Chin-Chung Wu

Cytotoxic Triterpenoids from the Stems of Microtropis japonica

Bioassay-guided fractionation of a methanol extract obtained from stems of Microtropis japonica led to the isolation of six new ursane-type triterpenoids (1-6) and a new 2,3-seco-oleanane-type triterpenoid (7), together with seven known compounds. The structures of the new compounds were elucidated using spectroscopic data analysis. Among the known compounds isolated, the main component, 8 (ursolic acid), was active for HL60 cells, and its effects on histone hyperacetylation and the inhibition of histone deacetylase (HDAC) activity were investigated.

Lupane-Type Triterpenoids from Microtropis fokienensis and Perrottetia arisanensis and the Apoptotic Effect of 28-Hydroxy-3-oxo-lup-20(29)-en-30-al

Seven new lupane triterpenoids were isolated from bioactive methanol extracts of Microtropis fokienensis (1- 4) and Perrottetia arisanensis (4-7), along with 18 known compounds. The structures of the new compounds were elucidated on the basis of spectroscopic data analysis. All triterpenoids were evaluated for their in vitro cytotoxicity toward seven human cancer cell lines. Compound 8 (28-hydroxy-3-oxo-lup-20(29)-en-30-al) was among the most cytotoxic substances obtained and was found to induce apoptosis of human leukemia HL60 cells and mediate cleavage of PARP and up-regulation of Bax proteins.

Anthranilic acid-based inhibitors of phosphodiesterase: Design, synthesis, and bioactive evaluation

Our previous studies identified two 2-benzoylaminobenzoate derivatives 1, which potently inhibited superoxide (O(2)˙(-)) generation induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve their activities, a series of anthranilic acid derivatives were synthesized and their anti-inflammatory effects and underlying mechanisms were investigated in human neutrophils. Of these, compounds 17, 18, 46, 49, and 50 showed the most potent inhibitory effect on FMLP-induced release of O(2)˙(-) in human neutrophils with IC(50) values of 0.20, 0.16, 0.15, 0.06, and 0.29 μM, respectively. SAR analysis showed that the activities of most compounds were dependent on the ester chain length in the A ring. Conversely, a change in the linker between the A and B ring from amide to sulfonamide or N-methyl amide, as well as exchanges in the benzene rings (A or B rings) by isosteric replacements were unfavorable. Further studies indicated that inhibition of O(2)˙(-) production in human neutrophils by these anthranilic acids was associated with an elevation in cellular cAMP levels through the selective inhibition of phosphodiesterase 4. Compound 49 could be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases.

HPW-RX40 restores anoikis sensitivity of human breast cancer cells by inhibiting integrin/FAK signaling

Anoikis is defined as apoptosis, which is induced by inappropriate cell-matrix interactions. Cancer cells with anoikis resistance tend to undergo metastasis, and this phenomenon has been reported to be associated with integrin and FAK activity. HPW-RX40 is a derivative of 3,4-methylenedioxy-β-nitrostyrene, which is known to prevent platelet aggregation by inhibition of integrin. In the present study, we investigated the effect of HPW-RX40 on an anoikis-resistant human breast cancer cell line MDA-MB-231. HPW-RX40 inhibited cell aggregation and induced cell death in suspending MDA-MB-231 cells, but had only little effect on the monolayer growth of adherent cells. Analysis of caspase activation and poly (ADP-ribose) polymerase (PARP) cleavage confirmed anoikis in HPW-RX40-treated suspending cancer cells. HPW-RX40 also affected the Bcl-2 family proteins in detached cancer cells. Furthermore, HPW-RX40 inhibited detachment-induced activation of FAK and the downstream phosphorylation of Src and paxillin, but did not affect this pathway in adherent cancer cells. We also found that the expression and activation of β1 integrin in MDA-MB-231 cells were reduced by HPW-RX40. The combination of HPW-RX40 with an EGFR inhibitor led to enhanced anoikis and inhibition of the FAK pathway in breast cancer cells. Taken together, our results suggest that HPW-RX40 restores the anoikis sensitivity in the metastatic breast cancer cells by inhibiting integrin and subsequent FAK activation, and reveal a potential strategy for prevention of tumor metastasis.

Inhibition of the interactions between metastatic human breast cancer cells and platelets by β-nitrostyrene derivatives.

