Host-guest molecular encapsulation of cucurbit[7]uril with dillapiole congeners using docking simulation and density functional theory approaches

Structural Chemistry - Binding affinity and intermolecular interactions are essential characteristics that could be used to comprehend molecular recognition between molecules in supramolecular...     

Aqueous fraction of Nephelium ramboutan-ake rind induces mitochondrial-mediated apoptosis in HT-29 human colorectal adenocarcinoma cells

The aim of this study was to investigate the cytotoxic and apoptotic effects of Nephelium ramboutan-ake (pulasan) rind in selected human cancer cell lines. The crude ethanol extract and fractions (ethyl acetate and aqueous) of N. ramboutan-ake inhibited the growth of HT-29, HCT-116, MDA-MB-231, Ca Ski cells according to MTT assays. The N. ramboutan-ake aqueous fraction (NRAF) was found to exert the greatest cytotoxic effect against HT-29 in a dose-dependent manner. Evidence of apoptotic cell death was revealed by features such as chromatin condensation, nuclear fragmentation and apoptotic body formation. The result from a TUNEL assay strongly suggested that NRAF brings about DNA fragmentation in HT-29 cells. Phosphatidylserine (PS) externalization on the outer leaflet of plasma membranes was detected with annexin V-FITC/PI binding, confirming the early stage of apoptosis. The mitochondrial permeability transition is an important step in the induction of cellular apoptosis, and the results clearly suggested that NRAF led to collapse of mitochondrial transmembrane potential in HT-29 cells. This attenuation of mitochondrial membrane potential (Δψm) was accompanied by increased production of ROS and depletion of GSH, an increase of Bax protein expression, and induced-activation of caspase-3/7 and caspase-9. These combined results suggest that NRAF induces mitochondrial-mediated apoptosis.     

Spectroscopic studies on the binding of bromocresol purple to different serum albumins and its bilirubin displacing action

The interaction between bromocresol purple (BCP) and bovine serum albumin (BSA)/porcine serum albumin (PSA) was investigated both in the absence and presence of bilirubin (BR) using absorption/absorption difference spectroscopy. A significant red shift in the absorption maxima of BCP accompanied by a decrease in absorbance was indicative of BCP binding to albumin. The titration of BSA and PSA with BCP using absorption difference spectroscopy and analysis of results by Benesi-Hildebrand equation yielded the values of association constant, K as 9.9+/-0.9x10(4)Lmol(-1) and 4.1+/-0.3x10(4)Lmol(-1) for BSA and PSA, respectively. The differential extinction coefficient (Deltaepsilon) of 34,484M(-1)cm(-1) at 615nm and 41,870M(-1)cm(-1) at 619nm were estimated for BSA and PSA, respectively. Decrease in (DeltaAbs.)(615nm) of BCP-BSA complex with the increase in ionic strength suggested the role of hydrophobic interactions in the binding phenomenon. A significant blue shift in the absorption maxima and change in (DeltaAbs)(lambdamax) values of BR-albumin complexes upon addition of increasing concentrations of BCP revealed the BR displacing action of BCP on albumin molecule.