[Design, synthesis and biological assay of novel tripeptidic tetrazoles as inhibitors of 20S proteasome].

Ubiquitin-proteasome pathway (UPP) is one of the ways utilized for selective degradation of many proteins in cells, and the 20S proteasome takes the functional machinery where hydrolysis of targeted proteins takes place. Based on existing peptide inhibitors, a series of novel tripeptidic tetrazoles have been designed, synthesized, and the structures have been confirmed with 1H NMR, MS and elemental analysis. Among them, three compounds (6b, 6d and 6h) showed inhibitory activities of ChT-L of 20S proteasome.

ß-Escin sodium inhibits inducible nitric oxide synthase expression via downregulation of the JAK/STAT pathway in A549 cells.

ß-escin, a triterpene saponin, is one of the major active compounds extracted from horse chestnut (Aesculus hippocastanum) seed. Previous work has found that ß-escin sodium has antiinflammatory and antitumor effects. In the present study, we investigated its effect on cell proliferation and inducible nitric-oxide synthase (iNOS) expression in human lung carcinoma A549 cells. ß-escin sodium (5-40 µg/mL) inhibited cytokine mixture (CM)-induced nitric oxide (NO) production in A549 cells by reducing the expression of iNOS. ß-escin sodium suppressed phosphorylation and nuclear translocation of STAT1 (Tyr701) and STAT3 (Tyr705) induced by CM but did not affect the activation of c-Jun and NF-κB. ß-escin sodium inhibited the activation of protein tyrosine kinase JAK2. Pervanadate treatment reversed the ß-escin sodium-induced downregulation of STAT3 and STAT1. ß-escin sodium treatment enhanced an activating phosphorylation of the phosphatase SHP2. Small interfering RNA-mediated knockdown of SHP2 inhibited ß-escin sodium-induced phospho-STAT dephosphorylation. Moreover ß-escin sodium reduced the activation of p38 MAPK. Finally, ß-escin sodium inhibited the proliferation of A549 cells, did not change the cell membrane's permeability, nuclear morphology and size and the mitochondria's transmembrane potential of A549 cells. Taken together, these results demonstrate that ß-escin sodium could downregulate iNOS expression through inhibiting JAK/STAT signaling and p38 MAPK activation in A549 cells. ß-escin sodium has a marked antiproliferative effect on A549 cells at least in part by inhibiting the JAK/STAT signaling pathway, but not by a cytotoxic effect. ß-escin sodium would be useful as a chemopreventive agent or a therapeutic against inflammatory-associated tumor. © 2011 Wiley Periodicals, Inc.

Synthesis and biological activity of flavanone derivatives.

A series of new flavanone derivatives of farrerol was synthesized by a convenient method. The in vitro anti-tumor activity of these compounds was evaluated against human Bel-7402, HL-60, BGC-823 and KB cell lines, the protein tyrosine kinase (PTK) inhibitor activity was also tested. Their cytoprotective activity was tested using hydrogen peroxide (H2O2)-induced injury in human umbilical vein endothelial cells. Their in vitro anti-atherosclerosis activity was tested on vascular smooth muscle cells by the MTT method using tetrandrine as a positive contrast drug. The structures of all compounds synthesized were confirmed by 1H, 13C NMR and ESI-MS. Most of the compounds exhibited good pharmacological activity and the preliminary structure-activity relationships were described.

In vitro anticancer property of a novel thalidomide analogue through inhibition of NF-kappaB activation in HL-60 cells.

AIM: To investigate the anticancer property and possible mechanism of action of a novel sugar-substituted thalidomide derivative (STA-35) on HL-60 cells in vitro. METHODS: TNF-alpha-induced NF-kappaB activation was determined using a reporter gene assay. The MTT assay was used to measure cytotoxicity of the compound. The appearance of apoptotic Sub-G1 cells was detected by flow cytometry analysis. PARP cleavage and protein expression of NF-kappaB p65 and its inhibitor IkappaB were viewed by Western blotting. RESULTS: TA-35 (1-20 micromol/L) suppressed TNF-alpha-induced NF-kappaB activation in transfected cells (HEK293/pNiFty-SEAP) in a dose- (1-20 micromol/L) and time-dependent (0-48 h) manner. It was also shown that STA-35 exerted a dose-dependent inhibitory effect on HL-60 cell proliferation with an IC(50) value of 9.05 micromol/L. In addition, STA-35 induced apoptosis in HL-60 cells, as indicated by the appearance of a Sub-G1 peak in the cell cycle distribution, as well as poly ADP-ribose polymerase (PARP) cleavage. Subsequently, both NF-kappaB p65 and its inhibitor IkappaB gradually accumulated in cytoplasmic extracts in a dose- and time-dependent manner, indicating the blockage of NF-kappaB translocation induced by TNF-alpha from the cytoplasm to the nucleus. CONCLUSION: A novel sugar-substituted thalidomide derivative, STA-35, is potent toward HL-60 cells in vitro and induces apoptosis by the suppression of NF-kappaB activation.

