http://www.revistadechimie.ro REV.CHIM.(Bucharest)♦68♦No. 8 ♦2017 1776 QSPR Correlation of Physico-chemical Descriptors with the Molecular Surface Area and Rf of Ten Polyphenolic Compounds, Separated from Vegetal Extracts by TLC RENATA MARIA VARUT 1 *, LUCIANA TEODORA ROTARU 2 , MARIUS CIPRIAN VARUT 1 1 University of medicine and pharmacy, Pharmacy Department I, 2-4 Petru Rares, 200349, Craiova, Romania 2 University County Hospital Craiova, Emergency & First Aid Department, University of Medicine and Pharmacy of Craiova, Emergency Department - SMURD, 1 Tabaci Str., 200642, Craiova, Romania Polyphenols are important constituents of plants, being demonstrated that long term consumption of them have potential health benefits as antioxidant. In the experimental part of the study we separated ten polyphenolic compounds by thin layer chromatography (TLC) from hydroalcoholic hypoglycemic plant extracts (Ericaceae family). In the theoretical study part we consider important to characterize the structural properties of the substances using molecular mechanics studies. The selected physico-chemical descriptors were: HOMO and LUMO orbitals frontier, water solubility, partition coefficient, dipole moment, heat of formation, stabilization energy of the molecule and number of proton donor groups. We realized a comparative QSPR regression correlation study of molecular surface area and Rf with the selected desriptors. From studies we observed the relationship between the two parameters Rf and MSA, which correlates very well with common descriptors. Keywords: antioxidants, TLC, QSPR * email: rennata_maria@yahoo.com; Phone(+ 04)0760289916 Polyphenols are secondary metabolites of plants, being involved in defense against ultraviolet radiation or aggression by pathogens. Long term consumption of diets rich in plant polyphenols have positive antioxidant effects on the human body, reducing de development risk of cancers, cardiovascular diseases, diabetes, osteoporosis and neurodegenerative diseases. The most important classes are classified in phenolic acids, flavonoids, stilbenes and lignans. All plant phenolic compounds arise from a common intermediate, phenylalanine, or a close precursor, shikimic acid, having a similar basic skeleton [1]. Researchers are often encouraged to use theoretical data in their studies in order to support their experimental results. Therefore, many publications in different research areas contain substantial quantum chemical calculations. Formulas used for molecular modeling programs allow molecular geometry optimization and calculation of physico-chemical parameters, that requires time and material resources to be experimentally determined. The information thus obtained are now used in various industries, including the pharmaceutical industry to improve the therapeutic activity of the drugs, or to contribute to the design and synthesis of new compounds with improved pharmaceutical properties [2,3]. In the present study were calculated different descriptors that can contribute to thin layer chromato- graphic separation of ten polyphenolic compounds, using molecular mechanics studies. We also performed simple and multiple regressional correlations of molecular surface area (MSA) and Rf with physico-chemical and structural properties of the analyzed compounds. Experimental part Thin Layer Chromatography (TLC) analysis The polyphenolic compounds were identified using aluminum backed silica gel GF 254 Merck TLC plates (20× 20cm, activated for 60 min. at 105°C) as the stationary phase and ethyl acetate-formic acid -water (80:8:12, v/v/ v) as mobile phase [4]. Analyzed samples were 20% ethanol solutions. To obtain the hydrolyzed solutions, 3 mL of each extract were refluxed with 3 mL of 10% HCl solution for 30 min in an electric bath. After cooling they were extracted twice with 7 mL of diethyl ether. Apolar layers were combined, filtered through anhydrous sodium sulphate and brought to the residue which was solubilized in 3 mL of absolute methanol. 0.1 mg/mL methanol solutions of rutin, hyperoside, isoquercitrin, kaempferol, luteolin, chlorogenic acid (Roth, Germany), quercetol, ferulic acid (Sigma-Aldrich, Germany) and caffeic acid (Merck, Germany) were used as reference solutions. 10 μl of the test samples/reference solutions were applied to the starting line, the tapes having 1 cm width with 1.5 cm between them. The plates were developed over a path of 8 cm. Revelation was done by sputtering 10% ethanol solution of diphenylboriloxyethylendiamine (DFBOA, Sigma-Aldrich, Germany). The plates were examined in UV light ( λ 365 nm) and photographed before and after the revelation, using an Epson Photo PC 3000 Z Mod G 790A and Camag Reprostar 3 System [5]. Descriptors tested for having an important role in migration differences of the selected compounds on chromatographic plate are: HOMO and LUMO orbitals frontier, water solubility, partition coefficient, dipole moment, heat of formation, stabilization energy of the molecule and number of proton donor groups. The water solubility, partition coefficient and the number of hydrogen donor groups were taken from literature [6], the stabilization energy of the molecules was calculated using the program HyperChem 8, and the other descriptors value was obtained using software package MOPAC 2016. For the QSPR study we browse the following steps: - molecular modeling of chemical structures for the ten substances using HyperChem program 8 [7] (semi- empirical optimization PM 3/ SCF) [8]. - quantum molecular calculations of the molecular geometries using MOPAC 2016. The output data contains