Microwave-assisted extraction of shikimic acid from different morphological parts of water hyacinth (Eichhornia crassipes)

Water hyacinth is a proliferative aquatic weed which destructs biodiversity. Though water hyacinth is a notorious weed, it is a useful resource if used judiciously. One of the important compounds in water hyacinth is shikimic acid, a precursor to produce antiviral drug oseltamivir phosphate. A greener extraction of shikimic acid, phenolic compounds and estimation of antioxidant activity of extract were performed using microwave-assisted extraction from the different morphological parts of water hyacinth. Impact of parameters such as extraction time, solvent volume, temperature and power has been studied. Among various parts of the plant, stem contained higher shikimic acid (2.70%, w/w), leaves had higher total phenolic content (12.15 mg GAE/ g biomass) and extract from stem exhibited the maximum antioxidant activity (75.13%). Further, the optimization of process parameters using central composite design was employed to maximize the yield of shikimic acid (2.61%, w/w) which was achieved at 1.08 min, 45 °C, and 30 mL. Although Ultrasound-assisted extraction has provided a higher yield (3.2%, w/w) of shikimic acid compared to microwave-assisted extraction, the extraction time was reduced by 96% in case of microwave-assisted extraction, thereby reducing energy consumption, utility requirement and carbon emission.