No abstract

Three differently substituted naturally occurring, biologically active carbazole derivatives viz. ekeberginine, murrayaquinone A and glycozoline were synthesized in good yield using short and simple routes. Prenyl group was selectively introduced at C4 position using Stille coupling reaction in the synthesis of ekeberginine. Murrayaquinone A was synthesized using Raney nickel mediated desulfurization of dithiane as a key step.Synthesis of glycozoline was achieved in two steps from 3-methyl carbazole via an intermediate 3-bromo-6-methyl carbazole.

Two novel routes are elaborated for the synthesis of the naturally occurring alkaloid bouchardatine (I).

Two new, efficient and simple routes using Heck-type reaction and intramolecular cyclization were developed for the synthesis of the naturally occurring cytotoxic alkaloid 2-(4-oxo-3,4-dihydroquinazolin-2-yl)-1H-indole-3-carbaldehyde (bouchardatine).

In this study, a siderophore, pyoverdine (PVD), has been isolated from Pseudomonas sp. and used to develop a fluorescence quenching-based sensor for efficient detection of nitrotriazolone (NTO) in aqueous media, in contrast to other explosives such as research department explosive (RDX), picric acid, and trinitrotoulene (TNT). The siderophore PVD exhibited enhanced fluorescence quenching above 50% at 470 nm for a minimal concentration (38 nM) of NTO. The limit of detection estimated from interpolating the graph of fluorescence intensity (at 470 nm) versus NTO concentration is found to be 12 nM corresponding to 18% quenching. The time delay fluorescence spectroscopy of the PVD–NTO solution showed a negligible change of 0.09 ns between the minimum and maximum NTO concentrations. The in silico absorption at the emission peak of static fluorescence remains invariant upon the addition of NTO. The computational studies revealed the formation of inter- and intramolecular hydrogen-bonding interactions between the energetically stable complexes of PVD and NTO. Although the analysis of Stern–Volmer plots and computational studies imply that the quenching mechanism is a combination of both dynamic and static quenching, the latter is dominant over the earlier. The static quenching is attributed to ground-state complex formation, as supported by the computational analysis.