Evaluation of antioxidant capacity and phenolic content in ethanolic extracts of leaves and flowers of some Asteraceae species.

Medicinal plants contain large amount of natural antioxidant compounds, which enable them to neutralize free radicals. Asteraceae family is an important source of phytochemical compounds.

The objective of this research is to find out the antioxidant potential and radical scavenging from the leaf and flowers of five species (Artemisia absinthium L., Arctium lappa L., Silybum marianum L., Centaurea cyanus L. and Echinops ritro L.) of the Asteraceae family. This research includes recent patents (US20110179530A1) in plant biotechnology.

The plant extract obtained by absolute extraction method was investigated for Total Phenolic Content (TPC), total Flavonoid Content (TFC), Total Antioxidant Capacity (TAC), and Chain Breaking Activity (CBA). THIOBARBIOTURIC ACID (TBA), 2,2-diphenyl-1-picrylhydrazyl (DPPH), IC50, nitric oxide (NO), hydrogen peroxide (H2O2), superoxide (O-) radical scavenging and Ferric Reducing Antioxidant Power (FRAP) were also measured.

The results showed the highest values for the TPC, TBA, FRAP and DPPH radical scavenging related to A. absinthium. While, A. lappa extract showed the maximum content for TFC, TAC, CBA and O2 radical scavenging. In addition, our results indicated that E. ritro is a good source of NO2 and H2O2 radical scavenging activity (P<0.05). Our findings suggest that the flower is more successful than the leaf.

Artemisia absinthium, A. lappa and E. ritro can be used as an easily accessible source of natural antioxidants and as a possible food supplement or in pharmaceutical industry.