Synthesis of 6-Aminopropyl-6H-indolo[2,3-b]quinoxaline Derivatives

Evaluation of Anti-Neuroinflammatory Activity of Isatin Derivatives in Activated Microglia

Neuroinflammation plays a crucial role in the progression of Alzheimer's disease and other neurodegenerative disorders. Overactivated microglia cause neurotoxicity and prolong the inflammatory response in many neuropathologies. In this study, we have synthesised a series of isatin derivatives to evaluate their anti-neuroinflammatory potential using lipopolysaccharide activated microglia as a cell model. We explored four different substitutions of the isatin moiety by testing their anti-neuroinflammatory activity on BV2 microglia cells. Based on the low cytotoxicity and the activity in reducing the release of nitric oxide, pro-inflammatory interleukin 6 and tumour necrosis factor α by microglial cells, the N¹-alkylated compound 10 and the chlorinated 20 showed the best results at 25 µM. Taken together, the data suggest that 10 and 20 are promising lead compounds for developing new neuroprotective agents.

Efficient synthetic access to novel indolo[2,3-b]quinoxaline-based heterocycles

BACKGROUND

This paper showed the synthetic capability of the indolo[2,3-b]quinoxaline nucleus to be provided as an excellent precursor for the synthesis of various heterocyclic compounds. These synthetic routes proceed via the formation of 3-(6H-indolo[2,3-b]quinoxalin-6-yl)propane hydrazide (2). The carbohydrazide 2 and its reactions with different reagents give five and six-membered rings, such as 1,3,4-thiadiazole, 1,3,4-oxadiazole, 1,2,4-triazole, and 1,2,4-triazine.

METHODS

All chemicals used in the current study were of analytical grade. Melting points were determined using an APP Digital ST 15 melting point apparatus and were uncorrected. FT-IR spectra were recorded on a Pye-Unicam SP3-100 and Shimadzu-408 spectrophotometers in KBr pellets and given in (cm-1) KBr. The NMR spectra were detected by a Bruker AV-400 spectrometer (400 MHz for 1H, 100 MHz for 13C and 40.55 MHz for 15N), Institute of Organic Chemistry, Karlsruhe, Germany. Chemical shifts were expressed as δ (ppm) with TMS as an internal reference. Mass spectrometry was provided on a Varian MAT 312 instrument in EI mode (70 eV).

RESULTS

The target compounds were obtained, and their structures were completely elucidated by various spectral and elemental analyses (Ft-IR, 1H-NMR, 13C-NMR, and mass spectrometry).

CONCLUSION

The current work showed a view of the reactivity of the carbohydrazide group. The carbohydrazide 2 was obtained from the hydrazinolysis of carboethoxy compound 1 and exploited as a key intermediate to synthesize heterocyclic compounds with different rings.

7-Substituted pyrrolo[2,3-d]pyrimidines for the synthesis of new 1-deazapyrimido[1,2,3-cd]purines

Few examples of new heterocyclic 1-deazapyrimido[1,2,3-cd]purine derivatives were synthesized by intramolecular cyclization of methyl 7-(oxiran-2-ylmethyl)-7H-pyrrolo[2,3-d]pyrimidine-6-carboxylates. The latter were obtained by iodolactonization of 7-allylpyrrolo[2,3-d]pyrimidine-6-carboxylic acids.

Synthesis, cytotoxic evaluation and DNA binding study of 9-fluoro-6H-indolo[2,3-b]quinoxaline derivatives

New quaternary ammonium salts of 9-fluoro-6H-indolo[2,3-b] derivatives were synthesized. These compounds possessed enhanced DNA binding ability and improved antitumor activity.

A Green Synthesis of Indolo[2,3-b]Quinoxaline Derivatives

A simple, efficient and eco-friendly synthesis of a series of structurally new indolo[2,3- b]quinoxaline derivatives has been developed. The synthesis mainly relies on the condensation reaction of various isatins with o-phenylenediamine in water with the use of benzyltriethylammonium chloride as catalyst. The protocol is very simple, avoids toxic solvents and catalysts, is easy to work-up and is thus especially ‘green’.