Optimization of extraction conditions for phenolic compounds from neem (Azadirachta indica) leaves

The objective of this study was to optimise the extraction conditions for phenolic compounds from neem (Azadirachta indica) leaves using response surface methodology (RSM). A central composite rotatable design (CCRD) was applied to determine the effects of acetone concentration (%), extraction time (mins), and extraction temperature (oC) on total phenolic content (TPC) from neem (Azadirachta indica) leaves. The independent variables were coded at five levels and their actual values were selected based on the results of single factor experiments. Results showed that acetone concentration and extraction time were the most significant (p<0.001) factor affecting the TPC. The optimum extraction conditions were found to be acetone concentration of 48.49%, extraction time of 59.25 mins, and extraction temperature of 40.88oC. Under the optimised conditions, the experimental value for TPC was 4661.17 mg GAE/100 g DW, which reasonably close to the predicted value (4649.16 mg GAE/100 g DW).