Effective Detection of Phenylalanine Using Pyridine Based Sensor.

Pyridine based organic molecule as probe has been synthesized for the detection of phenylalanine (PA) biomarker. The synthesized probe is characterized by 1H and 13C NMR and mass spectroscopic studies. The photophysical properties for the probe has recorded by colorimetric and fluorimetric techniques. The quenching has been observed between the probe and PA through ICT (Intermolecular Charge Transfer Mechanism). Under optimized conditions, the probe detects PA selectively in the presence of other biologically important biomolecules. The practical application for PA has been successfully applied in human blood serum and urine.

Development of Optical Biosensor for the Detection of Glutamine in Human Biofluids Using Merocyanine Dye.

Merocyanine dye based fluorescent organic compound has been synthesized for the detection of glutamine. The probe showed remarkable fluorescent intensity with glutamine through ICT (Intermolecular Charge Transfer Mechanism). Hence, it is tested for the detection of glutamine using colorimetric and fluorimetric techniques in physiological and neutral pH (7.2). Under optimized experimental conditions, the probe detects glutamine selectively among other interfering biomolecules. The probe has showed a LOD (lower limit of detection) of 9.6 × 10-8 mol/L at the linear range 0-180 µM towards glutamine. The practical application of the probe is successfully tested in human biofluids.

Small molecule induced toxic human-IAPP species characterized by NMR.

In this study, the effect of CurDAc, a water-soluble curcumin derivative, on the formation and stability of amyloid fibers is revealed. CurDAc interaction with amyloid is structurally selective, which is reflected in a strong interference with hIAPP aggregation while showing weaker interactions with human-calcitonin and amyloid-ß1-40 in comparison. Remarkably, CurDAc also exhibited potent fiber disaggregation for hIAPP generating a toxic oligomeric species.

Highly Selective and Sensitive Colorimetric and Fluorimetric Sensor for Cu2.

A newly designed fluorescent and colorimetric probe was synthesized and selective detection of cu2+ was successful in aqueous medium. The design strategy exhibited strongly fluorescent when binding with cu2+ based on the change in structure between spirocyclic to a non-cyclic form of rhodamine based dye. The UV visible spectra of probe (6GS2) exhibited three absorption peaks at 229, 309 and 530 nm respectively. The emission spectra of fluorescent probe exhibited wavelength at 550 nm. The peak intensity increases during the addition of copper ion to probe through n-π transition. The probe characterized by different techniques like NMR, absorption, emission, mass and test strips methods. Graphical Abstract .

Synthesis of ß-Ketoamide Curcumin Analogs for Anti-Diabetic and AGEs Inhibitory Activities.

Two different series of novel ß-ketoamide curcumin analogs enriched in biological activities have been synthesized. The synthesized compounds were screened for their in vitro anti-diabetic and AGEs inhibitory activities and exhibited potent to good anti-diabetic and AGEs inhibitory activities. The molecular docking study was also performed with the α-amylase enzyme.

I2-Catalyzed Oxidative Cross-Coupling Reaction of Methyl Ketones and 2-(2-Aminophenyl) Benzimidazole: Facile Access to Benzimidazo[1,2-c]quinazoline.

A general and efficient iodine-catalyzed metal-free oxidative cross-coupling reaction of methyl ketones with 2-(1H-benzo[d]imidazol-2-yl)aniline has been established. This is a new synthetic strategy for the synthesis of benzimidazo[1,2-c]quinazoline derivatives involving C(sp3)-H oxidation, condensation, and cyclization processes.

Evaluation of antimicrobial activity of glycinate and carbonate derivatives of cholesterol: Synthesis and characterization.

A series of glycinate and carbonate derivatives of cholesterol (4a-t) were synthesized, characterized and assessed for their in vitro antimicrobial activity. Our results revealed that the compounds exerted inhibitory activities against gram-negative bacteria and fungi.

Multiple biological activities and molecular docking studies of newly synthesized 3-(pyridin-4-yl)-1H-pyrazole-5-carboxamide chalcone hybrids.

A series of fifteen new chemical entities, 3-(pyridin-4-yl)-1H-pyrazole-5-carboxamide chalcones (6a-o), were synthesized as new hybrids with enriched biological activities compared to their parent molecules. The compounds were characterized by 1H NMR, 13C NMR, Mass and IR spectral studies. Their antibacterial, anti-inflammatory and antioxidant activities have been evaluated. These compounds showed moderate to good antibacterial, anti-inflammatory and antioxidant activities. The molecular docking analysis was performed with cyclooxygenase enzyme to ascertain the probable binding model.

Curcumin based chemosensor for selective detection of fluoride and cyanide anions in aqueous media.

The conjugate N,N-dimethyl curcumin analogue fluorophore dye 1 has been synthesized and its performance as a sensor was demonstrated. As a fluoride and cyanide sensor it enabled visual detection, and showed changes in UV-vis and fluorescence spectra in the presence of fluoride and cyanide ions in aqueous medium. The Job's plot indicated that the formation of a complex between dye-1 fluoride ions has a 1 : 1 stoichiometric ratio.

Optically Biaxial, Re-entrant and Frustrated Mesophases in Chiral, Non-symmetric Liquid Crystal Dimers and Binary Mixtures.