Effect of beta-escin sodium on endothelial cells proliferation, migration and apoptosis.

beta-Escin, the major active compound in extracts of the horse chestnut Aesculus hippocastanum seed, has shown clinically significant activity in chronic venous insufficiency (CVI). Our previous studies had shown that beta-escin sodium inhibited angiogenesis in chick chorioallantoic membrane (CAM) and in aortic disk assay. In this study, we explored the direct effect of beta-escin sodium on proliferation, migration and apoptosis in human umbilical vein endothelial cells (HUVECs) and ECV304 cells. Sulforhodamine B (SRB) assay showed that beta-escin sodium (10, 20, 40 microg/ml) inhibited endothelial cells (ECs) proliferation dose-dependently. beta-escin sodium also induced ECs apoptosis at 40 microg/ml. Cell migration was evaluated by an improved wound assay: barren spot assay. And the direct effect on cell motility excluding influence of cell proliferation was examined by High Content Screening (HCS, Cellomics) assay. The data indicated that beta-escin sodium suppressed ECs migration and cell motility. Western blot results suggested that beta-escin sodium acts on ECs possibly by increasing expression of thrombospondin-1 (TSP-1), and decreasing expression of PKC-alpha and activation of p44/42 mitogen-activated protein kinase (ERK) and p38 mitogen-activated protein kinase (p38 MAPK). Our findings give the evidence that beta-escin sodium might have potential anti-angiogenic activity via its direct effects on ECs.

Cytotoxic activity of some Asarum plants.

The cytotoxic activity against some tumor cell lines of 16 commonly used species of Asarum was evaluated in this study. All of these plants were widely used in Asian countries as traditional medicines or folk medicines. Their inhibitory activities against four tumor cell lines (HL-60, BGC-823, KB and Bel-7402) were compared. It was observed that 10 of the tested extracts (eight ethanol extracts and two water extracts) among 32 extracts of these plants showed cytotoxic activity. Those 95% ethanol extractions from A. caudigerellum, A. forbesii, A. inflatum and A. maximum exhibited the highest cytotoxic activity, and 95% ethanol extracts or water extracts of A. sieboldii var. seoulense, A. himalaicum, A. splendens and A. crispulatum showed selective activity against one or two cells among the tested tumor cells. This is the first report of Asarum plants possessing cytotoxic activity against tumor cell lines.

Small-molecule compounds targeting the STAT3 DNA-binding domain suppress survival of cisplatin-resistant human ovarian cancer cells by inducing apoptosis.

Constitutive activation of signal transducer and activator of transcription 3 (STAT3) plays important roles in oncogenic occurrence and transformation by regulating the expression of diverse downstream target genes important for tumor growth, metastasis, angiogenesis and immune evasion. Feasibility of targeting the DNA-binding domain (DBD) of STAT3 has been proven previously. With the aid of 3D shape- and electrostatic-based drug design, we identified a new STAT3 inhibitor, LC28, and its five analogs, based on the pharmacophore of a known STAT3 DBD inhibitor. Microscale thermophoresis assay shows that these compounds inhibits STAT3 binding to DNA with a Ki value of 0.74-8.87 µM. Furthermore, LC28 and its analogs suppress survival of cisplatin-resistant ovarian cancer cells by inhibiting STAT3 signaling and inducing apoptosis. Therefore, these compounds may serve as candidate compounds for further modification and development as anticancer therapeutics targeting the DBD of human STAT3 for treatment of cisplatin-resistant ovarian cancer.

Synthesis and anti-inflammatory activity of N-phthalimidomethyl 2,3-dideoxy- and 2,3-unsaturated glycosides.

3,4,6-Tri-O-acetyl-D-galactal, 3,4,6-tri-O-acetyl-D-glucal and 3,6,2',3',4'6'-hexa-O-acetyl-D-lactal were reacted with N-hydroxymethylphthalimide and boron trifluoride etherate to produce the corresponding phthalimidomethyl unsaturated glycosides via Ferrier rearrangement. When the galactal derivative was used, a non-Ferrier rearrangement product was also isolated as a minor product under classical Ferrier conditions. Phthalimidomethyl deoxy glycosides were readily prepared by hydrogenation of the unsaturated glycosides. Following deacetylation, the anti-inflammatory activities of these compounds were tested on mice and three were found to possess potent activity compared to hydrocortisone sodium succinate (HSS).

