Original Article PREDICTION OF LOG P AND SPECTRUM OF QUERCETINE, GLUCOSAMINE, AND ANDROGRAPHOLIDE AND ITS CORRELATION WITH LABORATORY ANALYSIS SANDRA MEGANTARA * , MUTAKIN, JUTTI LEVITA Department of Pharmaceutical Analysis and Medicinal Chemistry, Faculty of Pharmacy, Universitas Padjadjaran Email: smegantara@gmail.com Received: 19 Sep 2015 Revised and Accepted: 09 Sep 2016 ABSTRACT Objective: This study was aimed to confirm the result of computational prediction of log P and spectrum (ultraviolet-visible, 1 H-NMR, 13 Methods: Quercetine, glucosamine and andrographolide, were downloaded from ChemSpider and were geometry optimised. Log P and spectrum were calculated and predicted and the data obtained were compared with laboratory results. The correlation was calculated by employing mean absolute deviation (MAD), mean square error (MSE), mean forecast error (MFE), and mean absolute percentage error (MAPE) parameters. C-NMR) of quercetin, glucosamine and andrographolide with laboratory analysis. Results: The smallest energy value of geometry optimisation was provided by ab initio method. Log P prediction showed good accuracy, with r-value 0.995 and p-value 0.05 respectively. The error parameters were: MAD 0.19; MSE 0.06; MFE 0.16, and MAPE 8.62%, respectively. Prediction of λ maximum by ab initio, semiempirical, and molecular mechanics were respectively: MAD 2.67, 6.67, and 28.67; MSE 8.67, 45.33, and 830; MFE 2.67, 6.67, and 28.67; and MAPE 1.10%, 2.79%, and 11.99%; r-value 0.997, 0.997, and 0.979; and p-value 0.044, 0.043, and 0.129. 1 H-NMR and 13 Conclusion: There is a positive correlation between computational ab initio calculation method with experimental results in predicting log P and spectrum of quercetine, glucosamine, and andrographolide. C-NMR spectra prediction were: MAD 0.73 and 1.58; MSE 1.15 and 7.41; MFE 0.27 and 0.69; MAPE 18.35% and 2.68%; r-value 0.942 and 0.986; and p-value 0.001 and 0.001. Keywords: Ab initio, Lipophilicity, Molecular mechanics, Semiempirical, Ultraviolet-visible, 1 H-NMR, 13 © 2016 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license ( C-NMR http://creativecommons. org/licenses/by/4. 0/) DOI: http://dx.doi.org/10.22159/ijpps.2016v8i11.9101 INTRODUCTION The rapid development of computational techniques finds its way to be very helpful for related sciences, e. g. for chemistry to predict physicochemical properties of compounds. According to quantum chemistry, a molecular system is described by a wavefunction which can be found by solving the Schrődinger equation: Ĥ Ψ = Ε Ψ In the end, this equation will describe the positions of the nuclei and electrons in the system. Quantum chemistry should be applied for ‘small system’, which can be treated at a very high level, when electronic properties are sought (electric moments, polarizabilities, shielding constants in NMR, etc) [1]. Energy is one of the most important parameters in science. All computational chemistry techniques define energy such that the system with the lowest energy is the most stable. In formulating a mathematical representation of molecules, it is necessary to define a reference system that is defined as having zero energy. This zero of energy for ab initio or density functional theory (DFT) corresponds to having all nuclei and electrons at an infinite distance from one another. Most empirical methods use a valence energy that corresponds to having the valence electrons removed and the resulting ions at an infinite distance. Most molecular mechanics methods use stainless molecule as zero energy [2]. In this work, we confirmed the accuracy of computational technique prediction on physicochemical properties (log P) and spectrum (ultraviolet-visible, 1 H-NMR, 13 C-NMR) of quercetin (fig. 1a), glucosamine (fig. 1b), and andrographolide (fig. 1c) by comparing it to laboratory analysis. Therefore, computational calculations could be used to simplify and shorten the long process of analytical works in the laboratory. These three compounds were selected to represent molecule with aromatic and carbonyl chromophores which have π  π* and n  π* electronic transitions (quercetine), a molecule which lacks of the chromophore (glucosamine), and molecule without aromatic chromophore (andrographolide). These three compounds have been proven to show anti-inflammatory activity in animals [3-8]. Fig. 1: Chemical structures of quercetine (a), glucosamine (b), PITC-glucosamine (c), and andrographolide (c) International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 8, Issue 11, 2016