Determination of antioxidant capacity of Heracleum platytaenium boiss. extracts

Plants, products obtained from plants, and purified substances have been subject to the many studies. Antioxidants, which are secondary metabolites that plants produce primarily to protect themselves, provide benefits to humanity in many ways when consumed with food or in their purified form. For these reasons, the antioxidant capacity of the water and ethyl alcohol extracts of the leaf and flower parts of the Heracleum platytaenium Boiss. plant which belongs to the Apiaceae family were investigated. In order to evaluate its antioxidant activity; 1,1-Diphenyl 2-picryl hydrazil (DPPH) free radical scavenging activity, 2,2-Azino-bis (3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, Cu2+-Cu+ reducing capacity (CUPRAC) method), Fe3+-Fe2+ reducing capacity, total phenolic compound and total flavonoid content determinations were carried out, and the results were compared with BHA, BHT, α-Tocopherol, and Trolox as reference antioxidants. In this study, only CUPRAC methods gave similar results with Trolox standard. In the Fe3+-Fe2+ reducing capacity method, low radical scavenging activity was observed in all of the extracts compared to the standards. In DPPH free radicals scavenging activity, only leaf-water (63 μg mL-1) extract behaved like BHT (63 μg mL-1), other extracts were found to be lower capacity than standards as followed; leaf-alcohol (86.63 μg mL-1), flower-alcohol (99.00 μg mL-1), flower-water (115.5 μg mL-1). IC50 values of ABTS radical scavenging capacity were determined as follows; flower-water (3.73 μg mL-1) > leaf-water (3.69 μg mL-1) > α-Tocopherol (3.32 μg mL-1) > flower-alcohol (3.12 μg mL-1) > Trolox (2.90 μg mL-1) > BHA (2.83 μg mL-1) > leaf-alcohol (2.72 μg mL-1) > BHT (2.60 μg mL-1). Because high IC50 value means low antioxidant activity, leaf alcohol extract showed better activity than BHA, Trolox, and α-Tocopherol standards in this method.