Electroretinogram Characteristics and the Spectral Mechanisms of the Median Ocellus and the Lateral Eye in Limulus polyphemus

Electrical responses (ERG) to light flashes of various wavelengths and energies were obtained from the dorsal median ocellus and lateral compound eye of Limulus under dark and chromatic light adaptation. Spectral mechanisms were studied by analyzing (a) response waveforms, e.g. response area, rise, and fall times as functions of amplitude, (b) slopes of amplitude-energy functions, and (c) spectral sensitivity functions obtained by the criterion amplitude method. The data for a single spectral mechanism in the lateral eye are (a) response waveforms independent of wavelength, (b) same slope for response-energy functions at all wavelengths, (c) a spectral sensitivity function with a single maximum near 520 mµ, and (d) spectral sensitivity invariance in chromatic adaptation experiments. The data for two spectral mechanisms in the median ocellus are (a) two waveform characteristics depending on wavelength, (b) slopes of response-energy functions steeper for short than for long wavelengths, (c) two spectral sensitivity peaks (360 and 530–535 mµ) when dark-adapted, and (d) selective depression of either spectral sensitivity peak by appropriate chromatic adaptation. The ocellus is 200–320 times more sensitive to UV than to visible light. Both UV and green spectral sensitivity curves agree with Dartnall's nomogram. The hypothesis is favored that the ocellus contains two visual pigments each in a different type of receptor, rather than (a) various absorption bands of a single visual pigment, (b) single visual pigment and a chromatic mask, or (c) fluorescence. With long duration light stimuli a steady-state level followed the transient peak in the ERG from both types of eyes.     

Asymmetric synthesis and biological evaluation of Danshensu derivatives as anti-myocardial ischemia drug candidates

The synthesis and bioactivities of Danshensu derivatives (R)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)propanoate (1a), (R)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)propanoate (1b) and their racemates 7 and 10 were reported in this paper. These derivatives were designed to improve their chemical stability and liposolubility by protecting Danshensu’s phenolic hydroxyl groups with acetyl or methylene which could be readily hydrolyzed to release bioactive Danshensu. The asymmetric synthesis of 1a and 1b were achieved by catalytic hydrogenation of (Z)-methyl 2-acetoxy-3-(3,4-diacetoxyphenyl)-2-propenoate (6a) and (Z)-methyl 2-acetoxy-3-(3,4-methylenedioxyphenyl)-2-propenoate (6b) in excellent enantiomeric excesses (92% ee and 98% ee, respectively) and good yields (>89%). An unexpected intermediate product, (Z)-2-acetoxy-3-(3,4-dihydroxyphenyl)acrylic acid (4c) was obtained with high chemoselectivity in 86% yield by keeping the reaction temperature at 60 °C and its structure was identified by X-ray single crystal diffraction analysis. 1a, 1b and their racemates 7, 10 as well as 4c exhibited potent protective activities against hypoxia-induced cellular damage. The in vitro test showed that all these compounds could increase cell viability, and inhibit lipid hyperoxidation. Furthermore, 1a and 4c could inhibit apoptosis by regulating the expression of apoptosis-related molecule in gene and protein levels, up-regulating the expression of bcl-2 and down-regulating bax and caspase-3. The in vivo test indicated that 4c exhibited anti-myocardial ischemic effects featured by reducing infarction size and increasing the level of the intracellular enzymes detectable in serum. Therefore, these Danshensu derivatives may be good drug candidates for anti-myocardial ischemia therapy and merit further investigation.     

Cell-pool tryptophan phases in ergot alkaloid fermentation

Three cell-pool tryptophan phases are recorded as characteristics of the alkaloid fermentation byClaviceps paspali grown on a simple defined medium without tryptophan. Within the early phase designated “tryptophan down” the alkaloid-biosynthetic activity of the mycelium attains the maximum, protein synthesis is reduced and extracellular proteases are formed. Cell-pool tryptophan level (b) drops, tryptophan synthetase activity (c) intensifies and sums of logb+logc after different time intervals remain constant. In the subsequent “tryptophan up” phase tryptophan level (b) increases, alkaloid yield (a) becomes a function of time and reaches the top level still tolerable by tryptophan synthetase. The difference of the logb—logc is constant. The tryptophan synthetase diminishes its activity simultaneously with the alkaloid-biosynthetic activity of the mycelium. The district between the “tryptophan down” and “tryptophan up” phase is an especially promising target for the investigation of the regulation of alkaloid formation and continuous fermentation of these compounds. During the third, i.e. “tryptophan over” phase, cell-pool tryptophan accumulates and attains a concentration exerting a negative effect on the alkaloid biosynthesis.     

