D. Premnath

Binding of a chromen-4-one Schiff’s base with bovine serum albumin: capping with β-cyclodextrin influences the binding

This work deals with the synthesis of 6-methyl-3-[(4′-methylphenyl)imino]methyl-4H-chromen-4-one (MMPIMC), its binding to β-cyclodextrin, and the influence of the cyclodextrin complexation on the compound’s binding to bovine serum albumin (BSA). The 1:2 stoichiometry for the complexation of MMPIMC with β-cyclodextrin is determined with the binding constant of 1.90 × 104 M−2. The structure of host–guest complex plays a role in protein binding of MMPIMC. One- and two-dimensional NMR spectra are used to determine the mode of binding of the guest to β-cyclodextrin cavity and the structure of the inclusion complex is proposed. The binding of MMPIMC with BSA in the absence and the presence of β-cyclodextrin is studied. The binding strengths of MMPIMC–BSA (1.73 × 105 M−1) and β-cyclodextrin-complexed MMPIMC–BSA (9.0 × 104 M−1) show difference in magnitude. The Förster Resonance Energy Transfer efficiency and the proximity of the donor and acceptor molecules, are modulated by β-cyclodextrin. Molecular modeling is used to optimize the sites and mode of binding of MMPIMC with bovine serum albumin.

Alteration of the Binding Strength of Dronedarone with Bovine Serum Albumin by β-Cyclodextrin: A Spectroscopic Study

We report the influence of β-cyclodextrin on the binding of the drug dronedarone with bovine serum albumin. The stoichiometry, the binding constant, and the mode of binding of the derivative with β-cyclodextrin are studied by UV–Visible absorption, fluorescence, and 2 Dimensional Rotating Frame Overhauser Effect Spectroscopy (2D ROESY NMR) spectroscopic techniques. The structure of the 1:1 inclusion complex is proposed. The binding of free dronedarone with bovine serum albumin and β-cyclodextrin-bound dronedarone are studied by fluorescence quenching and Förster resonance transfer. The decreased magnitude of the Stern–Volmer constant and the binding constant for the interaction of dronedarone with bovine serum albumin in the presence of β-cyclodextrin are articulated. The donor-to-acceptor distances in the presence and the absence of β-cyclodextrin are compared. The binding sites of the dronedarone with bovine serum albumin are reported by molecular modeling. Dronedarone binds to the sub-domain III of bovine serum albumin. The 3-(dibutylaminopropoxy)benzoyl moiety of dronedarone binds with bovine serum albumin. Encapsulation with β-cyclodextrin decreases the binding strength of dronedarone with bovine serum albumin.

Synthesis and spectroscopic characterization of fluorescent 4-aminoantipyrine analogues: Molecular docking and in vitro cytotoxicity studies.

Two substituted aromatic carbonyl compounds (compounds 1 and 2) of 4-aminoantipyrine were synthesized by condensation of fluorine substituted benzoyl chlorides and 4-aminoantipyrine. The structures of synthesized derivatives were established on the basis of UV-Vis, IR, and Mass, (1)H, (13)C NMR and Fluorescence spectroscopy. Both compounds showed significant fluorescence emission and two broad emission bands were observed in the region at 340 nm and 450 nm on excitation at 280 nm. Theoretically to prove that the molecule has anticancer activity against cervical cancer cells, the compounds were analyzed for molecular docking interactions with HPV16-E7 target protein by Glide protocol. Furthermore, 4-aminoantipyrine derivatives were evaluated for their in vitro cytotoxic activity against human cervical cancer cells (SiHa) by MTT assay. Compound 1 showed two fold higher activity (IC50=0.912 μM) over compound 2, and its activity was similar to that of Pazopanib, suggesting that although the two compounds were chemically very similar the difference in substituent on the phenyl moiety caused changes in properties.

Loading of chromenones on superparamagnetic iron oxide-modified dextran core–shell nanoparticles: openness to bind to β-cyclodextrin and DNA

This paper presents the loading of chromenones, viz., flavanone, hesperetin, naringenin, coumarin 6 and coumarin 7 onto aminoethylamino-modified dextran-coated superparamagnetic iron oxide core–shell nanoparticles. The chemically modified iron oxide core–shell nanoparticles retain their superparamagnetic behaviour even upon chromenone loading. The accessibility of loaded chromenones to DNA for binding is analysed using UV-visible absorption and fluorescence spectroscopy. β-Cyclodextrin is used as an aid to detect whether the chromenones are buried inside the aminoethylamino-modified dextran-coated superparamagnetic iron oxide core–shell nanoparticle shell or available on the surface to readily bind to the macromolecular target. The stoichiometry of the loaded chromenones with the β-cyclodextrin inclusion complex is 1 : 1 in all cases, except with naringenin which binds to two β-cyclodextrin molecules. Coumarin 7 shows a fluorescence quenching upon binding to calf thymus DNA. This study could improve the understanding of the mode of binding of small molecules loaded on magnetic nanoparticles to DNA.

Design, Synthesis, Spectral Analysis, In Vitro Anticancer Evaluation and Molecular Docking Studies of Some Fluorescent 4-Amino-2, 3-Dimethyl-1-Phenyl-3-Pyrazolin-5-One, Ampyrone Derivatives

The commenced work deals with the synthesis, characterization and evaluation of biological activities of 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one. The synthesis was done by the condensation of aromatic acid chlorides with 4-aminoantipyrine. The structures of synthesized derivatives were elucidated using IR, Mass, 1H NMR and 13C NMR spectroscopy, and their UV–Visible and fluorescence properties were studied. The compounds showed significant dual fluorescence. Molecular docking was used to understand the small molecule–receptor protein interaction. The derivatives were screened for their in vitro cytotoxic activity against the reference drug pazopanib on human cervical cancer cell line (SiHa) using MTT assay.

Synthesis, molecular docking and antibacterial evaluation of 2-(4-(4-aminophenylsulfonyl)phenylamino)-3-(thiophen-2-ylthio)naphthalene-1,4-dione derivatives

AbstractA new series of 2-(4-(4-aminophenylsulfonyl) phenylamino)-3-(thiophen-2-ylthio)naphthalene-1,4-dione derivatives (3a-3n) were synthesized and characterized by spectral techniques. To understand the interaction of binding sites with bacterial protein receptor, the docking study was performed by the GLIDE program and compound N-(4-(4-(1,4-dioxo-3-(thiophen-2-ylthio)-1,4-dihydronaphthalen-2-ylamino)phenylsulfonyl)phenyl)-3-methylbenzamide (3b) exhibited good glide and E model scores of −5.89 and −94.90, respectively. Moreover among all the molecules studied including the standards used, namely Sparfloxacin (4.8 μg/mL) and Norfloxacin (no inhibition observed) for their antibacterial property, compound N-(4-(4-(1,4-dioxo-3-(thiophen-2-ylthio)-1,4-dihydronaphthalen-2-ylamino)phenylsulfonyl)phenyl)-4-nitrobenzamide (3e) exhibited the lowest minimum inhibitory concentration (MIC) value of 1.3 μg/mL against Proteus vulgaris.