Constituents with a Novel Skeleton Isolated from Amentotaxus formosana

A novel compound consisting of two diterpenoid substructures, amentotaxin BA ( 1 ), and two novel terpenoids with a new skeleton, amentotaxins WA ( 2 ) and WB ( 3 ), were isolated from the barks and heart woods of Amentotaxus formosana, respectively. Their structures, including the relative configuration, were elucidated from spectroscopic data and a computer‐generated plot for the 3D structure.     

Hadron magnetic moment in the spinor strong interaction model

Hadron magnetic moments are considered in the framework of the spinor strong interaction theory for hadron spectra proposed by the author. Expressions of magnetic moments of ground-state hadrons are derived. These differ from the conventional ones in that they are no longer phenomenological and are basically relativistic. Pseudoscalar mesons have no magnetic moment. Charged vector meson magnetic moment values are given. The magnetic moment operators operate in the internal space, so that the ground-state octet baryons have the same spin-space symmetry, including the A. A formula for the ground-state octet baryon magnetic moment is derived from the basic spinor strong interaction baryon equations previously given, essentially without approximation and in a way analogous to the way in which the electron magnetic moment is derived.     

A Diterpenoid with a New Skeleton and Cytotoxic Terpenoids Isolated from Amentotaxus formosana

The new diterpenoid 6α‐hydroxy‐ent‐kaur‐16‐en‐15‐one ( 1 ) and a diterpenoid with a new skeleton, i.e., amentotaxin BB ( 5 ), as well as three new lanostanoids, i.e., (3β,23R)‐3‐methoxy‐24‐methylenelanost‐8‐en‐23‐ol ( 6 ), (23S)‐23‐methoxy‐24‐methylenelanost‐8‐en‐3‐one ( 7 ), and (3β,24ξ)‐3‐methoxy‐24‐methyl‐9,19‐cyclolanostan‐25‐ol ( 8 ), were isolated from the bark and leaves of Amentotaxus formosana. Their structures, including the relative configurations, were elucidated from spectroscopic data. Compound 1 and a known compound, ent‐kaur‐16‐en‐15‐one ( 2 ), showed potent cytotoxic effects against a number of cancer cells in vitro.     

Synthesis of 2‐Phenylthiazoles from α‐Tosyloxyketones and Thiobenzamide in [Bmim][PF6] Ionic Liquid at Ambient Temperature

The room temperature ionic liquid, 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate [bmim][PF₆] is used as a ‘green’ recyclable alternative to classical molecular solvents for the cyclocondensation of α‐tosyloxyketones with thiobenzamide to prepare 2‐phenylthiazoles in good yields.     

Ionic Liqids in Organic Synthesis: The Pummerer Reaction

Pummerer‐type reaction was carried out with α‐acyl sulfides and phenyliodine(III) bis(trifluoroacetate) (PIFA) instead of α‐acyl sulfoxides in the room temperature ionic liquid 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate [bmim][PF₆] under mild conditions to give the ene adducts 3 in good yields.     

Determination of biotin on a protein by quantitative sodium dodecyl sulfate-capillary gel electrophoresis of monomeric avidin

Sodium dodecyl sulfate-capillary gel electrophoresis (SDS-CGE) is performed to quantify monomeric avidin and biotin on a protein. Under non-reducing SDS-CGE conditions, avidin migrates as monomers exhibiting apparent molecular mass 17,000. In the presence of a biotin-protein conjugate, monomeric avidin binds the conjugate and forms a larger complex that migrates later in the separation. The difference between the remaining monomeric avidin and the initial amount is the portion of monomeric avidin bound to the conjugate. Accordingly, the number of biotin on the protein can be calculated. The assay is linearly responsive to increasing biotin loading in a biotinylation reaction of a protein. Accuracy of the assay is also demonstrated by good sample dilution recovery. Excellent quantitative reproducibility < 2% (relative standard deviation) is obtained for both intra- and inter-day measurements. Main advantages of the method include the use of monomeric avidin that minimizes steric hindrance to capture biotin on a protein and assay automation on a capillary electrophoresis apparatus.     

Hypervalent Iodine(III) Mediated Synthesis of 2‐Substituted‐5‐Aryloxazoles

A direct and efficient method for the preparation of 2‐substituted‐5‐aryloxazoles was realized by reaction of aryl methyl ketones with various nitriles in the presence of phenyliodine(III) triflate.     

Temperature Effects on Structural and Functional Properties of Rat Lens Phe71 Mutant αA‐Crystallins

In order to explore whether hydrophobicity or charge at the 71^th residue is important for chaperone‐like activity, wild type (wt) and two mutant αA‐crystallins, F71W and F71R, with an extra 11 residues including 6 histidines tagged at the N‐terminal were prepared. Chaperone‐like activity toward dithiotreitol (DTT) induced insulin aggregation showed the 11 extra residues had little effect. The activity for F71W was as active as the wild type, while F71R was much less active. For the wild type and F71W, the activity increased with the increase of molar quantity; surprisingly, for F71R it caused a drastic decline. ANS fluorescence measurements showed F71R had the highest surface hydrophobicity, suggesting positive charge at this site caused the conformational alteration leading to the increase of hydrophobicity and this hydrophobicity resulted in the formation of high molecular weight aggregates (> 2000 kDa) observed from the thermal stability study. The thermal stability study revealed F71W was the most thermally stable crystallin. Chaperone‐like activity studies at various temperatures suggested the monomer and oligomer, 650 kDa, were responsible for chaperone function and surface hydrophobicity was not the prerequisite for activity. Near‐UV CD studies showed β‐sheet was the major secondary structure for all three crystallins and F71R had a higher percentage of random coil.     

Facile approach to polyurea/malonamide dendrons via a selective ring‐opening addition reaction of azetidine‐2,4‐dione

A bifunctional compound [(4‐isocyanato‐4′(3,3‐dimethyl ‐2,4‐dioxo‐acetidino)diphenylmethane] (MIA) has been used as a building block for the synthesis of novel polyurea/malonamide dendrons. This is based on selectively sequential addition reactions of amines to isocyanato‐azetidine‐2,4‐diones. After incorporation of the MIA onto the growing dendrons, rapid entry into polyurea/malonamide dendrons was achieved via a convergent route with the processing advantages of easy purification, high yield, and rapid synthesis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 682–688, 2005