Caged Dexamethasone to Photo-control the Development of Embryos through Activation of the Glucocorticoid Receptor.

Efficient tools for controlling molecular functions with exquisite spatiotemporal resolution are much in demand to investigate biological processes in living systems. Here we report an easily synthesized caged dexamethasone for photo-activating cytoplasmic proteins fused to the glucocorticoid receptor. In the dark, it is stable in vitro as well as in vivo in both zebrafish (Danio rerio) and Xenopus sp, two significant models of vertebrates. In contrast, it liberates dexamethasone upon UV illumination, which has been harnessed to interfere with developmental steps in embryos of these animals. Interestingly, this new system is biologically orthogonal to the one for photo-activating proteins fused to the estrogen ERT receptor, which brings great prospect for activating two distinct proteins down to the single cell level.

In vitro antitubercular activity of extract and constituents from the stem bark of Disthemonanthus benthamianus

ABSTRACT A new C-glycosylflavone, apigenin 7-methyl ether 6-C-[β-xylopyranosyl-(1→3)-β-glucopyranoside] named distemonanthoside was isolated from the stem bark of Distemonanthus benthamianus Baill., Fabaceae, along with six known compounds, sitosterol 3-O-β-D-glucopyranoside, 4-methoxygallic acid, syringic acid, quercetin, 6"-O-acetylvitexin, quercetin 3-O-β-D-glucopyranoside. The structures of those compounds and others were determined through spectral analyses. Compounds distemonanthoside, sitosterol 3-O-β-D-glucopyranoside, 4-methoxygallic acid and quercetin were tested against a clinical isolate strain of Mycobacterium tuberculosis AC 45; they exhibited good to moderate antitubercular activities with MIC values ranged from 31.25 to 125 µg/ml.