Digest Journal of Nanomaterials and Biostructures Vol. 6, No 4, October-December 2011, p. 1605-1617 HEPATOPROTECTIVE FLAVONOID BIOCONJUGATE / β-CYCLODEXTRIN NANOPARTICLES: DSC – MOLECULAR MODELING CORRELATION I. A. PÎNZARU a1 , D. I. HĂDĂRUGĂ a1* * Corresponding author: daniel.hadaruga@chim.upt.ro , N. G. HĂDĂRUGĂ b1 ,L. CORPAŞ b , I. GROZESCU c , F. PETER a a “Politehnica” University of Timişoara, Faculty of Industrial Chemistry and Environmental Engineering, Applied Chemistry and Organic-Natural Compounds Engineering Department, 300006-Timişoara, Victory Sq. 2, Romania, b Banat’s University of Agricultural Sciences and Veterinary Medicine, Faculty of Food Processing Technology, Food Quality Department, 300645-Timişoara, C. Aradului 119, Romania c National Institute for Research & Development in Electrochemistry and Condensed Matter, 300224-Timisoara, Plautius Andronescu 1, Romania 1 These authors contributed equally to the article (they are principal authors) The paper presents the biosynthesis of some rutin- and silybin-fatty acid bioconjugates with potential enhanced hepatoprotective activity and complexation of these new compounds with β-cyclodextrin by using the crystallization from ethanol-water solution method. Bioconjugate / β-cyclodextrin nanoparticles were analyzed by differential scanning calorimetry (DSC) and the energy of dissociation of water molecules was evaluated, as well as other calorimetric parameters. On the other hand, molecular modeling and docking experiments on the molecular encapsulation of these bioconjugates in β-cyclodextrin were performed by using molecular mechanics MM+ program from the HyperChem 5.1 package. The interaction energy evaluated from docking experiments correlates with some DSC parameters (i.e. water dissociation energy, value or inflection temperatures of the water dissociation peaks - the dissociation peak are shifted after encapsulation). Statistically significant correlation was obtained also between water dissociation energy and logP (logarithm of the octanol/water partition coefficient of bioconjugates) for rutin and silybin derivative classes. All samples were better classified by using principal component analysis (PCA) with DSC and theoretical docking parameters. (Received September 8, 2011; accepted October 14, 2011) Keywords: flavonoid-fatty acid bioconjugates, β-cyclodextrin, nanoparticles, hepatoprotective agents, DSC, molecular modeling, docking experiments 1. Introduction Flavonoids and derivatives are widely distributed in raw products as well as in many foods and have an important effect in maintaining health and preventing diseases (principally, they have anticancer, antioxidant, antimicrobial, and anti-inflammatory biological activities) [1-4]. The biochemical effects of flavonoids can be divided into four categories [5]: (1) binding affinity to biological polymers; (2) binding of heavy metal ions; (3) catalysis of electron transport; and (4) ability to scavenge free radicals.