Optimum parameter selection and modeling of batch extraction of betulinic acid from leaves of Vitex Negundo Linn

Abstract

Extraction of betulinic acid from leaves of Vitex Negundo Linn was carried out in a series of solvents (methanol, ethanol, isopropyl alcohol, and water). Methanol was found to be the best solvent. Maximum recoverable amount of betulinic acid was determined by Soxhlet extraction using methanol as solvent. Batch extraction of betulinic acid was carried out separately, to estimate the effect of operating parameters (e. g. particle size speed of agitation, solid loading and temperature) on the recovery of betulinic acid. Concentration of betulinic acid was estimated in the extracted mass by reverse phase, RP-HPLC system with symmetry C-18 column, and UV detector (λ=210nm). Extraction parameters were optimized for betulinic acid. An unsteady state diffusion model (as a flat particle geometry for leaves) was proposed to predict the experimental data. The experimental data fitted well with the model proposed and effective diffusivities of betulinic acid through cellulose matrix of leaves were estimated (1.7 to 51.5 × 10-13 m2/sec) at various temperatures. Diffusion of betulinic acid increases with temperature and thus the energy of activation required for diffusion was evaluated by Arrhenius equation and found to be 125.50 kJ/mol.