Dopamine release and molecular modeling study of some coumarin derivatives

4-aryl-2-amino-6-(4-hydroxy-2-oxo-2H-chromen-3-yl)-pyridin-3-carbonitrile (1), 4-aryl-2-oxo-6-(4-hydroxy-2-oxo-2H-chromen-3-yl)-pyridin-3-carbonitriles (2a-2c), 3-(6-aryl-1,2,5,6- tetrahydro-2-thioxopyrimidin-4-yl)-4-hydroxy-2H-chromen-2-one (3a, 3b) and pyrazol-3-yl-4-hydroxycoumarin derivatives (4a-4c, 5, 6a, 6b, 7a, 7b, and 8a-8c) were prepared in order to measure their % change dopamine release in comparison to amphetamine as reference, using PC-12 cells in different concentrations. In addition, the molecular modeling study of the compounds into 3BHH receptor was also demonstrated. The calculated inhibition constant (k_i) implemented in the AutoDock program revealed identical correlation with the experimental results to that obtained binding free energy (ΔG_b) as both parameters revealed reasonable correlation coefficients (R²) being 0.51 involving 10 compounds; (1, 2b, 2c, 3a, 3b, 4a, 4b, 6a, and 8c).     

Low-level chemiluminescence of hydroperoxide-supplemented cytochrome c

Ferricytochrome c showed low-level chemiluminescence, with a light-emission measured of about 1×10³–3×10³ counts/s, when supplemented with organic hydroperoxides. Tertiary hydroperoxides (cumene hydroperoxide and t-butyl hydroperoxide) showed a saturation behaviour at about 5mm-hydroperoxide, whereas primary hydroperoxides showed a quadratic dependence on the hydroperoxide concentration. Chemiluminescence depended linearly on cytochrome c concentration, and optimal light-emission was observed at [t-butyl hydroperoxide]/[ferricytochrome c] ratios of 160–500. Hydroperoxide-supplemented ferricytochrome c consumed O₂ at a rate of 1.0μmol/min per μmol of cytochrome c; the rate of O₂ uptake was linearly related to the concentration of cytochrome c. The Soret absorption band of ferricytochrome c decreased about 64% after incubation with t-butyl hydroperoxide, whereas the 530nm band was almost totally abolished. Light-emission was (a) inhibited competitively by cyanide. (b) inhibited by singlet-oxygen quenchers (e.g. β-carotene), scavengers (e.g. dimethylfuran) and traps (e.g. histidine and tryptophan) and (c) increased by singlet-oxygen-chemiluminescence enhancer 1,4-diazabicyclo[2.2.2]-octane. Superoxide dismutase had no effect on the present system. The participation of free radicals is suggested by the effect of the radical trap 2,5-di-t-butylquinol. Singlet-oxygen dimol emission seems to be mainly responsible for the observed light-emission; a mechanism that can account for the major part of the present experimental observations is proposed.     

Diheteroarylmethyl substituted titanocenes: A novel class of possible anti-cancer drugs

From the reaction of tert-butyl lithium or n-butyl lithium with N-methylpyrrole (1a), furan (1b) or 2-bromo-thiophen (1c), 2-N-methylpyrrolyl lithium (2a), 2-furyl lithium (2b) or 2-thiophenyl lithium (2c), respectively, was obtained. When reacted with 6-(2-N-methylpyrrolyl) fulvene (3a), 6-(2-furyl) fulvene (3b) or 6-(2-thiophenyl) fulvene (3c), the corresponding lithiated intermediates were formed (4a-c). Titanocenes (5a-c) were obtained through transmetallation with titanium tetrachloride. When these titanocenes were tested against pig kidney epithelial (LLC-PK) cells, inhibitory concentrations (IC₅₀) of 32 μM, 140 μM, and 240 μM, respectively, were observed. These values represent improved cytotoxicity against LLC-PK, compared to their ansa-analogues.     

Concentration and Metabolic Turnover of Indoles in Germinating Kernels of Zea mays L

The amounts and rates of metabolic turnover of the indolylic compounds in germinating kernels of sweet corn were determined. Knowledge of pool size and rate of pool turnover has permitted: (a) identification of indole-3-acetyl-myo-inositol as the major chemical form for transport of indole-3-acetic acid (IAA) from endosperm to shoot; (b) demonstration that the free IAA of the endosperm is turning over rapidly with a half-life of 3.2 hours; (c) identification of esters of IAA as the immediate precursors of IAA in the endosperm and shoot; (d) demonstration that neither tryptophan nor tryptamine is a major precursor of IAA for the seed or shoot; (e) identification of IAA-myo-inositol glycosides as precursors of IAA-myo-inositol.     