[Inhibitory effects of 11 coumarin compounds against growth of human bladder carcinoma cell line E-J in vitro].

OBJECTIVE: To screen antitumor active compounds, drug-like or leading compounds from Chinese traditional and herbal drugs. METHODS: Eleven coumarin compounds isolated from the Chinese traditional and herbal drugs were studied for their antitumor activities in vitro by determining the inhibition rates against growth of human bladder carcinoma cell line E-J. RESULTS: It showed that umbelliferone, scoparone, demethylfuropinarine, isopimpinellin, forbesoside, columbianadin, decursin and glycycoumarin inhibited the growth of human bladder carcinoma cell line E-J in vitro and their activities showed a concentration-effect relationship. The inhibitory effects of forbesoside, columbianadin, decursin and umbelliferone, with IC50 values of 7.50x10(-7), 2.30x10(-6), 6.00x10(-6) and 1.30x10(-6) mol/L, respectively, were stronger than those of the other tested compounds. However, xanthotoxin, esculin and sphondin did not inhibit the growth of human bladder carcinoma cell line E-J in this assay condition. CONCLUSION: These findings indicate that forbesoside, columbianadin, esculin, decursin and umbelliferone would be effective or regarded as potent drug-like or leading compounds against human bladder carcinoma.

Urea-containing peptide boronic acids as potent proteasome inhibitors.

A novel class of urea-containing peptide boronic acids as proteasome inhibitors was designed by introducing a urea scaffold to replace an amido bond. Compounds were synthesized and their antitumor activities were evaluated. After two rounds of optimizations, the compound I-14 was found to be a potent proteasome inhibitor. Compared with Bortezomib, I-14 showed higher potency against the chymotrypsin-like activity of human 20S proteasome (IC50 < 1 pM), similar potency against four different cancer cell lines (IC50 < 10 nM), and better pharmacokinetic profile. Furthermore, I-14 significantly inhibited tumor growth in Bel7404 mouse xenograft model. The excellent proteasome inhibition by I-14 was rationalized through docking and molecular dynamics studies.

[Analysis of hydrochloride 4-methyl-piperazine-1-carbodithioc acid 3-cyano-3,3-diphenyl-propyl ester and its metabolites in rats by HPLC-ESI/ITMSn].

AIM: To identify the main metabolites of hydrochloride 4-methyl-piperazine-1-carbodithioc acid 3-cyano-3,3-diphenyl-propyl ester (TM208) in rats. METHODS: Rat feces, urine and plasma samples were collected after ig 500 mg x kg(-1) TM208, then the samples were extracted and concentrated using ethyl acetate. The treated samples were analyzed by HPLC-ESI/ITMSn. The structures of metabolites were elucidated according to the rules of drug metabolism and disposition in vivo and the characteristic fragmentation behaviors of TM208 in ESI-ITMSn. RESULTS: Eight phase I metabolites were identified existing in rat feces, five of them were also found in rat urine and plasma, but no phase II metabolite was found. CONCLUSION: The HPLC-ESI/ITMSn method is rapid, highly sensitive and specific and it is suitable for the identification of TM208 and its metabolites in rats.

Proteasome Inhibitor YSY01A Enhances Cisplatin Cytotoxicity in Cisplatin-Resistant Human Ovarian Cancer Cells.

Cisplatin is one of the most common drugs used for treatment of solid tumors such as ovarian cancer. Unfortunately, the development of resistance against this cytotoxic agent limits its clinical use. Here we report that YSY01A, a novel proteasome inhibitor, is capable of suppressing survival of cisplatin-resistant ovarian cancer cells by inducing apoptosis. And YSY01A treatment enhances the cytotoxicity of cisplatin in drug-resistant ovarian cancer cells. Specifically, YSY01A abrogates regulatory proteins important for cell proliferation and anti-apoptosis including NF-κB p65 and STAT3, resulting in down-regulation of Bcl-2. A dramatic increase in cisplatin uptake was also observed by inductively coupled plasma-mass spectrometry following exposure to YSY01A. Taken together, YSY01A serves as a potential candidate for further development as anticancer therapeutics targeting the proteasome.

