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PubMed1989

Inhibition of 36Cl uptake by stilbene sulphonic acid derivatives and loop diuretics in rat submandibular salivary acini.

Acini were isolated from submandibular glands by enzymatic digestion and incubated in HCO3-containing and HCO3-free [hydroxyethyl-1-piperazine-ethane sulphonic acid (HEPES) buffered] solutions to compare the accumulation of the isotopic tracer 36Cl in the absence and presence of stilbene sulphonic acid derivatives and of loop diuretics. Tracer accumulation was similar in both solutions in the absence of inhibitors and reached 17-19 nmol/mg protein after 5 min of incubation. Exposure to 10(-3) M 4,4'-diisothiocyano-2,2'-stilbene disulphonic acid (DIDS) or to 10(-4) M bumetanide in HCO3-buffered medium resulted in significant reductions in both the initial phase (from 0 to 5 min) and the steady-state phase (5-30 min) of 36Cl accumulation. By contrast, in HCO3-free, HEPES-buffered incubation solution, DIDS was significantly less effective in reducing 36Cl accumulation, while bumetanide was somewhat more effective than in HCO3-buffered medium. At a higher dose (10(-3) M), furosemide was less effective than bumetanide in reducing the steady-state tracer content of the cells in the HCO3-buffered medium (22% versus 35% reduction), although the effects were similar in the initial phase of tracer uptake. Exposure to 10(-4) M 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid (SITS) caused an increase in the steady-state 36Cl content of the acini of 24 +/- 9%. Exposure to bumetanide and DIDS caused an additive reduction of tracer content, while exposure to bumetanide and SITS resulted in a smaller reduction than with bumetanide alone.(ABSTRACT TRUNCATED AT 250 WORDS)

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1993

Inhibition of phosphatidylcholine secretion by stilbene disulfonates in alveolar type II cells.

Various agents stimulate the secretion of lung surfactant from alveolar type II cells by increasing intracellular Ca2+, cyclic adenosine-3':5'-monophosphate (cAMP), or diacylglycerol. A few agents, including the purified surfactant protein A, are known to inhibit the secretion by an unknown mechanism. In the present study, we demonstrated that stilbene disulfonic acids, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) and 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid (SITS), are potent but reversible inhibitors of lung surfactant secretion. The inhibition was concentration dependent, and the EC50 was 5 microM for DIDS and 50 microM for SITS. The inhibition was not specific to agonists for any one type of receptor, and was also observed for secretion stimulated by 8-bromo-cAMP, or tetradecanoyl phorbol acetate, suggesting that the site of inhibition was distal to the generation of intracellular second messengers. This was also supported by the failure of DIDS to block the stimulus-mediated increase in diacylglycerol content of type II cells. Further, DIDS and SITS were also inhibitory for basal secretion. Based on the reversibility of inhibition and the fact that inhibition was observed with both basal and stimulated secretion, we suggest that stilbene disulfonic acids affect a component of the exocytosis process that occurs at or near the plasma membrane.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1995

Molecular and enzymatic characterization of two stilbene synthases from Eastern white pine (Pinus strobus). A single Arg/His difference determines the activity and the pH dependence of the enzymes.

Pinus strobus (Eastern white pine) contains stilbenes biosynthetically derived from cinnamoyl-CoA (pinosylvin) or dihydrocinnamoyl-CoA (dihydropinosylvin). We screened a P. strobus cDNA library with a stilbene synthase (STS) probe from Pinus sylvestris. The eight isolated cDNAs represented two closely related STS genes with five amino acid differences in the proteins. The enzyme properties were investigated after heterologous expression in Escherichia coli. Both proteins preferred cinnamoyl-CoA against dihydrocinnamoyl-CoA and thus represented pinosylvin synthases. Otherwise they revealed large differences. STS1 had only 3-5% of the activity of STS2, its pH optimum was shifted to lower values (pH 6), and it synthesized with cinnamoyl-CoA a second unknown product. Site-directed mutagenesis demonstrated that a single Arg-to-His exchange in STS1 was responsible for all of the differences. The proton acceptor properties of His are discussed as the reason for the properties of STS1.

Acyltransferases↗
PubMed1996

Inhibition of stilbene estrogen-induced cell proliferation of renal epithelial cells through the modulation of insulin-like growth factor-I receptor expression.

