Approach to the "Missing" Diarylsilylene: Formation, Characterization, and Intramolecular C-H Bond Activation of Blue Diarylsilylenes with Bulky Rind Groups.

The treatment of the bulky Rind-based dibromosilanes, (Rind)SiBr () [Rind = 1,1,7,7-tetra-R-3,3,5,5-tetra-R--hydrindacen-4-yl: EMind (: R = Et, R = Me) and Eind (: R = R = Et)], with two equivalents of BuLi in EtO at low temperatures resulted in the formation of blue solutions derived from the diarylsilylenes, (Rind)Si: (). Upon warming the solutions above -20 °C, the blue color gradually faded, accompanying the decomposition of and yielding cyclic hydrosilanes () via intramolecular C-H bond insertion at the Si(II) center. The molecular structures of the bulky Eind-based and were confirmed by X-ray crystallography.

Role of the thiosugar ring in the inhibitory activity of salacinol, a potent natural α-glucosidase inhibitor.

Herein, ring-cleaved (24) and truncated (25) analogues of an azasugar, 1-deoxynojirimycin (23), exhibited inhibitory activity ( = 4-10 μM) equal to that of the parent compound (1, = 14 μM). Based on this structure-activity relationship (SAR), four ring-cleaved (26a-26c and 27c) and three truncated (28a-28c) analogues of salacinol (1), a potent thiosugar-ring-containing α-glucosidase inhibitor, were synthesised. Bioassay results revealed that all the synthetics were inactive, indicating that the 5-membered thiosugar ring of 1 played an essential role in the potent activities of sulfonium-type inhibitors.

Total Synthesis of Calanthoside, a Potential Hair Growth Stimulant: A Facile Synthetic Approach via One-Pot - and -Glucosidic Bond Formation.

The first total synthesis of calanthoside (), which exhibits potent proliferative activity against human hair follicle dermal papilla cells, has been achieved in seven steps with an overall yield of 43% on a gram scale starting from anthranilic acid (). The synthetic strategy features a one-pot process involving thioglucoside bond formation via nucleophilic substitution reaction and enol-glucosylation for building the -,-bisdesmoside structure of . Moreover, the one-pot reaction showed broad substrate adaptability to several sugar donors other than d-glucose, thus affording ,-bisglycoside intermediates in ∼84% yield.

Biosynthetic diversification of non-ribosomal peptides through activity-based protein profiling of adenylation domains.

We describe activity-based protein profiling for analyzing the adenylation domains of non-ribosomal peptide synthetases (ABPP-NRPS) in bacterial proteomes. Using a range of non-proteoinogenic amino acid sulfamoyladenosines, the competitive format of ABPP-NRPS provided substrate tolerance toward non-proteinogenic amino acids. When coupled with precursor-directed biosynthesis, a non-proteinogenic amino acid (-allyl-L-serine) was successfully incorporated into gramicidin S.

Infused juice concentrate of Japanese plum Prunus mume attenuates inflammatory vascular remodeling in a mouse model of hypertension induced by angiotensin II.

Fruit from the Prunus mume tree is a traditional food in Japan. Recently, bainiku-ekisu, an infused juice concentrate of Japanese Prunus mume, is attracting attention as a health promoting supplement. Angiotensin II (Ang II) plays a central role in development of hypertension.