Lobohedleolide and (7Z)-lobohedleolide,new cembranolides from the soft coral lobophytum hedleyi whitelegge

The structures of lobohedleolide (1) and (7Z)-lobohedleolide (2), two new cembranolides containing the α,β-unsaturated carboxylic acid system isolated from the Japanese soft coral Lobophytum hedleyi Whitelegge, were elucidated from spectral and chemical evidence, and the absolute configuration of (1) was determined by X-ray analysis of its p-bromophenacyl ester (9). Lobohedleolide (1) showed growth inhibition of the in vitro Hella cells.     

Synthesis and absolute configuration of +-lineatin,the pheromone of trypodendronlineatum

A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.0^4,7] nonane, $\text{1}$) was achieved. The stereochemistry of (+)-lineatin was established as 1$\text{R}$, 4$\text{S}$, 5$\text{R}$, 7$\text{R}$ by an X-ray crystallographic analysis of an intermediate $\text{1}$$\text{5}$.     

Structures of Ganoderic Acid A and B,Two New Lanostane Type Bitter Triterpenes from Ganoderma lucidum (FR.) KARST.

The structures of two new bitter triterpenes, ganoderic acid A and B. isolated from a mushroom Ganoderma lucidum (FR.) Karst. (Polyporaceae) were determined as 1 and 2 on the basis of spectral data. Ganoderic acid A is a novel highly oxidized triterpene bearing a boat-shaped A-ring of lanostane.     

Ion chromatographic separation of hydrogen ion and other common mono- and divalent cations

We introduced an approach to the ion chromatographic determination of common mono- and divalent cations including hydrogen ion and demonstrated the ability of a C30 column dynamically coated first with dodecylsulfate and then with 18-crown-6 ether to separate the cations by ion-exchange mechanism. Using an ethylenediamine solution containing a small concentration of 18-crown-6 ether and lithium dodecylsulfate at pH 6.2 as eluent, the cations were eluted in the order Li < Na+ < NH4+ < H+ < K+ < Mg2+ < Ca2+ with symmetrical peaks. The conductivity vs. concentration plots were linear about three orders of magnitude, from millimolar to micromolar; and the detection limits were all < 0.6 microM. Rainwater was analyzed directly using this ion chromatographic system with satisfactory results.     

Size-controlled deposition of Ag nanoparticles on alumina with the assistance of a photo-induced chromic reaction, and study of their catalytic properties

This paper describes a promising method to synthesize supported metal catalysts based on a photochromic reaction. Highly dispersed Ag nanoparticles (NPs) with a mean diameter of ca. 10 nm stabilized by 3-mercaptopropionic acid (3-MPA) were prepared as a colloidal precursor solution. The zeta electric potential was found to be negatively charged in the region of pH higher than 5 due to the presence of dissociated carboxylate ions (-COO(-)), which led to electric repulsion between Ag NPs and kept the solution in a highly dispersed colloidal state. In the presence of photochromic molecules, trans-2-hydroxychalcone, the photo-irradiation gradually decreased the electric charge on the nanoparticles owing to the formation of flavylium cations, which induced the assembly of Ag NPs. Such photo-induced assembly-dispersion control of Ag NPs enables size selective deposition on a catalyst support, which is controlled by varying the photo-irradiation time.     

Scale-up of wet kneading in a novel vertical high shear kneader

A novel multi-functional vertical high shear kneader has been developed and its performance in wet kneading has previously been reported [Watano et al., Chem. Pharm. Bull., 50(3), 341-345 (2002)]. In this study, scale-up of wet kneading in the novel vertical high shear kneader was conducted. Pharmaceutical excipients composed of lactose, cornstarch and micro-crystalline cellulose were used as powder samples. Kneading operations were conducted under various operating conditions and three different vessel scales. The dried pellets were then prepared by extruding the wet kneaded masses through a dome-type extruder and their drying by a fluidized bed. The physical properties such as strength and disintegration time of the dried pellets were evaluated. It was found that the properties of the dried pellets and their scale-up characteristics were well expressed by an agitation power per unit vessel volume and dimensionless Froude number.     

meso‐Diketopyripentaphyrin and Diketopyrihexaphyrin as Macrocyclic Tripyrrinone Ligands for NiII Ions

We report expanded porphyrins with pyridine rings and two neighboring carbonyl groups, which allow Ni^II ions to coordinate to the tripyrrinone‐type NNNO coordination structure with Ni?O bonds. The selectivity of tripyrrinone is superior to other pyrrolic or pyridinic cavities of expanded porphyrins. Introduction of α‐carbonyl pyridine next to the tripyrrolic conjugated structure is a powerful strategy for regioselective metalation of flexible expanded porphyrinoids.     

Single-molecule force spectroscopy for studying kinetics of enzymatic dextran elongations

Catalytic elongation of dextran by a single molecule of dextransucrase (DSase) was directly monitored by observing the movements of the positions of a rupture peak, which represented the adhesive force between an isomaltoheptaose (dextran 7-mer)-immobilized probe and a DSase-immobilized mica surface. This was initiated with the addition of sucrose monomers. From the histograms of the rupture peaks after elongation reactions on each individual enzyme and the continuous peak shift of certain single enzymes, the catalytic elongation rate constant (k(cat)) was ascertained to be 1.2-2.7 s(-1).     

Condensed pyridazines. Part IV. Reductive cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-rnethylacrylatc (I) to pyrido[2,3-c] pyridazines and the acid-catalysed cyclization of I to a pyrano[2,3-d] pyridazine

Reduction followed by cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate (I) to pyrido[2,3-c]pyridazines by treatment with triethyl phosphite or hydrazine hydrate as the reducing agents is described. Compound I was also reductively cyclized with sodium borohydride. Treatment of I with concentrated sulfuric acid gave 8-chloro-3,6-dimethyl-2,5-dioxo-5,6-dihydro-2H-pyrano[2,3-d] pyridazine (VII) which also could be synthesized by another independent route. A mechanism for the cyclization is proposed.     

Prolongation of life span of stroke-prone spontaneously hypertensive rats (SHRSP) ingesting persimmon tannin

The effects of persimmon tannin on pathophysiological changes in stroke-prone spontaneously hypertensive rats (SHRSP) were investigated. When the persimmon tannin was chronically ingested by SHRSP, the life span was significantly prolonged, yet the effect on blood pressure was slight. The incidences of brain hemorrhage and infarction were also significantly decreased by this treatment. To elucidate the mechanisms involved in these events, the effects of condensed tannins, including persimmon tannin, on free radicals and lipid peroxidation were examined in vitro. Using electron spin resonance analysis, we found that these tannins have a potent, concentration-dependent scavenging action toward active oxygen free radicals. These tannins strongly inhibited lipid peroxidation in rat brain homogenates, in a concentration-dependent manner. Persimmon tannin inhibited lipid peroxidation similarly to (-)-epigallocatechin. Persimmon tannin was 20 times more effective than alpha-tocopherol in terms of the 50%-inhibitory concentration. The radical scavenging action and inhibition of lipid peroxidation by persimmon tannin may explain, in part, the prolongation of the life span of the SHRSP ingesting persimmon tannin.