In the present study, we have investigated the effects of stilbene estrogen, diethylstilbestrol (DES), on the proliferative activity and expression of insulin-like growth factor-I (IGF-I) receptor in Syrian hamster renal epithelial cells. DES exposure to renal epithelial cells caused both dose- and time-dependent increases in proliferative activity. We also tested the effects of antiestrogen ICI 182780 and insulin-like growth factor-I receptor (IGF-IR) antibody on cell proliferation. Cotreatment of cells with ICI 182780 (250 nM) and DES resulted in a 50% decrease in cell growth compared to DES alone. Treatment of cells with an anti-IGF-IR antibody (alpha IR3, 1 microgram/ml) also significantly reversed the growth-stimulatory effects of DES. A nuclear binding assay revealed that an enhanced level (approximately 2-fold) of [125I]IGF-I binding to nuclear protein occurred in DES treated renal epithelial cell nuclei compared to controls. IGF-I receptor gene expression analyzed by Northern blotting revealed that DES treatment increased the level of IGF-IR mRNA by 2-fold compared to controls. We also tested the effect of ICI compound on the induction of IGF-I receptor gene. The cotreatment of ICI 182780 strongly inhibited DES-induced IGF-I receptor gene expression (50-60% inhibition). Stimulation of the proliferative activity of renal epithelial cells by stilbene estrogen, its prevention by IGF-I receptor antibody, and inhibition of DES-induced proliferative activity and the expression of IGF-I receptors by ICI 182780 suggest the possibility that the stimulatory effect of DES on the proliferative activity of renal epithelial cells may be mediated through the up-regulation of IGF-I receptors.

Animals↗
PubMed2003

Diethylstilbestrol and tetrahydrochrysenes are calcium channel blockers in human platelets: relationship to the stilbene pharmacophore.

The effects of compounds with the stilbene pharmacophore [diethylstilbestrol (DES), DES derivatives, tetrahydrochrysene (THC), and THC derivatives] were examined for their ability to inhibit thrombin-induced Ca(2+) influx in human platelets. DES derivatives (DES dimethyl ether, DES dipropionate, dienestrol, and hexestrol) had lower inhibitory activity than DES. Esterification of DES with the bulky monobenzyl group eliminated inhibitory activity. Unsubstituted THC diol had the lowest inhibitory activity in the series of the THC derivatives bearing substituents in the 5,11 positions. These derivatives, either diethyl or dipropyl, cis or trans, were potent inhibitors of thrombin-induced [Ca(2+)](i) elevation (near 100% inhibition at 10 microM). Therefore, stilbene pharmacophore having bulk out of the plane of the double bond (from the twisting of the two aromatic rings or from addition of all substituents) seems to be requirement for the inhibitory activity. Free hydroxyl groups are also required for inhibitory activity, most likely for hydrogen bonding, since trans-diethyl tetrahydrochrysene dimethyl ether was inactive. Compounds bearing ethyl substituents (DES and THC derivatives) inhibited thrombin-induced release of calcium from the endoplasmic reticulum. These compounds also inhibited thapsigargin-induced Ca(2+) influx. This result implies that these compounds also block store-operated Ca(2+) influx directly, as well as internal Ca(2+) release. Compounds without ethyl substituents (trans-resveratrol, genistein, daidzein, and THC diol) only inhibited calcium influx into platelets.

Adult↗
PubMed2004

Relocation of the disulfonic stilbene sites of AE1 (band 3) on the basis of fluorescence energy transfer measurements.

Previous fluorescence resonance energy transfer (FRET) measurements, using BIDS (4-benzamido-4'-isothiocyanostilbene-2,2'-disulfonate) as a label for the disulfonic stilbene site and FM (fluorescein-5-maleimide) as a label for the cytoplasmic SH groups on band 3 (AE1), combined with data showing that the cytoplasmic SH groups lie about 40 A from the cytoplasmic surface of the lipid bilayer, would place the BIDS sites very near the membrane's inner surface, a location that seems to be inconsistent with current models of AE1 structure and mechanism. We reinvestigated the BIDS-FM distance, using laser single photon counting techniques as well as steady-state fluorescence of AE1, in its native membrane environment. Both techniques agree that there is very little energy transfer from BIDS to FM. The mean energy transfer (E), based on three-exponential fits to the fluorescence decay data, is 2.5 +/- 0.7% (SEM, N = 12). Steady-state fluorescence measurements also indicate <3% energy transfer from BIDS to FM. These data indicate that the BIDS sites are probably over 63 A from the cytoplasmic SH groups, placing them near the middle or the external half of the lipid bilayer. This relocation of the BIDS sites fits with other evidence that the disulfonic stilbene sites are located farther toward the external membrane surface than Glu-681, a residue near the inner membrane surface whose modification affects the pH dependence and anion selectivity of band 3. The involvement of two relatively distant parts of the AE1 protein in transport function suggests that the transport mechanism requires coordinated large-scale conformational changes in the band 3 protein.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2001

