Green, unexpected synthesis of bis-coumarin derivatives as potent anti-bacterial and anti-inflammatory agents.

A green and efficient protocol has been developed and a series of coumarin based pyrano[3,2-c]chromene derivatives (2) have been synthesized using multi-component reaction (MCR) approach. Unexpected 3-coumarinyl-3-pyrazolylpropanoic acids (3) and C4-C4 chromenes (5) have been isolated instead of expected product 4 by the reaction of compound (2) in formic acid at 90 °C for about 4-5 h and at 130 °C for about 8-10 h respectively. Further, C4-C4chromenes (5) formation was confirmed by intramolecular cyclization of compounds (3). These compounds were screened for their biological activities and most of them exhibited promising antibacterial activity. The anti-inflammatory assay was evaluated against HRBC membrane stabilization method and the compounds exhibit excellent anti-inflammatory activity. Molecular docking study has been performed for all the synthesized compounds with Klebsiella pneumoni aeacetolactate synthase and results obtained are quite promising.

Synthesis of Naked-eye Detectable Fluorescent 2H-chromen-2-One 2, 6-Dicyanoanilines: Effect of Substituents and pH on Its Luminous Behavior.

A variety of new coumarin derivatives containing C-4 bridged 2,6-dicyanoanilines (4a-4d) were synthesized via multicomponent one pot approach. These novel sensors were characterized by spectral analysis and a series of pH sensing fluorescence studies were performed, the results indicating that the sensors are highly selective and more effective at various pH. The fluorescence colour changes at different pH could be directly detected by naked eyes.

3,4-Dihydropyrimidinone-coumarin analogues as a new class of selective agent against S. aureus: Synthesis, biological evaluation and molecular modelling study.

Bacterial infections are increasingly difficult to combat as bacteria evolve resistance to antibiotic drugs and have severely compromised the arsenal of antibiotic drugs. On the other hand matrix metalloproteinases (MMPs) play a fundamental role in inflammation and extracellular matrix degradation in physiological and pathological conditions. In search of potent antibiotic, taking coumarin and dihydropyrimidinone as lead compound, a green, eco-friendly and efficient protocol has been developed and synthesized the dihydropyrimidin-2(1H)-one/thione derivatives of coumarin 3/4 from substituted 4-formylcoumarins 2 and ethylacetoacetate using urea/thiourea in the presence of catalytic amount of ceric ammonium nitrate is reported. All the synthesized compounds were evaluated for their antibacterial activity against four bacterial strains by broth dilution method. The tested compounds have exhibited promising in vitro potency with low MIC values against the drug susceptive S. aureus strain with low MIC values ranging from 0.2 to 6.25µg/mL. The in vivo anti-inflammatory potency of 3a-e and 4a-e by gelatin zymography is comparable to that of tetracycline. Molecular docking study performed for all the synthesized compounds with S. aureus DNA gyrase and results obtained were quite promising.

Synthesis, Characterization and Photophysical Studies of Tricoumarin-Pyridines.

A series of novel tricoumarin-pyridines have been synthesized by the reaction of 4-formyl coumarins and substituted 3-acetylcoumarin with ammonium acetate for the application in organic electronics as well as fluorescent dyes. The structures of all new compounds were confirmed and characterized by IR, 1H NMR and ESI-Mass analysis. All the important photo physical prerequisites for organic electronic application such as strong and broad optical absorption, thermal stability were determined for the synthesized molecules. Optical properties were studied by UV-Vis absorption and fluorescence spectroscopy. Optical band gaps of the tricoumarin-pyridines were found to be 2.72-3.10 eV as calculated from their onset absorption edge. The tricoumarin-pyridines were thermally stable up to 290-370 °C as determined by thermogravimetric analysis (TGA). Photophysical studies indicate the synthesized materials are promising candidates for organic electronic applications.

Synthesis, characterization and molecular docking studies of substituted 4-coumarinylpyrano[2,3-c]pyrazole derivatives as potent antibacterial and anti-inflammatory agents.

A green, eco-friendly and efficient protocol has been developed and synthesized a series of coumarin based pyrano[2,3-c]pyrazole derivatives (3) by multi-component reaction (MCR). Unexpected 3-coumarinyl-3-pyrazolylpropanoic acids (4) have been isolated by the reaction of compound (3) in acidic conditions. Further, intramolecular cyclization of compounds (4) leads to C4C4 chromons (9) and these compounds were screened for their biological activities using array of techniques. Most of the compounds exhibited promising antibacterial activity, in particular Gram-positive bacteria. The anti-inflammatory assay was evaluated against protein denaturation as well as HRBC membrane stabilization methods and compounds exhibit excellent anti-inflammatory activity in both methods. Molecular docking study has been performed for all the synthesized compounds with S. aureus dihydropteroate synthetase (DHPS) and results obtained are quite promising.

Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis.

Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5-12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics.