Response Surface Methodology for Optimization of Ultrasound Assisted Extraction of Swertiamarin from Enicostema littorale Blume

Secoiridoid glycosides comprise a group of important phyto-components from members of Gentianaceae. They possess significant antipyretic, anti-inflammatory, antidiabetic and hypolipedimic activities. This study is designed for the development of an effective method for extraction of a bioactive secoiridoid glycoside namely swertiamarin, from the whole plant of Enicostema littorale Blume. The conditions for its ultrasound assisted extraction (UAE) were determined using response surface methodology (RSM). RSM consisted of a Box-Behnken design (BBD). The optimal conditions were found to be: extraction with methanol-water (80:20 v/v) with a solid-to-solvent ratio of 1:22.5 w/v at a temperature of 47.8ºC for 81 min. The predicted yield of swertiamarin was 138.10 mg/g. Confirmation experiments under slightly adjusted conditions proved 98.68% validity for the model. UAE was found to be 2.88 fold more efficient than conventional method in extracting swertiamarin from E. littorale. HPTLC densitometric estimation of swertiamarin was used to determine the extraction efficiency of the developed method.