Most of the homoeologous pairing at metaphase I in wheat-rye hybrids is not chiasmatic

The use of telomeric C-bands in wheat-rye hybrids has made it possible to distinguish three types of wheat-wheat (1B^L) and wheat-rye associations (a, end-to-end extremely distal; b, end-to-ed distal; and c, interstitial) between homoeologous chromosomes at different metaphase I stages (early, middle and late) and also to estimate the actual recombination frequencies for such associations at anaphase I. There was a decrease of the a and b association frequencies during the different metaphase I stages, whereas the c type remained without variation in all stages. A good fit between the frequencies of c associations at metaphase I and the number of recombinant chromosomes at anaphase I, assuming a maximum of one chiasma per bond, was found; however, there was no correspondence between metaphase I and anaphase I data when all associations (a + b + c) were considered. In addition, rye-rye homologous pairing was observed at metaphase I, but no evidence for rye-rye recombination was found at anaphase I. The results indicate that most of end-to-end (a and b) homoeologous and nonhomologous associations are actually nonchiasmatic and are a remnant of prophase pairing.     

Reaction of 2-amino-2-deoxyheptoses with cyclic β-dicarbonyl compounds

The reaction between 2-amino-2-deoxyaldoses and β-dicarbonyl compounds yields polyhydroxyalkylpyrroles. Thus, 6,6-dimethyl-2-(D-galacto-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4a), 6,6-dimethyl-2-(D-gluco-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4b), and 6,6-dimethyl-2-(D-manno-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (4c) have been obtained from 5,5-dimethylcyclohexane-1,3-dione (2) and 2-amino-2-deoxyheptoses having D-glycero-L-gluco (1a), D-glycero-D-ido (1b), and D-glycero-D-talo (1c) configurations, respectively. 2-Amino-2-deoxy-D-glycero-L-manno-heptose (1d), the epimer of 1a, also reacts with 2, to yield 4a. In a similar way, 1a, 1b, and 1c react with cyclohexane-1,3-dione (3), to give 2-(D-galacto-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5a), 2-D-gluco-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5b), and 2-(D-manno-pentitol-1-yl)-4,5,6,7-tetrahydroindol-4-one (5c), respectively.     

Oxidation of 1,4-alkanediols into γ-lactones via γ-lactols using Rhodococcus erythropolis as biocatalyst

Whole cells of Rhodococcus erythropolis DSM 44534 grown on ethanol, (R)- and (S)-1,2-propanediol were used for biotransformation of racemic 1,4-alkanediols into γ-lactones. The cells oxidized 1,4-decanediol (1a) and 1,4-nonanediol (2a) into the corresponding γ-lactones 5-hexyl-dihydro-2(3H)-furanone (γ-decalactone, 1c) and 5-pentyl-dihydro-2(3H)-furanone (γ-nonalactone, 2c), respectively, with an EE(R) of 40–75%. The transient formation of the γ-lactols 5-hexyl-tetrahydro-2-furanol (γ-decalactol, 1b) and 5-pentyl-tetrahydro-2-furanol (γ-nonalactol, 2b) as intermediates was observed by GC–MS. 1,4-Pentanediol (3a) was transformed into 5-methyl-dihydro-2(3H)-furanone (γ-valerolactone, 3c) whereas (R)- and (S)-2-methyl-1,4-butanediol (4a) was converted to the methyl-substituted γ-butyrolactones 4-methyl-dihydro-2(3H)-furanone (4c₁) and 3-methyl-dihydro-2(3H)-furanone (4c₂) in a ratio of 80:20 with a yield of 55%. Also cis-2-buten-1,4-diol (5a) was transformed resulting in the formation of 2(5H)-furanone (γ-crotonolactone, 5c). At the higher pH values of 8.8 the yield of lactone formed was improved; however, the enatiomeric excesses were slightly higher at the lower pH of 5.2.     

