Regioselective ring opening of unsymmetrical cyclic ethers with the A1C13-NaI-acetonitrile system: Application to hydroxylation of ent-kaurene.

Unsymmetrically substituted 5-membered cyclic ethers were effectively cleaved with the A1C1₃-NaI-CH₃CN system at the less hindered carbon atom to afford δ-iodoalcohols. Conversion of ent-kaurene to ent-14α- and ent-12β-hydroxykaurene was achieved through the ring opening of the cyclic ether with the present system as a key step.     

Ribonuclease protection assay on microchip electrophoresis

We describe the potential of microchip electrophoresis with a Hitachi SV1210, which can be used to evaluate the integrity of total RNA, for the analysis of mRNA expression. The ribonuclease (RNase) protection assay was performed by using microchip electrophoresis with cyanine 5 (Cy5) labeled 248-base antisense RNA probe (riboprobe) encoding adipose-type fatty acid binding protein (A-FABP) as the riboprobe. The fluorescence intensity corresponding to the protected RNA fragment increased in a dose-dependent manner with respect to the complementary strand RNA. Results were obtained in 120 s, and the same amount of Cy5-labeled antisense riboprobe as used in the conventional method can be used. Furthermore, 8 times more sensitive detection of mRNA by microchip electrophoresis could be obtained. An obvious increase in the mRNA expression of A-FABP, which is known as a differentiation marker of adipocytes, occurred during the adipocyte differentiation of 3T3-L1 cells. These results clearly indicate the potential of microchip electrophoresis for the analysis of mRNA expression in cells.     

Organic Synthesis by Means of Metal Complexes. X1Copper Catalyzed Oxidation of o-Phenylenediamine to Mucononitrile

This paper describes a simple stereospecific synthesis of cis,cis-mucononitrile and its derivatives in hig hyields. The procedure is based on the oxidation of o-phenylenediamine derivatives with molecular oxygen catalyzed by cuprous salts. Oxidative coupling of aniline with molecular oxygen catalyzed by cuprous chloride gives azobenzene². Also it is known that o-phenylenediamine (PDA) is oxidized in the presence of ferric³, Cobaltous⁴, and cupric chlorides⁵to afford 2,3-diaminophenazine or 2-amino-3oxophenazine. The formation of a metal nitrogen bonded intermediate, followed by intermolecular reaction was postulated in these oxidation reactions.^6,7.Mechanistic consideration of these reactions leads us to expect that the oxidation of PDA with molecular oxygen under selected conditions should proceed intramolecularly with ring claevage to give mocononitrile(MNL). PDA is converted into MNL by using stoichimetricamount of nickel peroxide⁸or lead terraacetate⁹, but the yields are low. We now wish to report a selective oxidative ring cleavage of PDA. rather than the phenazine formation, to give MNL in a very high yield.     

An Extension of the Prüfer Code and Assembly of Connected Graphs from Their Blocks

 We give an extension of the Prüfer code in order to count connected labeled graphs whose blocks are of given type. The Prüfer code records the way of assembling a connected labeled graph from its blocks. Received: March 15, 2001 Final version received: June 25, 2002 Acknowledgments. The author thanks R. Sawae and T. Sugawara for many helpful discussions and kind assistance. The author wishes to thank also the referees for precious comments and advices.     

Accurate quantitation of salivary and pancreatic amylase activities in human plasma by microchip electrophoretic separation of the substrates and hydrolysates coupled with immunoinhibition

A high-performance determination system for alpha-amylase isoenzyme activities in human plasma involving microchip electrophoresis with a plastic chip was developed. The combination of microchip electrophoresis for substrate and hydrolysate separation and an immunoinhibition method for the differentiation of isoenzyme activities using antihuman salivary amylase (S-AMY) mAb allowed the highly selective determination of amylase isoenzyme (S-AMY and pancreatic amylase (P-AMY)) activities even in a complex matrix such as a crude plasma sample. We used 8-aminopyrene-1,3,6-trisulfonic acid (APTS)-labeled maltohexaose (G6) as a substrate. Amylase in a human plasma sample hydrolyzed APTS-G6 into APTS-maltotriose (G3) and G3, which was measured as the fluorescence intensity of APTS-G3 on microchip electrophoresis. A double logarithm plot revealed a linear relationship between amylase activity and fluorescence intensity in the range of 5-500 U/L of amylase activity (r2=0.9995, p<0.01), and the LOD was 4.38 U/L. Amylase activities in 13 subjects determined by the present method were compared with the results obtained by conventional methods with nitrophenylated oligosaccharides as substrates, respectively. Good correlations were observed for each method on simple linear regression analysis (both p<0.01). The reproducibilities of within-days for total amylase and P-AMY were 2.98-6.27 and 3.83-6.39%, respectively, and these between-days were 2.88-5.66 and 3.64-5.63%, respectively. This system enables us to determine amylase isoenzyme activities in human plasma with high sensitivity and accuracy, and thus will be applicable to clinical diagnosis.     

Efficient total synthesis of (+)-negamycin, a potential chemotherapeutic agent for genetic diseases

Herein, we describe an efficient strategy for the total synthesis of (+)-negamycin using commercially available achiral N-Boc-2-aminoacetaldehyde as starting material with 42% overall yield for a limited number of steps.     

One-step synthesis of heteroaromatic-fused pyrrolidines via cyclopropane ring-opening reaction: application to the PKCbeta inhibitor JTT-010

A ring-opening reaction of cyclopropanes with five-membered heteroaromatics having a leaving group at C(2) was found to provide heteroaromatic-fused pyrrolidines in one step. This reaction was successfully applied to the synthesis of the protein kinase C-beta inhibitor JTT-010, which possesses a dihydropyrrolo[1,2-a]indole core.     

Label-Free Imaging of Intracellular Temperature by Using the O−H Stretching Raman Band of Water

We propose a label-free method for measuring intracellular temperature using a Raman image of a cell in the O−H stretching band. Raman spectra of cultured cells and the medium were first measured at various temperatures using a Raman microscope and the intensity ratio of the two regions of the O−H stretching band was calculated. The intensity ratio varies linearly with temperature in both the medium and cells, and the resulting calibration lines allow simultaneous visualization of both intracellular and extracellular temperatures in a label-free manner. We applied this method to the measurement of temperature changes after the introduction of FCCP (carbonyl cyanide-p-trifluoromethoxyphenylhydrazone) in living cells. We observed a temperature rise in the cytoplasm and succeeded in obtaining an image of the change in intracellular temperature after the FCCP treatment.     

Andirolides H–P from the flower of andiroba (Carapa guianensis,Meliaceae)

Three new gedunins, an andirobin, three mexicanolides, and two phragmalin-type limonoids named andirolides H (1), I (2), J (3), K (4), L (5), M (6), N (7), O (8), and P (9) were isolated from an oil of the flower of Carapa guianensis Aublet (Meliaceae). Their structures including the absolute configurations were determined by means of the NMR and CD spectra as well as FABMS. Andirolide H (1) showed antimalarial activity against Plasmodium falciparum in vitro.     

Absolute quantum yield of O(1D2) in the photolysis of ozone in the hartley band

The absolute quantum yield of O(¹D₂) in the photolysis of ozone in the Hartley band, between about 230 and 280 nm, has been determined using the isotopic exchange reaction between C¹⁶O₂ and ¹⁸O(¹D₂). A value of 1.00 ± 0.05 has been obtained within a 95% confidence limit. A value of unity may therefore be accepted as the average quantum yield of O(¹D₂) atoms in the 230–280-nm region within an uncertainty of only several percent.