Discovery of novel heteroarylmethylcarbamodithioates as potent anticancer agents: Synthesis, structure-activity relationship analysis and biological evaluation.

A series of new analogs based on the structure of lead compound 10 were designed, synthesized and evaluated for their in vitro anti-cancer activities against four selected human cancer cell lines (HL-60, Bel-7402, SK-BR-3 and MDA-MB-468). Several synthesized compounds exhibited improved anti-cancer activities comparing with lead compound 10. Among them, 1,3,4-oxadiazole analogs 17o showed highest bioactivity with IC50 values of 1.23, 0.58 and 4.29 µM against Bel-7402, SK-BR-3 and MDA-MB-468 cells, respectively. It is noteworthy that 17o has potent anti-proliferation activity toward a panel of cancer cells with relatively less cytotoxicity to nonmalignant cells. The further mechanistic study showed that it induced apoptosis and cell cycle arrest through disrupting spindle assembly in mitotic progression, indicating these synthesized dithiocarbamates represented a novel series of anti-cancer compounds targeting mitosis.

The cytotoxic activity of ursolic acid derivatives.

Ursolic acid and 2alpha-hydroxyursolic acid isolated from apple peels were found to show growth inhibitory activity against four tumor cell lines, HL-60, BGC, Bel-7402 and Hela. Structural modifications were performed on the C-3, C-28 and C-11 positions of ursolic acid and the cytotoxicity of the derivatives was evaluated. The SAR revealed that the triterpenes possessing two hydrogen-bond forming groups (an H-donor and a carbonyl group) at positions 3 and 28 exhibit cytotoxic activity. The configuration at C-3 was found to be important for the activity. Introduction of an amino group increased the cytotoxicity greatly. A 3beta-amino derivative was 20 times more potent than the parent ursolic acid. The 28-aminoalkyl dimer compounds showed selective cytotoxicity.

Diastereoisomeric saponins from Albizia julibrissin.

The structures of four new diastereoisomeric triterpenoidal saponins Julibroside J5, J8, J12 and J13 (1-4) isolated from Albizia julibrissin Durazz. (Leguminosae) have been determined on the basis of comprehensive spectroscopic analysis and chemical degradation. Julibroside, J8 and J13 showed marked cytotoxic activities against Bel-7402 cancer cell line at 100 microg/mL.

[Pilot study on the mechanisms of growth inhibitory effect of cinobufagin on HeLa cells].

OBJECTIVE: To study the effect of cinobufagin (CBG) on HeLa cell proliferation, and to analyze its mechanism. METHODS: Proliferation inhibition in vitro was evaluated by MTT and Sulforhodamine B (SRB) assays in several human tumor cell lines, including Bel-7402, HeLa, MCF-7, BGC-823 and HL60. The cycle of HeLa cells was analyzed by flow cytometry. Two-dimensional electrophoresis was applied to analyze the influence of CBG on HeLa cell proteomics. RESULTS: CBG had inhibitory effects on proliferation of five human cancer cell lines, and the IC(50) values were 0.011 micromol/L (Bel-7402), 0.019 micromol/L (HeLa), 0.116 micromol/L (MCF-7), 0.149 micromol/L (BGC-823) and 1.369 micromol/L (HL60), respectively. HeLa and Bel-7402 cells were among the most sensitive. Flow cytometry assay indicated that the treatment of HeLa cells with various concentrations of CBG for 72 h was able to increase the cell number at G(2)/M phase, from 17.3% up to 35.6%. The results of two-dimensional electrophoresis showed that treatment of HeLa cells with 0.02 micromol/L CBG for 48 h resulted in apparent changes of certain small molecular weight (30,000 - 90,000) acidic proteins (pH 4 - 6). CONCLUSION: Cinobufagin has significant inhibitory effect on growth of five human cancer cells in vitro. It may lead to cell cycle arrest of HeLa cells at G(2)/M phase. It can also change the expression of some small molecular acidic proteins in HeLa cells.

[Z-ajoene causes cell cycle arrest at G2/M and decrease of telomerase activity in HL-60 cells].