Novel benzyl-substituted molybdocene anticancer drugs

From the reaction of 6-(p-methoxyphenyl) fulvene (1a), 6-(3,4-dimethoxyphenyl) fulvene (1b) and 6-(3,4,5-trimethoxyphenyl) fulvene (1c) with LiBEt₃H, lithiated cyclopentadienide intermediates (2a-c) were synthesised. These intermediates were then transmetallated to molybdocene using MoCl₄ (synthesized in situ) to yield the benzyl-substituted molybdocenes bis-[(p-methoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3a), bis-[(3,4-dimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3b), and bis-[(3,4,5-trimethoxybenzyl)cyclopentadienyl] molybdenum (IV) dichloride (3c). The molybdocene 3a was characterised by single crystal X-ray diffraction. All three molybdocenes had their cytotoxicity investigated through MTT based preliminary in vitro testing on the human renal cell line Caki-1 in order to determine their IC50 values and compare them with the corresponding titanocene and vanadocene dichloride derivatives. Molybdocenes 3b-c were found to have the same IC50 values of 290 μM, while 3a yielded a value of 84 μM, respectively     

Synthesis of Pyrrolo[2′,3′:4,5]Furo[3,2-c]Pyridine-2-Carboxylic Acids

1H-Pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylic acid (6a) and its 1-methyl (6b) and 1-benzyl (6c) derivatives were synthesized. 3-(5-Methoxycarbonyl-4H-furo[3,2-b]-pyrrole-2-yl)propenoic acid (1) was converted to the corresponding azide 2, which in turn was cyclized to give 3 by heating in diphenylether. The pyridone 3 obtained was aromatized with phosphorus oxychloride, then reduced with zinc in acetic acid to give methyl 1H-pyrrolo[2′,3′:4,5]furo[3,2-c]pyridine-2-carboxylate (5), which by hydrolysis gave the corresponding carboxylic acid 6a.     

Synthesis and antitumor activity of novel 1-substituted phenyl 3-(2-oxo-1,3,4-oxadiazol-5-yl) β-carbolines and their Mannich bases

A series of novel 1-(substituted phenyl)-3-(2-oxo-1,3,4-oxadiazol-5-yl) β-carbolines (4a–e) and the corresponding Mannich bases 5–9(a–c) were synthesized and evaluated for their in vitro antitumor activity against seven human cancer cell lines. Compounds of 4a–e series showed a broad spectrum of antitumor activity, with GI₅₀ values lower than 15 μM for five cell lines. The derivative 4b, having the N,N-dimethylaminophenyl group at C-1, displayed the highest activity with GI₅₀ in the range of 0.67–3.20 μM. A high selectivity and potent activity were observed for some Mannich bases, particularly towards resistant ovarian (NCI-ADR/RES) cell lines (5a, 5b, 6a, 6c and 9b), and ovarian (OVCAR-03) cell lines (5b, 6a, 6c, 9a, 9b and 9c). In addition, the interaction of compound 4b with DNA was investigated by using UV and fluorescence spectroscopic analysis. These studies indicated that 4b interact with ctDNA by intercalation binding.     

Synthesis of 4-substituted pyrido[2,3-d]pyrimidin-4(1H)-one as analgesic and anti-inflammatory agents

4-Substituted-pyrido[2,3-d]pyrimidin-4(1H)-ones 4a–c were synthesized by oxidation of 4-substituted-dihydropyrido[2,3-d]pyrimidin-4(1H)-ones 3a–c which were in turn prepared from arylidenemalononitriles 1a–c and 6-aminothiouracil 2. The reactivity of compounds 4a–c towards some reagents such as formamide, carbon disulfide, urea, thiourea, formic and acetic acids were studied. All the synthesized compounds were characterized by spectroscopic means and elemental analysis. Compound 4c exhibited 64% and 72% analgesic activity. Also, compound 4b showed 50% and 65% anti-inflammatory activity. Interestingly these compounds showed one-third of ulcer index of the reference aspirin and diclofenac.     

Reversible association processes of globular proteins. I. Insulin

1.

1. The dissociation of insulin is favored by (a) an increase in charge, (b) a decrease in ionic strength, and (c) an increase in temperature.     

Biotransformation of heterocyclic dinitriles by Rhodococcus erythropolis and fungal nitrilases

2,6-Pyridinedicarbonitrile (1a) and 2,4-pyridinedicarbonitrile (2a) were hydrated by Rhodococcus erythropolis A4 to 6-cyanopyridine-2-carboxamide (1b; 83% yield) and 2-cyanopyridine-4-carboxamide (2b; 97% yield), respectively, after 10 min. After 118 h, the intermediates 1b or 2b were transformed into 2,6-pyridinedicarboxamide (1c; 35% yield) and 2,6-pyridinedicarboxylic acid (1d; 60% yield) or 2-cyanopyridine-4-carboxylic acid (2c; 64% yield), respectively. The nitrilase from Fusarium solani afforded cyanocarboxylic acids 1e and 2c after 118 h (yields 95 and 62%, respectively). 3,4-Pyridinedicarbonitrile (3a) and 2,3-pyrazinedicarbonitrile (4a) were inferior substrates of nitrile hydratase and nitrilase.     

