Optimization of Microwave-assisted Extraction Technique for Flavonoids and Phenolics from the Leaves of Oroxylum indicum (L.) Kurtz Using Taguchi L9 Orthogonal Design

Background An experimental design to obtain bioactive ingredients from Oroxylum indicum (L.) Kurtz was performed applying microwave-assisted extraction (MAE). Recently, tremendous research interest and benefits have been observed for extracting active constituents from plant materials using the microwave. Objectives This work aimed to develop an optimized, green, efficient, alternative procedure for extracting flavonoid and phenolic (total flavonoid content TFC and total phenolic content TPC) from leaves of Oroxylum indicum (L.) Kurtz. Materials and Methods A total of 1 g of the powdered sample was extracted using classical Soxhlet apparatus for 48 hr to ensure exhaustive extraction; simultaneously, maceration and ultrasound-assisted extraction were also carried out using 1 g of the plant sample for 12 hr and 60 min at 25˚C, respectively. The optimization of MAE was done using Taguchi L9 orthogonal design. The optimum operating conditions were microwave power (160 W), soaking time (4 min), irradiation time (4 min), and temperature (57˚C). Results The microwave method has shown 70% higher yield than other conventional techniques in a shorter time, along with increased TFC and TPC. Conclusion The TPC, TFC, and total antioxidant capacity (TAC) values are higher in the extract obtained by MAE extracts in comparison to other techniques. The extraction technique will be an ideal tool to safeguard the thermolabile plant constituents that will be more environmentally friendly.