Anti-inflammatory sesquiterpenes from Curcuma zedoaria

This is a preprint of an article whose final and definitive form has been published in the NATURAL PRODUCT RESEARCH © 2006 copyright Taylor & Francis; NATURAL PRODUCT RESEARCH is available online at: http://www.informaworld.com/openurl?genre=article&issn=1478-6419&volume=20&issue=7&spage=680ArticleNATURAL PRODUCT RESEARCH. 20(7): 680-685 (2006)journal articl

An efficient synthesis of procyanidins. Rare earth metal Lewis acid catalyzed equimolar condensation of catechin and epicatechin

ArticleTETRAHEDRON LETTERS. 48(33): 5891-5894 (2007)journal articl

Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation

Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2–10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2–6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement

The Initial-Final Mass Relation among White Dwarfs in Wide Binaries

We present the initial-final mass relation derived from 10 white dwarfs in wide binaries that consist of a main sequence star and a white dwarf. The temperature and gravity of each white dwarf was measured by fitting theoretical model atmospheres to the observed spectrum using a $\chi^{2}$ fitting algorithm. The cooling time and mass was obtained using theoretical cooling tracks. The total age of each binary was estimated from the chromospheric activity of its main sequence component to an uncertainty of about 0.17 dex in log \textit{t} The difference between the total age and white dwarf cooling time is taken as the main sequence lifetime of each white dwarf. The initial mass of each white dwarf was then determined using stellar evolution tracks with a corresponding metallicity derived from spectra of their main sequence companions, thus yielding the initial-final mass relation. Most of the initial masses of the white dwarf components are between 1 - 2 M$_{\odot}$. Our results suggest a correlation between the metallicity of a white dwarf's progenitor and the amount of post-main-sequence mass loss it experiences - at least among progenitors with masses in the range of 1 - 2 M$_{\odot}$. A comparison of our observations to theoretical models suggests that low mass stars preferentially lose mass on the red giant branch.Comment: 28 pages, 8 figures, accepted for publication in Ap

Structural insights into the HBV receptor and bile acid transporter NTCP

B型肝炎ウイルスの受容体“胆汁酸輸送体”の立体構造を解明. 京都大学プレスリリース. 2022-05-18.Roughly 250 million people are infected with hepatitis B virus (HBV) worldwide, and perhaps 15 million also carry the satellite virus HDV, which confers even greater risk of severe liver disease. Almost ten years ago the HBV receptor was identified as NTCP (sodium taurocholate co-transporting polypeptide), which interacts directly with the first 48 amino acid residues of the N-myristoylated N-terminal preS1 domain of the viral large (L) protein. Despite the pressing need for therapeutic agents to counter HBV, the structure of NTCP remains unsolved. This 349-residue protein is closely related to human apical sodium-dependent bile acid transporter (ASBT), another member of the solute carrier family SLC10. Crystal structures have been reported of similar bile acid transporters from bacteria, and these models with ten transmembrane helices are believed to resemble strongly both NTCP and ASBT. Using cryo-electron microscopy we have solved the structure of NTCP bound to an antibody, clearly showing the transporter has no equivalent to the first transmembrane helix of other SLC10 models, leaving the N-terminus exposed on the extracellular face. Comparison of the different structures indicates a common mechanism of bile acid transport, but the NTCP structure also displays a pocket formed by residues known to interact with preS1, presenting new and enticing opportunities for structure-based drug design