Extraction of ursolic acid from Ocimum sanctum leaves: Kinetics and modeling

Ursolic acid (UA) is a triterpene compound which shows significant biological potential. This study deals with the optimization and kinetics of UA extraction from Ocimum sanctum (OS) leaves in a stirred batch extraction. The influence of various extraction parameters on the extraction yield has been studied. The optimum extraction conditions were extraction time 40 min, speed of agitation 1000 rpm, temperature 323 K, solute to solvent ratio of 1:120. This resulted in 11.21 mg of UA/g of dried leaf powder of OS. The extraction kinetics behavior of UA from OS revealed that the extraction of UA followed a first order kinetics. The kinetic expression developed by Spiro and Siddique was used and the model is in good agreement with the experimental results. The diffusion coefficient determined ranged from 2 x 10(-11) to 6.10 x 10(-11) m(2)/s for the all set of experiments. The activation energy for the extraction of UA was found to be E-a = 10.45 kJ/mol. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.