Ultrasound-assisted extraction of shikimic acid and determination of total phenolic compounds in water hyacinth: Grey-based Taguchi optimization

Abstract

Shikimic acid (SA) is a precursor for formulating the antiviral drug oseltamivir phosphate (Tamiflu®). Ultrasound-assisted extraction was employed to extract shikimic acid using water as a solvent and to determine total phenolic compounds (TPC) from water hyacinth. Grey-based Taguchi optimization was used to optimize the yield of shikimic acid and TPC by varying four distinct parameters. The best results for the yield of SA, i.e., 3.3 % (20 min time, 20 mL water volume, 60 % amplitude, and 40 % pulse ratio) and 3.2 % (30 min time, 20 mL solvent volume, 40 % amplitude, and 40 % pulse ratio) were observed using single and multi-response optimization, respectively for the stem. The best results for TPC, i.e., 12.24 mg GAE/ g biomass (20 min time, 40 mL solvent volume, 40 % amplitude, and 30 % pulse ratio) and 10.53 mg GAE/ g biomass (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) were obtained using single and multi-response optimization, respectively for leaves. The extraction was also performed for a whole plant (without segregation), and 1.66 % yield of SA (20 min time, 20 mL solvent volume, 50 % amplitude, 40 % pulse ratio) and TPC value of 8.84 mg GAE/ g biomass (40 min time, 30 mL solvent volume, 40 % amplitude, 40 % pulse ratio) were obtained.