Optimal Extraction of Gallic Acid from Suaeda glauca Bge. Leaves and Enhanced Efficiency by Ionic Liquids

摘要

The ultrasound-assisted extraction (UAE) was initially applied to extract gallic acid from Suaeda glauca Bge. using 70% ethanol as extraction solvent. Temperature, liquid-solid ratio, and extraction time were optimized by response surface methodology (RSM), obtaining maximum levels of gallic acid (6.30 mg·g~(-1)) at 51° C, 19.52 mL·g~(-1), and 42.68 min, respectively. The obtained model was statistically significant (p < 0.0001). The verification experiments at the optimum conditions yielded gallic acid for 6.21mg·g~(-1). Subsequently, under optimal conditions, four ionic liquids were used to extract gallic acid from Suaeda glauca Bge. The results indicated that the presence of l-hexyl-3-methylimidazohum chloride allowed increasing the EE of gallic acid up to 8.90 mg·g~(-1). This might be interpreted in terms of the molecular interaction between ionic liquid and gallic acid. The use of ionic liquids involves a stronger gallic acid extraction capacity than conventional organic volatile solvents. A promising alternative process is proposed for the extraction of gallic acid of Suaeda glauca Bge.