Design, synthesis, and biological evaluation of novel (1-thioxo-1,2,3,4-tetrahydro-ß-carbolin-9-yl)acetic acids as selective inhibitors for AKR1B1.

New substituted (1-thioxo-1,2,3,4-tetrahydro-ß-carbolin-9-yl)acetic acids were designed as the inhibitor of AKR1B1 based upon the structure of rhetsinine, a minor alkaloidal component of Evodia rutaecarpa, and twenty derivatives were synthesized and evaluated. The most active compound of the series was (2-benzyl-6-methoxy-1-thioxo-1,2,3,4-tetrahydro-ß-carbolin-9-yl)acetic acid (7m), which showed comparable inhibitory activity for AKR1B1 (IC(50)=0.15µM) with clinically used epalrestat (IC(50)=0.1µM). In the view of activity and selectivity, the most potent compound was (2-benzyl-6-carboxy-1-thioxo-1,2,3,4-tetrahydro-ß-carbolin-9-yl)acetic acid (7t), which showed strong inhibitory effect (IC(50)=0.17µM) and very high selectivity for AKR1B1 against AKR1A1 (311:1) and AKR1B10 (253:1) compared with epalrestat.

6,7-Dihydroxy-4-phenylcoumarin as inhibitor of aldose reductase 2.

We report the structure-activity relationship of a series of coumarins as aldose reductase 2 (ALR2) inhibitors and their suppressive effect on the accumulation of galactitol in the rat lens. We evaluated their ALR2 selectivity profile against sorbitol dehydrogenase and aldehyde reductase (ALR1). Our study revealed that substitutions in the C7 OH group enhanced the potency toward ALR2, while the C6 OH group interferes with ALR1 inhibition activity. Having the phenyl moiety at C4 leads to improved potency and improved selectivity. A molecular docking study suggested that 6,7-dihydroxy-4-phenylcoumarin (15) binds to ALR2 in a different manner from epalrestat. Furthermore, compound 15 clearly suppressed galactitol accumulation in a dose-dependent manner. These results provide an insight into the structural requirements of coumarins for developing a new-type of selective ALR2 inhibitor.

In silico approach to identify the expression of the undiscovered molecules from microarray public database: identification of odorant receptors expressed in non-olfactory tissues.

Although both genomic sequencing and expression analysis are becoming indispensable for biological research, methods that can effectively survey large public gene expression repositories remain to be established. In this study, we developed an approach for the retrieval of tissue-specific expression information for certain genes from public databases; our approach was based on performance of a basic local alignment search tool search against probes on DNA microarray chips. To test the effectiveness of this approach, we examined the expression of human odorant receptors in non-olfactory tissues, as recent studies showed that such non-olfactory odorant receptors have physiological and pathophysiological significance. When we screened a large expression data set using this approach, we were able to effectively identify candidate odorant receptors in non-olfactory tissues and confirmed their expression by reverse transcription-polymerase chain reaction. Using receiver-operating characteristic curve analysis, the sensitivity and the specificity of this approach were 60 and 68%, respectively, indicating that the use of this technique would efficiently identify the previously unidentified expression of odorant receptors in non-olfactory tissues. Taken together, the in silico approach, as shown in the present study, would facilitate to elucidate the function of genes of interest.

Analysis of amino acid sequences of penicillin-binding protein 2 in clinical isolates of Neisseria gonorrhoeae with reduced susceptibility to cefixime and ceftriaxone.

Neisseria gonorrhoeae strains with reduced susceptibility to cefixime and ceftriaxone, with minimum inhibitory concentrations (MICs) of cefixime of 0.125-0.25 microg/ml and ceftriaxone of 0.031-0.125 microg/ml, were isolated from male urethritis patients in Tokyo, Japan, in 2006. The amino acid sequences of PenA, penicillin-binding protein 2, in these strains were of two types: PenA mosaic and nonmosaic strains. In the PenA mosaic strain, some regions in the transpeptidase-encoding domain in PenA were similar to those of Neisseria perflava/sicca, Neisseria cinerea, Neisseria flavescens, Neisseria polysaccharea, and Neisseria meningitidis. In the PenA nonmosaic strain, there was a mutation of Ala-501 to Val in PenA. In addition, we performed homology modeling of PenA wild-type and mosaic strains and compared them. The results of the modeling studies suggested that reduced susceptibility to cephems such as cefixime and ceftriaxone is due to a conformational alteration of the beta-lactam-binding pocket. These results also indicated that the mosaic structures and the above point mutation in PenA make a major contribution to the reduced susceptibility to cephem antibiotics.