<![CDATA[This study evaluated the biological activity (antioxidant assay) of Polygonum minus extracted using Supercritical Fluid Extraction (SFE) added with different types of co-solvents. The seven co-solvents employed were water, methanol, ethanol, 50% methanol, 50% ethanol, 70% methanol and 70% ethanol for selection of the best co-solvent prior to optimization of SFE. 70% methanol produced the highest total yield of extract (33.1%) compared to other co-solvents. The antioxidant capacity was then evaluated using four different assays: the total phenolic content (TP), the total flavonoid content (TF), the ferric reducing/antioxidant power (FRAP) and the free radical-scavenging capacity of 2,2-diphenyl-1-picrylhydrazyl (DPPH). The highest TP and TF were from 70% methanol extract (11.2 ± 0.15 mg GAE/g sample (mg GAE/g) and 11.9 ± 0.03 mg CAE/g sample (mg CEQ/g) respectively). 70% metanol extract also showed the highest FRAP value (346.7 ± 0.66 µmol Fe (II)/g sample) and the highest percentage of DPPH radical inhibition was also shown by 70% methanol extract (88.7 ± 0.40%). There was a positive correlation between the antioxidant capacity (FRAP and DPPH) with those of TP and TF contents. Therefore, the best co-solvent chosen for further optimization of SFE is 70% methanol.]]>
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