Identification, Characterization and Evaluation of Crystal Forms of Quinine Sulphate

Crystal engineering concept has been utilized to modify the physico-chemical parameters of a naturally occurring alkaloid, quinine sulphate, by exploring its H-bond interactions to generate different forms. Quinine sulphate is found to exist in four different crystal forms. The Forms I and II depict endo/exo events suggesting conversion of metastable low melting forms to higher melting and stable form indicated by sharp melting endotherms. The low melting form IL is found to be monotropically related to high melting Form IH while low melting Form IIL is enantiotropically related to high melting Form IIH. The Form III and IV showed broad endotherms accompanied by mass loss in TGA prior to melting indicating the existence of solvatomorphism. The solvent molecules are tightly bound in the crystal lattice of the drug molecules which is shown by high values of the binding energies of the solvents in these two forms. The enthalpy of solution was found to be endothermic for all the forms which followed the order: Form O > Form II > Form III > Form I > Form IV and is further related to the lattice energy suggesting Form II to be least crystalline. The solubility for Form II was found to be highest with maximum release rate in dissolution studies. The effectiveness of new polymorphic forms was confirmed by performing in vivo antimalarial activity against P. berghei infection. The studies have shown an increase in antimalarial activity of Form IV concluding a successful development of new polymorphic form.

Binding studies of trans-resveratrol with superoxide dismutase (SOD1): Docking assessment and Thermoanalysis

The binding pursuits of trans-resveratrol(t-RSV),an amazing health supplement are investigated with an antioxidant enzyme,superoxide dismutase(SOD1).The aim of the study is to dock t-RSV on the adrenaline binding site on SOD1 in order to explore its potential to act as a safety net against amyotrophic lateral sclerosis(ALS),a fatal neurodegenerative disorder that affects motor neurons.In silico GLIDE docking methodology and in vitro microcalorimetry technique is utilized for the investigation of binding parameters of t-RSV with SOD1.The study provides useful and distinct information about the amino acids involved in the interactions at molecular level along with the nature of forces involved in binding of t-RSV with SOD1.The docking analysis using the scoring functions of Schrodinger’s Glide package depicts that GLU100,PRO28,LYS23,TRP32 residues of the peptide backbone on SOD1 interact with phenolic groups of t-RSV.The information on thermodynamic parameters,i.e.binding constant(Kb),free energy(△G)and enthalpy(△H)generated through calorimetric titrations suggests that the reaction between t-RSV and SOD1 is spontaneous and exothermic.Both the studies are found to be in close agreement with each other based as far as the magnitude of binding constant(Kb=9.9×10^4)is concerned.