OBJECTIVE: To investigate the molecular mechanisms of Z-ajoene mitosis blocking and telomerase inhibitory effects on HL-60 cells. METHODS: Proliferation inhibition of HL-60 cell line was evaluated by MTT assay. Z-ajoene-induced mitotic blocking effect was investigated by flow cytometry. Immunoblotting analysis was used to determine cell cycle regulatory proteins. The telomerase activity of HL-60 cells was detected by TRAP-silver stain assay. Telomerase hTRT and TP1 mRNA level were determined by RT-PCR. RESULTS: Z-ajoene displayed great proliferation inhibiting effect on HL-60 cells. Progressive increase in the percentage of mitotic block at G(2)/M phase was observed from 4 h to 12 h after treatment with 10 micromol/L Z-ajoene, with a peak at 10 h, which was 1.95 times higher than that in control. Z-ajoene also caused an increase in cyclin B1 accumulation and a decrease of p34(cdc2) expression. But Z-ajoene did not change the level of cyclin A. After treating with 10 micromol/L Z-ajoene for 24 h, the telomerase activity of HL-60 cells was also decreased in a dose-independent manner. Furthermore, telomerase hTRT and TP1 mRNA levels decreased after 10 micromol/L Z-ajoene treatment for 24 h. CONCLUSION: The results suggest that Z-ajoene has potent anti-cancer activity, and that its inhibitory effect on telomerase activity and on cell growth might be the result of G(2)/M phase blocking.

Anticancer Effect of a Novel Proteasome Inhibitor, YSY01A, via G2/M Arrest in PC-3M Cells in vitro and in vivo.

YSY01A is a new tripeptideboronic acid and an analog of PS341. However, YSY01A's antitumor effects and mechanism have not yet been elucidated. This study demonstrates that YSY01A inhibited proteasome activity by combining with the chymotrypsin-like (CT-L) site (ß5i/ß5), the post-glutamyl peptide hydrolase (PGPH) site (ß1i/ß1) and the trypsin-like (T-L) site (ß2i/ß2) in special fluorgonic substrates and proteasome probe tests. We explored the anticancer effect using methyl thiazolyltetrazolium (MTT) or sulforhodamine B (SRB), and PC-3M cells were sensitive to YSY01A among the four cancer cell types tested. The YSY01A antiproliferative effect was stronger than that of PS341. In vivo, YSY01A (1.25, 2.25, and 3.25 mg/kg) inhibited PC-3M cell xenograft tumor growth, and the tumor volume inhibition rate was approximately 40% to 60%. YSY01A arrested PC-3M cells in the G2/M phase of the cell cycle by flow cytometry (FCM). Many proteins related to the cell cycle were analyzed using western blot, and YSY01A was shown to increase p21, p27, cyclinB1, P-cdc2 (tyr15) and wee1 protein expression in both cells and tumor tissue in a concentration-dependent manner. YSY01A, a proteasome inhibitor, exerts anticancer effects on PC-3M cells in vitro and in vivo. The mechanism of the YSY01A-mediated antitumor effect is that the cell cycle is arrested at the G2/M stage. This study suggests that YSY01A may be a novel therapeutic agent for prostate cancer.

[Studies on the biotransformation of escin Ia by human intestinal bacteria and the anti-tumor activities of desacylescin I].

OBJECTIVE: To study Biotransformation of escin Ia by the crude enzymes of human intestinal bacteria and Lactobacillus brevis, determine the structures of biotransformation products and assay the inhibitory effect of desacylescin I on the tumor cell growth. METHODS: The escin Ia was incubated with crude enzymes of human intestinal bacteria and Lactobacillus brevis in vitro, respectively. The biotransformation products were isolated and purified by the chromatographic methods and the structures were determined by the spectroscopic techniques. RESULTS: Escin Ia was converted into isoescin Ia, desacylescin I, 21beta-O-tigloylprotoaescigenin and protoaescigenin by crude enzymes of human intestinal bacteria and Lactobacillus brevis. Desacylescin I showed potentially inhibitory effects on tumor cell growth of mouse sarcoma-180, hepatic carcinoma H(22) and lung carcinoma in vivo. CONCLUSION: The results suggest that Escin Ia was a prodrug and its structure can be converted by human intestinal bacteria and Lactobacillus brevis. Desacylescin I as a biotransformation product showed potentially inhibitory effects on mouse tumor, and a potential candidate for anti tumor agents.

NO inhibitory guaianolide-derived terpenoids from Artemisia argyi.

An unusual dimeric guaianolide, artemilinin A (1) and a sesquiterpene-monoterpene lactone, isoartemisolide (2), were isolated from the leaves of Artemisia argyi. Their structures were elucidated on the basis of extensive spectroscopic analysis (IR, HR-ESIMS, 1D- and 2D-NMR), and the absolute configurations were determined by CD spectra and quantum chemical ECD calculation. Furthermore, in in vitro assay, compound 2 exhibited pronounced inhibition on the lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV-2 microglial cells with an IC50 value of 4.00µM.