Synthesis of a singly bridged resorcinarene-dimer by Mannich reaction with N,N′-diethylethylenediamine and formaldehyde: self-inclusion of bridging diazahexamethylene unit in methanol

Mannich reaction of resorcin[4]arene with N,N′-diethylethylenediamine and formaldehyde produced a singly bridged resorcinarene-dimer bearing sixteen hydroxyl groups at their peripheral positions, which exists in a closed capsular conformation including the diazahexamethylene bridge chain between the two resorcinarene units in CD₃OD.     

New colorimetric detection of glucose by means of electron-accepting indicators: ligand substitution of [Fe(acac)3-n(phen)n]n+ complexes triggered by electron transfer from glucose oxidase

A new colorimetric detection technique for glucose, based on electron transfer from glucose oxidase (GODred) to iron(III) acetylacetonate(acac)/phenanthroline(phen) mixed complexes, is developed. When GOD is added to an aqueous mixture that contains tris(acetylacetonato)iron(III) complex (FeIII-(acac)3), 1,10-phenanthroline (phen), and glucose, the color immediately changes from pale yellow to red. The red color originates from formation of tris(1,10-phenanthroline)iron(II) complex ([FeII(phen)3]2+). Differential pulse voltammetry indicates that cationic, mixed-ligand complexes of [Fe(acac)3-n-(phen)n]n+ are formed upon mixing the labile FeIII(acac)3 complex and phenanthroline. The cationic mixed-ligand complexes electrostatically bind to GOD (pI 4.2), and are easily reduced by electron transfer from GODred. This electron transfer is not affected by the presence of oxygen. The reduced complex [FeII(acac)3-n(phen)n](n-1)+ then undergoes rapid ligand exchange to FeII (phen)3. Formation of the colored FeII complex is repressed when the salt concentration in the mixture is increased, or when anionic bathophenanthroline disulfonate (BPS) is employed in place of phenanthroline. The use of labile metal complexes as electron acceptors would be widely applicable to the design of new biochromic detection systems.     

Measurement of neutrons from an electron accelerator by rem-counter

In the measurement of neutrons from the medical electron accelerator by a rem counter, two problems disturb accurate measurements. One is the pile-up of signals produced by X-rays during each X-ray burst and the other is the increased counting loss caused by bunched nature of yielded neutrons. The time spectrum of neutrons measured by the rem counter 2202 D (manufactured by Studsvik) rises up to a maximum value by about 20 microseconds and then falls down exponentially with a time constant of about 90 microseconds. On the other hand, that of X-rays is roughly rectangular with several microseconds width. A time discriminating system was prepared to be combined with the rem counter, which was triggered by leading edge of electron beam pulses, rejected pile-up signals due to X-ray bursts, and counted pulses of neutrons in a specified time window. The system discriminated the pile-up enough to measure neutrons at a X-ray dose rate of at least 30 mGy/h. Nonparalyzable counting loss correction was practicable upto about 10 mSv/h for the beam pulse rate of 85 Hz, in which the dead time of the rem counter was estimated as 4 microseconds.     

Inhibitors of nitric oxide production from the rhizomes of Alpinia galanga: structures of new 8-9' linked neolignans and sesquineolignan

The 80% aqueous acetone extract from the rhizomes of Alpinia galanga showed nitric oxide (NO) production inhibitory activities in mouse peritoneal macrophages. From the aqueous acetone extract, three new 8-9' linked neolignans, galanganal, galanganols A and B, and a sesquineolignan, galanganol C, were isolated together with nine known phenylpropanoids and p-hydroxybenzaldehyde. The structures of new neolignans were determined on the basis of physicochemical and chemical evidence. In addition, the inhibitory effects of the constituents from the rhizomes of A. galanga on NO production induced by lipopolysaccharide in mouse peritoneal macrophages were examined. Among them, galanganal (IC50=68 microM), galanganols B (88 microM) and C (33 microM), 1'S-1'-acetoxychavicol acetate (2.3 microM), 1'S-1'-acetoxyeugenol acetate (11 microM), trans-p-hydroxycinnamaldehyde (ca. 20 microM), trans-p-coumaryl alcohol (72 microM), and trans-p-coumaryl diacetate (19 microM) were found to show inhibitory activity.     

Bioactive Saponins and Glycosides. Part 29

Three new acylated oleanane‐type triterpene saponins, theasaponins A₆ ( 1 ), A₇ ( 2 ), and B₅ ( 3 ), were isolated from the saponin fraction of the seeds of the Japanese tea plant Camellia sinensis together with the known constituent foliatheasaponin III ( 4 ). The structures of the glycosides 1 – 3 were elucidated on the basis of spectroscopic, chemical, and physico‐chemical evidence.     

