No 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 Labisia pumila (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% v/v). 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 L. pumila, and thus the usage of this solvent system should be considered for further optimization studies.

Labisia pumila, locally referred to as kacip fatimah, is one of the important herbs utilised in traditional medicine. Nonetheless, to the best of the researchers’ knowledge, the optimum application of Supercritical Fluid Extraction (SFE) has not been reported for Labisia pumila (L. pumila) extraction and the understanding of this study may offer preliminary insight into the preparation of standardised extracts of L. pumila enriched with natural antioxidants prior to commercialisation at the industrial level. Response surface methodology (RSM) was used to optimise supercritical carbon dioxide extraction (SC-CO2) of functional phenolic compounds from L. pumila leaves. The factors studied were pressure, temperature, percentage of ethanol in co-solvent, and co-solvent concentration. The results demonstrated that the percentage of ethanol in co-solvent, temperature, and co-solvent concentration in the supercritical mixture had significant effects on the extraction of L. pumila. Based on the RSM results, the optimal SC-CO2 extraction conditions were at 283 bar, 32 °C, 78% (v/v) of ethanol-water in co-solvent, and 16% (v/v) of co-solvent concentration, which allowed the recovery of 14.051 ± 0.76% (g/g) of extraction yield, 1.2650 ± 0.10% (g/g) of gallic acid, 0.441 ± 0.29% (g/g) of methyl gallate, and 1.382 ± 0.37% (g/g) of caffeic acid. The experimental values were in agreement with the one predicted by RSM models, confirming the suitability of the model for optimisation of the extraction conditions.