Extraction of phenolics from Azadirachta indica flowers

Azadirachta indica is a well-known tree for the medicinal use of its leaves, barks and flowers. It has been identified as a rich source of phenolics which attribute to its medicinal properties. However, these phenolics should be extracted appropriately to effectively utilize them in various applications. This study focused on maximizing the extraction yield of total phenolics and total anthocyanins along with maximum 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity from edible flowers of A. indica as a function of solid:liquid ratio, ethanol concentration, extraction temperature and time. The data was subjected to response surface methodology and the corresponding second order polynomial models were generated. The results showed that the polynomial models for all responses were significant, did not show lack of fit and presented determination of coefficients above 95%. This indicates the suitability of the models for prediction purposes. Using desirability function, the optimum extraction process parameters to obtain maximum values of all responses were found to be solid:liquid ratio 1:32.2, ethanol concentration 42.72%, extraction temperature 55 °C and time 39.25 minutes. Under these optimal conditions, the experimental values for total phenolic content was 85.44±2.41 mg gallic acid equivalents per gram of dry weight, total anthocyanin content was 44.32±2.75 µg cyanidin-3-glucoside per gram of dry weight and DPPH radical scavenging activity was 31.43±1.67%. These values were in close agreement with the predicted values and did not show any significant difference (p<0.05). The identified optimized conditions could be used to extract phenolics from A. indica flowers in a cost effective and efficient manner.