AIMS The interactions between cancer cells and platelets have been recognized to play an important role in cancer progress as well as metastasis, and interference with cancer-platelet interactions is an attractive strategy for cancer therapy. In the present study, two β-nitrostyrene derivatives: 3, 4-methylene-dioxy-β-nitrostyrene (MNS) and 4-O-benzoyl-3-methoxyl-β-nitrostyrene (BMNS) have been tested for their inhibitory effect on platelet activation caused by metastatic human breast cancer MDA-MB-231 and Hs578T cells. MAIN METHODS Washed human platelets were co-incubated with breast cancer cells, and platelet aggregation was determined turbidimetrically. Platelet adhesion to cancer cells and P-selectin expression were measured by flow cytometry. Platelet-derived growth factor (PDGF) released from cancer cell-stimulated platelets was determined by enzyme-linked immunosorbent assay (ELISA). KEY FINDINGS MNS and BMNS prevented cancer cell-induced platelet aggregation, P-selectin expression, and PDGF secretion. Moreover, the β-nitrostyrenes reduced platelet adhesion to cancer cells, suggesting the initial cancer-platelet interactions are inhibited. In contrast to current antiplatelet strategies, the glycoprotein IIb/IIIa (GPIIb/IIIa) antagonist RGDS peptide only prevented cancer cells-induced platelet aggregation, but not platelet adhesion and secretion; whereas the cyclooxygenase inhibitor aspirin and the adenosine diphosphate (ADP) scavenger apyrase affected neither platelet aggregation nor platelet secretion. SIGNIFICANCE The inhibitory effects of the β-nitrostyrene derivatives on cancer-platelet interactions may offer a potential approach for repressing cancer metastasis.

New cytotoxic lupane triterpenes from Perrottetia arisanensis.

Eight new lupane triterpenes, including 7beta-cis-coumaroylbetulinic acid (1), 7beta-trans-coumaroylbetulinic acid (2), 7beta-cis-coumaroyl-3-epi-betulinic acid (3), 7beta-trans-coumaroyl-3-epi-betulinic acid (4), 7beta-cis-coumaroylbetulonic acid (5), 7beta-trans-coumaroylbetulonic acid (6), 7beta-hydroxybetulinaldehyde (7) and 28-norlup-20(29)-ene-3alpha,17beta-diol (8), together with fifteen known compounds were isolated from the bioactive methanol extract of the stems of Perrottetia arisanensis. The structures of the new compounds were elucidated by spectroscopic and HR-ESI-MS analysis. All new compounds were evaluated for their cytotoxicity against six human cancer cell lines. Among them, lupane triterpene coumaroyl esters 1-6 showed moderate cytotoxicity with IC (50) values ranging from 3.75 to 21.29 microM. This is the first report for lupane triterpenes with a phenylpropane moiety substituted at C-7.

Pandalisines A and B, novel indolizidine alkaloids from the leaves of Pandanus utilis

Two novel alkaloids named pandalisines A (1) and B (2), constituting a new class of C8-substituted indolizidine moiety, were isolated from the leaves of Pandanus utilis. The structures of these new compounds were established by their mass and spectroscopic data. The absolute configuration was determined by the comparison of experimental CD and calculated ECD spectra. A plausible biosynthetic pathway for compounds 1 and 2 is advanced. The cytotoxic activities of the isolated alkaloids against A-549, Hep-G2, and MDA-MB-231 cancer cell lines were evaluated. The result showed that 1 and 2 are the first non-cytotoxic indolizidine alkaloids.

HPW-RX40 Prevents Human Platelet Activation by Attenuating Cell Surface Protein Disulfide Isomerases

Protein disulfide isomerase (PDI) present at platelet surfaces has been considered to play an important role in the conformational change and activation of the integrin glycoprotein IIb/IIIa (GPIIb/IIIa) and thus enhances platelet aggregation. Growing evidences indicated that platelet surface PDI may serve as a potential target for developing of a new class of antithrombotic agents. In the present study, we investigated the effects of HPW-RX40, a chemical derivative of β-nitrostyrene, on platelet activation and PDI activity. HPW-RX40 inhibited platelet aggregation, GPIIb/IIIa activation, and P-selectin expression in human platelets. Moreover, HPW-RX40 reduced thrombus formation in human whole blood under flow conditions, and protects mice from FeCl3-induced carotid artery occlusion. HPW-RX40 inhibited the activity of recombinant PDI family proteins (PDI, ERp57, and ERp5) as well as suppressed cell surface PDI activity of platelets in a reversible manner. Exogenous addition of PDI attenuated the inhibitory effect of HPW-RX40 on GPIIb/IIIa activation. Structure-based molecular docking simulations indicated that HPW-RX40 binds to the active site of PDI by forming hydrogen bonds. In addition, HPW-RX40 neither affected the cell viability nor induced endoplasmic reticulum stress in human cancer A549 and MDA-MB-231 cells. Taken together, our results suggest that HPW-RX40 is a reversible and non-cytotoxic PDI inhibitor with antiplatelet effects, and it may have a potential for development of novel antithrombotic agents.

Cytotoxic abietane diterpenes from Gelonium aequoreum

Seventeen ent-abietane diterpenes, including gelomulides K–X (1–14), and three known compounds, were isolated from a dichloromethane-soluble extract of Gelonium aequoreum through bioassay-guided fractionation. Their structures were identified by spectroscopic methods, and stereochemistry was confirmed by X-ray crystallographic analysis, CD spectral data, and Mosher’s method. The isolates were evaluated for in vitro cytotoxic activity, and compounds 1 and 3 showed moderate cytotoxicity against lung (A549), breast (MDAMB-231 and MCF7), and liver (HepG2) cancer cell lines. 2007 Elsevier Ltd. All rights reserved.