Evaluation of the dynamic properties of polymer latex particles interacting with quartz interface by evanescent wave dynamic light scattering

The diffusion behavior of polymer latex particles in dispersion near the quartz interface has been estimated by evanescent wave dynamic light scattering (EVDLS) technique. The diffusion coefficient of the particles was measured as a function of the distance between the particle and interface. The apparent diffusion coefficient estimated by EVDLS was small for particles near the interface and increased upon increasing the distance from the interface, and then saturated at a certain value which is close to the value expected for free-motion. The range of the distance over which diffusion was affected by interaction with the interface depended on the added salt concentration. This means that the diffusion of the particle is influenced by an electrostatic interaction between the particle and quartz interface in addition to the hydrodynamic effect near the wall. This range was found to be more than 800?nm at 0?M salt condition but about 400?nm at 10^-4 and 10^-3?M salt conditions. Hence it is appropriate to say that the hydrodynamic effect reaches up to 400?nm and the electrostatic effect is longer ranged, more than 800?nm, for the system studied here. The EVDLS technique is a very powerful tool for quantitative estimations of the dynamic behavior of the particle near the interface and for estimation of the range where the wall effect is dominant. EVDLS will give us an answer to the question of “where is the ‘interface’ and where is the ‘bulk’?”.     

Design and synthesis of sulfur based inhibitors of matrix metalloproteinase-1

Fibroblast collagenase (MMP-1), a member of the matrix metalloproteinases family, is believed to be a pathogenesis of arthritis, by cleaving triple-helical type II collagen in cartilage. From the similarity of the active site zinc binding mode with hydroxamate, we designed and synthesized alpha-mercaptocarbonyl possessing compounds (3-5), which incorporated various peptide sequences as enzyme recognition sites. The P4-P1 peptide incorporating compound (3) exhibited as potent inhibition as the hydroxamate (1) and the carboxylate (2) type inhibitors, with an IC50 of 10(-6) M order against MMP-1. But the inhibitor (3) related compounds (6-8) displayed decreased or no inhibitory potencies. These results suggest that the existence of both the carbonyl and thiol groups might be critical for the inhibition, and the distance between the two functional groups is important for inhibitory potency. For Pn' peptide incorporating compounds (4a-k), except for 4h and 4k, all compounds showed IC50 values under sub-nanomolar. Among them, for potent inhibition, Leu was better than Phe and Val as the P1' amino acid, and the P2' position amino acid was necessary, and preferentially Phe. Insertion of the Pn peptide into 4d or 4k, giving compounds 5a-c, did not increase the activities of 4d and 4k. Substitution of the mercapto group with other functional groups lost the activity of compound 4a. The stereochemical preference at the thiol-attached position was also determined by preparation of both isomers of 4a. It was found that the S configuration compound (36b) is approximately 100 times more potent than the corresponding R-isomer (36a).     

Design and synthesis of carboxylate inhibitors for matrix metalloproteinases

A series of carboxylate compounds were prepared from N(alpha)-substituted 2,3-diaminopropionic acid and were tested for efficacy as matrix metalloproteinase (MMP) inhibitors. During modeling of the initial compound 10a, we utilized three-dimensional structure modeling software (InsightII/Discover Ver. 2.98). Some of the prepared carboxylate derivatives, such as carbamate compounds (12c,d, 22) and sulfonamide compounds (14b,c), proved to be effective MMP-1 inhibitors (with IC50 values of a 10(-6) M order), depending on the substituent at the N(alpha)-position of 2,3-diaminopropionic acid. Some of them were also evaluated for inhibition of stromelysin-1 (MMP-3), and the sulfonamide compound 14c exceeded the lead compound 5b in its MMP-3 inhibitory potency. For the carbamate compounds, we investigated the minimum molecular size at which the MMP-1 inhibitory potency was maintained, and found that this was P3-P1' compound 10b.     

Enzyme immunoassay of angiotensin II in human plasma.

We established a highly sensitive double-antibody enzyme immunoassay (EIA) for angiotensin (ANG) II. For competitive reactions, the ANG II-antibody was incubated with ANG II standard (or sample) and beta-D-galactosidase-labeled ANG III (delayed addition). Free and antibody-bound labeled antigen were separated using an anti-rabbit immunoglobulin G (IgG) coated immunoplate. The enzyme activity on the plate was fluorometrically determined. The present immunoassay allows detection of 0.4 to 72 fmol/well of ANG II. Using the present EIA, ANG II-like immunoreactivity (-LI) in human plasma was determined. The level of ANG II-LI in human plasma from 10 healthy volunteers was 33.3 +/- 10.4 pmol/l.     

Ion-chromatographic behavior of alkali metal cations and ammonium ion on zirconium-adsorbing silica gel

The preparation and evaluation of zirconium-adsorbing silica gel (Zr-Silica) as an ion-exchange stationary phase in ion chromatography for inorganic anions and cations was carried out. The Zr-Silica was prepared by the reaction of silanol groups on the surface of the silica gel with zirconium butoxide (Zr(OCH2CH2CH2CH3)4) in ethanol. The ion-exchange characteristics of the Zr-Silica were evaluated using 10 mM tartaric acid at pH 2.5 as eluent. The Zr-Silica was found to act as a cation-exchanger under the eluent conditions. The retention behavior of alkali and alkaline earth metal cations was then investigated. The Zr-Silica column was proved to be suitable for the simultaneous separation of alkali metal cations and ammonium ion. Excellent separation of the cations on a 15 cm Zr-Silica column was achieved in 25 min using 10 mM tartaric acid as eluent.