On-off switching of gel formation by red-ox reaction

Organogelator candidates which consist of the ferrocene unit have been prepared. It has been suggested that two amino acid residues in the structure are necessary to form a stable organogel. Addition of an oxidizing agent such as NaClO induces the collapse of the gel, and reproduction of the gel was observed by addition of a reducing agent such as glutathione. It has been found out that the on-off switching of gel formation can be achieved by red-ox reaction.     

Structure-activity studies of 3-benzoylpropionic acid derivatives suppressing adjuvant arthritis.

3-Benzoylpropionic acid derivatives possess an immunomodulative activity and suppress adjuvant arthritis. To understand how substituents affect the biological activity, the quantitative structure-activity relationships of 30 compounds were analyzed by the adaptive least-squares method. For the suppressing activity in rats, the electronic effects and the structural feature of the substituent on benzene ring were suggested to be important. To reinforce and confirm the correlation, 4 additional compounds of phenoxybutyric acid derivatives were synthesized and tested with the rat adjuvant-induced arthritis. These compounds were found to have potent suppressing activity.     

Investigation of an Olfactoryly Active Ring-Like Conformer of a Chain-Type Odorant, (3S)-3,7-dimethyloctanal,by computer calculation and graphics

The odor of (3S)-3,7-dimethyloctanal, a chain-type odorant, has some resemblance to that of ethyl (1 R, 6S)-2,2,6-trimethylcyclohexane-1-carboxylate, a ring-type odorant. We investigated the ring-like conformers of (3S)-3,7-dimethyloctanal. Two approaches, (i) systematic conformational analysis and (ii) construction of the initial structure by referring to the structure of the ring-type odorant, were considered in the search for ring-like conformers of the chain-type odorant. As a result, it was found that two stable ring-like conformers of (3S)-3,7-dimethyloctanal, obtained from the two approaches, resembled conformers of ethyl (1R, 6S)-2,2,6-trimethylcyclohexane-1-carboxylate in their three-dimensional structural features. The shapes of the two ring-like ones were not exactly the same but were quite similar. Therefore, the two ring-like conformers were considered to approximate the olfactoryly active conformer that binds and stimulates the same odor receptor as that for ethyl (1R,6S)-2,2,6-trimethylcyclohexane-1-carboxylate. In addition, ring-like conformers of another chain-type odorant, 2-methylpent-2-enal, were investigated to check the validity of the calculation method used.     

Spermine moiety attached to the C-5 position of deoxyuridine enhances the duplex stability of the phosphorothioate DNA/complementary DNA and shows the susceptibility of the substrate to RNase H

Novel phosphorothioate-modified oligodeoxynucleotides (S-ODNs) containing a deoxyuridine derivative bearing a spermine moiety at the C-5 position were synthesized. The study of the thermal stability and the thermodynamic stability showed that the modified S-ODNs have been able to form the stable duplexes with the complementary DNA. It was also found that the duplex composed of the modified S-ODN and its complementary RNA strand is the substrate for Escherichia coli RNase H, and the cleavage of the RNA strand by the enzyme was almost similar as in the case of the unmodified one.     

Atropisomers of 1-(acyl or aroyl)-2-naphthylindolines. Isolation,X-ray crystal structure and conformational analysis

A series of pairs of stable diastereomeric atropisomers caused by restricted rotation around the Csp3-Csp2 bond of [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethyl-2,3-dihydroindol-1-yl]-(3- or 4-substituted phenyl)-methanone or [2-(2-hydroxynaphthalen-1-yl)-3,3-dimethyl-2,3-dihydroindol-1-yl]-1-alkanone were isolated. The conformational analyses of the atropisomers were performed based on the X-ray crystallographic and (1)H-NMR spectral data. It became clear that rotation about the C2-naphthyl bond is restricted at room temperature, whereas the >NCO-Ar bond rotates freely.