans-resveratrol decreased relative CYP1B1 mRNA levels after 5 h, but not after 1.5 or 3 h, of exposure. trans-Resveratrol treatment at 5, 7.5, 10, or 20 microM for 5 h produced a concentration-dependent decrease in CYP1B1 mRNA levels. The extent of suppression was approximately 50% at 20 microM concentration. The suppressive effect was not a consequence of a toxic response to the compound as assessed by a cell proliferation assay. Overall, our novel finding that trans-resveratrol inhibits the catalytic activity and suppresses the constitutive gene expression of CYP1B1 leads to the possibility that this nutraceutical confers protection against toxicity and carcinogenicity induced by compounds that undergo CYP1B1-catalyzed bioactivation.

Cytotoxic isoprenylated flavans of Broussonetia kazinoki.

Two new prenylflavans [kazinols Q (1) and R (2)] and five known compounds [kazinols D (3), K (4), and H, 7,4'-dihydroxyflavan (5), and oleanolic acid] were isolated from the root bark of Broussonetia kazinoki. The cytotoxic activity of 1-5 was evaluated against several different cell lines.

Bioactive constituents of Morus australis and Broussonetia papyrifera.

The biological activities of the active principles of two plants in the Moraceae have been investigated. A new prenylflavonoid, australone A (1), and a new triterpenoid, 3 beta-[(m-methoxybenzoyl)oxy]urs-12-en-28-ioc acid (2) were isolated from the root bark of Morus australis, and their structures determined by spectroscopic methods. Also isolated from this plant were seven known compounds, morusin (3), kuwanon C (4), betulinic acid, beta-amyrin, quercetin, ursolic acid, and compound A. Morusin (3) showed significant effects on arachidonic acid-, collagen-, and PAF-induced platelet aggregation, while kuwanon C (4) was active in the arachidonic acid- and PAF-induced platelet aggregation assays. In biological work on a second plant, Broussonetia papyrifera, broussoflavonols F (5) and G (6), broussoflavan A (7), and broussoaurone A (8) potently inhibited Fe(2+)-induced lipid oxidation in rat-brain homogenate. Compounds 5-7 also significantly inhibited the proliferation of rat vascular smooth muscle cells.