Invisible but common motion in organic crystals: a pedal motion in stilbenes and azobenzenes.

Some molecules that have a molecular skeleton similar to stilbenes and azobenzenes are known to show an orientational disorder in the crystals. Some of the disorders are known to be dynamic and mediated by a pedal motion in crystals. Dynamic processes of (E)-stilbene (1) and (E)-3,3',4,4'-tetramethylazobenzene (2) in the crystals were investigated by X-ray diffraction analyses. The dynamic disorder and the pedal motion were detected at higher temperature, even in the molecules that showed no traces of the disorder at room temperature. The results demonstrated that the pedal motion should always be taken into account, even if no disorder is detected. The reasons for the nonoccurrence of the disorder and for the prevalence of the pedal motion are also discussed.

Journal Article↗
PubMed2003

Synthesis of twist-twist pi-conjugated di-sec-alkylstilbenes and stilbene polymers.

Twist-twist pi-conjugated (TTPC) pi systems promise unique properties with their 90 degrees twist angles. Di-sec-alkyl substituted stilbenes, 5, were prepared by low-valent titanium coupling of phenyl ketones, 4. Long alkyl chains stopped the coupling reaction. Stilbenes 5 were shown to be approximately 90% TTPC. Inserting TTPC units into poly(p-phenylene) polymers created highly fluorescent, soluble, TTPC pi systems with weak electronic segmentation for organic light emitting diode (OLED) studies.

Journal Article↗
PubMed2005

Effect of oxygen on the formation and decay of stilbene radical cation during the resonant two-photon ionization.

Formation and decay of radical cations of trans-stilbene and p-substituted trans-stilbenes (S.+) during the resonant two-photon ionization (TPI) of S in acetonitrile in the presence and absence of O(2) have been studied with laser flash photolysis using a XeCl excimer laser (308 nm, fwhm 25 ns). The transient absorption spectra of S.+ were observed with a peak around 470-490 nm. The formation quantum yield of S.+ (0.06-0.29) increased with decreasing oxidation potential (E(ox)) and increasing fluorescence lifetime (tau(f)) of S, except for trans-4-methoxystilbene which has the lowest E(ox) and longer tau(f) among S. The considerable low yield and fast decay in a few tens of nanoseconds time scale were observed for trans-4-methoxystilbene.+ in the presence of O(2), but not for other S.+ . It is suggested that formation of the ground-state complex between trans-4-methoxystilbene and O(2) and the distonic character of trans-4-methoxystilbene.+ with separation and localization of the positive charge on the oxygen of the p-methoxyl group and an unpaired electron on the beta-olefinic carbon are responsible for the fast reaction of trans-4-methoxystilbene.+ with O(2) or superoxide anion, leading to the considerable low yield and fast decay of trans-4-methoxystilbene.+ . The mechanism based on the transient absorption measurement of S.+ during the TPI is consistent with the relatively high oxidation efficiency of trans-4-methoxystilbene among S based on the product analysis during the photoinduced electron transfer in the presence of a photosensitizer such as 9,10-dicyanoanthracene and O(2) in acetonitrile.

Journal Article↗
PubMed1999

Dioxirane Epoxidation of 10-Membered-Ring Stilbene Lactams as Synthetic Precursors to Protoberberines.

