Mapping study of an ultrasonic bath for the extraction of andrographolide from Andrographis paniculata using ultrasound

• Reports ultrasound assisted extraction of andrographolide from Andrographis paniculata L.
• Mapping of ultrasound bath for higher extraction yield.
• UAE yielded 27.97 mg/g only in 10 min compared to 42.46 mg/g by soxhlet in 4 h.

In the present work, extraction of andrographolide from Andrographis paniculata L. was carried out by mapping an ultrasound bath to identify the active and passive zones within it. This helps in accurately placing the extraction vessel in the bath for obtaining a maximum yield. Various parameters of extraction like choice of solvent, time of ultrasound exposure, solute to solvent ratio, temperature, position and depth of extraction vessel, the frequency used, and input power were investigated. Aluminum foil weight loss test was also performed at different positions and its results were compared with the results obtained for extraction at same positions. Results revealed a similar trend in variation for both the investigations. Highest yield of andrographolide obtained was 27.97 mg/g, at position 11, at a depth of 2.54 cm, in only 10 min of ultrasound irradiation, using 1:40 solute to solvent ratio, at a frequency of 22 kHz, utilizing 134 W of power with 50% ethanol as the solvent. Calorimetric studies were also carried out within the reaction vessel at these positions, to determine the actual power being utilized for extraction. Power dissipated at these locations differed from each other and maximum power was found to be dissipated at position 11. This study implies the significance of the above mentioned parameters in mapping of an ultrasound bath which can further be used for extraction of biomolecules from natural products.