Sixteen optically active, non-symmetric dimers, in which cyanobiphenyl and salicylaldimine mesogens are interlinked by a flexible spacer, were synthesized and characterized. While the terminal chiral tail, in the form of either (R)-2-octyloxy or (S)-2-octyloxy chain attached to salicylaldimine core, was held constant, the number of methylene units in the spacer was varied from 3 to 10 affording eight pairs of (R & S) enantiomers. They were probed for their thermal properties with the aid of orthoscopy, conoscopy, differential scanning calorimetry and X-ray powder diffraction. In addition, the binary mixture study was carried out using chiral and achiral dimers with the intensions of stabilizing optically biaxial phase/s, re-entrant phases and important phase sequences. Notably, one of the chiral dimers as well as some mixtures exhibited a biaxial smectic A (SmAb ) phase appearing between a uniaxial SmA and a re-entrant uniaxial SmA phases. The mesophases such as chiral nematic (N*) and frustrated phases viz., blue phases (BPs) and twist grain boundary (TGB) phases, were also found to occur in most of the dimers and mixtures. X-ray diffraction studies revealed that the dimers possessing oxybutoxy and oxypentoxy spacers show interdigitated (SmAd ) phase where smectic periodicity is over 1.4 times the molecular length; whereas in the intercalated SmA (SmAc ) phase formed by a dimer having oxydecoxy spacer the periodicity was found to be approximately half the molecular length. The handedness of the helical structure of the N* phases formed by two enantiomers was examined with the aid of CD measurements; as expected, these enantiomers showed optical activities of equal magnitudes but with opposite signs. Overall, it appears that the chiral dimers and mixtures presented herein may serve as model systems in design and developing novel materials exhibiting the apolar SmAb phase possessing D2h symmetry and nematic-type biaxiality.

Chemodivergent, One-Pot, Multi-Component Synthesis of Pyrroles and Tetrahydropyridines under Solvent- and Catalyst-Free Conditions Using the Grinding Method.

A highly efficient, chemoselective synthesis of a library of polysubstituted pyrroles and tetrahydropyridines has been achieved through the one-pot, multicomponent reactions of ethyl (E)-3-(aryl/alkyl amino) acrylates, 2,2-dihydroxy-1-arylethan-1-ones, and malononitrile under solvent- and catalyst-free grinding conditions. The selective formation of pyrrole or tetrahydropyridines relied on substitution of the N-aryl of ethyl (E)-3-(4-arylamino) acrylates. These reactions presumably occurred via a domino Knoevenagel condensation and Michael addition followed by an intramolecular cyclization sequence of reactions in a single transformation.

Biological evaluation and molecular docking studies of new curcuminoid derivatives: Synthesis and characterization.

In the present study, three series of dimethylamino curcuminoids viz. 4-phenylaminomethyl curcumin (3a-d), arylidene curcumin (3e) and pyrazole curcumin (3f-i) derivatives have been synthesized and studied for their in vitro anti-inflammatory, antioxidant and antibacterial activities. Synthesized dimethylamino curcuminoid derivatives namely 3d, 3e, 3h and 3i have shown potent anti-inflammatory properties than parent curcumin. Molecular docking interactions of dimethylamino curcuminoids derivatives against cyclooxygenase enzymes (COX-1 and COX-2) were studied.

Influence of a curcumin derivative on hIAPP aggregation in the absence and presence of lipid membranes.

The deposition of aggregates of human islet amyloid polypeptide (hIAPP) has been correlated with the death of ß-cells in type II diabetes mellitus. The actual molecular mechanism of cell death remains largely unknown; however, it has been postulated that the process of aggregation from monomeric hIAPP is closely involved. A possible cause of cellular toxicity may be through the disruption of structural integrity of the cell membrane by IAPP. Herein, a water-soluble curcumin derivative, CurDAc, is used to investigate the mitigation of hIAPP aggregation in the absence and presence of lipid membrane.

A green and efficient protocol for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives via a one-pot, four component reaction by grinding method.

An efficient grinding protocol for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives from acetylene ester, hydrazine hydrate, aryl aldehydes and malononitrile under solvent free conditions has been achieved with excellent yields. The structures of the synthesized compounds were deduced by spectroscopic techniques and the compounds were further evaluated for their in vitro antioxidant and antimicrobial activities.

Synthesis and biological evaluation of new symmetric curcumin derivatives.

A series of novel curcumin bisacetamides aiming of enriching their biological activities have been synthesized. The synthesized compounds were screened for their in vitro antioxidant, anti-inflammatory and cytotoxic activities. All the compounds exhibited potent to good anti-inflammatory, antioxidant and noteworthy cytotoxic activities.

Inhibitory Activity Of Curcumin Derivatives Towards Metal-free And Metal-induced Amyloid-ß Aggregation.

When Alzheimer's disease (AD) progresses, several pathological features arise including accumulation of misfolded protein aggregates [e.g., amyloid-ß (Aß) plaques], metal ion dyshomeostasis, and oxidative stress. These characteristics are recently suggested to be interconnected through a potential factor, metal-associated Aß (metal-Aß) species. The role of metal-Aß species in AD pathogenesis remains unclear, however. To elucidate the contribution of metal-Aß species to AD pathology, as well as to develop small molecules as chemical tools and/or theranostic (therapeutic and diagnostic) agents for this disease, curcumin (Cur), a natural product from turmeric, and its derivatives have been studied towards both metal-free and metal-induced Aß aggregation. Although Cur has indicated anti-amyloidogenic activities and antioxidant properties, its biological use has been hindered due to low solubility and stability in physiologically relevant conditions. Herein, we report the reactivity of Cur and its derivatives (Gd-Cur, a potential multimodal Aß imaging agent; Cur-S, a water soluble derivative of Cur that has substitution at the phenolic hydroxyls) with metal-free Aß and metal-Aß species. Our results and observations indicate that Gd-Cur could modulate Cu(II)-triggered Aß aggregation more noticeably over metal-free or Zn(II)-induced analogues; however, Cur-S was not observed to noticeably modulate Aß aggregation with and without metal ions. Overall, our studies present information that could aid in optimizing the molecular scaffold of Cur for the development of chemical tools or theranostics for metal-Aß species.