Silylated stilbene lactams 1, prepared by intramolecular addition of an aryl radical to a trimethylsilylacetylene, were converted into protoberberines by dimethyldioxirane (DMD) epoxidation and subsequent acid-catalyzed cyclization of the epoxysilane with HCl. Treatment of the nonsilylated trans- and cis-stilbene derivatives with DMD afforded 13-hydroxytetrahydroprotoberberines and 13a-hydroxy-13-ketotetrahydroprotoberberines as the main products. Tetrahydroprotoberberines were also obtained in excellent yields by the reaction of both silylated and nonsilylated lactams with hydriodic acid.

Journal Article↗
PubMed1999

Regioselective Synthesis of Isoquino[1,2-b][3]benzazepines (Homoprotoberberines) through 11-Membered-Ring Stilbene Lactams Obtained by Radical Macrocyclization.

Silylated 11-membered-ring stilbene lactams 3 (E and Z) were easily prepared by intramolecular addition of an aryl radical to a trimethylsilylacetylene. Oxidation of their hindered stilbene double bonds with dioxiranes gave oxidative cleavage of their electron-rich aromatic rings. However, reduction of the amide to an amine functionality in both lactams (E and Z) triggers a regioselective [7,6]-transannular cyclization to isoquino[1,2-b][3]benzazepines (homoprotoberberines).

Journal Article↗
PubMed2005

Effect of pressure on pedal motion in stilbene molecular crystals and its dependence on the crystallographic site.

We report computer simulation of a stilbene molecular crystal as a function of pressure up to 4 GPa. Molecular structure and the crystal structure of stilbene have been characterized by calculating the radial distribution function and dihedral angle distribution, features associated with pedal motion and cell parameters. Results suggest that the population of minor conformer at site 2 disappears altogether above 1.25 GPa. In contrast, the population of minor conformer at site 1 remains at around 12%. Pedal motion is not observed beyond a pressure of 0.8 and 1.4 GPa at site 1 and site 2, respectively. Specific heat and compressibility exhibit an anomaly around 1.25 GPa. The anomaly seems to be associated with the disappearance of pedal motion at site 2. Initially, increase in pressure leads to an increase in the magnitude of lattice energy, but beyond 0.5 GPa it decreases.

Journal Article↗
PubMed2006

Statistical theory of collisional energy transfer in molecular collisions. trans-stilbene deactivation by argon, carbon dioxide, and n-heptane.

Recent advances in experimental techniques have made it possible to measure the full conditional probability density P(E, E') of the energy transfer between two colliding molecules in the gas phase, one of which is highly energized and the other in thermal equilibrium at a given temperature. Data have now become available for trans-stilbene deactivation by the three bath gas molecules Ar, CO2, and n-heptane (C7H16). The initial energies of trans-stilbene are set to 10 000, 20 000, 30 000, and 40 000 cm (-1). The results show that exceptionally large amounts of energy are transferred in each collision. By application of our partially ergodic collision theory (PECT), we find that the energy transfer efficiency betaE ranges from a rather normal value of 0.15 for n-heptane at the highest excitation energy to 0.93-nearly in the ergodic collision limit-for the argon bath gas at high excitation energy. Generally, the PECT produces a good fit of the data except for the nearly elastic peak in the case of n-heptane, where PECT produces a rounded and downshifted peak in contrast to a sharply defined elastic maximum of the monoexponential functional fit produced from the original experimental data obtained by kinetically controlled selective ionization in the work of the group of Luther in Göttingen. This problem is analyzed and found to be related partly to the lack of treatment of glancing collisions in the theory with a remaining uncertainty due to the weak dependence of energy transfer efficiency on nearly elastic collisions. A summary of the present state of understanding shows that collisional activation and deactivation of reactant molecules is more efficient and more statistical than has been previously realized.

Journal Article↗
PubMed2006

Photoinduced single- versus double-bond torsion in donor-acceptor-substituted trans-stilbenes.

The electronic absorption and fluorescence spectra, quantum yields for fluorescence (Phi(f)) and trans --> cis photoisomerization (Phi(tc)), and fluorescence lifetimes of trans-4-(N-arylamino)-4'-cyanostilbenes (2H, 2Me, 2OM, 2CN, and 2Xy with aryl = phenyl, 4-methylphenyl, 4-methoxyphenyl, 4-cyanophenyl, and 2,5-dimethylphenyl, respectively), trans-4-(N-methyl-N-phenylamino)-4'-cyanostilbene (2MP), trans-4-(N,N-diphenylamino)-4'-cyanostilbene (2PP), trans-4-(N-methyl-N-phenylamino)-4'-nitrostilbene (3MP), and three ring-bridged analogues 2OMB, 2MPB, and 3MPB are reported. Whereas fluorescence and torsion of the central double bond account for the excited decay of the majority of these donor-acceptor substituted stilbenes in both nonpolar and polar solvents (i.e., Phi(f) + 2Phi(tc) approximately 1), exceptions are observed for 2OM, 3MP, and 3MPB in solvents more polar than THF and for 2Me and 2MP in acetonitrile as a result of the formation of a weakly fluorescent and isomerization-free twisted intramolecular charge transfer (TICT) state (i.e., Phi(f) + 2Phi(tc) << 1). The TICT state for 2OM, 2Me, and 2MP results from the torsion of the stilbenyl-anilino C-N single bond, but the torsion of the styryl-anilino C-C bond is more likely to be responsible for the TICT state formation of 3MP and 3MPB. In conjunction with the behavior of aminostilbenes 1, a guideline based on the values of Phi(f) and Phi(tc) for judging the importance of a TICT state for trans-stilbenes is provided. Accordingly, the TICT state formation is unimportant for the excited decay of trans-4-(N,N-dimethylamino)-4'-cyanostilbene (DCS). In contrast, our results support the previously proposed TICT state for trans-4-(N,N-dimethylamino)-4'-nitrostilbene (DNS).

Journal Article↗
PubMed2005

Photoinduced gelation by stilbene oxalyl amide compounds.

Oxalyl amide derivatives bearing 4-dodecyloxy-stilbene as a cis-trans photoisomerizing unit were synthesized. The trans derivative acted as a versatile gelator of various organic solvents, whereas the corresponding cis derivative showed a poor gelation ability or none at all. In diluted solution (c = 2.0 x10(-5) mol dm(-3), ethanol), the cis isomer was photochemically converted into the trans isomer within 4 min. Depending on the radiation wavelength, the trans isomer was stable or liable to photodecomposition. When exposed to irradiation, a concentrated solution of the cis isomer (c = 2.0 x 10(-2) mol dm(-3), ethanol) turned into a gel. The FT-Raman, FT-IR, and 1H NMR spectra demonstrated that the gelation process occurred because of a rapid cis --> trans photoisomerization followed by a self-assembly of the trans molecules. Apart from the formation of hydrogen bonding between the oxalyl amide parts of the molecules, confirmed by FT-IR spectroscopy, it was assumed that the pi-pi stacking between the trans-stilbene units of the molecule and a lipophilic interaction between long alkyl chains were the interactions responsible for gelation.

Journal Article↗
PubMed1998

Isolation, identification, and antioxidant activity of three stilbene glucosides newly extracted from vitis vinifera cell cultures

Suspension cultures of Vitis vinifera L. (Vitaceae) produce many hydroxylated stilbene glucosides found in red wine. From these cells, we isolated and characterized glycosylated stilbenes, (Z)-piceatannol (3,5,3',4'-tetrahydroxystilbene) -3-O-beta-d-glucopyranoside (6) and (E)- and (Z)-resveratrol (3,5, 4'-trihydroxystilbene)-4'-O-beta-d-glucopyranoside (2 and 7, respectively), which have not previously reported to be constituents of Vitis vinifera or wine. The ability of these compounds to act as radical scavengers was investigated using 1,1 diphenyl-2-picryl-hydrazyl, a stable free radical. Antioxidant activities were assessed by their capacity to prevent Cu2+-induced lipid peroxidation in human low-density lipoprotein.

Journal Article↗
PubMed2003

Photoisomerisation and fluorescence behaviour of polyphenylene-based stilbene dendrimers.

The photoinduced structural changes of three polyphenylene-based stilbene dendrimers, G1, G2, and G3, has been studied. They all exhibit fluorescence emission with considerably higher quantum efficiency and longer fluorescence lifetimes compared with the parent stilbene. These dendrimers undergo mutual cis --> trans isomerisation on direct irradiation with 310 nm light at room temperature. In a solvent glass at 77 K, one-way cis --> trans isomerisation was observed for G2. A volume-conserving isomerisation mechanism is presumed to be operating in the cis-to-trans isomerisation of G2 at 77 K.

Journal Article↗