Kinetic evaluation of Azadirichtin and related phytoconstituents extraction from Azadirachta indica (neem) and Melia azedarach (chinaberry) seeds using ultrasound assisted extraction and maceration

The comparative extraction of total phenolic compounds from A. indica and M. azedarach seed powder using two different methodologies is evaluated. The solvent screening was done using soxhlet extraction for six different solvents and methanol had the maximum extraction capacity for both seed powder. Extraction of total phenolic compounds from A. indica and M. azedarach seed powder was done using maceration and ultrasound. The kinetics and extraction mechanism was evaluated using popular three empirical and five semi-empirical models along with scanning electron micrograph analysis. The rate constants showed an enhancement in extraction kinetics of about 4.5 fold for M. azedarach and 7.8 fold for A. indica seeds using ultrasound. Based on model evaluation, extraction using maceration for both seeds follows inter-particle diffusion as the rate-limiting step with non-swelling behaviour. Whereas, in the case of ultrasound, the dependence of rate is on the diffusion of solute within the solid and the solid surface to the solvent. In addition, HPLC and GC-MS analysis suggested differences in the composition of extracts and some important phytochemicals were extracted in larger quantities using ultrasound as compared to maceration.