Co-Solvent Selection for Supercritical Fluid Extraction (SFE) of Phenolic Compounds from Labisia pumila

Abstract

A preliminary study was conducted to study the effects of different types and concentrations of co-solvents based on yield, composition and antioxidants capacity of extract prior to optimization studies of supercritical fluid extraction (SFE) of <i>Labisia pumila</i> (locally referred to as 'kacip fatimah'). The following co-solvents were studied prior to the optimization of supercritical carbon dioxide (SC-CO₂) technique: ethanol, water, methanol, as well as aqueous solutions of ethanol-water and methanol-water (50% and 70% <i>v</i>/<i>v</i>). By using the selected co-solvents, identification of phenolic acids (gallic acid, methyl gallate and caffeic acid) was determined by using High-Performance Liquid Chromatography (HPLC). Then, the antioxidant capacity was evaluated by using three different assays: total phenolic content (TPC), ferric reducing/antioxidant power (FRAP) and free radical-scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). SC-CO₂ with 70% ethanol-water co-solvent was superior in terms of a higher combination of phenolic compounds extracted and antioxidants capacity. Overall, SC-CO₂ with co-solvent 70% ethanol-water technique was efficient in extracting phenolic compounds from <i>L. pumila</i>, and thus the usage of this solvent system should be considered for further optimization studies.