Synthesis of (±)-lineatin,the unique tricyclic pheromone of Trypodendron lineatum (olivier)

(+-)-3,3,7-Trimethyl-2,9-dioxatricyclo[4.2.1.0^{4, 7}]noname

and (+-)-3,3,7-trimethyl-2,9-dioxatricyclo[3.3.1.0^{4, 7}] nonane

were synthesized. The latter was shown to be (+-)-lineatin, an ambrosia beetle pheromone.     

Effect of oral pretreatment with antibiotics on the hydrolysis of salicylic acid-tyrosine and salicylic acid-methionine prodrugs in rabbit intestinal microorganisms.

We examined the hydrolysis mechanism of salicylic acid-tyrosine (salicyl-tyrosine) and salicylic acid-methionine conjugate (salicyl-methionine) in rabbits by exploring their behavior following intraduodenal and intracecal administration (72 and 36 mumol/kg, respectively: salicylic acid equivalent). A large amount of salicyl-methionine was absorbed following intraduodenal administration of salicyl-methionine, without being metabolized to salicylic acid in the small intestinal mucosa. On the contrary, salicylic acid was detected in the blood following intraduodenal administration of salicyl-tyrosine, suggesting that salicyl-tyrosine was metabolized in the small intestinal mucosa. After oral pretreatment of rabbits with kanamycin sulfate (6 x 400 mg) or tinidazole (6 x 160 mg), the hydrolysis of salicyl-tyrosine and salicyl-methionine following intracecal administration was inhibited significantly, indicating that the intestinal microorganisms were responsible for the biotransformation of these prodrugs. Furthermore, in rabbits orally pretreated with both kanamycin sulfate and tinidazole, a significant inhibition of salicylic acid formation from salicyl-tyrosine and salicyl-methionine following intracecal administration was observed.     

Stability of a novel hexapeptide, (Me)Arg-Lys-Pro-Trp-tert-Leu-Leu-OEt, with neurotensin activity, in aqueous solution and in the solid state

The stability and some physicochemical properties of a novel hexapeptide, (Me)Arg-Lys-Pro-Trp-tert-Leu-Leu-OEt (I), with neurotensin activity, were investigated. The degradation of I in aqueous solution was observed as a pseudo-first order reaction. By determining the degradation rate of I at various pH values, it was found that I was most stable at around pH 4. The activation energies of the degradation in aqueous solutions at pH 2.2, 6.1, 7.0 and 8.0 were 16.3, 22.2, 23.9 and 24.2 kcal/mol, respectively. The enzymatic hydrolysis of I was studied in vitro with a porcine liver esterase at 37 degrees C. The degradation of I in this system was observed as a pseudo-first order reaction. The degradation rate of I in the presence of the esterase was about 10000 times larger than the rate in a buffer solution. I in the solid state was stable under 65 degrees C and labilized by strong light and/or high humidity. The pKa1, pKa2 and pKa3 of I were 7.1, 10.0 and 11.3, respectively. The partition coefficients between n-octanol and the buffer solution at pH values ranging from 2 to 11 were measured. The partition coefficient increased with the increase of the pH value. But the value at pH 7.0 was 2.10 x 10(-2), which was very low. The solubility of I in aqueous solution was more than 10 mg/ml. From the results of the powder X-ray diffraction pattern, I in the solid state was found to be amorphous. The dissolution rates in the 1st and 2nd fluid of JPXI at 37 degrees C and 100 rpm were 19.4 and 9.0 mg/cm2.min, respectively.     

High Molecular Orientation in Mono- and Trilayer Polydiacetylene Films Imaged by Atomic Force Microscopy

Atomically flat monolayer and trilayer films of polydiacetylenes have been prepared on mica and silicon using a horizontal deposition technique from a pure water subphase. Langmuir films of 10,12-pentacosadiynoic acid (I) and N-(2-ethanol)-10,12-pentacosadiynamide (II) were compressed to 20 mN/m and subsequently polymerized by UV irradiation at the air-water interface. Blue and red forms of the films were prepared by varying exposure times and incident power. Polymerization to the blue-phase films produced slight contractions of 2 and 5% for the films of II and I, respectively. Longer UV exposures yielded red-phase films with dramatic film contraction of 15 and 32% for II and I, respectively. The horizontal deposition technique provided transfer ratios of unity with minimal film stress or structure modification. Atomic force microscopy images revealed nearly complete coverage of the substrate with atomically flat films. Crystalline domains of up to 100 micrometers of highly oriented polydiacetylene molecules were observed. The results reported herein provide insight into the roles of molecular packing and chain orientations in converting the monomeric film to the polymerized blue and red phases. Copyright 2000 Academic Press.     

Properties of χ-alumina as related to catalysis

-Alumina was synthesized by thermal decomposition of aluminium(III) isopropoxide, and its properties were investigated. The change in its surface area with increasing calcination temperature resembled that of -alumina. Both aluminas had the same acid strength, and their activities in isomerization of 1-butene were the same. -Alumina as a support for molybdenum catalyst in the epoxidation of allyl alcohol also behavedin the same manner as -alumina. Thus -alumina has almost the same catalytic properties as -alumina.     

Determination of a new cerebral vasodilator 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-[2-(N-benzyl-N-methylamino)]-ethyl ester 5-methyl ester hydrochloride (YC-93) in plasma by electron capture gas chromatography

A highly sensitive method for the quantitative determination of 2,6-dimethy-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-[2-(N-benzyl-N-methyl-amino)]-ethyl ester 5-methyl ester hydrochloride (YC-93) in plasma is described. After extraction, YC-93 was oxidized to pyridine analogue with nitrous acid and detected by electron capture gas chromatography. The sensitivity was 2–3 ng/ml, which is suficient to determine plasma concentrations of YC-93 after oral administration of clinical doses to humans.