Depsidones and other constituents from Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides with potent inhibitory effect on motility of zoospores of grapevine pathogen Plasmopara viticola

In our search for secondary metabolites regulating the motility behavior of zoospores of the grapevine downy mildew pathogen Plasmopara viticola, we found that extracts from an endophytic fungus Phomopsis sp. CAFT69 and its host plant Endodesmia calophylloides remarkably impaired motility of zoospores followed by lysis. The active principles in the extracts were isolated and identified as two new compounds, namely excelsional (1a) and 9-hydroxyphomopsidin (2a), together with excelsione (1b), phomopsidin (2b), alternariol (3a), alternariol-5-O-methyl ether (3b), the hitherto undescribed 5′-hydroxyalternariol (3c), altenusin (4) from the fungus, xanthochymol (5) and 1,5-dihydroxy-3-methoxyxanthone (mesuaxanthone, 6) from the plant. Bioassays revealed that compounds 1a/b, 2a/b, and 3a–6 displayed motility inhibition and lytic activities against zoospores of the grapevine downy mildew pathogen P. viticola in a dose- and time-dependent manner from 1 to 10 μg/mL. Their structures were elucidated by extensive spectroscopic analyses including 2D NMR techniques. This is the first report of an endophyte and its natural products from E. calophylloides and the first isolation of compounds 5 and 6 from this plant.     

Synthesis and characterization of new coordination polymers generated from oxadiazole-containing ligands and IIB metal ions

The coordination chemistry of the oxadiazole-containing rigid bidentate ligands 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (L1) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (L2) with inorganic IIB metal salts have been investigated. Five new coordination polymers (1-5) were prepared by solution reactions and fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Cd(L1)₂(CH₃CN)₂](ClO₄)₂ · (CH₃CN)₂ (1) crystallized in the monoclinic space group P2₁/c, a = 8.4028(5) Å, b = 21.3726(13) Å, c = 10.5617(7) Å, β = 95.1200(10)°, and Z = 2. In the solid state, it adopts an infinite two-dimensional polymeric structural motif with effective cross section of ca. 14.31 × 14.31 Å. Cd(L2)(H₂O)(NO₃)₂ (2) crystallized in the monoclinic space group Ia, a = 7.1203(5) Å, b = 22.2475(15) Å, c = 20.2652(16) Å, β = 90.6080(10)°, and Z = 8. In the solid state, the two Cd(II) centers are connected to each other by L2 ligands and bridging nitrates into a two-dimensional network. [ZnCl₂(L1)] (3) and [HgI₂(L1)] · CH₃CN (4) crystallized in the monoclinic crystal system (3: P2₁/c, a = 5.3702(3) Å, b = 20.4800(11) Å, c = 12.4093(7) Å, β = 94.7930(10)°, and Z = 4; 4: P2/n, a = 17.2733(11) Å, b = 5.2173(3) Å, c = 20.4069(13) Å, β = 102.8690(10)°, and Z = 4). In the solid state, Zn(II) and Hg(II) metal centers are connected to each other by L1 ligands into a zigzag chain motif. Compound 5 (HgBr₂(L2) is different from 3 and 4, monoclinic, P2(1)/n, a = 5.470(4) Å, b = 16.271(13) Å, c = 16.486(12) Å, β = 93.197(15)°, and Z = 4) adopts a novel one-dimensional helical chain motif which resulted from the relative different coordinated orientation of the two N-donors on L2 ligand.     

Dimethylsulfoxide as a potential tool for analysis of compartmentation in living plant cells

Data are presented which indicate that dimethylsulfoxide (DMSO) acts selectively on the plasma membrane of cultured tobacco cells, rendering it more permeable to small molecules, while having a far smaller effect on the permeability of the vacuolar membrane. The results which support this conclusion are: (a) DMSO (5 to 10%, by volume) causes complete release of [¹⁴C]tryptophan newly synthesized from [¹⁴C]indole while causing efflux of only about 20% of the total intracellular tryptophan pool; (b) similar concentrations of DMSO do not cause substantial release from these cells of phenolic compounds or preloaded neutral red, nor of β-cyanin from fresh beet discs; (c) kinetic studies of release of tryptophan and neutral sugars and of efflux of ⁸⁶Rb⁺ show that DMSO selectively promotes rapid release of a portion of the total pool, followed by a substantially slower release of the remaining pool; (d) when tobacco cell protoplasts are incubated in the presence of 7.5% (by volume) DMSO, rapid lysis is observed concomitant with the release of intact vacuoles. These data indicate that a procedure involving a brief treatment of intact plant cells or tissues with DMSO may be used to assess the distribution of metabolites between cytoplasmic and vacuolar compartments.