Total phenolic content and antioxidant activity of kesum (Polygonum minus), ginger (Zingiber officinale) and turmeric (Curcuma longa) extract

Herb and spices namely kesum, ginger and turmeric were extracted by using juice extractor without the additional of solvent. These herb and spices were determined for moisture content and the extracts were analyzed for total phenolic content (TPC) and antioxidant activity (DPPH radical scavenging assay and FRAP ferric-reducing antioxidant power assay). The yield of kesum, ginger and turmeric extraction was 23.6%, 58.6% and 66.4%, respectively. The results showed that, there was significant difference (P < 0.05) in total phenolic content and antioxidant activity for kesum, ginger and turmeric extracts. Kesum extract had the highest total phenolic content followed by ginger and turmeric extract. A significant and positive high Pearson’s correlations between TPC and DPPH assay (r = 0.86) and between TPC and FRAP assay (r = 0.91) respectively was observed for all plants extracts. This indicated that phenolic compounds were the main contributor of antioxidant activity in plants. However, there was no synergistic effect observed for all plants extract mixture.