Isolation and Purification of Phenolic Acids from Sugarcane (Saccharum officinarum L.) Rinds by pH-Zone-Refining Counter-Current Chromatography and Their Antioxidant Activity Evaluation

Abstract

The phenolic acids exhibit significant antioxidant, antiinflammatory, antimutation, and tyrosinase inhibitory effects. A high efficient and specific method for separation of phenolic acids from the sugarcane rinds based on pH-zone-refining counter-current chromatography technique was established. The separation was performed with a solvent system of methyl tert-butyl ether/acetonitrile/water at a volume ratio of 4:1:5, where 5 mM trifluoroacetic acid was added to the upper phase as a retainer and 3 mM NH4OH was added to the lower phase as an eluter. As a result, three phenolic acids including 4.8 mg of caffeic acid, 12.9 mg of ferulic acid, and 65.2 mg of p-coumaric acid were successfully purified in one run from 1.00 g crude extract with the purities of 93.4, 94.6, and 98.8%, respectively. 2,2-Diphenyl-1-picrylhydrazyl radical and total antioxidant capacity assay were used to evaluate antioxidant activities. The separated individual phenolic acid had higher antioxidant activity than their mixture. Caffeic acid showed the greatest antioxidant activity, followed by ferulic acid and p-coumaric acid.