Abstract: In this study, the total phenolic content (TPC) and total flavonoid content (TFC) and antioxidant activities of methanol extracts from whole plants and different parts of Heraclenm dissectum were compared. In order to study the difference in antioxidant activity in vitro, total antioxidant capacity was estimated by ferric reducing antioxidant power, superoxide anion, hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2’-azino-bis (3-ehtylbenzothiazoline-6- sulfonic acid) (ABTS) radical scavenging methods. The results showed that TPC in tender leaves was 30.51 mg/g, which was 1.25 and 1.78 times higher than whole plants and tender stems, respectively. TFC in tender leaves was 28.92 mg/g, which was 1.34 and 4.00 folds increased relative to whole plants and tender stems. The ferric reducing antioxidant power and superoxide anion and hydroxyl radical scavenging capacity of different parts of H. dissectum were in the decreasing order: tender leaves > whole plants > tender stems > control group (VC). The ABTS radical scavenging capacity was ranked in a descending order as follows: tender leaves > whole plants > control group (Trolox) > tender stems. The DPPH radical scavenging capacity followed the decreasing order: tender leaves > tender stems > control group (VC) > whole plants. In summary, the extracts of H. dissectum had strong scavenging capacity against superoxide anion and hydroxyl, followed by DPPH and ABTS radicals, but weak ferric reducing ability.

Key words: Heraclenm dissectum, polyphenols, antioxidant activity