A new lignan from the seeds of Sphaerophysa salsula

A novel lignan: sphaerophyside SC was isolated from ethanolic extract of the seeds of Sphaerophysa salsula (Pall.) DC. The structure of the compound was elucidated mainly on the basis of the 1D NMR and 2D NMR data.     

Effective photoexcitation in gold nanowells based on localized surface plasmon

The localization of the surface plasmon (SP) field in nanospace using wavelength-sized gold wells prepared on a glass substrate and its application to excite fluorophores immobilized on the bottom surfaces have been studied.     

Geometric indices and the Alexander polynomial of a knot

It is well-known that any Laurent polynomial satisfying and is the Alexander polynomial of a knot in . We show that can be realized by a knot which has the following properties simultaneously: (i) tunnel number 1; (ii) bridge index 3; and (iii) unknotting number 1.

     

Synthesis of potent beta-secretase inhibitors containing a hydroxyethylamine dipeptide isostere and their structure-activity relationship studies

Several beta-secretase inhibitors were designed based on hydroxyethylamine dipeptide isostere (HDI) structures and were synthesized by a methodology using the aza-Payne rearragement and O,N-acyl transfer reactions to study their structure-activity relationships. Among these pseudopeptides, effective compounds were developed as the first beta-secretase inhibitors containing the HDI transition state mimic with potent enzyme inhibitory activity (IC50 < 100 nM).     

Formal catalytic asymmetric total synthesis of fostriecin

The common synthetic intermediate of a potent and promising anticancer agent, fostriecin, was synthesized using a unique method that combines four catalytic asymmetric reactions as shown above.