Two new dimeric acridone alkaloids from Glycosmis citrifolia

Two new acridone dimers, glycobismines-F (1) and -G (2), were isolated from the roots of Glycosmis citrifolia collected in Taiwan. The structures of the new compounds were determined based on spectral analysis.     

Entrap-immobilization of biocatalysts on cellulose acetate-inorganic composite gel fiber using a gel formation ofcellulose acetate–metal (Ti, Zr) alkoxide

We developed a new entrap-immobilization method, using a gel formationof cellulose acetate and metal (Ti, Zr) alkoxide. Several biocatalysts(-galactosidase, -chymotrypsine, invertase, urease, lipase andSaccharomyces cereviciae) were successfullyentrap-immobilized on this composite gel fiber. The immobilization process wassimple and the resultant immobilized biocatalysts on the gel fiber were easy tohandle. It is considered that the biocatalysts are physically entrapped amongthe gel networks and distribute throughout the gel fiber. The gel fiber wasstable in phosphate buffer solution, electrolyte solution and organic solvent,because the gel formation was due to coordination interaction between celluloseand transition metal. Therefore, it can be applicable as a support for abiotransformation in various reaction media. We examined some enzyme reactionsand biotransformation using the immobilized biocatalysts on this gel fiber andevaluated this immobilization matrix in the reactions compared to the resultsobtained by the other immobilization method. The immobilized biocatalyst showedstable activity for repeated cycles and over a long period of time. Moreover,continuous reaction could be carried out in a column reactor packed with thisimmobilized biocatalyst.     

Dimethyltyrosine, the Viagra of Opioids

Introduction Theintroductionof2′,6′dimethyl L tyrosine(Dmt)[1]attheN terminusofTyr Tic(1,2,3,4tetra hydroisoquinoline3carboxylicacid)containingδopi oidantagonists[2—8]enhancesreceptoraffinityand invitrobioactivitytoseveralordersofmagnitude[1]and itsap…     

Phosphorylation of Histone H2AX Generated by Linear Alkylbenzene Sulfonates and its Suppression by UVB Exposure

We previously demonstrated that the nonionic surfactants, nonylphenol polyethoxylates (NPEOs) induced the phosphorylation of histone H2AX (γ‐H2AX), accompanied by DNA double‐strand breaks (DSBs), and that exposure to ultraviolet (UV) degraded NPEOs, which sometimes enhanced their DNA‐damaging ability. In this study, we showed that linear alkylbenzene sulfonates (LAS), general anion surfactants, also generated DSBs with γ‐H2AX, and this ability was attenuated by UVB exposure. In the human breast adenocarcinoma cell line, MCF‐7, γ‐H2AX was generated in a dose‐dependent manner immediately after cells were treated with LAS, and this was attributed to the formation of DSBs and was independent of cell cycle phases. The ability to generate γ‐H2AX was markedly reduced in LAS exposed to UVB. HPLC analysis revealed that LAS were a mixture of various alkyl chain lengths, the peaks of which were detected at individual retention times. UVB evenly decreased all peaks of LAS, without migration of peaks to other retention times, which indicated that UVB may degrade the benzene ring of LAS, but did not shorten the alkyl chains. UVB is an important environmental factor in the degradation of LAS exhibiting the ability to induce DSBs, the most serious type of DNA damage.     

Numerical study of interaction of two vortex rings

Three-dimensional interaction of vortices with finite core is investigated numerically using the Rosenhead-Moore approximation. As the computational scheme in this approximation cannot deal with the structure of the vortex core, a bundle of vortex elements is employed to represent a single physical vortex tube. After the validity of this method was confirmed by comparing the numerical result for a single vortex ring composed of various number of the elements with the analytical solution, two cases of interaction of two vortex rings were studied. The first case is two vortex rings traveling along a common axis, and the second is two vortex rings moving side by side along parallel axes. Comparison with the experiments showed good agreement.